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This document contains information relevant to the following options:

Woolwich

Ferries

Bridges

Tunnels

Gallions Reach

Ferries

Bridges

Tunnels

Belvedere

Ferries

Bridge

Tunnels

GALLIONS REACH MARINE ASPECTS STUDY

(REPORT G) Halcrow

17 May 2013

This document builds previous work to develop and refine the ferry land-based infrastructure design as well as carrying

out an estimation of boarding and alighting times for the various ferry

options. The report also considers and compares the hydrodynamic impacts of

bridges, tunnels and ferries.

The highway engineering elements of the land-based infrastructure design is

reported separately in Report F.

Report ref 472413/62/001 version 004

Gallions Reach River Crossings (Task 102) Marine Aspects

Document: 472413/62/001 Version: 04

Preliminary Design Report

Transport for London

July 2014

Halcrow Group Limited Burderop Park, Swindon, Wiltshire SN4 0QD

tel 01793 812479 fax 01793 812089 halcrow.com

Halcrow Group Limited is a CH2M HILL company

Halcrow Group Limited has prepared this report in accordance with the instructions of client xxx for the client’s sole and specific use.

Any other persons who use any information contained herein do so at their own risk.

© Halcrow Group Limited 2014

Gallions Reach River Crossings (Task 102) Marine Aspects



July 2014

Gallions Reach River Crossings – (Task 102) Marine Aspects


Document history




This document has been issued and amended as follows:

Version Date Description Created by Verified by Approved by

01 24/04/13 First Issue for TfL comments TA/MG TA MG

02 17/05/13 Final Issue TA/MG NK MG

03 15/07/13 Minor amendment following

TfL comments

MG MG MG

04 01/07/14 Minor clarifications to Section

2.1 and executive summary only

MG MG MG



Contents

1 Executive Summary 6

2 Introduction 9

2.1 Background 9

2.2 Scope of the Preliminary Design 10

2.3 Definitions 10

3 Information Sources 11

3.1 Provided by TfL 11

3.2 Other Sources 12

3.3 Added Value 13

4 Geotechnical Considerations 14

4.1 Review of Available Information 14

4.2 General Overview of Conditions on the River Banks (Chain Ferry Option) 14

4.3 General Overview of Conditions in the River 17

4.4 Advice and Comment on the Feasibility of Piling 18

4.5 Advice and Comment on the Feasibility of Solid Slipway Structures 18

4.6 Advice and Comment on the Feasibility of Cofferdams 19

5 Preliminary Infrastructure Design for Propeller Driven Ferry 20

5.1 Design Parameters 20

5.2 Standards Used 20

5.3 Design Considerations and Assumptions 21 5.3.1 Vertical Geometry 21

5.3.2 Horizontal Geometry 22

5.3.3 Pontoons 22

5.3.4 Linkspans 25

5.3.5 Approach Structures 26

5.3.6 Berthing Dolphins 26

5.3.7 Pontoon Restraint Dolphins 26

5.3.8 Number of Lanes 27

5.3.9 Existing Flood Defences 28

5.3.10 Ancillary Infrastructure 28

5.3.11 Passive Provision for Third Vessel 29

5.4 Construction Considerations 30 5.4.1 Constructability 30

5.4.2 Closures/Diversions 30



5.4.3 Utilities 30

5.4.4 Programme 31

5.5 Proposed Operational Procedures 31 5.5.1 Maintenance 32

6 Preliminary Infrastructure Design for Chain Ferry 33

6.1 TfL Design Parameters 33

6.2 Standards Used 33

6.3 Design Considerations and Assumptions 33 6.3.1 Vertical Geometry 33

6.3.2 Horizontal Geometry 34

6.3.3 Design of Slipways 34

6.3.4 Chains and Chain Tensioners 35

6.3.5 Number of Lanes 36

6.3.6 Existing Flood Defences 37

6.3.7 Ancillary Infrastructure 37

6.3.8 Passive Provision for Third Vessel 37

6.4 Construction Considerations 38 6.4.1 Constructability 38

6.4.2 Closures/Diversions 39

6.4.3 Utilities 39

6.4.4 Programme 40

6.5 Proposed Operational Procedures 40 6.5.1 Maintenance 41

7 Estimates of Alighting and Boarding Times 43

7.1 Propeller Driven Ferry 43 7.1.1 Two lanes – Assumptions for Alighting Model 43

7.1.2 Two lanes – Results of Alighting Model 43

7.1.3 Two lanes – Assumptions for Boarding Model 44

7.1.4 Two lanes – Results of Boarding Model 45

7.1.5 Four lanes – Assumptions for Alighting Model 46

7.1.6 Four lanes – Results of Alighting Model 47

7.1.7 Four lanes – Assumptions for Boarding Model 47

7.1.8 Four lanes – Results of Boarding Model 47

7.1.9 Six lanes – Assumptions for Alighting Model 48

7.1.10 Six lanes – Results of Alighting Model 48

7.1.11 Six lanes – Assumptions for Boarding Model 48

7.1.12 Six lanes – Results of Boarding Model 49

7.1.13 Summary of Overall Alighting and Boarding Time 50

7.2 Chain ferry 50 7.2.1 Assumptions for Alighting Model 51



7.2.2 Results of Alighting Model 51

7.2.3 Assumptions for Boarding Model 52

7.2.4 Results of Boarding Model 52

7.2.5 Summary of Overall Alighting and Boarding Time 54

7.2.6 Additional Traffic Lanes 54

7.3 Validation of Alighting and Boarding Time Estimates 55

8 Discussion of Alternatives 56

8.1 Re-use of Existing Woolwich Ferry Vessels 56

8.2 Alternative Linkspan Arrangement for Propeller Ferry 57

8.3 Self-Beaching Propeller Ferry 58

9 Hydrodynamic Impact Assessment 60

9.1 Hydrodynamic Features 60 9.1.1 Flow rates 60

9.2 Ferry 60 9.2.1 Effect on Water Level 61

9.2.2 Effects on Tidal Propagation 62

9.2.3 Effects on Flow Distribution 62

9.2.4 Effects on Sediment Transportation 62

9.2.5 Effects on Environment 63

9.2.6 Effects on Navigation 63

9.3 Revised Chain Ferry (Piled Slipway) 63 9.3.1 Effect on water level 64

9.3.2 Effects on flow distribution 64

9.3.3 Effects on sediment transportation 64



9.3.6 Construction phase 65

9.4 Bridge (Concrete Box Girder) 65 9.4.1 Effects on Water Level 65





9.4.6 Construction Phase 66

9.5 Bridge (Steel Arch) 67 9.5.1 Effects on Water Level 67








9.6 Immersed Tunnel 68 9.6.1 Effects on Water Level 68






9.7 Bored Tunnel 69

9.8 Conclusions 69

10 Environmental Issues 71

10.1 Comparison of Ferry Types 71

11 Risk Assessment 74

11.1 Significant Risks 74

11.2 Retired Risks from Previous Study 75

11.3 Construction (Design and Management) Regulations 2007 75

12 Cost Estimates 76

12.1 Assumptions 76

12.2 Risk and Optimism Bias 76

12.3 Summary of Ferry Options 77

13 Conclusions and Recommendations 78

13.1 Summary of Infrastructure Options 78

13.2 Recommendations 79

Appendices

Appendix A List of Figures, Tables and Graphs

Appendix B Glossary of Abbreviations

Appendix C Preliminary Design Drawings

Appendix D Environmental Summary Table

Appendix E Risk Register

Appendix F Designer’s Risk Assessment

Appendix G Cost Estimates

Appendix H Outline Construction Programmes



Doc no: 001 Version: 04 Date: July 2014 472413 Filename: Gallions Reach Crossings Marine Aspects – Preliminary Design Report – Version 04.doc

6

1 Executive Summary There are currently only a handful of crossings of the River Thames in East London.

Transport for London (TfL) is investigating the possibility of a new crossing at

Gallions Reach to provide additional road‐based connectivity in this area. A series of

work packages have been commissioned to develop preliminary designs for

alternative crossing schemes.

Halcrow was commissioned by TfL in March 2013 to undertake work in connection

with the marine aspects of the preliminary design packages, including development

of ferry infrastructure proposals and hydrodynamic impact assessment of all crossing

options.

The design of infrastructure for two ferry options has been considered by Halcrow; a

pontoon and linkspan arrangement for a propeller driven ferry and a slipway

arrangement for a chain ferry. Each option has been developed to a level which

presents workable solutions, given the information currently available, with outline

cost estimates and construction programmes. In some cases, amendments to the

feasibility design have been necessary where new information has been available or

greater consideration of structural forms has been undertaken. A review of available

geotechnical information has resulted in the conclusion that a solid slipway for a

chain ferry is impractical due to the large amount of unsuitable, possible

contaminated, material that would need to be removed to reach adequate conditions

for the foundations. For this reason, the alternative option of a piled slipway has been

progressed instead.

Each infrastructure proposal is accompanied by an explanation of the likely

construction methodology and suggested operational procedures. These factors will

need further development throughout a more detailed design phase but certain

assumptions have been necessary at this stage to determine the most appropriate

preliminary designs. The underlying assumption regarding operation of a new ferry

service at Gallions Reach is that TfL requires a minimal level of staffing.

As part of the examination of operational procedures, Halcrow has developed robust

estimates of boarding and alighting times for each ferry type. These will dictate the

frequency of service and the hourly capacity of the crossing, which can then be

compared to other crossing options. It is noted that a ferry service would not be able

to provide the same capacity as a fixed crossing but a cost benefit analysis by TfL may

yield a positive result for such a substantially less expensive option. In summary, the

time taken to turn around the ferry varies depending upon the number of traffic lanes

provided. The complete boarding and alighting operation can take between 10 and 15

minutes for both options. It is noted, however, that berthing of a propeller driven

ferry requires a higher level of skill and will take longer than berthing of a chain ferry

which grounds on its slipway.

A significant aspect of the infrastructure design for a propeller driven ferry is the use

of pontoons for the ferry to berth to. TfL raised the possibility of using

decommissioned vessels from the Woolwich Ferry service as pontoons. Whilst this

would be commendable from a sustainability perspective, the idea has been

discounted due to the logistical problem of maintaining a service at Woolwich until

the new service opens and the likely cost of converting the old ferry vessels into

pontoons. It is possible to have a propeller driven ferry terminal without pontoons.




7

Such a system would employ a mechanically operated linkspan which follows the

level of the tide. Unlike the current Woolwich operation, linkspans would not have to

be lowered and raised at each berthing and advancements in technology would result

in much lower energy consumption. Development of this solution is outside the

scope of this task and TfL is not currently in a position to investigate it further. The

main principles are detailed in this report for completeness should TfL wish to give it

further consideration in future. An alternative system using a self‐beaching propeller

driven ferry is also discussed at the request of TfL. This option has several similarities

to a chain ferry in terms of slipway infrastructure, but it is discounted as a viable

alternative on the grounds that it is less advantageous. The particular regime of

currents and tides in the River Thames would require the installation of berthing

dolphins and a higher level of crew skill.

The marine aspects task for TfL also includes hydrodynamic impact assessment for

all crossing options. Halcrow has worked with other consultant teams to determine

the effect of various bridge and tunnel crossing options as well as the two types of

ferry terminal described above. A number of factors have been considered in this

assessment including the effects on currents, sedimentation and the river

environment. With the exception of a bored tunnel, which is not anticipated to have

any significant effect upon the river above it, the infrastructure for a propeller driven

ferry is assessed as having the least hydrodynamic impact. This is primarily due to

the smaller cross sectional blockage caused by piles as opposed to large bridge piers

or a dredged channel for an immersed tube tunnel.

Environmental issues associated with a ferry crossing of the River Thames at Gallions

Reach have been considered using industry standard general topic headings. The

most significant environmental impacts arise from energy use, biodiversity and

visual impact. The overall environmental impact of each type of ferry infrastructure

are similar, though each option has different primarily impacts; a propeller driven

ferry has a greater effect upon energy consumption and visual impact whereas a

chain ferry affects biodiversity and hydrodynamic processes to a greater extent.

Community links and transportation connections are improved by the introduction of

a ferry service, though frequency of service is a key consideration. Although boarding

and alighting times for each ferry option are similar, a chain ferry is expected to

provide a more frequent service, largely due to a faster berthing time.

A risk register has been developed using the “live” risk register produced by

Halcrow for a previous feasibility study. The risk rating for each risk item has been

revisited to reflect the more advanced level of design development. Where

appropriate, certain risks have been retired and others have been added as new

design considerations have been introduced. The most significant risks relate to

planning and procurement, particularly legal processes.

With the exception of poor ground conditions which has resulted in the discounting

of a solid slipway for chain ferries, the highest ranking specific design related risks

are in connection with safety. A chain ferry in particular carries the inherent risk of

regular tidal washing of the slipway which would, without regular cleaning, result in

a slippery surface. Another difficulty with a chain ferry is the segregation of

pedestrians and cyclists from vehicles where the location of the ferry on the slipway

can vary between each crossing. The most significant risk for a propeller driven ferry

is the hazard to other river users that the terminals and ferries present.




8

Outline cost estimates are included in this report for comparison of the ferry

infrastructure options with each other and with fixed crossings being developed by

other consultants. The propeller driven ferry infrastructure varies in cost between

approximately £24million and £38million depending upon the number of traffic lanes

used, which determines the number and size of structural components. A chain ferry

slipway is sized to accommodate the width of two ferries and any change in the

number of traffic lanes is only reflected in the cost of highway connections to the top

of the slipways, which is outside the scope of this task. As a result, an estimate of cost

for the chain ferry option is approximately £20million.

In conclusion, the recommended approach to the delivery of a possible ferry crossing

at Gallions Reach is that of a chain ferry using a piled slipway. The major benefits of

this option over a propeller driven ferry are a lower construction cost, fewer

operatives and faster turnaround times. It is considered that a four‐lane highway

approach will provide the best compromise between highway construction cost, land

take, manageability of vehicle movements and alighting and boarding times.

The elimination of a solid slipway for geotechnical reasons has not mitigated

environmental and hydrodynamic impacts down to a similar level as the

infrastructure for a propeller driven ferry and this is a major disadvantage that

remains for such an option. It will be essential to develop an operational regime that

ensures safety through the management and/or segregation of motorised and non‐

motorised users and regular cleaning of tidal deposits from the slipways.




9

2 Introduction

2.1 Background

Transport for London (TfL) has commissioned a series of studies into crossings of the

River Thames at Gallions Reach. Access across the river in this area of East London is

currently provided by the Blackwall Tunnel and the ageing Woolwich Ferry service.

TfL is investigating options for providing additional road‐based connectivity in this

area. To provide evidence to support decision‐making, this report assesses the

feasibility, issues and costs of a number of crossing options at Gallions Reach.

The alignment of each crossing at Gallions Reach is within a safeguarded zone for the

previously proposed Thames Gateway Bridge and links the London Boroughs of

Newham in the north with Greenwich in the south.

Figure 1 Location of Gallions Reach (Google Maps, 2013)

Crossing types considered include:

Bridge structure;

Bored / immersed tube tunnel(s); and

Ferry for vehicles, pedestrians and cyclists.

TfL requires development of preliminary designs for each crossing type to allow the

decision making process to progress towards selection of a preferred option.

Gallions Reach

crossing area

Existing Woolwich Ferry Thames Barrier

London City Airport




10

2.2 Scope of the Preliminary Design

TfL commissioned Halcrow in March 2013 to undertake the marine aspects package

from the studies into a River Thames crossing at Gallions Reach. This involves the

following key tasks:

Design development of ferry infrastructure; and

Assessment of the likely effects of all crossing options on the hydraulic

regimes of the river.

This work builds upon a study undertaken by Halcrow in 2009/10 which considered

the feasibility of a possible ferry replacement of the existing Woolwich Ferry service

with a new ferry at Gallions Reach. In order to develop ferry options further,

Halcrow is required to establish principal dimensions of the structural components of

terminals associated with a propeller driven and a chain driven ferry.

Each type of ferry terminal will be developed to consider the following aspects:

Safe access and waiting areas for pedestrians and cyclists;

Interface with highway access designs;

Control room/staff accommodation/maintenance facilities;

Treatment of the existing flood defence wall; and

Any effect on utilities from proposed infrastructure.

Design parameters for the size and capacity of each type of ferry have been provided

by TfL in consultation with renowned ferry expert Bill Moses MBE PhD MA. The

design vessels are larger with higher capacity than those in the previous feasibility

study and the preliminary design is to take account of this in an estimation of the

likely boarding/alighting times in conjunction with variations in the number of traffic

lanes to be used.

TfL would pursue a Transport and Works Act 1992 (TWA) Order for construction of

the chosen option and the preliminary design shall include sufficient information to

input into the engineering aspects of this.

In addition to the preliminary design, the brief requires an outline cost estimate, risk

register and construction programme for each ferry option to enable TfL to determine

the likely benefit in relation to the whole‐life cost.

The nature and extent of hydrodynamic effects from temporary and permanent

works in the river associated with ferry infrastructure, bridge construction or

immersed tube tunnel shall be described and compared. These comparisons will also

inform TfL’s decision on a preferred option for further development.

2.3 Definitions

For the avoidance of doubt, the term “linkspan” in this report is used to describe an

articulating structure that links the ferry to a fixed structure, or that links a pontoon

with the shore. It does not include the fixed approach structures or pontoons that are

considered as part of the preliminary designs for a propeller driven ferry.




11

3 Information Sources Halcrow has made use of a number of information sources in the development of

preliminary designs for ferry infrastructure and the hydrodynamic analysis of all

relevant crossing options. TfL provided a package of reports and drawings from

related studies and Halcrow has made contact with other organisations to obtain

further data as necessary.

3.1 Provided by TfL

TfL has provided several documents from previous studies as listed in Table 1 below.

This information has been reviewed by Halcrow as part of the preliminary design

study.

Date Title Information included

February

2010

Halcrow Group Limited

Woolwich Ferry Replacement

and Gallions Reach Ferry

Feasibility Study:

Final Report

(TB/TFFS/REP/002)

Feasibility of a replacement ferry

service at Woolwich and/or new ferry

service at Gallions Reach;

Environmental and hydrodynamic

impacts of options;

Cost estimates and constructability

considerations.

May 2012 Mott Macdonald

Gallions Reach River Crossing

Study, Tunnel Engineering;

(298348/MNC/TUN/001)

Feasibility of a fixed crossing of the

River Thames at Gallions Reach;

Environmental impacts of options;

Cost estimates and constructability

considerations.

August

2011

Mott Macdonald

New Thames River Crossing,

Extended Phase 1 Ecological

Assessment

Assessment of ecological features in

Gallions Reach area;

Recommendations for further

ecological surveys.

October

2011

Mott Macdonald

Thames Benthic Ecology

Survey Report

Results of marine ecology and intertidal

benthic survey of Woolwich and

Gallions Reach areas;

Assessment of impact of ferry terminal

options;

Recommendations for further surveys.

December

2012

MARICO Marine

Woolwich Ferry Replacement

Project, Navigational Risk

Assessment for Different Types

of Ferry Systems at Gallions

Reach

Analysis of the risks to vessel

navigation through the Gallions Reach

area created by new ferry infrastructure

in the river.

December

2008


Drawing TBTGRC‐P2‐TGB‐006

(rev 4)

Clearance constraints (air draft for river

vessels and headroom for aircraft) for

proposed Thames Gateway Bridge (not

needed for this study).




12


July 2012 TfL Roads Directorate, Traffic

Design Engineering (TDE)

Proposed highway access

designs

Drawings of highway alignment

designs at the north and south sides of

the safeguarded corridor;

Queuing/stacking arrangements for

waiting ferry users.

September

1985


East London River Crossing –

Interpretative Report Vol. 1 to 3

Referred to as part of geotechnical

information review.

April 1992 Halcrow Group Limited

East London River Crossing –

Supplementary Interpretative

Report


information review.

Soil Mechanics Limited

Thames Gateway Bridge Site

Investigation – Location 1

Factual Report on Ground

Investigation

Report No A7028 – 1


information review.

July 2007 Mortimore, R

Thames Gateway Bridge

Boreholes; Chalk Core Logging

Report 1D0101‐G0G00‐00543


information review.

Table 1 Documentation received from TfL

3.2 Other Sources

In addition to the information provided by TfL, Halcrow has made use of a number

of other data sources as summarised in Table 2 below:


April

2013


Task 95 – Tunnel Engineering

and Highway Engineering

(version 1.0)

Referred to in hydrodynamic impact

assessment.

April

2013

Atkins

Gallions Reach Fixed Link

Bridge Concept Engineering,

Options Study Report (rev 1.0)

5118859/060/001


assessment.

March

1978

FHWA Bridge Division

HDS‐1: Hydraulics of Bridge

Waterways


assessment.




13


June 2010 Lloyds Register Marine

Consultancy Services London

Woolwich Free Ferries:

Operational Cost Estimate ( rev

0 and rev 1)

Referred to in discussion of alternatives

– existing Woolwich vessels are

considered to be sound.

April

2013

Discussion with

representatives of Torpoint

Ferry

Drawings, photographs and advice

from operator of Torpoint chain ferry.

July 1999 Maritime and Coastguard

Agency

Merchant Shipping (Counting

and Registration of Persons on

Board Passenger Ships)

Regulations 1999

Referred to in operational procedures.

December

2007


N Burt and R Dobiecki

Technical Note P3‐T291

Overview of the results from

Site Investigation Contract 01‐

2007


information review.


Technical Note P3‐T289

EGGS Bridge Pier 5 ‐ Pile

Group Assessment


information review.

Table 2 Other sources of information used in this task

3.3 Added Value

Halcrow has developed a comprehensive understanding of the Gallions Reach area

and the process of procuring a crossing in this location through several years of

working with TfL on the Thames Gateway Bridge (TGB) and Woolwich Ferry

Replacement projects. Where appropriate, existing Halcrow knowledge has been

used and refreshed as necessary. In some cases, this knowledge is outside the scope

of the current task, but is included to provide additional support to proposals where

it is considered to be of note.




14

4 Geotechnical Considerations As part of this task, Halcrow has carried out a review of available geotechnical

information provided by TfL and from its own experience on the former East London

River Crossing (ELRC) and TGB schemes. This review has informed the preliminary

design process.

4.1 Review of Available Information

A number of site investigation (SI) campaigns were undertaken for the proposed

Thames River crossing, in the past, for the original scheme (ELRC) and the

subsequent one, namely TGB. There were three SI campaigns investigating the route

of the ELRC dating back to 1980, then 1983 and final one was conducted in 1990. To

supplement this information and provide specific and current information a further

SI was carried out in 2007 for the TGB scheme. The plan of the most relevant

exploratory locations is shown on the TfL drawing No: TBTGTA/P3/ASI/011.

The TGB SI scope focused predominantly on specific structures:

intermediate piers of the river bridge;

unfinished viaduct to the north of the river bridge (EGGS bridge); and

a communications tower for the PLA in Woolwich Arsenal.

Hence it does not provide a site wide coverage; however, it offers very detailed

analysis of Chalk Formation in the river channel as logged by Professor R.

Mortimore.

The ELRC site investigations encompassed the whole of the approach road network

as well as the main river crossing. Many of the exploratory locations are relatively far

from the site of the currently proposed ferry schemes hence bear little relevance for

the design.

The two river crossing options proposed, for two different types of ferry operation,

will require two different types of load/off‐load structures as one, propeller driven

ferry, will need deeper water for berthing and the other, chain ferry, would in essence

load/off‐load in the dry. In other words, the structures required for the propeller

driven ferry will be located in the river channel and require piled or deep foundations

and the structures for the chain ferry are proposed at the river bank and mudflats

utilising contained earthworks by means of embedded retaining walls.

As the ELRC SI campaigns were more extensive on land, and the TGB one focused on

soil strata in the river channel, the former was used predominantly for the

geotechnical assessment of the chain ferry option and the latter one for the propeller

driven ferry option, as it offers an assessment of the chalk classification.

4.2 General Overview of Conditions on the River Banks (Chain Ferry Option)

The geological profile on both banks, North and South, in general comprises:

Made Ground and very soft to firm Alluvial Clay, including distinctive sub‐layers of

peat, which overlie course grained River Terrace Gravel underlain by White

(formerly Upper) Chalk. The chalk was proven to nearly ‐90mOD during the ELRC SI

campaigns.




15

The superficial Made Ground layer was formed by raising river banks in recent

history. This layer just below the existing ground surface is predominantly granular

and comprises: building rubble, furnace slag and ash, glass, plastic and timber. The

basal part of this layer is predominantly made up of reworked alluvial clay which has

been mixed with the manmade material mentioned previously.

The Alluvial Clay is very soft becoming soft and in places firm (probably due to

desiccation). It is of high to very high plasticity and contains traces and pockets of

organic matter and peat. At depth, inclusions of bands and pockets of sand as well as

occasional chalk gravel were observed. As the Made Ground is absent from mudflats,

in the river channel, a superficial layer of underconsolidated very soft silty clay of

very recent (Holocene) river deposits is present at the surface, which predominantly

plots below the A Line on the plasticity chart suggesting that this material is

predominantly silt of high plasticity.

Peat is predominantly soft friable and probably fibrous as most of the Atterberg Limit

results plotted below the A‐line. Due to the fibrous nature of the Peat, it is considered

inappropriate to estimate effective shear strength characteristics of the material. The

nature of Peat is probably one of the main reasons for the high (apparent) undrained

shear strength measured.

River Terrace Gravel underlies Alluvial Clay over most of the site including the river

channel. The formation predominantly comprises medium dense slightly to very

sandy Gravel. Gravel is fine to coarse, sub‐angular to rounded of quartzite. This

formation at certain locations was reported as gravelly Sand. The fact that the grading

envelope is quite wide contributes to the large scatter of Standard Penetration Test

(SPT) results. However this is a common feature for a coarse granular material. There

are some indications that River Terrace Gravel at isolated locations contains pockets

of loose material in the region of mudflats.

The current (CIRIA 574) classification of Chalk Formation was only possible from the

latest (2007) SI data as summarized in Prof. Mortimore’s report. This is because the

previous site investigations used percussive drilling techniques destroying the

structure of the chalk and making classification impossible. It should be noted that

the following assessment of the Chalk is representative of the formation below the

river bed and that weathering can be expected to be more pronounced, with a thicker

de‐structured starting sub‐layer over land. Based on the ELRC SI it can be expected

that the Chalk starts from ‐9.5mOD to ‐11mOD on the northern bank. This was

corroborated by the CPT tests carried out in 2007 SI (test ref nos: CPT364 to CPT370).

However the boreholes sunk at the proposed location of the northern pier suggest

that the top of chalk is somewhat lower around ‐16.0mOD. This could be due to the

normal erosion by the river flow.

Exploratory core logs from the ELRC SI and TGB SI are more consistent at the south

side and near the south bank of the river than on the north. Here the top horizon of

the chalk is between ‐10.0mOD and ‐15.0mOD.

At the location of the northern pier of the former TGB scheme, the de‐structured

(Class Dc/Dm) chalk is approximately 6m to 7m thick. The de‐structured chalk is

directly followed by class A (A1 to A4) intact material. The location of southern pier

shows more gradual transition from destructured chalk at the top horizon, which

varies in thickness from 1.5m to 6.0m. De‐structured chalk is followed by relatively




16

thin layers of class B and C. However it should be noted that 10m below the top

horizon of chalk class A is encountered.

The two tables below show a typical soil profile with basic characteristic values for

the north and south river banks respectively. The average values are presented,

sometimes as a range.

It should be noted that the main difference between the stratigraphy on the north and

the south riverbanks is the apparent absence of the Peat layer on the south. The Peat

was only observed some 500m further south from the river. It is also noted that the

Made Ground is not present on the intertidal mudflats in the river channel.

Layer Thickness

(m)

Moisture

Content

(%)

γ

(kN/m3)

SPT

‘N’

Su

(kPa) ϕʹ (◦)

Eu

(MPa)

E’

(MPa)

Made

Ground 4 – 5 no data 18.0 8 – 20 35(1) 26(1) 12.25 9.8

Alluvium 4 [6(2)] 40 – 70 16.5 ‐ 25 26 7 5.6

Peat 3 210 11.5 ‐ 30 ‐ 7 5.6

Terrace

Gravel 6 ‐ 20.0 30 ‐ 36 ‐ 50

Chalk

Dc/Dm 7 31 18.0 ‐ ‐ ‐ ‐ ‐

Chalk C

and better not proven 22 20.5 36 3.5(3) ‐ ‐ ‐

Table 3 North bank stratigraphy and basic parameters

(1) Strength values for Made Ground were derived with the view that the significant

quantity of this material was generated by reworking alluvial clay and mixing with

manmade material, not just directly from testing such as SPT.

(2) These thicknesses are relevant to what appear to be paleo‐channels or in‐filled

erosion features.

(3) Unconfined Compressive Strength (UCS) in mega‐pascals (MPa)




17

Layer Thickness

(m)

Moisture

Content

(%)

γ

(kN/m3)

SPT

‘N’

Su

(kPa) ϕʹ (◦)

Eu

(MPa)

E’

(MPa)

Made

Ground 3 – 5 no data 18.5 9 35 30(1) 12.25 9.8

Alluvium 5 [10(2)] 45 18.0 ‐ 30

[10(3)] 29

10.5

[3.5]

8.4

[2.8]

Terrace

Gravel 4 ‐ 20.0 30 ‐ 35 ‐ 35

Chalk

Dc/Dm 1.5 – 6.0 30 18.0 ‐ ‐ ‐ ‐ ‐

Chalk C

and better not proven 24 19.8 30 4.0(4) ‐ ‐ ‐

Table 4 South bank stratigraphy and basic parameters

(1) Strength values for Made Ground were derived with the view that the significant

quantity of this material was generated by reworking alluvial clay and mixing with

manmade material, not just directly from testing such as SPT.

(2) These thicknesses are relevant to what appear to be paleo‐channels or in‐filled

erosion features.

(3) Parameters for alluvial clay on mudflats

(4) Unconfined Compressive Strength (UCS) in mega‐pascals (MPa)

4.3 General Overview of Conditions in the River

Chalk below the river bed was the focal point of the 2007 SI.

Boreholes and cone penetration tests carried out in the current river channel proved

that river deposits varied in thickness from 2.40m (CPT 2) to 7.60m (CPT 3) and

directly overlay Chalk.

The depth to the chalk, observed in the 2007 SI, was shallower than was originally

anticipated at the borehole locations and the thickness of the overlying river deposits

varied from 0.90m (BH305) to 1.90m (BH 301 and BH302). The top horizon of chalk

was discussed in the section above. Chalk was then encountered to the base of each

hole. Standard penetration testing in chalk, which measures the resistance of soil to

penetration and is an indicator of shear strength of soil, was relatively consistent

throughout different SI campaigns. SPT ‘N’ values on the southern side of the river

(BH302) appear to become consistently greater than 50 from ‐22m OD. On the

northern side, SPT ‘N’ values become generally greater than 50 from ‐16m OD.

This difference in the value of SPT ‘N’ between the south and north side of the river

was suspected before the 2007 SI and was thought to result from a possible

displacement of the chalk beds by a fault running between the bridge pier locations.

New SPT ‘N’ values recorded a difference of approximately 6m between the eastern

and western side of the river.




18

To reduce the uncertainty in the chalk weathering profile the Chalk was logged by

Prof. Rory Mortimer. Prof Mortimer concluded that a gentle dip of strata to the south

is present and a fault is possible within the area of BH303 and between the two sets of

boreholes. This potential fault, however, appears not to be the main reason behind

the differing SPT ‘N’ values.

Despite the use of modern techniques and detailed logging, the depth of the

weathered chalk between the northern and the southern side of the river cannot be

fully explained but is believed to represent differences in the local weathering profile.

4.4 Advice and Comment on the Feasibility of Piling

Predictions of differential settlement and the ability of the foundations to deal with

the considerable imposed horizontal loads are critically dependent on the local

weathering profile, together with the associated strength and stiffness properties, of

the Chalk stratum. The settlement aspects are particularly relevant to spread

foundations that rely primarily on bearing pressure to resist the vertical and

overturning loads; as a result, the founding level and hence constructability will

depend to a large extent on the weathering profile. For these reasons a piled solution

would be less sensitive to ground variation, and hence produce less risk to the

construction and the contract. Nevertheless, as stability of piled structures will be

derived from chalk the weathering profile at exact locations will be crucial for the

final design of the foundations.

One of the piling methods thought appropriate would be to install a permanent steel

casings into the top of the Chalk by a metre or so, where bored cast‐in‐situ reinforced

concrete piles would be constructed thorough the casing into better quality Chalk. If

constructed carefully cast‐in‐situ piles are more efficient in developing shaft

resistance in the Chalk than the alternative of driven steel tubular piles, since driven

piles produce a lot of fracturing which significantly reduces the structural strength of

good intact chalk. Also the precedent empirical data on which design of bored piles is

based is far more robust; hence the design can probably be less conservative.

Nevertheless, comparisons of cost and construction programme should be

undertaken before final selection of pile type.

In addition to the advantage over caisson type foundations that rely heavily on the

quality of chalk at the top horizon of the formation, which would be weathered and

variable, piled foundation construction would pose less disruption to the river traffic.

4.5 Advice and Comment on the Feasibility of Solid Slipway Structures

Alluvial clay present on the north and the south river bank is normally consolidated

and highly compressible. It also contains a considerable amount of organic matter

and sub‐layers of peat, on the northern bank. Peat has an extremely high water

content and compressibility potential. Because of this the slipways for a chain ferry

cannot be founded directly on the Alluvium.

Possible solutions are:

Piled deck on a grid, toeing into the Chalk – Prefabricated, either tubular steel

or reinforced concrete piles, could be used to minimize generation of spoil

and a need for disposal off site;




19

Remove and Replace – Alluvial clay would need to be removed in

cofferdams and replaced with relatively coarse granular step graded and self

compacting material where it has to be placed under water. How easy the

installation of cofferdams will be will depend on water depth and thickness

of soft alluvial deposits and the level of top of Chalk. The spoil resulting from

excavation of Alluvium could be contaminated, which would require

specialist treatment and disposal;

Ground Improvement by Accelerated Consolidation – Depending on the

project programme and imposed loads and/or settlement tolerances of the

slipway structures it would be possible to pre‐load the compressible soil and

accelerate settlement by installing vertical drains. This option would not be

suitable where significant thickness of organic material/peat is present. Peat

is susceptible to significant prolonged deformation which is not associated

with drainage of pore water and it is very difficult to predict; or

Ground Improvement by Soil Mixing – There are different soil mixing

techniques available these days. This method increases the shear strength of

soft fine grained soil by admixing with stabilizing agents such as cement,

PFA, lime, etc. This technique can be expensive if large quantities of soil need

to be mixed and if high strength (say above 70kPa) of finished product is

required. The advantages of both ground improvement techniques are that

they are relatively low tech solutions requiring relatively simple plant as well

as that they do not require fabrication and erection of structural elements.

Also spoil generation is reduced to a minimum. However, there may be

issues with potential contamination of the river water.

Each of the techniques involving replacement or treatment of the Alluvial clay would

make construction of a solid slipway potentially costly and difficult option. It is

recommended that a piled slipway is investigated.

4.6 Advice and Comment on the Feasibility of Cofferdams

It is believed that cofferdams offer a viable construction technique and certainly can

be used at the proposed river crossing at the Gallions Reach. However their stability

(hence their cost) would primarily depend on the thickness and the state of the

weathered chalk as overlying granular river deposits have been proven to be thin and

possibly absent in some locations. A detailed investigation at exact locations is highly

recommended due to the soluble nature of the chalk material where variations over

short distances can be significant.

It is believed that the standard large section steel sheet piling is feasible. Heavy

percussive driving plant and relatively large steel sections would be required to reach

required penetration into structured chalk in order to achieve stability.




20

5 Preliminary Infrastructure Design for Propeller Driven Ferry The first option considered for a ferry at Gallions Reach is that of propeller driven

vessels berthing at a pontoon on each side of the river, which is connected to the

shore by a hinged linkspan. The pontoon remains at a constant level in the water and

tidal movements are accommodated by articulation of the linkspan without the need

for any powered mechanical systems.

Design of the ferry vessels themselves is outside the scope of this task and TfL has

provided parameters for their size and capacity, which will be progressed to detailed

design by others.

5.1 Design Parameters

TfL has specified the following parameters to be used in the design of the

infrastructure for a propeller driven ferry:

Ferry ‐ 2 no. vessels (with passive provision for a third vessel);

‐ 90 Passenger Car Unit (PCU) capacity;

‐ 6 traffic lanes (2 x 2.7m wide outer lanes for cars, 4 x 3.0m wide

inner lanes for HGVs);

‐ PCU length of 5.0m, including longitudinal gap between vehicles;

‐ 80m maximum overall length, 22.5m beam, 3.0m draft; and

‐ Passenger lounge on one side of vessel.

Holding area ‐ Liaison with highways designer to ensure sufficient land side area

for waiting vehicles.

Lane options ‐ Investigate 2, 4 and 6 lanes connecting shore to ship.

5.2 Standards Used

The following standards have been used in the preliminary design of infrastructure

for the propeller driven ferry option:

BS 6349: pt 4 (1994) Maritime structures. Code of practice for design of

fendering and mooring systems.

Linkspan design to BS 6349: pt 8 (2007) Maritime structures. Code of practice

for the design of Ro‐Ro ramps, linkspans and walkways.

Other standards referred to within BS 6349 (BS 5400 for vehicular structures,

Lloyds rules for marine structures)




21

5.3 Design Considerations and Assumptions

5.3.1 Vertical Geometry

The vertical geometry of the transition from shore to ship is established by

consideration of a number of factors including:

Tidal variation, normal and extreme;

Vessel threshold height;

Recommended gradients;

Transitions between elements; and

On‐shore tie‐in levels.

For preliminary design purposes the following assumptions are made:

The threshold height of the ferry vessels is assumed to be approximately 2

metres;

The on‐shore tie in level is assumed to be at the level of the flood defences

(+10.6m CD);

Normal operating tide levels are assumed to be from MLWS to MHWS

(+0.42m CD to +7.08m CD); and

Extreme tide levels are assumed to be from LRT to HRT (‐0.69m CD to

+8.53m CD).

The level of the roadway at the linkspan adjustment should be set as low as possible,

but high enough to avoid inundation and wave overtopping under normal

circumstances. The preliminary design sets the roadway level at the abutment at

+8.7m CD. This is one metre above HAT, providing a reasonable margin for wave

activity. This roadway level is also around 0.2 metres above HRT, which would avoid

complete inundation under extreme tidal levels.

The roadway should descend from the on‐shore tie‐in level at a normal highway

gradient of 5% or less. This level change requires a length of roadway of 38 metres,

which is considerably less than the length of roadway required from other

considerations.

BS 6349: pt 8 recommends that the gradient of the linkspan element between the

abutment and the pontoon should be a maximum of 10% at normal operating levels

and 12.5% at extremes. In this particular case the governing gradient is 10% at MLWS.

It is advantageous to minimise the length of linkspan required by setting the roadway

level as high as is practicable above the water level at the point where the linkspan

joins the pontoon. This can be achieved by providing a slight slope on the top profile

of the pontoon between the landing area for the vessel’s ramp and the linkspan

connection. For the preliminary design the level of the linkspan roadway is set at 2.7

metres above water level.

For the governing gradient case at MLWS the linkspan descends from +8.7m CD to

+3.1m CD. At a gradient of 10% the minimum length of linkspan required is 56.3

metres, which is rounded to 57 metres. The gradient at LRT is 11.8%, less than the

maximum recommended value of 12.5% for the extreme condition.




22

5.3.2 Horizontal Geometry

The location of the ferry at its berth is obtained by positioning the ferry vessel in a

depth of water at low tide, sufficient to accommodate its draft with an allowance for

under‐keel clearance. The preliminary design positions the ferry close to the 4m CD

contour as shown on Port of London Authority (PLA) Chart 325, dated September

2011. This provides 1 metre under‐keel clearance at Chart Datum, which covers all

normal tides. It should be noted that at extreme tides the under‐keel clearance would

reduce, for example at the lowest recorded tide level it would reduce to around 0.3 m

with a consequent risk of grounding.

Roadway widths (2 lanes) are taken as 7.4 metres between kerbs as recommended by

BS 6348: pt 8.

An access walkway of 2 metres clear width is provided for pedestrians, again as

recommended by BS 6349: pt 8. It is assumed that cyclists would dismount and access

the ferry vessel using the same walkway.

A separate service walkway is provided with a clear width of 1 metre for use by staff.

The position of the northern connection to the highway network is in close proximity

to an outlet of the Northern Outfall Sewer. This may be an issue which could result in

some adjustment of the final position of the northern terminal.

5.3.3 Pontoons

The pontoon design should provide a stable platform, capable of supporting the

weight of the linkspan and being permanently ballasted to float horizontally.

It is assumed that the pontoon is essentially a passive platform serving one design of

ferry, thus requiring no sophisticated ballasting system to respond rapidly to vessels

of different threshold height.

As vehicles, particularly HGVs, traverse the linkspan and pontoon the pontoon

experiences freeboard and trim changes that can adversely affect the vertical

transition angles between the linkspan and pontoon and between the pontoon and

the ferry vessel, causing vehicles to ground. Similarly vehicles moving on the ferry

vessel’s deck also affect its ramp transition angles. This should be studied in detail

when the vessel design is available.

The preliminary design of pontoons in the feasibility study assumed that vehicles

would turn by up to 90 degrees (at the South terminal) from the end of the linkspan

to board the ferry and vice versa for alighting from the ferry. Halcrow has carried out

Autotrack swept path analyses to determine the minimum size of pontoon that could

accommodate such manoeuvres.




23

Figure 2 Swept path for articulated HGV boarding vessel

Figure 3 Swept path for articulated HGV leaving vessel




24

Figure 4 Swept path for rigid HGV boarding vessel

Figure 5 Swept path for rigid HGV leaving vessel

As can be seen in Figure 2, Figure 3, Figure 4 and Figure 5 above, a pontoon of

approximately 40m x 40m in plan would be necessary to accommodate the

movements of HGVs turning through 90 degrees. This size of pontoon is significantly

larger than that assumed at the feasibility stage, for which buoyancy to carry the

necessary loading would have been the primary sizing factor. A pontoon of this size




25

would incur a much greater cost for construction, transportation to site and

maintenance as well as presenting a greater risk to navigational for other vessels on

the river.

This matter was discussed with TfL as part of this task and a decision has been taken

following a suggestion from TfL to assume the necessary turning movements are

carried out via a curved approach structure (similar to the current Woolwich Ferry

arrangement) such that vehicles would travel over the pontoon in as close to a

straight line as possible. This enables a reduction in the size of the pontoon from that

required above.

Figure 6 Example of curved approach structure at Woolwich (Google Maps, 2013)

For preliminary design a pontoon size is chosen and checked for trim and freeboard

changes under vehicle loading. For the chosen size of 30m x 30m a convoy of 40 tonne

HGVs on the linkspan causes the pontoon to rise by around 0.2 metres at the vessel

ramp landing area. Two HGVs traversing the vessel’s ramp causes the pontoon to fall

by around 0.2 metres at the landing area. The ability of the ship’s ramp to

accommodate such movements is not known at this stage, however the magnitude of

the movements is considered to be reasonable.

5.3.4 Linkspans

The length of the linkspan and the various width allowances are as discussed above.

The range of movement of the linkspan element is accommodated by the provision of

appropriate bearings that permit large rotations at the abutment end and large

rotations coupled with translation at the pontoon end. This caters for the rise and fall

of the pontoon with the tide and allows for pitching rotation.




26

Rolling rotation, about the axis of the pontoon in line with the linkspan, is more

problematic, requiring the linkspan to twist. The previous feasibility study envisaged

through truss linkspan structures, which are stiff under this action and intolerant of

such rotations.

For preliminary design purposes a plate girder U‐frame structure is assumed. Whilst

this provides greater flexibility to accommodate twisting than a through truss it

should be stressed that the response of the pontoon/linkspan system should be

assessed in detail before any detailed design is undertaken. Such motions would be

induced by, for example, wave activity or the effect of passing ships.

Vehicular loading on the linkspan is taken as HRo loading in accordance with

BS6349: pt 8, which covers the effects of all permitted normal vehicles licensed under

the Road Vehicles (Construction and Use) Regulations. It is assumed that abnormal

weight vehicles would not be permitted to use the facility, alternative routes across

the river being available elsewhere.

5.3.5 Approach Structures

The approach structures are designed as multi‐span viaduct structures leading from

the shore to the linkspan abutment, supported on piles in the river bed.

The structures envisaged would make extensive use of standard pre‐cast concrete

bridge components for the roadway slab to minimise the need for temporary works

for formwork construction over the river.

5.3.6 Berthing Dolphins

For the layout and preliminary design of berthing dolphins berthing mode b) as set

out in BS 6349: pt 4 has been assumed, using the maximum recommended dolphin

spacing of 25% of the length of the vessel. This berthing mode is based on berthing

the vessel against the dolphins and then making a slow approach towards the

linkspan or pontoon.

Berthing energy is derived from the displacement mass of the berthing vessel and its

transverse approach velocity. For preliminary design purposes the mass of the ferry

vessel is estimated by its block dimensions (Length x Breadth x Draft) to which a

block coefficient of 0.7 is applied, being a typical value for ferries. The transverse

berthing velocity is assessed from Figure 1 of BS 6349: pt 4, assuming berthing

category b) (difficult berthing, sheltered) giving a normal berthing velocity of 0.25

m/s.

Berthing forces are derived from the berthing energy and the load/deflection

characteristics of the chosen fenders.

Typically ferry vessels are constructed with a belting, which protrudes from the hull

at the level of the main deck for the purpose of berthing. To avoid contact with other

areas of the hull it is important to consider the way fenders deflect. For preliminary

design parallel motion fenders are considered, which incorporate a mechanism that

ensures the fender face remains vertical as the fender deflects.

5.3.7 Pontoon Restraint Dolphins

The pontoon restraint dolphins are required to resist the horizontal forces applied to

the pontoons, which arise from vehicular traffic, wind, wave, current and berthing.




27

The wave height at the site is assumed to be 0.5 metres for preliminary design

purposes. The actual wave climate at the site should be evaluated before detailed

design is undertaken.

Discussions with PLA during the previous feasibility study identified a maximum

current velocity in the River Thames of 6 knots. General published information for

the Thames warns of currents of up to 4 knots. For preliminary design a normal and

extreme current velocities of 4 knots and 6 knots respectively are assumed.

For berthing it is assumed that fenders are provided on the pontoon for a berthing

velocity appropriate to the berthing mode discussed above. For the berthing mode

considered, in the absence of factual data, BS 6349: pt 4 suggests a berthing velocity of

0.15 m/s, which is assumed for preliminary design.

5.3.8 Number of Lanes

TfL has requested consideration of 2, 4 and 6 traffic lanes connecting shore to ship.

This will have an effect on boarding and alighting times as well as cost.

Halcrow has investigated options and concluded that a linkspan structure with more

than two lanes is not a viable solution. The pontoon can be subject to differential

vertical movements at each side, particularly when acted upon by wash from passing

vessels. This results in a landing area for the lower end of the linkspan which is not

always level. The linkspan must accommodate this by having sufficient torsional

flexibility and a very wide linkspan with sufficient flexibility is likely to be

structurally unstable.

A solution would be to use multiple linkspans of two lanes each. The approach

structures would also have to be widened to accommodate more traffic lanes. The

existing Woolwich Ferry service has approach structures with four traffic lanes; two

in each direction. A similar arrangement would be possible at Gallions Reach though

it should be noted that this will result in additional piling in the river to support such

a structure. However, an additional benefit can be realised in the flexibility to deal

with vehicle movements around obstructions such as breakdowns in the queue whilst

they are awaiting recovery.

An important consideration when investigating multiple traffic lanes is that six lanes

of traffic alighting from the ferry will need to be clear of the pontoon before boarding

traffic can be allowed to enter this area. Queuing traffic would not be permitted on

the linkspans so it is feasible to use linkspans in a bi‐directional arrangement (ie. the

same lanes are used by both alighting and boarding vehicles in consecutive

operations). Given that queuing traffic could occupy half the total number of lanes on

the approach structures it is sensible to provide linkspans with half the number of

lanes as the approach structures.

If four traffic lanes are provided via two separate linkspans, it would be possible to

accommodate them within the same width of pontoon required for a two lane

solution as this width is determined by the width of the ferry vessel. However, the

effect of an additional linkspan on pontoon restraint structures, potential fouls with

piling or the performance of the pontoon under traffic loading has not yet been

considered.

Any introduction of multiple traffic lanes will still need to be linked to the existing

highway network eventually. Any more than two lanes of alighting traffic would




28

create a “bottleneck” at the connection with the highway network, though it is

expected that the access roads from the ferry terminals to the highway network have

sufficient length and the movement of alighting vehicles can be sufficiently controlled

to allow all vehicles to be clear of the linkspans without causing delay to boarding

vehicles.

Six lanes of traffic would require a larger pontoon to accommodate the width of

linkspans landing upon it. In addition to the cost of more linkspans, this would

introduce a significant additional capital cost for the pontoons alone and present a

greater hazard to river navigation. With a six lane solution, the problem of

integrating multiple lanes of alighting traffic into the highway is exacerbated even

further. For these reasons, a maximum of four linkspan lanes has been considered.

In summary, the most viable solution based on a high‐level cost/benefit consideration

is a four lane approach structure with a single two‐lane linkspan to the pontoon.

Boarding vehicles will queue at the top of the linkspan and both lanes of the linkspan

will be used in each direction for consecutive alighting and boarding operations. This

decision is also informed by estimates of alighting and boarding times discussed in

section 7.

5.3.9 Existing Flood Defences

It is known from previous studies and discussions that the Environment Agency, as

manager of the flood defence walls, would prefer an option which requires little or no

modification to the existing provisions at Gallions Reach. A solution which does not

raise major objections from the Environment Agency is considered much more likely

to progress to construction.

In the course of developing preliminary designs, Halcrow has determined that it is

possible to achieve the required geometrical parameters with a solution which passes

over the existing flood defences, eliminating the need for costly specialist flood gates.

Indeed, the shorter approach lengths that could be achieved by starting from a lower

level and penetrating the walls would not result in a pontoon being positioned any

closer to the river bank due to depth constraints.

For these reasons, only the option of starting from the flood defence level of 10.6m

CD has been considered for the preliminary design.

5.3.10 Ancillary Infrastructure

The remote and open nature of the Gallions Reach site presents a need to provide

shelter for non‐motorised users whilst waiting for the ferry to arrive. A proprietary

shelter as used for bus stops may not be able to accommodate the number of non‐

motorised users if cyclists are included. However, a similar lightweight shelter with a

larger capacity can be positioned along the footpath at the top of the linkspans to

afford protection from the elements. It is not proposed to provide shelter along the

length of the approach structures but this could quite easily be accommodated if

necessary. A lightweight windshield which may incorporate a cantilevered roof could

be mounted to the edge beams and/or parapets of the approach structures, though

the effect of wind loading on the resulting increase in cross‐sectional area would need

to be checked at detailed design stage.

It is known that a key consideration for TfL is to develop a solution which requires a

minimal level of staffing, particularly in comparison with the existing Woolwich




29

Ferry service. Further details of staffing levels are provided in the section of this

report which deals with operational procedures but it has been assumed that only a

relatively small cabin would need to be provided for staff welfare. A standard sized

“Portacabin” type building provided just inland from each terminal is considered

adequate to contain toilet, hand washing and rest facilities for operatives. There is

also expected to be sufficient room in the same building for a small administration

office if required.

Tolling is assumed to be via a cashless freeflow system using Automatic Number

Plate Recognition (ANPR), and not expected to be controlled from the ferry terminals.

Facilities for maintenance will consist of a secure and enclosed storage area roughly

6m x 6m. This will contain consumables and spares for keeping the terminals and

limited parts of the vessels in proper working order.

Other infrastructure requirements will include navigation lighting on the pontoon

and streetlighting for vehicles using the approach structures, linkspan and pontoon.

An electrical supply will also be necessary to provide power to pumps in the

pontoons. Firefighting equipment can consist of a saltwater pump using the river as a

supply. This removes the need for a water supply to the terminals and the associated

difficulties of providing and maintaining a supply pipe through the articulated

linkspan section. The terminal structures have been designed with gradients which

will aid drainage through gravity. Discrete penetrations in the roadway channels can

be provided to discharge run‐off directly into the river, subject to obtaining any

necessary consents.

5.3.11 Passive Provision for Third Vessel

The scope of this task requires consideration of passive provision for a third vessel.

The nature of the terminals for the propeller driven ferry would allow three vessels to

operate in rotation at peak times with no change to the infrastructure. The total

crossing time is a combination of berthing, alighting, boarding and sailing times. It is

expected that the sailing time would be relatively short in comparison to the berthing,

unloading and loading time. This could lead to a third vessel waiting for a terminal to

be available, delaying the crossing time and causing an obstruction to other river

users. In this circumstance, the need for a third vessel is questionable.

A non‐passive solution which would allow the use of three vessels would be to

construct additional infrastructure consisting of an extra linkspan and pontoon in the

opposite orientation to those in the preliminary design (ie. pointing in the upstream

direction), connected to the same approach structure. This would be a significant and

costly modification but it could be achieved at a later date with minimal disruption to

the existing terminals. The application of such a solution to service an additional

vessel is unlikely to provide sufficient justification for the additional cost of

infrastructure. It would be more appropriate to provide a total of four vessels in this

instance, which would effectively cost the same again as the preliminary design for

two vessels.

Given the factors above, it is considered unlikely that provision of a third vessel

would be practicable on the grounds of operability and/or cost.




30

5.4 Construction Considerations

The preliminary design of the proposed pontoon and linkspan terminal solution has

considered a likely method of construction to optimise efficiency in cost and

programme. A detailed construction methodology will need to be developed as the

design progresses, preferably in consultation with an experienced marine

construction contractor.

5.4.1 Constructability

The preliminary design of infrastructure for a propeller driven ferry uses

prefabricated elements and precast sections wherever possible for ease of

construction. Major elements such as the pontoons and linkspans are likely to be

constructed away from the site by specialist fabricators and delivered as single

elements for installation. In the case of pontoons, these can be floated up the river

with tugs. The linkspans can also be delivered using a barge on the river to minimise

disruption on the local highway network.

The approach structures will consist of precast concrete beams supported on precast

concrete crossheads at the top of each set of piles/columns, connected with an insitu

concrete stitch. These can be installed quickly and provide a temporary working

platform for access to complete the deck with insitu concrete from a mobile pump.

Piling for the approach structures and dolphins will require the use of specialist river‐

based marine piling equipment. During construction, this equipment will present an

additional hazard to navigation in the river and will need to be suitably marked and

lit to warn vessels of its presence.

5.4.2 Closures/Diversions

The proposed site for both north and south terminals is within (or very close to) the

safeguarded corridor for the Thames Gateway Bridge. In the vicinity of the

infrastructure itself, there are no existing highways that would require closure or

diversion in the construction or operation phases.

On the south bank of the river, the scheme will need to take account of the existing

Thames Path. It is anticipated that pedestrians crossing the main access route to the

ferry can be accommodated by an at‐grade crossing where vehicles boarding or

alighting the ferry would have priority to eliminate delays to the ferry schedule.

5.4.3 Utilities

Based on information available for the area, there are no known utilities within the

footprints of either the northern or southern terminals.

Connections will need to be made to the electricity network for provision of power to

tolling equipment, operational facilities and navigational lighting. Existing power

networks are available in the vicinity of each terminal to which these connections are

assumed to be possible.

In the case of navigational marking equipment, an uninterruptable power supply will

need to be provided. This is anticipated to consist of a back‐up generator in the

vicinity of the operator facilities at each terminal.




31

Telecommunications lines will also be necessary for the use of the operator and to

convey tolling information to a control centre which is assumed to be remote from the

ferry location.

5.4.4 Programme

The likely planning and procurement programme for provision of a ferry service at

Gallions Reach was considered by Halcrow in the 2009/10 Woolwich Ferry

Replacement and Gallions Reach Ferry Feasibility Study. Whilst this programme is

outside the scope of this task, Halcrow considers it to still be appropriate and has

refreshed it for the current start dates. The start date for construction of a propeller

driven ferry is based upon the date of completion of this planning and procurement

programme. This programme is included in Appendix H.

An outline programme for construction of the propeller driven ferry infrastructure is

included in Appendix H. This programme deals with construction works alone as

defined in the TfL brief for this task. Where appropriate, works are carried out

simultaneously on each side of the river. However, mobilization of multiple marine

piling rigs is not considered cost effective and would present a greater navigational

obstacle. Piling on one side of the river at a time will introduce a sequenced

construction for the approach structures and dolphins.

The overall construction duration from mobilisation to commencement of operation

is estimated to be two years and three months. This duration is based upon an

assumption that design and construction of pontoons and linkspans is let by TfL to a

specialist contractor up to 18 months in advance of the terminal construction contract.

5.5 Proposed Operational Procedures

The propeller driven ferry infrastructure has been designed assuming a minimal level

of staffing. The use of pontoons provides a self‐adjusting system to accommodate

tidal levels and ensure that it will always be at the same level relative to the ferry

vessel. This eliminates the need for an operative to adjust the linkspan angle at each

berthing.

Whilst consideration of the number of crew on the ferry vessel is outside the scope of

this task, it is recognized that navigation and berthing for a propeller driven ferry will

require more crew than for a chain ferry. It is assumed that the ferry crew will also be

able to deal with boarding and alighting traffic at the lower end of the linkspan,

providing direction to users as necessary.

Landside operations are expected to be carried out with a minimum of four

operatives on each side of the river (for traffic marshalling, mooring hands and

supervisors).

Vehicles would not be permitted to queue on linkspans or on the pontoon. This is

primarily a consideration of avoiding congestion between traffic queuing to board the

ferry and those vehicles which are alighting. Depending upon the number of traffic

lanes chosen, waiting vehicles would queue either behind the line of the flood

defences or at the top of the linkspan(s).

Ferry crew would communicate with an operative at the head of queue to advise

when vehicles are clear of the pontoon and the identity of the final vehicle. Once this

final vehicle has cleared the top of the linkspan, the landside operative would release




32

the queuing vehicles, keeping a tally of PCUs. If more than a full ferry load of

vehicles is queuing, a number of vehicles corresponding to slightly lower than the

capacity of the vessels would be released by the landside operative. This is in order to

avoid congestion and/or the need to send vehicles back to the waiting area (which

would be extremely difficult in the case of HGVs).

Waiting pedestrians and cyclists could queue at the top of the linkspan, with suitable

provision of shelter as discussed in this report under ancillary structures. The

gradients of the approach structures, linkspans, pontoons and ferry ramp will enable

easy access for mobility impaired users. Non‐motorised users could be released at the

same time as vehicles and can safely board the ferry due to segregation provided

along the entire approach.

Alighting would follow the same procedure as boarding but in reverse. There is

considered to be no benefit in simultaneous alighting and boarding operations. The

number of available traffic lanes means that only half as many lanes could be used in

each direction, with no resulting net gain in time. Simultaneous movement of

alighting and boarding vehicles is also likely to increase the risk of disruption due to

queuing and/or clashes with space constraints. For these reasons, a simultaneous

alighting and boarding approach has therefore been discounted.

It is assumed that pedestrians and cyclists would use the ferry service free of charge.

Whilst it would be relatively simple to keep a tally of the number of non‐motorised

users as they board the ferry, this is not considered to be necessary for a crossing at

Gallions Reach. The Merchant Shipping (Counting and Registration of Persons on

Board Passenger Ships) Regulations 1999 require a record of the number of persons

on board a vessel but the relatively short river crossing at Gallions Reach satisfies

clauses 13(i) and 13(ii) for exemption. This is thought to be the case for the existing

Woolwich Ferry, where the number of non‐motorised users is recorded but the

number of occupants in vehicles is not recorded. It should be noted that an

application for exemption from these regulations needs to be made to the local

Maritime and Coastguard Agency Marine Office.

When the ferry is not in service (ie. outside operating hours), it is anticipated that one

vessel would be moored at each of the terminals.

5.5.1 Maintenance

Maintenance of the ferry vessels is assumed to be carried out at a dry dock facility

away from the terminal location. Until the ferry design is finalised such facilities

cannot be investigated, but this aspect is outside the scope of the infrastructure

preliminary design task. It is, however, anticipated that the size and draft of the

vessels would rule out a similar arrangement to that at Woolwich where vessels are

positioned on a maintenance grid at high tide.

The remaining maintenance tasks will consist of greasing linkspan bearings/joints,

cleaning and replacing worn parts from pumps and eventual reapplication of

protective coatings to the metal surfaces of linkspans and pontoons.

The propeller driven ferry infrastructure has been designed on the basis that

dredging will not be required for construction or throughout the service life of the

ferry.




33

6 Preliminary Infrastructure Design for Chain Ferry The second option considered for a ferry at Gallions Reach is a chain ferry service

utilising slipways on each side of the river. The ferries pull themselves along chains,

which run along each side of the vessel and are anchored and tensioned on the shore.

Design of the ferry vessels themselves is outside the scope of this task and TfL has

provided parameters for their size and capacity, which will be progressed to detailed

design by others.

6.1 TfL Design Parameters

Ferry ‐ 2 no. vessels (with passive provision for a third vessel);

‐ 8.0m separation between vessels on the same slipway;

‐ 90 Passenger Car Unit (PCU) capacity;

‐ 6 traffic lanes (2 x 2.7m wide outer lanes for cars, 4 x 3.0m wide

inner lanes for HGVs);

‐ PCU length of 5.0m, including longitudinal gap between vehicles;

‐ 80m maximum overall length, 25.8m beam, 2.5m draft; and

‐ Passenger lounge on one side of vessel.

Holding area ‐ Liaison with highways designer to ensure sufficient land side area

for waiting vehicles.

Lane options ‐ Investigate 2, 4 and 6 lanes on each slipway.

6.2 Standards Used

Whilst no formal design standards have been adopted at this stage for the

preliminary design of infrastructure for the chain ferry option, the geometrical

requirements described in the following sections are based upon industry best

practice.

6.3 Design Considerations and Assumptions

6.3.1 Vertical Geometry

The top of the slipway is set at the flood defence level of 10.6m CD to avoid the need

to breach the flood defences. The lower end of the slipway is set at ‐0.5m CD.

Photographs of the Torpoint Ferry operation indicate that the vessel grounds the

inner portion of its two‐part ramp on stools. The stools contact the slipway at

approximately the water level on the slipway. At Lowest Astronomical Tide (LAT),

the water level is 0.00m CD, therefore the lowest point of contact, excluding extreme

low water levels, is at 0.00m CD. An allowance of 0.5m below this level has been

included to allow for tolerance or extreme events. The overall height of the slipway is

therefore 11.1m.

The gradient of the slipway is a compromise between a shallow gradient for the safe

use by both pedestrians and vehicles and a steeper gradient which would be




34

beneficial to the vessel. There appears to be no standard that provides guidance on

recommended gradients for such installations so best practice has been adopted. A

gradient of 1 in 8 (or 12.5%) has been set for the slipway. This gradient is commonly

used for beaching type ferries both conventionally powered and chain driven. A 1 in

8 gradient gives an overall length of slipway of 88.8m from its lower end up to the

flood defence level.

6.3.2 Horizontal Geometry

The setting out point for the outer end of the slipway is the ‐3m CD contour. The

draft of the vessels is 2.5m and an underkeel clearance of 0.5m has been allowed.

This gives a level of 3.0m below the lowest operating level of 0.0m CD (LAT).The

lower end of the slipway is 20m inside the ‐3.0m CD contour (This is a 2.5m rise at a

gradient of 1 in 8). From this point, the slipway rises at 1 in 8 to the flood defence

level of +10.6m CD, a total length of 88.8m. As can be seen in the drawings in

Appendix C, the plan length of the slipway arrives at the +10.6m CD level just

riverward of the flood defence lines on both sides of the river.

The slipway on the north bank has been relocated some 100m north of the original

proposed position to avoid clashing with the two outfalls on the north bank.

The width of the slipway is 80m, made up of 2 x 25.8m wide ferries with an 8m

central clearance and 10.2m clearance allowance on either side. The side clearance

should be reconsidered when designs are more developed to take account of the

down‐current drift of the ferry in operation.

The Gallions Barge Road mooring is directly in front of the south bank slipway and

will require to be lifted and relocated remote from the slipway.

The position of the north bank slipway overlays some of the remaining piles from a

previous jetty. These piles will have to be removed or cut down over the extent of the

slipway.

6.3.3 Design of Slipways

The construction of the slipway is affected by tidal water which must be considered

in the design. The outer end of the slipway is permanently submerged and as the

slipway rises, the time available above water increases until above the high water

mark, the slipway is permanently above water.

The ground conditions at the slipway locations indicate that the existing bank/ river

bed comprises very soft alluvium up to 7m thick overlying chalk. The alluvium,

especially within the river area, is considered too weak to support a ground bearing

slab. The options are therefore to remove the alluvium and to replace it with a more

competent material or to support the slipway on piles. Due to uncertainties over the

extent of alluvium to be removed, together with uncertainties over its disposal and

potential contaminants, a ground bearing slab option for the slipway has been

discounted as an unviable solution.

The proposed slipway comprises a series of vertical piles supporting a composite

precast/insitu concrete deck over the river section of the slipways. At the top of the

slipways, the slipway is ground bearing within cut and fill as appropriate.




35

The slipway has been designed for loading from the vessel and traffic loading. The

vessel is assumed to ground only its ramp at one end on stools. It has been assumed

that the stools effectively moor the vessel to the slipway and a preponderance of

300kN has been assumed for the loading from the stools. It is assumed that there are

four stools per ramp on each end of the vessel (ie. eight stools in total per vessel) and

that the preponderance load is shared evenly between the stools.

As discussed in more detail under the heading of boarding and alighting time

estimates, it is not possible to provide a physical segregation between

pedestrians/cyclists and vehicles on a chain ferry slipway.

6.3.4 Chains and Chain Tensioners

Simplified calculations, based on the drag and wind forces acting on the ferries have

been carried out to estimate the pull forces required within the chains. To determine

drag and wind forces on the ferry, the following assumptions have been made

The maximum speed of the ferry is 6Kn (3m/s); and

The maximum operational wind speed is 40 Kn (20m/s).

The proposed chain has a diameter of 42mm.

The length of each chain will be approximately 700m, therefore creep in the chain

plus wear on the links during use may lengthen the chain significantly. Regular

maintenance of the chain will involve a regime of checking for wear and extension

with removal of links as necessary to achieve a relatively consistent total length.

Following discussion with the operator of the Torpoint Ferry and without a detailed

specification for the ferry vessel, chain tensioners are considered necessary for this

location. Their function is primarily to take up slack on the chains in front of the ferry

as it approaches the slipway to berth. Without such a system, the momentum of the

approaching ferry may cause it to “overtake” its chains when the rate at which they

are pulled through the vessel slows. For this reason, it is proposed to provide chain

tensioning equipment at each side of the river.

A self‐adjusting chain tensioning system is employed at Torpoint (refer to Figure 7

below) and is considered to be a suitable example of a system that could also work at

Gallions Reach. This system has a relatively small footprint and relies on gravity

rather than powered equipment to maintain the required tension in the chains. It

should be noted that maintenance of this system will require training of operatives.

As the design of the ferry develops it may be possible to eliminate the need for chain

tensioners, replacing them with anchorages at each shore instead. These could consist

of piled foundations and are estimated to be up to approximately 40% of the cost of

the chain tensioners. In the development of cost estimates for the chain ferry, a

conservative allowance for the more expensive tensioners has been included. Relative

to the cost of the overall infrastructure proposal, the additional cost is considered to

be minor.




36

Figure 7 Chain tensioning gantry at Torpoint Ferry (Tamar Crossings 2002)

6.3.5 Number of Lanes

TfL has requested consideration of 2, 4 and 6 traffic lanes on each slipway. As the size

of the slipway is determined by the width of the ferries, which accommodate six

traffic lanes each, this will have an effect on boarding and alighting times. It is

expected that the operational regime of the chain ferry will require all alighting

vehicles to be clear of the slipway before boarding vehicles are allowed to enter the

area. Therefore, the use of multiple lanes for alighting and boarding will be the fastest

procedure.

Any introduction of multiple traffic lanes will still need to be linked to the existing

highway network eventually. Any more than two lanes of alighting traffic would

create a “bottleneck” at the connection with the highway network, though it is

expected that the access roads from the ferry to the highway network have sufficient

length and the movement of alighting vehicles can be sufficiently controlled to allow

all vehicles to be clear of the slipway without causing delay to boarding vehicles.

An increasing number of traffic lanes will result in additional cost in the estimates for

highway configurations (outside the scope of this task). However, an additional

benefit can be realised in the flexibility to deal with vehicle movements around

obstructions such as breakdowns in the queue whilst they are awaiting recovery.

For the chain ferry option, the infrastructure arrangement does not impose any

restriction on the number of traffic lanes. For this reason it is possible to utilise any

number of lanes, subject to the availability of land to accommodate the required

width of highway approach. However, the estimation of alighting and boarding

times in section 7 would suggest that there is a balance to be achieved between the

number of lanes (and associated cost of construction) and the benefit in time savings

that can be realised.




37

A highway approach using four lanes is considered to be the best compromise. This

would also allow a greater level of control than six lanes for marshalling staff, who it

is expected would follow a particular method of loading the ferry (eg. loading edge

lanes first and keeping HGVs in the centre lanes only).

6.3.6 Existing Flood Defences

The required vertical geometry can be achieved by starting from the level of the

existing flood defences. There is little or no benefit in penetrating the flood defences

to reduce the length of slipways as this would bring the lower end of the slipways too

close to the river bank to accommodate the required draft of the specified vessels

without expensive and ongoing dredging.

6.3.7 Ancillary Infrastructure

The waiting area for non‐motorised users of the chain ferry is assumed to be inland of

the flood defence walls. This would be less exposed than the waiting area for a

propeller driven ferry but it is considered appropriate to provide a shelter

nonetheless. As described for the propeller driven ferry, a large capacity lightweight

shelter can be positioned at the top of the slipways to afford protection from the

elements.

It is known that a key consideration for TfL is to develop a solution which requires a

minimal level of staffing, particularly in comparison with the existing Woolwich

Ferry service. Further details of staffing levels are provided in the section of this

report which deals with operational procedures but it has been assumed that only a

relatively small cabin would need to be provided for staff welfare. A standard sized

“Portacabin” type building provided just inland from each slipway is considered

adequate to contain toilet, hand washing and rest facilities for operatives. There is

also expected to be sufficient room in the same building for a small administration

office if required.

Tolling is assumed to be via a cashless freeflow system using ANPR, and not

expected to be controlled from the ferry terminals.

Facilities for maintenance will consist of a secure and enclosed storage area roughly

6m x 6m. This will contain consumables and spares for keeping the slipway, chains

and limited parts of the vessels in proper working order. A further area needs to be

reserved for slipway cleaning equipment and temporary storage of arising from the

cleaning operations.

Navigation lighting at the lower end of the slipway and streetlighting for vehicles

will require an electrical supply. The most appropriate method for firefighting at the

chain ferry terminals is considered to be through dedicated hydrants, which will

require a new mains water supply to be provided. The gradient of the slipways will

result in any run‐off discharging directly into the river. This is likely to require land

drainage consents.

6.3.8 Passive Provision for Third Vessel

The scope of this task requires consideration of passive provision for a third vessel.

The layout of the chain ferry slipway means that in theory any number of vessels can

be accommodated, provided a slipway of sufficient width is constructed. A chain

ferry follows a pre‐determined course and berths in the same lateral position on the




38

slipway, subject to currents, every time. Widening the slipway is not a passive

solution however and would require greater land take in the river, with associated

hydrodynamic and environmental impacts.

A wider slipway to accommodate a third vessel would require further consideration

of the highway connection to it. It may not be practicable to provide sufficient

capacity and flexibility in the highway to allow users to board and alight any of three

possible vessels. Again, this would not be a passive provision.

In summary, it is not considered possible to have passive provision for a third chain

ferry. The level of intervention required would result in further design effort and

significant capital investment. However, should an additional vessel be required, it is

considered possible to construct an extension to the slipways with minimal

disruption to operations.

6.4 Construction Considerations

The preliminary design of the proposed slipway terminal solution has considered a

likely method of construction to optimise efficiency in cost and programme. A

detailed construction methodology will need to be developed as the design

progresses, preferably in consultation with an experienced marine construction

contractor.

6.4.1 Constructability

As discussed in previous sections, a solid slipway is not considered an appropriate

solution for the ground conditions. Piling for the slipways will require the use of

specialist river‐based marine piling equipment. During construction, this equipment

will present an additional hazard to navigation in the river and will need to be

suitably marked and lit to warn vessels of its presence.

For a piled slipway, the deck structure will consist of precast concrete beams

supported on insitu crossheads at the top of each set of piles/columns. These can be

installed quickly and provide a temporary working platform for access to complete

the deck with insitu concrete from a mobile pump.

The upper end of the slipway, down to about mid tide level could be built in the dry

with the works scheduled around the tides. The lower section of the slipway is only

exposed for a short period, therefore there are three options for construction.

Firstly, the construction could be undertaken in the short periods when the slipway is

above water. This would lead to both very slow construction and potential quality

issues with the works being submerged after only a short period of exposure so is not

recommended.

Secondly, the construction could be undertaken in the wet, using divers for the

periods when the slipway is submerged. However, visibility in the river is poor and

currents are relatively fast, therefore this would increase the difficulty of the already

difficult construction. Again, this option is not recommended.

Thirdly, the works could be constructed within a cofferdam. The cofferdam would

allow the works to be carried out in dry conditions without disruption due to tidal

waters, therefore both programme and quality can be maintained. The main




39

disadvantage of a cofferdam is the cost of its provision, maintenance and removal but

it is the most suitable solution in terms of constructability.

The main benefit of constructing the lower end of the slipway within a cofferdam is

that the cost, programme and quality of the works can be more closely controlled.

The potential risks of working either in the wet or the dry on a tidal window are such

that they are considered unacceptable. Therefore the preliminary design of the

slipway has been undertaken assuming that the lower half of the slipway is

constructed within a cofferdam. The upper half of the slipway is above water level for

more than 50% of the time and works could be undertaken around the tides using

land‐based access and equipment.

At the lower end of the slipway, the depth of water excluded by the cofferdam could

be up to 10m deep to allow for works below the finished level of the slipway. In

order to minimise the internal strutting within the cofferdam, it is proposed to

construct the lower 40m of slipway in two sections 80m wide by 20m long, each

within cofferdams immediately adjacent to each other. It would be possible to

minimise costs by installing the two cofferdams one after the other, re‐using the

common wall of sheet piling between the two positions.

6.4.2 Closures/Diversions

The proposed site for both north and south slipways is within (or very close to) the

safeguarded corridor for the Thames Gateway Bridge. In the vicinity of the

infrastructure itself, there are no existing highways that would require closure or

diversion in the construction or operation phases.

On the south bank of the river, the scheme will need to take account of the existing

Thames Path. It is anticipated that pedestrians crossing the main access route to the

ferry can be accommodated by an at‐grade crossing where vehicles boarding or

alighting the ferry would have priority to eliminate delays to the ferry schedule.

6.4.3 Utilities

Based on information available for the area, there are no known utilities within the

footprints of either the northern or southern slipways.

Connections will need to be made to the electricity network for provision of power to

tolling equipment, operational facilities and navigational lighting. Existing power

networks are available in the vicinity of each slipway to which these connections are

assumed to be possible.

In the case of navigational marking equipment, an uninterruptable power supply will

need to be provided. This is anticipated to consist of a back‐up generator in the

vicinity of the operator facilities at each slipway.

Telecommunications lines will also be necessary for the use of the operator and to

convey tolling information to a control centre which is assumed to be remote from the

ferry location (ie. an addition to the existing London congestion charging scheme).

A mains water supply will need to be extended from the existing network to the

terminal locations for the provision of fire hydrants.




40

6.4.4 Programme

As for the propeller driven ferry option, the likely planning and procurement

programme for a chain ferry will retain the same logic as presented by Halcrow in the

2009/10 Woolwich Ferry Replacement and Gallions Reach Ferry Feasibility Study.

The start date for construction of a chain ferry is based upon the date of completion of

this planning and procurement programme.

An outline programme for construction of the chain ferry infrastructure is included in

Appendix H. This programme deals with construction works alone as defined in the

TfL brief for this task. Where appropriate, it is assumed that works are carried out

simultaneously on each side of the river. However, mobilization of multiple marine

piling rigs is not considered cost effective and would present a greater navigational

obstacle. Piling on one side of the river at a time will introduce a sequenced

construction for the slipways.

The overall construction duration from mobilisation to commencement of operation

is estimated to be two years and nine months. This is some six months longer than the

construction duration for propeller driven ferry infrastructure and reflects the use of

largely prefabricated elements in the other option.

6.5 Proposed Operational Procedures

The chain ferry infrastructure has been designed assuming a minimal level of

staffing. Whilst consideration of the number of crew on the ferry vessel is outside the

scope of this task, it is recognized that navigation and berthing for a chain ferry will

require only a few crew members. The crew can have a relatively lower level of skill

in comparison to propeller driven ferry crew, as the course of the vessel is

predetermined by the route of the chains. It is assumed that the ferry crew will also

be able to deal with the positioning of boarding traffic and this is likely to be the

major factor in determining the number of crew.

Landside operations could feasibly be carried out with as little as two operatives on

each side of the river. This eliminates the hazards associated with lone working in the

relatively remote location whilst providing flexibility to allow continual operation

whilst one operative deals with user issues or takes a break.

Waiting vehicles would queue at the top of the slipways behind the line of the flood

defences. Given the relatively short straight length of the slipways, an operative at the

head of queue would be able to judge when to release the queuing vehicles, keeping a

tally of PCUs. If more than a full ferry load of vehicles is queuing, a number of

vehicles corresponding to slightly lower than the capacity of the vessels would be

released by the landside operative thought this is less critical than for the longer

approach to a propeller driven ferry and final additions to the number of vehicles

could be made relatively quickly.

Waiting pedestrians and cyclists could queue at the top of the slipway, with suitable

provision of shelter as discussed in this report under ancillary structures. The use of a

slipway and ferry ramp will enable access for mobility impaired users, however the

gradients are relatively steep. The only practicable solution would be for ferry staff to

assist passengers when required.

As physical segregation from vehicles is not possible with a chain ferry, non‐

motorised users would have to be carefully controlled to ensure segregation from




41

vehicles. Segregation in time (ie. pedestrians and cyclists are released either before

vehicles are allowed to board or after all vehicles have boarded) is the safest

procedure, but this would increase alighting and boarding times and subsequently

affect crossing frequency. Taking an example from the Torpoint Chain Ferry, signage

and staff announcements could be employed to ensure the safe passage of non‐

motorised users at the same time as vehicles.

Alighting would need to be controlled by the ferry crew to ensure lines of vehicles on

the vessel are released in such a way that a bottleneck as they approach the fewer

number of lanes on the highway network is avoided.

It is assumed that pedestrians and cyclists would use the ferry service free of charge.

Whilst it would be relatively simple to keep a tally of the number of non‐motorised

users as they board the ferry, this is not considered to be necessary for a crossing at

Gallions Reach. As for the propeller driven ferry, this service is considered to be

exempt from the Merchant Shipping (Counting and Registration of Persons on Board

Passenger Ships) Regulations 1999. It should be noted that an application for

exemption from these regulations needs to be made to the local Maritime and

Coastguard Agency Marine Office.

When the ferry is not in service (ie. outside operating hours), it is anticipated that one

vessel would be moored at each of the slipways. However, the variation in tidal range

would require each vessel to be moored just short of the slipway. If the vessel were to

be moored closer to the shore at high tide, it could be beached until the next high tide,

which may not coincide with the scheduled resumption of service. Dedicated access

to and from the vessel will need to be provided for crew at the beginning and end of

each day. Whilst a bespoke gangplank arrangement could be designed, it is

envisaged that a simple and effective solution would be to provide a small craft for

crew access as part of the vessel specification.

It should be noted that overnight mooring of the vessels off the lower end of the

slipways would not cause them to encroach into the navigation channel in the river.

6.5.1 Maintenance

The removal of the ferry vessels and transportation to a suitable maintenance facility

is a more complicated operation for a chain ferry than for a propeller driven ferry.

Once removed from the chains, the vessels are assumed to be tugged to a remote dry

dock facility for maintenance. Until the ferry design is finalised such facilities cannot

be investigated, but this aspect is outside the scope of the infrastructure preliminary

design task. It is however considered that maintenance activities themselves would

be relatively simple and many tasks could be carried out without the need to take the

vessel away.

The remaining maintenance tasks will primarily consist of cleaning the slipways of

river deposits which would make them slippery and dangerous to users. An example

form the Torpoint Ferry is the most likely solution. A tractor at each slipway is used

with a purpose built cleaning tool on the front. This brushes and collects arisings

from the slipway which can then be deposited in a designated storage location for

collection and removal by a specialist contractor at regular intervals.




42

Figure 8 Slipway cleaning equipment used at Torpoint Ferry (Merlo 2007)

The chain ferry infrastructure has been designed on the basis that dredging will not

be required for construction or throughout the service life of the ferry.




43

7 Estimates of Alighting and Boarding Times Initial estimates of alighting and boarding times have been developed assuming a

system with 2 traffic lanes. For modelling the unloading and loading of the ferry, a

microsimulation model called VISSIM (developed by Planung Transport Verkehr

AG) was used. This is a car‐following model, which models the speed and gap

acceptance of drivers. It does this stochastically; different results will be produced

each time the model is run, as long as the random seed number is changed.

A fairly simple VISSIM model was created to model the vehicles loading on and off

the various ferry and highway configurations. This was primarily to observe the

occurrence of a “shockwave” or “concertina” effect, along the route from the waiting

area to the ferry. This is due to vehicles having to drop their speed when they go from

the linkspan to the pontoon (in the case of a propeller driven ferry) or from the

slipway to the ferry ramp (in the case of a chain ferry). This causes the vehicles

behind them to slow down, in turn impacting the vehicles behind these, creating a

wave effect which heads back up the line of vehicles, away from the linkspan or ferry

ramp where it started.

7.1 Propeller Driven Ferry

For the propeller driven ferry, additional VISSIM models have also been run for

terminal arrangements with four and six traffic lanes. The four‐lane model consists of

four lanes for marshalling vehicles on the approach structure and two lanes for

disembarking traffic. The advantage over the previous two‐lane model is that the

travel distance between the marshalling area and the ferry is reduced. The six‐lane

model consists of four marshalling vehicles on the approach structure and two lanes

for disembarking traffic with the same reduction in travel distance.

7.1.1 Two lanes – Assumptions for Alighting Model

In development of the VISSIM model for ferry alighting, the following assumptions

have been used:

This has the same dimensions as the loading model, but all the directions are

reversed;

It is assumed that only two of the 6 lanes of traffic in the ferry are allowed out

at any one time, to prevent a bottleneck between the pontoon and the

linkspan;

At the connection from the pontoon to linkspan, conflict areas are introduced,

to prevent the vehicles from the six different pontoon lanes running into each

other as they merge into the 2 lanes of the linkspan; and

There are no stop signs on this version of the model; the assumption is that the

vehicles can drive off the ferry.

7.1.2 Two lanes – Results of Alighting Model

The VISSIM model for alighting of the ferry using the above assumptions produces

the following results:




44

The shockwave effect does not occur as vehicles start off at less than 5mph,

and then increase their speeds to 10mph, rather than the other way round;

The model was run ten times. Each time, after 440 seconds (7 minutes and 20

seconds) all vehicles have disappeared from the system;

The first vehicle disappears from the system typically at 110 seconds (1

minutes and 50 seconds) in; and

The last vehicle has left the ferry typically around 342 seconds (5 minutes and

42 seconds) in.

The following figures show screenshots from the VISSIM model where the different

coloured “vehicles” represent the different lanes of traffic.

Figure 9 Screenshot of VISSIM 2-lane alighting simulation after 70 seconds



7.1.3 Two lanes – Assumptions for Boarding Model

In development of the VISSIM model for ferry boarding, the following assumptions

have been used:

No vehicle in the model travels faster than 10mph;

The linkspan and approach structure combined are represented as a 280m two

lane highway, with no lane change allowed;

Ferry

Linkspan

Pontoon

Approach structure




45

The linkspan is represented as a reduced speed area on the last 60m of this

section, with a maximum speed allowed of 5 mph;

The pontoon is represented as 6 connectors (length 28m), which connect the

two lanes of the linkspan and approach structure to the 6 lanes of the ferry.

These also are a reduced speed area, with a maximum speed allowed of 5mph;

The ferry is represented as a 6 lane section. It is a reduced speed area, with a

maximum speed allowed of 5mph;

It will take at least 5 seconds for vehicles to park once on the ferry. This is

represented in the model with a stop sign, at which the vehicles are delayed

for 5 seconds. After reaching the end of the ferry, vehicles wait for 5 seconds

then disappear from the model;

The distance of the ferry section which vehicles must drive across, is reduced

for vehicles entering the ferry later. As a compromise the section representing

the ferry is half the length of the actual ferry; and

The simulation starts with the first car leaving the marshalling area on the

land side of the river wall.

7.1.4 Two lanes – Results of Boarding Model

The VISSIM model for boarding of the ferry using the above assumptions produces


90 vehicles are uploaded into the system, with 15 set to go at each of the 6

possible routes available at the pontoon;


seconds) all vehicles have disappeared from the system. Note that this

disappearance occurs after vehicles have reached the section representing the

ferry;

It is about 240 seconds (4 minutes) until the last vehicle has entered the system

(ie. the last car has left the marshalling area);

It is about 130 seconds (2 minutes 10 seconds) until the first vehicle disappears

from the system (ie. the first car is parked.) This is a more conservative

estimate than was previously used;

It seems thus safe to assume that the previous estimate of 8 minutes for

loading is safe; and

The shockwave effect is observed slowing vehicles down.






46

Figure 12 Screenshot of VISSIM 2-lane boarding simulation after 60 seconds




7.1.5 Four lanes – Assumptions for Alighting Model


have been used:

For this version of the model, the combined linkspan and approach was

represented as a 90m section, with two lanes and no lane changing allowed;

From this six connectors represent the six lanes on the pontoon; these connect

the two lanes of the linkspan to the six lanes on the ferry. They all have a

horizontal length of 30m;

Vehicles in the model can go a maximum speed of 10mph, however a 5mph

reduced speed area is present on the linkspan, the pontoon and the ferry;

As with the previous alighting models, it is assumed that only two of the six

lanes of traffic on the ferry are allowed out at any one time, to prevent a

bottleneck between the pontoon and the linkspan; and




47

There are no stop signs on this version of the model; the assumption is that the

vehicles can drive straight off the ferry.

7.1.6 Four lanes – Results of Alighting Model




seconds) all vehicles have disappeared from the system. The median time

taken for all vehicles to disappear was 391 seconds (6 minutes 31 seconds);

The first vehicle disappears from the system typically at 71 seconds in; and

The last vehicle has left the ferry typically around 342 seconds (5 minutes and

22 seconds) in.


7.1.7 Four lanes – Assumptions for Boarding Model


have been used:

This was broadly the same as the four‐lane alighting model, but with the

directions reversed;

Vehicles in the model can go a maximum speed of 10mph, however a 5mph

reduced speed area is present on the linkspan, the pontoon and the ferry; and

As with the previous boarding models, stop signs at the end of the ferry link

delay the vehicles for 5 seconds before they disappear from the model.

7.1.8 Four lanes – Results of Boarding Model






ferry. The median time taken for all vehicles to disappear was 385 seconds (6

minutes 25 seconds);




48

It is about 281 seconds (4 minutes and 41 seconds) until the last vehicle has

entered the system (ie. the last car has reached the end of the marshalling

lanes on the approach structure); and

It is about 87 seconds until the first vehicle disappears from the system (ie. the

first car is parked on the ferry).


7.1.9 Six lanes – Assumptions for Alighting Model

In the six lane version of the model, there are still only two lanes available for

alighting, so this is considered to have the same alighting assumptions as the

four lane alighting model.

7.1.10 Six lanes – Results of Alighting Model

In the six lane version of the model, there are still only two lanes available for

alighting, so this is considered to have the same alighting results as the four

lane alighting model.

7.1.11 Six lanes – Assumptions for Boarding Model


have been used:

For the six lane loading model, the approach structure and linkspan are now

represented as two 90m two‐lane sections, with no lane changing allowed;

As with the previous loading models, stop signs at the end of the ferry section

delay the vehicles for 5 seconds before they disappear from the model;

The pontoon is now represented as six sections, with a horizontal length of

30m. These connect to the four lanes of the two sections as is shown in the

screenshot below:




49

Figure 18 Key to VISSIM 6-lane boarding regime

The traffic is loaded into the system as shown in Table 5 below:

Route Linkspan/Approach

section Pontoon section Number of PCUs

1 Linkspan 2, lane 2 1 15








Table 5 Boarding regime with six-lane arrangement for propeller driven ferry

Vehicles in the model can travel at a maximum speed of 10mph, however a

5mph reduced speed area is present on the linkspan, the pontoon and the

ferry.

7.1.12 Six lanes – Results of Boarding Model








Linkspan 2

Lane 1 Linkspan 1

Pontoon section

1

Lane 1

Lane 2

Lane 2 Ferry2

3

4

5

6




50


entered the system (ie. the last car has reached the end of the marshalling

lanes on the approach structure); and

It takes similar periods of time (ie. around 87 seconds) for the first vehicle to

leave the system, as it does for the four lane loading model. The additional

lanes do not speed the first vehicle out; they do however reduce delay for

vehicles queuing behind.


7.1.13 Summary of Overall Alighting and Boarding Time

The brief from TfL for estimating alighting and boarding times requires consideration

of the time taken from the ferry arriving at the terminal to the ferry departing. No

account is therefore taken of crossing or berthing time.

Combining the estimates of alighting and boarding times from the VISSIM model as

described in the above sections, the total anticipated times for alighting and boarding

with each arrangement of traffic lanes is given in Table 6 below:

Distance travelled in each

direction to/from ferry

Number of queuing

lanes

Total alighting &

boarding time

2 lanes 308m 2 (on land) 15 mins

4 lanes 88m 2 (top of linkspan) 13 mins

6 lanes 88m 4 (top of linkspan) 12 mins

Table 6 Comparison of alighting and boarding times for propeller driven ferry

7.2 Chain ferry

Additional VISSIM models are not considered necessary for the chain ferry with

different configurations of traffic lanes. In this instance, alighting and boarding times

have been estimated using a two‐lane VISSIM model only. The approach to the chain

ferry slipway is a straight section of road from the marshalling area, the length of

which does not vary between the different arrangements of traffic lanes, and there is

no physical restriction on the slipway to the number of traffic lanes that can be

accommodated. For this reason, the times for multiple lane arrangements are based

upon a pro‐rata of the two‐lane model results.




51

7.2.1 Assumptions for Alighting Model


have been used:

This has the same dimensions as the loading model, but all the directions are

reversed;

It is assumed that only two of the 6 lanes of traffic in the ferry are allowed out

at any one time, to prevent a bottleneck on the slipway;

At the connection on the slipway, conflict areas are introduced, to prevent the

vehicles from the six different lanes running into each other as they merge

into the 2 lanes of the landside highway; and

There are no stop signs on this version of the model; the assumption is that

the vehicles can drive straight off the ferry.

7.2.2 Results of Alighting Model



The shockwave effect does not occur as vehicles start off at less than 5mph,

and then increase their speeds to 10mph, rather than the other way round;


seconds) all vehicles have disappeared from the system;

The first vehicle disappears from the system typically at 54 seconds in; and

The last vehicle has left the ferry typically around 340 seconds (5 minutes 40

seconds) in.





Ferry

Slipway

Approach highway




52


7.2.3 Assumptions for Boarding Model


have been used:

No vehicle in the model travels faster than 10mph;

The access to the top of the slipway is represented as a 60m two lane road,

with no lane change allowed;

The slipway is represented as 6 connectors (length 60m), which connect the

two lanes of the access to the 6 lanes of the ferry;

The ferry is represented as a 6 lane 50m section. It is a reduced speed area,

with a maximum speed allowed of 5 mph;

It will take at least 5 seconds for vehicles to park once on the ferry. This is

represented in the model with a stop sign, at which the vehicles are delayed

for 5 seconds. After reaching the end of the ferry, vehicles wait for 5 seconds

then disappear from the model;

The distance of the ferry link which vehicles must drive across, is reduced for

vehicles entering the ferry later. As a compromise the section representing

the ferry is half the length of the actual ferry. For the chain ferry version, the

ferry section is thus 50m long; and

The simulation starts with the first car reaching the access to the top of the

slipway.

7.2.4 Results of Boarding Model



90 vehicles are uploaded into the system, with 15 set to go at each of the 6

possible routes available at the slipway;







entered the system (ie. the last car has reached the access to the top of the

slipway);




53

It is about 60 seconds (1 minute) until the first vehicle disappears from the

system (ie. the first car is parked.); and

The shockwave effect is observed slowing vehicles down a little, but not

much for this version of the ferry, as the slowing down occurs at one of the 6

entries to the ferry, rather than one of only two entries to the linkspan on the

propeller driven option. This means vehicles can avoid other vehicles by

taking a different access at the slipway, rather than being slowed down by

them.










54

7.2.5 Summary of Overall Alighting and Boarding Time

The brief from TfL for estimating alighting and boarding times requires consideration

of the time taken from the ferry arriving at the terminal to the ferry departing. No

account is therefore taken of crossing or berthing time.

Combining the estimates of alighting and boarding times from the VISSIM model as

described in the above sections, a total time of 665 seconds or 11 minutes and 5

seconds is anticipated. However, this is based on a boarding time of around 5

minutes and an alighting time of around 6 minutes which results from each vehicle in

the model having a pre‐determined lane on the ferry and vehicles being able to fan

out into more than two lanes on the slipway approach. In reality, the boarding time

can be expected to be slightly longer as each driver receives and reacts to directions.

Another anomaly arises from the fact that the position of a chain ferry on the slipway

can vary in two dimensions according to tides and currents. This makes it impossible

to provide a physical separation between pedestrians and vehicles. The only

longitudinal physical barrier on the slipways would be the chains for the ferry but

pedestrians cannot be expected to step over these chains and the area of slipway

beyond them may not be as easy to keep clean of slippery deposits as the central

section.

Separation of pedestrians and vehicles could be managed at each berthing by the

erection of temporary barriers, signage or staff announcements. This could allow

simultaneous movement of pedestrians and vehicles but would be a very labour‐

intensive approach. Separation in time is the most appropriate solution but this will

result in a further increase in the boarding and alighting times. The operational

regime for deal with safe segregation of users will need to be developed by the ferry

operator.

7.2.6 Additional Traffic Lanes

The VISSIM microsimulation used to estimate alighting and boarding times was

developed on the assumption that there are two lanes of queuing traffic waiting at the

top of the slipways. Unlike the propeller driven ferry terminals, there is greater

flexibility on the slipways to increase the number of traffic lanes.

Widening of the approaching highways to allow four or six lanes of queuing traffic

would clearly speed up boarding times, provided all lanes can be boarded

simultaneously. There would be an additional benefit in using six lanes for queuing

traffic as each lane would then directly correlate to a position on the ferry vessel and

remove the need for directing vehicles. This would be different from other examples

of chain ferries (eg. Torpoint ferry), where vehicles may only alight and board in

single file. Alighting vehicles would have to join the existing highway network at

some point and reducing from six or four lanes to one is expected to cause a

significant “bottleneck” which could tail back far enough to interfere with loading

operations. For this reason, the same number of alighting lanes has been assumed

throughout; hence alighting times are unchanged.

Table 7 below shows a comparison of the estimated alighting and boarding times for

each configuration of traffic lanes:




55

Distance travelled in each

direction to/from ferry

Number of queuing

lanes

Total alighting &

boarding time*

2 lanes 120m 2 11 mins

4 lanes 120m 4 8.5 mins**

6 lanes 120m 6 7.5 mins**

Table 7 Comparison of alighting and boarding times for chain ferry

* minimum time assuming simultaneous boarding and alighting of non‐motorised

users without single file boarding and alighting of vehicles

** pro‐rata estimation of boarding times (validated from VISSIM model results for

multiple lanes on propeller driven ferry)

7.3 Validation of Alighting and Boarding Time Estimates

Based upon information in the previous Halcrow feasibility study into ferry crossings

of the River Thames, it is understood that the existing Woolwich Ferry, which uses a

linkspan arrangement with a four‐lane approach structure, has a capacity of 35 PCUs

and requires a total of 5 minutes for alighting and boarding. In consideration of the

similar four‐lane propeller driven ferry option with a capacity of 90 PCUs, a pro‐rata

increase in alighting and boarding times would match the 13 minute estimate

presented in Table 6 above.




56

8 Discussion of Alternatives

8.1 Re-use of Existing Woolwich Ferry Vessels

An idea postulated by TfL’s expert advisor Bill Moses is to use the existing Woolwich

ferry vessels (with modifications) as pontoons in the new propeller driven ferry

terminals at Gallions Reach. Previous studies and inspections (most recently by

Lloyds Register in June 2010) of the vessels themselves have concluded that they still

have sound hull integrity. This suggests that, with ongoing maintenance, they could

remain afloat for many years to come.

Figure 27 Existing Woolwich Ferry vessel (Halcrow, 2009)

Whilst this idea could be technically feasible, it is believed that the necessary

modifications to the existing vessels would be prohibitively costly in comparison to

the provision of new purpose‐built pontoons. Likely modifications to the vessels

would include widening of the vehicle deck, sealing and ballasting to ensure the

vessels sits at the correct height in the water for the new ferry and removal of the

headroom obstruction posed by the current wheelhouse structure and associated

strengthening works to accommodate the possible loss of structural integrity such

modifications may cause.

Any new ferry service at Gallions Reach will have to be constructed whilst the

existing Woolwich Free Ferry service continues to operate. The Woolwich service

currently has three vessels; the Ernest Bevin, the John Burns and the James Newman.

Two vessels are normally in operation at any one time to provide a frequency of

approximately six crossings per hour in each direction. If two vessels were used as

pontoons for the new ferry terminals, only one vessel would remain in operation at

Woolwich, thus halving the frequency of crossings and introducing the risk of a

complete lack of service should the last remaining vessel break down.




57

In summary, whilst there is merit on the grounds of sustainability in re‐using the

existing Woolwich vessels, cost and impracticalities are judged to far outweigh the

benefits that such a proposal could realise.

8.2 Alternative Linkspan Arrangement for Propeller Ferry

In the process of developing a preliminary design for the ferry infrastructure options,

Halcrow has considered an alternative solution which may realise improved cost

effectiveness and operational regimes. As discussed in the basis of the preliminary

design Autotrack swept path analysis of HGV manoeuvres on the pontoon led to the

decision by TfL to adopt a curved approach structure to reduce or eliminate the need

to turn large vehicles on the pontoon itself. This principle then establishes the

possibility of removing the pontoon from the system altogether. A solution without a

pontoon also eliminates the sensitivity of such a large floating structure to wave and

wash action in the river.

The suggested arrangement for this alternative system is to have a lifting mechanism

at the end of each linkspan which follows the level of the tide through mechanical

control. Figure 28 and Figure 29 show similar arrangements designed by Halcrow for

Dublin Port in 2000. This is a similar principle to the current Woolwich arrangement

but, unlike at Woolwich where linkspans are raised and lowered fully at each

berthing operation, the relative levels of the linkspans and the water would remain

constant. Fine adjustment of the linkspan level could be controlled remotely from the

ferry as it approaches to berth.

Figure 28 Single deck mechanical linkspan at Dublin Port (Halcrow, 2000)




58

Figure 29 Double deck mechanical linkspan at Dublin Port (Halcrow, 2003)

It is envisaged that the operational regime for this type of terminal would include

lifting the linkspans to their uppermost position at the end of each day and locking

them in place to remove any load from the lifting mechanism.

TfL’s experience with the Woolwich Ferry suggests that a mechanical linkspan lifting

system would be subject to regular maintenance. Advances in technology and the

lesser strain on lifting equipment anticipated from less usage would be expected to

demonstrate the viability of this alternative. Halcrow has not carried out detailed cost

estimation as part of this task, but a cost saving in comparison to the proposed

solution utilising pontoons is confidently predicted.

Halcrow recommends that TfL investigates this option further as a separate study.

8.3 Self-Beaching Propeller Ferry

Section 6.3.1 refers to conventionally powered beaching type ferries. These were not

part of the original scope for this task, but have been considered at the request of TfL.

A self‐beaching propeller driven ferry utilises a slipway and ramp access in a similar

fashion to a chain ferry. There are numerous examples of self‐beaching ferries in the

UK, particularly in Scotland.

It is possible that a self‐beaching ferry can operate with a narrower slipway than the

chain ferry options explored in this task. This could have the advantage of more cost

effective infrastructure but would require a considerable level of skill in the crew for

navigation and berthing. Berthing with a ramp from the ferry onto the slipway is

usually sufficient to hold the vessel in position, however the River Thames is subject

to a particular regime of tides and currents that it is considered would render this

berthing method impossible. The vessel would have to be held in position with

berthing dolphins and, given that currents can act in both upstream and downstream

directions, such dolphins would need to be provided to both sides of the intended

berthing lane on the slipway.




59

Provision of berthing dolphins is expected to require a widened slipway to

accommodate some manoeuvring of the vessel. As a result, the slipway dimensions

are likely to be similar to that for a chain ferry.

The self‐beaching vessel itself would require a similar level of maintenance to the

conventional propeller driven ferry in terms of complexity and number of

interventions.

Although a self‐beaching propeller driven ferry option has several similarities to a

chain ferry, it is discounted as an alternative on the grounds that it is less

advantageous on the grounds that it requires additional berthing dolphins when

placed in the River Thames, a higher level of crew skill and is likely to have a more

costly maintenance regime.

Figure 30 Typical self-beaching propeller ferry (MV Loch Dunvegan – Caledonian MacBrayne)




60

9 Hydrodynamic Impact Assessment This assessment is based on design documents and drawings currently available for

each option. The current revision of documents, that are to provide the basis of

further design work currently being undertaken, are being used as the basis of the

hydrodynamic impact assessment. It is considered that the majority of further design

work currently being undertaken will have little effect on the hydrodynamic impacts

since features such as bridge piers or slipways are not likely to be modified

significantly.

Within the scope of this study, it is not possible to develop a detailed quantitative

analysis of each of the options. The study provides a comparative qualitative analysis

of each of the options supported by simple calculations where appropriate.

9.1 Hydrodynamic Features

The principal effect of each option is to cause a local change in the flow area of the

river channel in the vicinity of the structure. The hydrodynamic impact of the

structure depends, primarily, on the blockage ratio at the structure, defined in this

case, as the loss of cross‐sectional area as a percentage of the total flow area, without a

design option in place. It is calculated by comparing the cross sections of the river at

the appropriate location at both high and low spring tide with those of the river with

a design option added. Any features of the design that reduce the cross‐sectional area

are subtracted from the total area to yield the effective cross‐sectional area of each

design.

The addition of features along a parallel plane to the cross‐section considered may

cause localised upstream or downstream effects but this cannot be quantified without

a full analysis based upon a detailed hydrodynamic model. For the purposes of

option comparison, the use of blockage ratios is considered to be a suitable

calculation methodology.

In order to calculate the blockage ratios, the provided design drawings have been

used to develop cross sectional areas at the crossing location, using the chainage and

bed elevation values. These are then compared to the altered cross sections associated

with each option to evaluate changes in area.

9.1.1 Flow rates

The increase in water level (Afflux) associated with the design has been calculated

over a range of flows. The flows used cover a range representing a spring tide event.

These would be the highest flows normally expected in the tidal reaches of the

Thames and as such would represent the highest values of Afflux. The Afflux values

calculated therefore represent a worst case scenario.

9.2 Ferry

Blockage ratios throughout this report have been determined in the same manner as

in the existing feasibility study; Woolwich Ferry Replacement and Gallions Ferry

Feasibility Study undertaken by Halcrow in 2010.




61

Option

MHWS (3.8mOD) MLWS (‐2.8mOD) MWL (0.5mOD)

CSA

(m2)

HSA

(m2)

BR

(%)

CSA

(m2)

HSA

(m2)

BR

(%)

CSA

(m2)

HSA

(m2)

BR

(%)

2 Propeller

Driven

Ferries

3126 3031 3.0 7145 6951 2.7 4927 4779 3.0

2 Chain

Ferries (solid

slipways)

3126 3009 3.7 7145 6503 9.0 4927 4607 6.5

Table 8: Ferry Option Blockage Ratios

Where:

CSA: Cross ‐ sectional Area

HSA: hydro ‐ structure Area (CSA minus area of slipway, piles, pontoons etc)

BR: Blockage Ratio = 100 x (HSA/CSA‐1)

The chain ferry (with a solid slipway) has a greater Blockage Ratio than that of the

propeller driven ferry option, particularly at low tide, due in large to the need for

fixed concrete slipways on both the north and south banks of the Thames. Minimal

blockage ratio occurs through the propeller driven ferry option as the majority of the

access structures are hinged and are able to float meaning that they do not obstruct

the flow area.

9.2.1 Effect on Water Level

The HDS1‐hydraulics of bridge waterways method has been used to estimate the

backwater associated with the constriction of flow area associated with construction

of slipways and other structures incorporated in the design for a range of flows,

covering the expected maximum flow for a spring tide, at mean water level of

0.5mOD. The analysis is based on the equation shown below, where the k* and αtermsarebasedonblockagesandtheassociatedchange invelocityused todeterminetheAfflux.

∗ ∗ ∝2

∝2

The results are tabulated in Table 10 and Table 9 below.




62

Flow rate (m3/s) MWL (mOD)Average

velocity (m/s)Afflux (m) Afflux (mm)

1000 0.5 0.209 1.110x10‐4 0.1

2000 0.5 0.418 4.470x10‐4 0.4

3000 0.5 0.628 1.010x10‐3 1.0

4000 0.5 0.837 1.787x10‐3 1.8

Table 9: Back water Effect of Propeller Driven Ferry Option, calculated using the method described in HDS1- Hydraulics of Bridge Waterways.



1000 0.5 0.217 2.403x10‐4 0.2

2000 0.5 0.434 9.615x10‐4 1.0

3000 0.5 0.651 2.163x10‐3 2.2

4000 0.5 0.868 3.846x10‐3 3.8

Table 10: Back water Effect of Chain Ferry Option (solid slipway), calculated using the method described in HDS1- Hydraulics of Bridge Waterways.

9.2.2 Effects on Tidal Propagation

It is not anticipated that either of the ferry options will cause, other than locally,

significant changes to the propagation of tidal water levels in the Thames.

9.2.3 Effects on Flow Distribution

At lower tides, when the floating pontoons and jetties for the propeller driven ferry

are nearer to the channel bed, the flow velocity beneath them will increase, likely

increasing scour of the bed.

For the chain ferry option (with solid slipways), the majority of the redistributed flow

will be directed into the middle of the channel by the slipways which will increase

current speed and disrupt flow paths, making both velocity and direction of flow in

the area more varied.

Flows in the shallower waters towards the river margins will become more variable

in both speed and direction where flow velocities are increased and scour would

likely occur, whilst in areas of slower moving flow, accretion is likely.

Changes to the local suspended solids regime will be experienced while the riverbed

and inter‐tidal areas adjust to any changes during and following construction.

9.2.4 Effects on Sediment Transportation

The chain ferry option (with solid slipways) will introduce obstructions to the flow

within the channel potentially causing areas of more turbulent flow. There is also

potential for areas to have reduced energy, such as at the base of the toe, giving rise

to opportunities for both scour and accretion to occur.




63

Local variations in velocity and flow around piles and spillways will have an impact

on the sedimentation processes that occur in the river. It is not possible to accurately

state what these effects will be. It is likely that some areas within the crossing will

experience scouring, whilst others may experience depositions of sediment

depending on the variances within the flow. It is thought that the downstream side of

the piles would experience some scouring whilst the upstream side of slipways might

experience depositions if the velocities in the water held behind the slipway became

too low.

If dredging is employed to obtain a foundation level for the construction of the

slipways, this could result in potential impacts on sediment transport and the

environment.

The movement of the chain, as a result of ferry crossing would likely impact on bed

sediment as it rises and drops again along its length as the ferry crosses. It is not

possible to determine the extent of this impact; however it is only likely to be a local

impact, resulting in small amounts of additional sediment potentially in the water

column.

9.2.5 Effects on Environment

The construction of slipways for the chain ferry option would likely impact on

migration of aquatic species in the river. Smaller species tend to stay in the shallower

water at the fringes of the river, and would potentially be affected by the slipways,

especially at lower tides, when the slipways represent a larger blockage over the

depth.

9.2.6 Effects on Navigation

Both of the ferry options will have a navigational impact. However the propeller

driven ferry option will have the lowest blockage factor and the smallest impact on

the flow regime within the navigation channel. The chain ferry option, with a

blockage factor of around 9% during low water would have a greater impact than the

propeller driven option.

The impact that the flow would have on navigation is only related to the velocity of

the flow in the navigational channel. For the chain ferry, the average velocity in the

channel would likely increase by 6.5% at mean water level, with a value of

approximately 3% for the propeller driven option.

Both options would result in regular ferry crossing which would pose a hazard to

navigation in the channel and the chain required for the chain ferry could pose a

continual issue for navigation, although when not in use it would lie on the river bed

to any other vessels in the channel. When crossing, the chain would be more elevated

in the channel and would pose a more substantial hazard to navigation.

9.3 Revised Chain Ferry (Piled Slipway)

Following geotechnical advice that a solid slipway for the chain ferry option would

be impractical, the hydrodynamic impact of a piled slipway has also been considered.

This updated version of the ferry crossing design, with cross sections as shown in

drawing 472413‐011, is likely to be comparable to the existing chain ferry design, with

hydrodynamic impacts assessed for a concrete slipway arrangement. The revised

design proposal incorporates a number of concrete deck sections, supported by




64

beams linking the pile supports along the width of the slipway. This creates a number

of small openings along the length of the slipways, through which water may pass.

Due to the small opening size, it is likely that the flow through these areas will be

restricted significantly.

Option


CSA

(m2)

HSA

(m2)

BR

(%)

CSA

(m2)

HSA

(m2)

BR

(%)

CSA

(m2)

HSA

(m2)

BR

(%)

2 Chain

Ferries

(piled

slipways)

3126 3009 3.7 7145 6503 9.0 4927 4607 6.5

Table 11: Revised Ferry Option Blockage Ratios

Table 11 shows the blockage ratios associated with the design at 3 water levels. It can

be seen that the blockage ratios are less than the other designs.

The blockage ratio represents the restricted flow area associated with a structure in

the flow. This can be used to estimate changes in velocity, flow and afflux. In this

case, the flow areas under the slipway make up a large part of the total area of flow.

Due to the size of the openings, and the associated head losses, this type of analysis

would not be appropriate.

It could therefore be reasoned that the slipways would have similar impacts on the

hydrodynamics, although slightly reduced, to those associated with the concrete

slipway option.

9.3.1 Effect on water level

It is likely that the design would have some impact on the upstream water level, as

with the other proposed options, this impact would probably be only a few

millimetres. Due to the nature of the design, the method previously used to

determine the extent of the effect would not be appropriate.

9.3.2 Effects on flow distribution

It is thought that some of the flow under the slipways will be directed into the main

channel, especially at high water when losses under the slipway would be more

significant. This would result in changes to velocity in the channel and with flow

directions being altered locally.

9.3.3 Effects on sediment transportation

The revised chain ferry option will alter the flow paths within the channel, causing

local variations in velocity and flow direction, with increased turbulence around the

pile supports. This could increase sediment uplift in the area, increasing scour around

the piles.

The movement of the chain, as a result of ferry crossing would likely impact on bed

sediment as it rises and drops again along its length as the ferry crosses. It is not

possible to determine the extent of this impact; however it is only likely to be a local




65

impact, resulting in small amounts of additional sediment potentially in the water

column.


The construction of slipways for the chain ferry option would likely impact on

migration of aquatic species in the river. Smaller species tend to stay in the shallower

water at the fringes of the river, and would potentially be affected by the slipways,

especially at lower tides, when the slipways represent a larger blockage over the

depth.


The impact that the flow would have on navigation is only related to the velocity of

the flow in the navigational channel. For the new chain ferry design, the average

velocity in the channel would likely increase by between 6.5% and 3%.

The option would result in regular ferry crossing which would pose a hazard to

navigation in the channel and the chain required for the ferry could pose a continual

issue for navigation, although when not in use it would lie on the river bed to any

other vessels in the channel. When crossing, the chain would be more elevated in the

channel and would pose a more substantial hazard to navigation.

9.3.6 Construction phase

The design proposes the use of cofferdams during construction; these would impact

on migratory marine species during the construction phase, and would also have an

impact on sediment transport. The size of the cofferdams, as shown on drawing

472413‐011 would suggest that the blockage associated with them would be large,

even compared to the size of the slipway blockage. During the construction phase,

the impacts discussed above, could therefore be more significant.

9.4 Bridge (Concrete Box Girder)

Blockage ratios have been calculated for the bridge option at a number of water levels

as summarised in Table 12 below. It can be seen that the blockage ratios associated

with the bridge design are higher than those of the Ferry options.

Option


CSA

(m2)

HSA

(m2)

BR

(%)

CSA

(m2)

HSA

(m2)

BR

(%)

CSA

(m2)

HSA

(m2)

BR

(%)

Box Girder

Bridge

Crossing

3086 2716 12.08 6966 6108 12.32 4927 4352 11.67

Table 12: Concrete Bridge Blockage Ratios

9.4.1 Effects on Water Level


backwater associated with the constriction of flow area associated with bridge

abutments and piers for a range of flows at mean water level of 0.5mOD. This is the

same method used to determine the Afflux associated with the ferry options.




66

The results are tabulated in Table 13 below.



1000 0.5 0.203 4.834x10‐4 0.5

2000 0.5 0.406 1.934x10‐3 1.9

3000 0.5 0.609 4.354x10‐3 4.4

4000 0.5 0.812 7.734x10‐3 7.7

Table 13: Back water Effect of Concrete Bridge Option, calculated using the method described in HDS1- Hydraulics of Bridge Waterways.

With only relatively minor blockages from the piers of the bridge, the increase in

upstream water level has been found to be in the order of a few mm, with levels

ranging from 0.5mm to 8.0mm.


It is expected that local variations in velocity around the bridge piers will occur

resulting in fluctuations in flow around the piers. It is thought that these effects will

be most significant at the pier on the outside of the river bend as velocity will be

higher in this area of the river due to the irregular horizontal velocity profile

associated with the river bend.


It is likely that changes to the flow paths in the river due to the piers will result in

areas of high velocity at the downstream end of the piers. It is thought that this could

result in high levels of scour downstream of the piers. At the abutment on the

northern bank of the crossing, the flow would probably be similarly affected. It is

thought that in this area, where flow could be restricted at high tides, deposition of

sediments could occur.


The use of cofferdams during construction would potentially have an impact on fish

populations within the river. The abutment arrangement on the northern bank may

affect migration of fish species.


The bridge design has been developed in line with the navigation clearance and

navigation channel width proposed for the TGB scheme, therefore there should be

limited impact, however the piers would represent an additional collision hazard.

9.4.6 Construction Phase

A number of temporary berthing and access jetties would be required during the

construction phase. It is likely that these jetties would significantly reduce the cross

sectional area of flow through the stretch of river, affecting flow, velocity and water

level locally. This could further impact on environmental factors and sedimentation

processes occurring in the river.




67

9.5 Bridge (Steel Arch)

Comparing the blockage ratios of the steel and concrete bridge options, it can be seen

that the blockages associated with the steel bridge (see Table 14 below) are slightly

lower.

Option


CSA

(m2)

HSA

(m2)

BR

(%)

CSA

(m2)

HSA

(m2)

BR

(%)

CSA

(m2)

HSA

(m2)

BR

(%)

Steel Arch

Bridge

Crossing

3086 2716 12.08 6966 6108 12.32 4927 4352 11.67

Table 14: Steel Bridge Blockage Ratios



backwater associated with the constriction of flow area associated with bridge

abutments and piers for a range of flows at mean water level of 0.5mOD. This is the

same method used to determine the Afflux associated with the ferry options.

The results are tabulated in Table 13 below.



1000 0.5 0.203 4.200x10‐4 0.4

2000 0.5 0.406 1.680x10‐3 1.7

3000 0.5 0.609 3.780x10‐3 3.8

4000 0.5 0.812 6.726x10‐3 6.7

Table 15: Back water Effect of Steel Bridge Option, calculated using the method described in HDS1- Hydraulics of Bridge Waterways.

The afflux associated with the steel bridge option, is, as for the blockage ratios,

slightly lower than the afflux associated with the concrete bridge. The afflux levels

range from 0.4mm to 6.7mm.


Although the blockage ratio associated with the steel bridge option is lower than that

of the concrete design, it would be possible for the design to have a greater impact on

the flow distribution as there are a higher number of bridge piers, each of which is

likely to affect the flow paths of water in the channel. If the new alignment was used,

the bridge would be closer to the river bend, and the flow would be less uniformly

distributed along its width, giving greater flow, and velocity in the deeper channel on

the outside of the bend. It is likely that any effects associated with the bridge piers

would be more significant in this area.




68


There is potential for scour to occur on the downstream side of the bridge piers as

with the concrete design. This again could be more prevalent on the outside of the

bend if the new alignment was used. As all of the bridge piers are free standing, it is

unlikely that large dead spots of flow would occur in the channel, and therefore large

depositions of sediment would be unlikely.


The use of cofferdams during construction would potentially have an impact on fish

populations within the river. The abutment arrangement on the northern bank may

affect migration of fish species.


The bridge design has been developed in accordance with PLA specifications for

navigation clearance and navigation channel width, therefore there should be limited

impact, however the piers would represent an additional collision hazard.


A number of temporary berthing and access jetties would be required during the

construction phase. It is likely that these jetties would significantly reduce the cross

sectional area of flow through the stretch of river, affecting flow, velocity and water

level locally. This could further impact on environmental factors and sedimentation

processes occurring in the river.

9.6 Immersed Tunnel

Option


CSA

(m2)

HSA

(m2)

BR

(%)

CSA

(m2)

HSA

(m2)

BR

(%)

CSA

(m2)

HSA

(m2)

BR

(%)

Immersed

Tunnel

Crossing

3086 4645 ‐50.53 6966 9089 ‐30.48 4927 6845 ‐38.94

Table 16: Immersed Tunnel Blockage Ratios

Negative blockage ratios, as shown above in Table 16, denote an increase in cross

sectional area. In this case the dredging of the crossing area is to a depth such that,

when the submerged tunnel is placed in situ and locking and cover back fill is added,

the depth of the river to the top of the protective cover layer of the tunnel is

significantly greater than the original depth of the river.


Due to the reduction in bed level that would result from the implementation of the

submerged tunnel option, there would be a local increase in the cross sectional area of

flow. Depending on the full extent of the dredged area around the tunnel, this would

likely have an impact on the water level locally; unlike other options, however the

water level would likely drop marginally.




69


Local variations in flow distribution may occur within the channel, especially during

construction where features are not uniform over the width of the river creating the

potential for transverse flow paths and vortices.


It is thought that lower velocities through the dredged area will likely result in

deposition over time as the channel bed reforms. Sedimentation is likely to occur on

rock protection layer over the tunnel. This effect would likely occur over a long

period of time, however if during the construction phase, a surge tide or large fluvial

flow occurred, it would be possible for sedimentation, significant enough to partially

fill in the dredged tunnel channel to occur.


It is possible that the dredging required for the immersed tunnel option would have

an impact on the migration and populations of fish and other aquatic species within

the river.


A number of short term closures of the river, required when the tunnel sections are

floated into place, will have an impact on navigation in the river. It is possible that the

dredging phase of construction, in which the tunnel channel across the river is

dredged out to the required level could impact on navigation. Once the construction

phase has been completed, there are no foreseeable impacts on navigation associated

with the design, as the net effect of the design will be the formation of a small section

of deeper channel within the crossing.


In order to construct the immersed tunnel, the individual tunnel sections would have

to be manoeuvred into place on jetties or on floating barges. If jetties were used, they

would likely have a larger impact on water level as they would represent a larger

blockage ratio.

9.7 Bored Tunnel

It is not expected that the construction of a bored tunnel will have any significant

impact on the hydrodynamic feature of the Thames at Gallions Reach. The only issue

would arise from potential bed deformation as a result of the tunnelling, possibly

resulting from unforeseen geological features beneath the channel.

9.8 Conclusions

It is expected that all of the options, except the bored tunnel option would have an

impact on the hydrodynamics of the river locally at the crossing, the extent of which

would vary depending on tide and water level at the crossing.

Both of the ferry options and the bridge options would have an impact on the flow

distribution in the channel. A reduction in flow area results from each of these

options, and it is likely that this would result in changes in velocity in the channel as

well as an increased upstream water level. The changes in velocity could impact on




70

the sediment transport occurring in the river with the possibility of increased scour or

deposition occurring. There are likely to be impacts on navigation and environmental

factors such as fish migration during the construction phase of both the ferry and

bridge options due to the necessity of cofferdams during construction and the use of

additional access jetties during the bridge construction.

No issues have been identified for the bored tunnel option. The immersed tunnel

option is likely to have significant navigational and environmental impacts during

the construction phase due to large scale dredging and the positioning of the tunnel

sections. Initially, the immersed tunnel option would result in an increased flow area

over the dredged site and in the vicinity of the tunnel, it is possible however, that

over time, sediment depositions would accumulate in this area, re‐establishing the

bed topography to similar to the existing bed profile.

Table 17 below shows a comparison of the effects of each option in the long‐term

permanent case. The table shows a comparison in the likelihood and severity of the

effects on a scale, with 6 being the most likely or severe impact and 1 being the least

likely or the least severe.

Options

Effect Chain

Ferry*

Propeller

Ferry

Concrete

Bridge

Steel

Bridge

Immersed

Tunnel

Bored

Tunnel

Blockage Ratio 2 1 4 3 N/A N/A

Afflux

(low flow) 2 1 4 3 N/A N/A

Afflux

(high flow) 2 1 4 3 N/A N/A

Flow

distribution 4 3 5 6 2** 1

Sediment

transportation 4 3 6 5 2** 1

Environment 6 3 4 5 2** 1

Key

Lowest hydrodynamic impact

Highest hydrodynamic impact

Table 17: Option impact comparison

* The hydrodynamic impact of the alternative chain ferry utilising a piled slipway is

assessed as being similar to that for a solid slipway.

** Impacts during construction phase and short term are likely to be more significant.

The long term impacts, as classified above, depend on the time required to re‐

establish the existing bed profile.




71

10 Environmental Issues A high level appraisal in terms of the key environmental issues and risks associated

with each option was carried out by Halcrow for the Woolwich Ferry Replacement

and Gallions Reach Ferry Feasibility study in 2009/10. The environmental constraints

within the immediate study area, and significant features outside the immediate area,

were identified.

Data sources used by Halcrow for the initial appraisal included existing data from

Natural England, Multi‐Agency Geographic Information for the Countryside

(MAGIC), the Environment Agency (EA), English Heritage as well as baseline

information from environmental statements in the area (such as the Thames Gateway

Bridge Draft Updated Environmental Statement 2008).

The topics previously assessed have been revisited and updated where appropriate

for the principles of the preliminary design as it has developed. These key issues

remain subject to ongoing review as the project continues into more detailed stages.

The comparison of design options takes environmental issues and risks into

consideration. It is anticipated that detailed design of TfL’s preferred crossing option

would include a more in‐depth environmental appraisal.

A summary of environmental issues considered is included in Appendix D. The

following sections highlight particular issues of note for each type of ferry

infrastructure.

10.1 Comparison of Ferry Types

In addition to the summary of environmental issues in Appendix D, the same key

topic headings have been considered in the comparison of propeller driven and chain

driven ferry options. The results of this comparison are presented in Table 18 below:




72

Topic Propeller Driven Ferry Chain Ferry

Energy use and

material use

It is generally considered that a propeller driven ferry will use

more energy as it work against currents and makes berthing

manoeuvres. However, less frequent crossings are anticipated

which will offset this to some extent.

The structural components for the terminals (particularly

linkspans and pontoons) are likely to embody a significant

amount of energy in their production.

It is generally considered that a chain ferry will use less energy.

However, more frequent crossings are anticipated which will offset

this to some extent.

Depending upon the type of slipway used (ie. solid or supported

on piles), there could be significant quantities of concrete used for

this option.

General land use of

immediate area

There is no differentiation between the two options in this aspect as both options are in the same location.

Links with

transportation

Whilst very similar new highway links will be required to

service both options of ferry type, the propeller driven ferry is

expected to provide less of an improvement to accessibility

across the river as it would make fewer crossings per hour. This

is due to the effect on alighting and boarding times that the

length of the vehicular approach will have.

Whilst very similar new highway links will be required to service

both options of ferry type, the chain ferry is expected to provide a

greater improvement to accessibility across the river through more

frequent crossings. This is due to the more direct route for alighting

and boarding of vehicles.

Land take

requirements

Whilst very similar highway links will service both options of

ferry type, the propeller driven ferry will take less land in the

immediate area of the flood defence wall.

Whilst very similar highway links will service both options of ferry

type, the chain ferry is expected to take significantly more land in

the immediate area of the flood defence wall to accommodate a

slipway wide enough for two vessels.

Community and

pedestrian links

Whilst both options of ferry type will serve the same

community (including provision for pedestrians), the propeller

driven ferry is expected to make fewer crossings per hour due

to the effect on boarding and alighting times the length of the

vehicular approach will have.

Whilst both options of ferry type will serve the same community

(including provision for pedestrians), the chain ferry is expected to

make more crossings per hour due to the more direct route for

boarding and alighting of vehicles.

Biodiversity

There is little or no differentiation between the two options in

terms of the effect on landside biodiversity.

It is anticipated that disturbance to habitats in the river will be


terms of the effect on landside biodiversity.

The slipways necessary for a chain ferry are anticipated to have a




73

Topic Propeller Driven Ferry Chain Ferry

restricted by the use of a limited number of piles at each

terminal location.

significantly greater impact on biodiversity in the intertidal zone of

the river. This may be mitigated to a large extent by selection of a

“bridge” type slipway supported on piles.

Floodrisk There is no differentiation between the two options in this aspect as both options are in the same location.

Hydrodynamics

and sediment

transport

The propeller driven ferry is anticipated to have a

comparatively lesser effect upon hydrodynamics and sediment

transport (refer to Hydrodynamic Impact Assessment section of

this report).

The chain ferry is anticipated to have a comparatively greater effect

upon hydrodynamics and sediment transport (refer to

Hydrodynamic Impact Assessment section of this report).

Archaeology

(including UXO)

and heritage

features


terms of the effect on local archaeology or heritage features.

The smaller footprint of terminals for a propeller driven ferry

lessens the risk of discovering unexploded ordnance resulting

from extensive bombardment during the Second World War.


terms of the effect on local archaeology or heritage features.

The larger footprint of a chain ferry slipway increases the risk of

discovering unexploded ordnance resulting from extensive

bombardment during the Second World War.

Residential

properties,

receptors of air and

noise impacts

No air pollution impact is anticipated from the terminal

infrastructure. Modern propulsion systems are not anticipated

to present an air pollution issue. Given the existing use of the

river by other propeller driven vessels, noise at receptors is not

anticipated to increase with the introduction of the ferry service.

No air pollution impact is anticipated from the terminal

infrastructure. Modern propulsion systems are not anticipated to

present an air pollution issue. Whilst it is recognised that the noise

of chain ferry may be noticeable due to the difference from other

river traffic, modern chain ferries are not considered to be

particularly noisy.

Visual and

landscape impact

The infrastructure for a propeller driven ferry will comprise of

large pontoon and linkspan structures which will have a

significant visual impact for some distance along the river.

However, there are other large manmade structures in the

vicinity (eg. Barking flood barrier to the north and Tripcock Hill

to the south) which would remain dominant features.

Although terminals for a chain ferry will occupy a larger reach of

the river bank, their low‐level nature is expected to have a lesser

visual impact.

Table 18: Environmental comparison of ferry types




74

11 Risk Assessment Halcrow developed an initial risk register for the Woolwich Ferry Replacement and

Gallions Reach Ferry Feasibility Study in 2009/2010 through workshops with TfL.

This risk register is intended to be a live document which is to be developed further

under TfL’s ownership throughout the life of the scheme as options are progressed.

In order to continue the principles of risk management established in the previous

Halcrow study, the risk register presented in Appendix E has been revisited and

refreshed as appropriate for the scope of this preliminary design package. Each

existing risk item has been examined for its validity and ratings adjusted if necessary.

The issues highlighted in the risk register have been considered in the development

of preliminary designs. Any new risks that have emerged as the design process has

progressed have also been added to the risk register and given appropriate ratings.

11.1 Significant Risks

The most significant risks for a proposed ferry crossing at Gallions Reach are

summarised below:

Policy change following General, Local or Mayoral elections leads to

cancellation of scheme;

Existing safeguarding direction for crossing at Gallions Reach may be for a

bridge only, resulting in increased cost and delays associated with obtaining

necessary powers for a ferry crossing. Could possibly jeopardise the viability

of the scheme;

(Chain ferry only) Tidal river deposits on slipway causes slippery surface

which would be a danger to users;

(primarily chain ferry) EA will not give necessary consents due to

environmental or hydrodynamic impacts of the chosen design;

TWA Orders refused by Secretary of State, resulting in increased cost and

delays associated with obtaining necessary powers;

Higher cost of materials than anticipated;

Higher than anticipated tender prices from construction contractors; and

The following risks have been assessed as significant in the risk register but have

been mitigated in the preliminary design as described:

(Chain ferry only) Depth of unsuitable material to be removed for

construction of solid slipway is too large to be practicable/cost effective.

Mitigation: review geotechnical information and if necessary, choose a piled

slipway solution instead;

(Primarily propeller ferry) Further investigation of preliminary design options

results in infrastructure encroaching into the navigational envelope previously

considered in MARICO risk assessment.

Mitigation: design to consider repositioning of terminals as necessary to avoid

encroachment into navigational envelope, but navigational risk assessment

can be revisited if necessary;




75

Dredging may be necessary to accommodate larger vessels than originally

envisaged, which would damage habitats, increase construction costs and

present an ongoing maintenance liability.

Mitigation: design to consider repositioning of terminals as necessary to

eliminate the need for dredging as far as reasonably practicable;

Non‐motorised users endangered by vehicular movements and exposure to

elements.

Mitigation: design to include segregation of non‐motorised users from traffic

where possible with provision of adequate shelter; and

Welfare of operations staff.

Mitigation: design to include staff welfare facilities at each terminal.

11.2 Retired Risks from Previous Study

The previous version of the risk register was developed from a study which

considered a possible replacement of the existing Woolwich Ferry as well as a ferry

service at Gallions Reach. Several of the risks have been retired under the scope of the

Gallions Reach Marine Aspects task as they are applicable to the Woolwich operation

only.

A number of other risks have been retired as the brief for the Gallions Reach Marine

Aspects task addresses their causes. In the case of interface with construction works

for Crossrail, Thames Tideway Tunnel and the 2012 Olympic and Paralympic Games,

it is considered that ferry infrastructure construction will no longer overlap with the

demands on the local logistical network from these schemes.

The risk register in Appendix E continues to show all items, but those risks that have

been retired are annotated as such.

11.3 Construction (Design and Management) Regulations 2007

Through the development of preliminary design solutions in this task, Halcrow has

assumed the role of Designer as defined in Regulation 2 of the Construction (Design

and Management) Regulations 2007. Regulations 11 and 18 set out the duties of the

Designer which include the elimination of hazards and reduction of risks during the

design process as far as reasonably practicable. Any remaining health and safety risks

shall be advised for the benefit of the Client and future duty holders as the scheme

progresses.

In order to satisfy these requirements, a Designer’s Risk Assessment has been

prepared and is included in Appendix F.




76

12 Cost Estimates Cost estimates for each of the preliminary design options developed by Halcrow and

discussed in this report have been prepared for comparison by TfL with each other

and with other river crossing options.

12.1 Assumptions

The cost estimates contain a number of assumptions as follows:

Linkspans for the propeller driven ferry option will be fabricated off site and

transported by river (cost of transportation included in estimate);

Pontoons for the propeller driven ferry option will be fabricated off site and

floated up the river into position (cost of transportation included in estimate);

Marine piles will be of tubular steel construction, infilled with concrete;

The cost estimate for the chain ferry infrastructure includes the cost of chains

for the avoidance of doubt over their inclusion as part of the infrastructure or

part of the vessels;

The cost of any highway infrastructure is not included in these estimates as

this work is outside the scope of this task;

The four‐lane option for a propeller driven ferry incurs a pro‐rata cost increase

on approach structures from the two‐lane option. The pontoon widths

between two and four lane options can remain the same;

The six‐lane option for a propeller driven ferry incurs a pro‐rata cost increase

on approach structures, linkspans and pontoons from the two‐lane option;

The number of traffic lanes will not have an effect on the size of the slipway

for a chain ferry;

No allowance has been made for dredging, as it is assumed that this activity is

not permitted by PLA;

Staff accommodation cost estimates include for boundary fencing and

provision of slipway cleaning equipment in the case of the chain ferry option;

Maintenance of ferry vessels is assumed to be carried out in dry‐dock remote

from Gallions Reach and is not included in these cost estimates; and

Whilst it is assumed that the ferry service will be tolled, the cost of tolling

equipment cannot be quantified at this stage (and is outside the scope of this

task).

12.2 Risk and Optimism Bias

According to instruction from TfL, risk and contingency is excluded from the cost

estimate. However, it is recommended that a project risk contingency of 25% is

applied to the cost estimates presented in this report. This value has been derived

from the value of 30% in the previous feasibility study, with an appropriate reduction

to allow for the retirement of some risks from the risk register and further

development of the infrastructure solutions.




77

Specific issues which should be considered by TfL when determining an appropriate

level of Optimism Bias to apply to the cost estimates presented in this report are as

follows:

The scheme is considered to be “non‐standard” in terms of a highway link;

The scheme is at a point in its development between conception and preferred

route decision; and

A qualitative risk assessment has been carried out, though outline quantities

could be determined from the assessed cost impacts of each risk item.

12.3 Summary of Ferry Options

Table 19 presents a summary of the cost estimates for each option. A full build‐up of

costs for each option is provided in Appendix G:

Propeller Ferry Chain Ferry

2 traffic lanes £16,677,673 £13,926,290

On‐costs £7,254,788 £6,057,936

Total for 2 lanes £23,932,461 £19,984,226

4 traffic lanes £19,807,820 £13,926,290

On‐costs £7,507,164 £6,057,936

Total for 4 lanes £27,314,984 £19,984,226

6 traffic lanes £29,891,823 £13,926,290

On‐costs £8,354,764 £6,057,936

Total for 6 lanes £38,246,587 £19,984,226

Table 19 Summary of Cost Estimates




78

13 Conclusions and Recommendations

13.1 Summary of Infrastructure Options

Table 20 below provides a comparative summary of the two ferry infrastructure

options investigated at the preliminary design stage:


Cost Infrastructure is more

expensive.

Ferry vessel is expected to be

more expensive (outside scope

of this task).

Number and skill level of staff

will be higher.

Infrastructure is less expensive.

Ferry vessel is expected to be

less expensive (outside scope of

this task).

Number and skill level of staff

will be lower.

Programme Minimal piling and insitu

construction works are

expected to result in a shorter

construction period than for a

chain ferry.

Procurement of vessels (outside

scope of this task) may take

longer.

More temporary works and

significantly larger plan area of

insitu concrete works are

expected to take longer to

construct.

Procurement of vessels (outside

scope of this task) may be

quicker.

Constructability Can be constructed largely

using “modular” components.

Hazard to river navigation

presented by piling equipment

for approach structures and

dolphins.

Cofferdams would be needed

for construction of lower

sections of slipways.

Hazard to river navigation

presented by piling equipment

for suspended slipways.

Operation Self‐levelling terminal system

requires no operative

intervention but longer

approaches will require more

staff for co‐ordination of traffic.

Vessels will require highly

skilled key staff to navigate the

river and berth efficiently at

every crossing.

Pedestrians can be segregated

from vehicles easily.

Multiple vehicle lanes produce

Simple operation using staff

with a comparatively lower

level of navigational skill.

Safe segregation of pedestrians

and vehicles is not feasible

leading to longer boarding and

alighting times.

Multiple vehicles lanes for

boarding and alighting can be

accommodated on slipways.

Slipways will need to be kept

clean of river deposits from




79


faster turnaround times but are

more difficult to provide.

tidal washing.

Environmental

impact

The terminal infrastructure is

largely suspended above the

river, meaning less disruption

to the inter‐tidal zone of the

river and associated effects on

biodiversity.

Noise from a propeller ferry is

unlikely to be distinguished

from other river traffic by local

receptors.

Lower energy demand is

anticipated from a chain ferry.

A more frequent service is

possible through shorter berth,

alighting and boarding times.

The low‐level slipway terminals

will have a lower visual impact.

Hydrodynamic

impact

There is considered to generally

be lesser impact from a

propeller ferry due to the lower

blockage ratio presented by the

infrastructure.

A slipway would present a

significant blockage ratio which

is likely to have a greater effect

upon hydrodynamic processes.

Other risk The terminals for a propeller

driven ferry will present a

greater hazard to navigation in

the river.

Regular washing of the slipway

by the tide would present a

slippery surface requiring

regular cleaning.

Table 20 Comparative summary of ferry infrastructure options

13.2 Recommendations

It must be appreciated that a ferry crossing at Gallions Reach will not be able to

provide the same capacity as a fixed tunnel or bridge crossing. Bearing this in mind, if

TfL wishes to pursue a ferry crossing, the recommended option is that of a chain ferry

using a piled slipway.

Whilst a chain ferry would be more difficult to construct initially, with a longer

construction duration, it has more benefits than the propeller driven ferry in terms of

construction cost, number of operatives and vessel operation.

The slipway arrangement allows for flexibility in the number of highway lanes

servicing the ferry. An arrangement using four lanes is considered to be the best

compromise in terms of land take and highway construction cost, with turnaround

times of approximately 8.5 minutes per sailing.

Unfortunately, environmental and hydrodynamic impacts remain significant, despite

the elimination of a solid slipway in favour of a piles solution for geotechnical

reasons. This is a major disadvantage that remains for such an option.

A well considered operational regime will be essential to ensure the safety of users is

given paramount importance. Procedures for regularly cleaning the slipways of

slippery deposits and dealing with the interface between pedestrians and vehicles

would be amongst the highest priorities.



Appendix A

List of Figures, Tables and Graphs



Appendix A: List of Figures and Tables

Figures Page

Figure 1 Location of Gallions Reach (Google Maps, 2013) 9

Figure 2 Swept path for articulated HGV boarding vessel 23

Figure 3 Swept path for articulated HGV leaving vessel 23

Figure 4 Swept path for rigid HGV boarding vessel 24

Figure 5 Swept path for rigid HGV leaving vessel 24

Figure 6 Example of curved approach structure at Woolwich 25

Figure 7 Chain tensioning gantry at Torpoint Ferry (Tamar Crossings

2002)

36

Figure 8 Slipway cleaning equipment used at Torpoint Ferry (Merlo

2007)

42

Figure 9 Screenshot of VISSIM 2‐lane alighting simulation after 70

seconds

44


seconds

44


seconds

44

Figure 12 Screenshot of VISSIM 2‐lane boarding simulation after 60

seconds

46


seconds

46


seconds

46


seconds

46


seconds

47


seconds

48

Figure 18 Key to VISSIM 6‐lane boarding regime 49


seconds

50


seconds

51




seconds

51


seconds

52


seconds

53


seconds

53


seconds

53


seconds

53

Figure 27 Existing Woolwich Ferry vessel (Halcrow, 2009) 56

Figure 28 Single deck mechanical linkspan at Dublin Port (Halcrow, 2000) 57

Figure 29 Double deck mechanical linkspan at Dublin Port (Halcrow,

2003)

58

Figure 30 Typical self‐beaching propeller ferry (MV Loch Dunvegan –

Caledonian MacBrayne)

59

Tables

Table 1 Documentation received from TfL 12

Table 2 Other sources of information used in this task 13

Table 3 North bank stratigraphy and basic parameters 16

Table 4 South bank stratigraphy and basic parameters 17

Table 5 Boarding regime with six‐lane arrangement for propeller driven

ferry

49

Table 6 Comparison of alighting and boarding times for propeller

driven ferry

50

Table 7 Comparison of alighting and boarding times for chain ferry 55

Table 8 Ferry Option Blockage Ratios 61

Table 9 Back water Effect of Propeller Driven Ferry Option, calculated

using the method described in HDS1‐ Hydraulics of Bridge

Waterways.

62

Table 10 Back water Effect of Chain Ferry Option (solid slipway),

calculated using the method described in HDS1‐ Hydraulics of

Bridge Waterways.

62



Table 11 Revised Ferry Option Blockage Ratios 64

Table 12 Concrete Bridge Blockage Ratios 65

Table 13 Back water Effect of Concrete Bridge Option, calculated using

the method described in HDS1‐ Hydraulics of Bridge

Waterways.

66

Table 14 Steel Bridge Blockage Ratios 67

Table 15 Back water Effect of Steel Bridge Option, calculated using the

method described in HDS1‐ Hydraulics of Bridge Waterways.

67

Table 16 Immersed Tunnel Blockage Ratios 68

Table 17 Option impact comparison 70

Table 18 Environmental comparison of ferry types 73

Table 19 Summary of Cost Estimates 77

Table 20 Comparative summary of ferry infrastructure options 79



Appendix B

Glossary of Abbreviations



Appendix B: Glossary of Abbreviations

ANPR Automatic Number Plate Recognition

BR Blockage Ratio

BS British Standard

CD Chart Datum

CIRIA Construction Industry Research and Information Association

CPT Cone Penetration Tests

CSA Cross ‐ sectional Area

EA Environment Agency

ELRC East London River Crossing

HAT Highest Astronomical Tide

HGV Heavy Goods Vehicle

HRT Highest Recorded Tide

HSA Hydro ‐ structure Area

LAT Lowest Astronomical Tide

LRT Lowest Recorded Tide

MAGIC Multi‐Agency Geographical Information for the Countryside

MHWN Mean High Water Neaps

MHWS Mean High Water Springs

MLWN Mean Low Water Neaps

MLWS Mean Low Water Springs

MWL Mean Water Level

OD Ordnance Datum

PCU Passenger Car Unit

PLA Port of London Authority

PTV Planung Transport Verkehr AG

SI Site Investigation

SPT Standard Penetration Test

TDE Traffic Design Engineering

TfL Transport for London

TGB Thames Gateway Bridge

TWA Transport and Works Act 1992

UCS Unconfined Compressive Strength



Appendix C

Preliminary Design Drawings



Appendix C: Preliminary Design Drawings

Propeller Driven Ferry:

472413‐001 Layout Plan – 2 Lane Option



472413‐004 Typical Longitudinal Section

472413‐005 Plan on Ferry Berth – 2 Lane & 4 Lane Options

472413‐006 Plan on Ferry Berth – 6 Lane Option

472413‐007 Details Sheet 1 of 3



Chain Ferry:

472413‐010 Layout Plan

472413‐011 Longitudinal & Cross Sections

Highway Alignments (in consultation with Task 95 team) northern shore only:

472413‐201 Propeller Driven Ferry Layout Plan – 2 Lane Option



472413‐204 Chain Ferry Layout Plan – 2 Lane Option



100 20 90604030 50 70 80 100

SCALE 1:1000 (A1)

SCALE 1:2000 (A3)

METRES

LAYOUT PLAN

PROPELLER DRIVEN FERRY

2 LANE OPTION


www.halcrow.com

A CH2M Hill Company

GALLIONS REACH RIVER CROSSING

( TASK 95 & TASK 102 )

NOTES:

1. LEVELS ARE TO ORDINANCE DATUM

2. ALL DIMENSIONS ARE IN METRES UNLESS NOTED

OTHERWISE.

100 20 90604030 50 70 80 100

SCALE 1:1000 (A1)

SCALE 1:2000 (A3)

METRES

LAYOUT PLAN


4 LANE OPTION


www.halcrow.com

A CH2M Hill Company


( TASK 95 & TASK 102 )

NOTES:



OTHERWISE.

100 20 90604030 50 70 80 100

SCALE 1:1000 (A1)

SCALE 1:2000 (A3)

METRES


www.halcrow.com

A CH2M Hill Company


( TASK 95 & TASK 102 )

NOTES:



OTHERWISE.

LAYOUT PLAN


6 LANE OPTION

100 20 90604030 50 70 80 100

SCALE 1:1000 (A1)

SCALE 1:2000 (A3)

METRES


www.halcrow.com

A CH2M Hill Company


( TASK 95 & TASK 102 )

NOTES:



OTHERWISE.

CHAIN FERRY

LAYOUT PLAN

2 LANE OPTION

100 20 90604030 50 70 80 100

SCALE 1:1000 (A1)

SCALE 1:2000 (A3)

METRES


www.halcrow.com

A CH2M Hill Company


( TASK 95 & TASK 102 )

NOTES:



OTHERWISE.

CHAIN FERRY

LAYOUT PLAN

4 LANE OPTION

100 20 90604030 50 70 80 100

SCALE 1:1000 (A1)

SCALE 1:2000 (A3)

METRES


www.halcrow.com

A CH2M Hill Company


( TASK 95 & TASK 102 )

NOTES:



OTHERWISE.

CHAIN FERRY

LAYOUT PLAN

6 LANE OPTION



Appendix D

Environmental Summary Table



Environmental Issue Commentary

Energy use and material use Provision of a new ferry service at Gallions Reach would be linked to a cessation of services at Woolwich and may also

result in the removal of the redundant infrastructure, which should be disposed of in a sustainable matter.

New infrastructure at Gallions Reach will allow new technology to be used. The new technology is highly likely to

have a lower energy use than the existing Woolwich infrastructure. The energy demands of the proposed

infrastructure options will be considered at the detailed stage of the project.

The sustainability of materials used in the preferred option design will be assessed at the detailed stage of the project.

Ferry infrastructure which does not require electricity but relies on tidal power is preferable in terms of energy use.

General land use of immediate area There are relatively few residential areas to the north and south of the Gallions Reach area, particularly in comparison

to the Woolwich Ferry area.

A disused area of former industrial land and mixed land use area of the Royal Albert Basin are located on the north

river bank. This includes a commercial area, a residential area and the Docklands Campus of the University of East

London.

The residential area of Beckton and Gallions Reach Primary School, the London Industrial Park and Gallions Reach

Shopping Park are located north of the river.

Tripcock Park, Tilfen Landfill site, the residential areas of Broadwater and Gallions Reach and Discovery Primary

School are located on the south bank. South of these areas are Belmarsh Prison, the residential area of Thamesmead

and Abbey Wood and an industrial area.

The historical and current industrial land uses in the wider area should be taken into consideration at the detailed

stage of the project, due to the potential for contaminated land and water.

Links with transportation There is no existing road infrastructure leading to the river bank at the Gallions Reach location and therefore new road

infrastructure would be required to both the north and south of the river.

Demands for a ferry service at this location and the impact of removal of a ferry service from Woolwich on the road

network should be considered. Proposed public transport schemes that can be linked with the ferry service will have




to be considered at the detailed stage.

Land take requirements Land take would be required for the new road infrastructure and associated queuing/waiting provisions to the north

and south of the river.

South of the river approximately 1.1km of new highway would be required to connect the new ferry to the existing

highway network. provide a junction with Western Way approximately 250m west of the roundabout. It has been

confirmed from discussions with the highway preliminary designer that a signalised T‐Junction with Western Way

will be provided. There may also need to be a signalised junction where the new highway crosses Barnham Drive and

a bridge over the Gallions Canal.

North of Barnham Drive the highway would permanently occupy land within Tripcock Park. It is understood that

developer Tilfen submitted a planning application to London Borough of Greenwich in November 2009 for

landscaping of this area as part of the ‘Thamesis’ park development. Part of this park area encroaches into the corridor

being considered for any ferry option at Gallions Reach. Permanent highway access to a ferry terminal will require

reconfiguration of the current Tilfen plan.

All the land that would be required for the highway connection south of the river is in the ownership of Tilfen Land

Limited. Construction of the link would have to interface with Tilfen’s haul route to their licensed tip which connects

to Western Way at the point that the new junction would be provided. Previously it was suggested that tip traffic

could share the new highway to the north of the Gallions Canal.

North of the river the connection to the principal highway network would be via a combination of new and improved

highways to Gallions Roundabout. Atlantis Avenue which runs east from Gallions Roundabout could be dualled on

its south side and the existing signalised junction with Armada Way and Gallions Road could be modified. Atlantis

Avenue currently terminates at a signalised T‐Junction with Magellan Boulevard and it is proposed that this junction

would be modified to a cross roads with a new connection to the ferry continuing straight on from Atlantis Avenue.

The new connection to the ferry would follow an ‘S’ curve and the eastbound (towards ferry) carriageway would be

widened to provide stacking/waiting capacity as there would not be enough land available to provide an off‐line

waiting/parking area.




The land north of the river is generally in the ownership of the London Development Agency (LDA) although PLA

and Thames Water also have interests in land close to the river. Discussions would be required with LDA as to the

acceptability of taking land to dual Atlantis Avenue as this land is currently designated for development. The land

between Magellan Boulevard and the river is designated in the Royal Albert Basin masterplan to become a park and

there is an aspiration to extend the riverside footpath right through this area which may not be compatible with an

access road to a ferry.

Community and pedestrian links The Thames Path is located along the south bank of the river at Gallions Reach, however there are currently no river

crossing provisions for pedestrians.

Pedestrians from the residential areas north and south of the river wishing to cross at this location have to use the

Woolwich foot tunnel to the west. Vehicle users from the residential areas north and south have to use Woolwich

Ferry or divert further west to Blackwall Tunnel.

As there are no provisions for pedestrians currently, the demand for a pedestrian crossing is not known. Pedestrians

currently using the Woolwich Ferry to cross the river will need to use the Woolwich foot tunnel or walk to the

proposed Gallions Reach ferry. A survey of pedestrian demand at this location and at Woolwich Ferry and foot tunnel

should be carried out. In addition, the existing land use and planning applications for future land use, as well as

existing and proposed public transport links would have to be considered at the detailed stage in order to assess the

catchment area for a pedestrian crossing facility at this location.

Biodiversity A new ferry service at Gallions Reach would result in a change to the existing situation, as there would be construction

works in the river itself, on the river bed and on the mudflats of the river in an area of the river where there is

currently no development. There would also be changes arising from decommissioning the Woolwich Ferry, which is

expected to occur with the introduction of a new service at Gallions Reach.

There are no statutory designated sites within the immediate study area. The closest statutory designated sites are

Abbey Wood SSSI and Gilbert’s Pit’ a geological SSSI both located more than 2km south of the proposed ferry location.

There are a number of non statutory sites and locally designated sites within the immediate study area.

The Thames Estuary is a Site of Metropolitan Importance. The area of the Thames Estuary and Marshes that falls in the




immediate area is an Important Bird Area, an international initiative that aims to identify and protect a network of

sites for birds. The mudflats of the Thames fall under the Biodiversity Action Plan Priority Habitat as a rare or

threatened semi‐natural habitat.

The Thamesmead Historic Area and Wetlands is a site of Borough Importance on the south of the river.

The non statutory sites and locally designated sites within the immediate and wider area would have to be taken into

consideration at the more detailed stage of the project through further ecological surveys and assessments. In

particular impacts on the inter‐tidal zone will have to be considered.

The surveys may include aquatic ecology and ornithology surveys as well as terrestrial ecology surveys.

Floodrisk The last major tidal flooding of the Thames Estuary occurred in 1953 when hundreds of lives were lost: the Thames

Barrier and associated flood defences were constructed as a result of this event and were designed to protect against a

1 in 1000 year flood event in 2030. They are set at a height of +7.2m OD and are located approximately 1.6 km west of

the existing Woolwich ferry service.

The Environment Agency flood map shows that the Gallions Reach area is within Flood Zone 3, an area that could be

affected by flooding either from rivers or the sea. Some smaller parts of the area could be affected by an extreme flood

and are located in Flood Zone 2.

Taking the current flood risk assessment into consideration, the detailed stage of the project design is required to

include a PPS 25 Flood Risk Assessment.

Hydrodynamics and sediment transport A ferry service at Gallions Reach would introduce new structures at a location where there were previously no

structures.

Hydrodynamics and sediment transport are key issues that would need to be assessed further using detailed

modelling and analysis at the detailed stage of the project, once the preferred option has been selected and designed,

in order to mitigate any potential impacts such as build up of sediment, changes in hydrodynamics, dredging

requirements on other upstream or downstream sites.




As shown in the initial hydrodynamic comparisons in this report, the type of ferry infrastructure and its size, shape

and location would influence hydrodynamics and sediment transport.

Archaeology (including UXO) and heritage

features

There are fewer archaeological and heritage features within the immediate area. There are no listed buildings in the

immediate study area. The Royal Arsenal Conservation Area is not in the immediate area but may need to be taken

into consideration in terms of impacts from changes in traffic volumes at the detailed stage of the project. Newham

Archaeological Priority Area is located on the north bank and Greenwich Area of High Archaeological Interest is

located on the south bank of the river.

The heritage features in the immediate area include evidence of a prehistoric landscape in North Woolwich and

Thamesmead and historical ordnance testing ground area, where foundry cannon balls have been found at Gallions

Reach Urban Village.

An unexploded ordnance survey has been carried out and would need to be taken into account prior to any

construction works in the River Thames as the area was subject to bombardment in World War II.

Residential properties, receptors of air and

noise impacts

This option introduces new impacts for residents in Thamesmead and Beckton. It will lead to a change in the number

of residential properties and to the residential areas affected by traffic impacts associated with the ferry crossing.

The Gallions Reach area contains fewer residential properties on the north bank and south bank of the river in

comparison to the area of the existing Woolwich Ferry.

However, there may be impacts on other residential areas in the wider area around Gallions Reach. This change in

residents impacted by road traffic impacts such as air, noise and congestion will be assessed and determined at the

detailed stage of the project, taking the traffic study into consideration.

Visual and landscape impact The site is located within the Greater Thames Estuary National Character Area .This option will introduce a new visual

feature to the Gallions Reach area. Potential receptors of any visual and landscape impacts include residents in the

Albert Dock development, residents in Thamesmead as well as users of Tripcock Park and the Thames Path. The

detailed stage of the assessment will include the visual and landscape impacts, taking into consideration the landscape

character and maritime heritage of the River Thames.



Appendix E

Risk Register



(This page is blank for double‐sided printing)

Gallions Reach CrossingsMarine Aspects

Project Risk Register

Management Arrangements

This register records all currently identified threats and opportunities identified by the feasibility project team

Version No Date Prepared By Checked By Approved By Authorised Comments

Issue 1 22-Jan-10 Halcrow Group JPH MFG TfL Register prepared for Initial Ferry Feasibility Study

Issue 2 19-Apr-13 Halcrow Group MFG MFG TfL Register updated for Marine Aspects Outline Design

Risk Ranking Values

From To From To From To

1% 10% 1 0 10k 0 1wk 1

11% 25% 2 10k 50k 1wk 1mth 2

26% 50% 3 50k 250k 1mth 6mth 3

51% 75% 4 250k 500k 6mth 1yr 4

76% 100% 5 500k 1yr 5

-25 -20 -15 -10 -5 5 10 15 20 25

-20 -16 -12 -8 -4 4 8 12 16 20

-15 -12 -9 -6 -3 3 6 9 12 15

-10 -8 -6 -4 -2 2 4 6 8 10

-5 -4 -3 -2 -1 1 2 3 4 5

Insignificant

Marginal

ScoreScoreDescription Description

Improbable

Remote

Probability Impact (£) Impact (time)

Occasional

Probable

Significant

Substantial

Extreme

ThreatOpportunity

Frequent

Risk Register Gallions Reach Marine Aspects Transport for London

Risk Figures & Statistics Risk Mitigation Information

Category Sub-Category Risk/Opp Title Description Cause Effect Date By Status Last Updated Min (£k) Likely (£k) Max (£k) Opt (wks) Most (wks) Pess (wks)

1.01Planning &

Outline Design

Transport & Works Act

approval issues Risk LegislationTransport & Works Act orders

refusedNot considered to be an acceptable route by SoS

New legislative procedures required (CPO, PLA, MFA, TfL

Bill) 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 0 5 TfL

Early communication with DfT Transport & Works Act unit to establish whether acceptable or not 10

1.02Planning &

Outline Design


approval issues Risk LegislationTransport & Works Act orders

delayedLate application / unclear or

unacceptable solution Delay / cost of redesign 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 2 3 TfLLiaison during solution development 6

1.03Planning &

Outline Design


approval issues Risk PLA approvals

Delay to or lack of approval/consent to TfL

applications (eg. temporary works licence, PLA opinion on

chains)Late application / unclear or

unacceptable solution Delay / cost of redesign 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 2 2 TfLOngoing liaison with PLA 2

1.04Planning &

Outline Design


approval issues RiskPLA navigation

aidsUnknown extent of PLA

requirements

Further design work required (for chain or self-propelled -

don't yet know) Delay/additional cost 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 1 0 TfLEarly and ongoing discussions with PLA 1

1.05Planning &

Outline Design


approval issues Risk Navigation aids

Replacement PLA radar or other navigation aids not procured in time for construction of terminal

infrastructure to commenceDifficulty in agreeing

requirements with PLA Delay / loss of revenue 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 0 2 TfL

Retired:Outside scope of Gallions Reach Marine Aspects outline design 2

Time scoreProb. Score

Total Risk Score

Owner Strategy

Risk Register IdentificationRisk No. Cost score

1.05 Outline Design approval issues Risk Navigation aids infrastructure to commence requirements with PLA Delay / loss of revenue 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 0 2 TfL Aspects outline design 2

1.06Planning &

Outline Design


approval issues RiskConsultation on

proposed solution Acceptability of solutionObjections by key stakeholders

and/or users Re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 4 2 2 TfLEarly liaison with stakeholder groups 8

1.07Planning &

Outline Design


approval issues Risk Legislation

Existing order for crossing at Gallions Reach may be for a

bridge onlyFerry crossing may require new

orders to be drawn up Delay/increased cost or

cancellation 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 0 0 TfL

TfL to take legal advice on whether existing bridge orders can be used for a ferry

potential cancellation

2.01Planning &

Outline DesignConsents & approvals Risk EA consents

Delay of EA approval for necessary consents (also applicable to MFA & PLA)

Late application / unclear or unacceptable solution Delay 13/01/2010 Tfl/Halcrow Open 19/04/2013 3 2 3 TfL

Agree objective criteria with stakeholders and meet regularly.Proposals being developed further 9

2.02Planning &

Outline DesignConsents & approvals Risk

Works outside Transport & Works Act

Planning process for highway improvements remote from ferry

terminals

Highway improvements may still require conventional planning

process Delay 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 1 1 TfL

Establish whether Transport & Works Act will cover these works early. If not, start planning process ASAP 1

Establish whether Transport & Works Act will cover tolling early If

2.03Planning &


Tolling system & enforcement Tolling system approval delays

Tolling regime may still require conventional approval process Delay 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 2 2 TfL

will cover tolling early. If not, start approval process ASAP 4

2.04Planning &


Tolling system & enforcement

Tolling system seen as additional costs to locals in comparison to

existing free service at Woolwich Adverse local reaction to tolls Reputation 13/01/2010 Tfl/Halcrow Open 19/04/2013 3 2 1 TfL

TfL to publicise benefits of new service (ie. greater capacity) 6

2.05Planning &

Outline DesignConsents & approvals Opp

Tolling system & enforcement

Tolling system brings in additional revenue Toll revenue stream Cost reduction 13/01/2010 Tfl/Halcrow Open 19/04/2013 3 -3 0 TfL -9

2.06Planning &


London City Airport Interference with navigation aids

LCY may impose restrictions on scheme (particularly temporary

works) Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 1 1 TfL Early liaison with LCY 1

2.07Planning &

Outline DesignConsents & approvals Risk Ecology

Requirements to protect fish paths

Proposed solution may not be acceptable to EA (eg. Slipway

across shallow bank area) Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 1 1 TfL Early liaison with EA 1

2.08Planning &


Apron on southern foreshore

Interruption of mud reach flow by chain

Objections by PLA, MFA & EA about effect of works on river Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 5 3 TfL

Early liaison with EA/PLA/MFA in conjunction with hydrodynamic impact assessment 5

Retired:Outside scope of Gallions Reach Marine Aspects outline design -

3.01Planning &

Outline DesignLocal Authority

Obligations RiskPlanning

conditions TrafficRestrictions on traffic levels or

further mitigation requiredAdditional data and modelling

required (micro-simulation) 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 1 1 TfL

p gassumed to be carried out by others 1

3.02Planning &



conditions AestheticsProposed solution does not meet aesthetic requirements Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 1 1 TfL

Establish and agree planning conditions with local authority early 1

3.03Planning &



conditions Noise

Noise from chain ferry (residual noise after mitigation through

vessel design) Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 3 1 1 TfL

Establish and agree planning conditions with local authority early 1

4.01Planning &

Outline DesignAgreements with

landowners RiskAgreements with

landowners

Failure to reach agreement resulting in objections to Transport & Works Act

Delays in procurement & construction processes mean

deadlines are missed Delay/re-negotiation 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 1 1 TfL

Retired:Outside scope of Gallions Reach Marine Aspects outline design - assumed to be carried out by others 1

Project Risk Register 1 of 5





Total Risk Score

Owner Strategy


5.01Planning &

Outline DesignWorkforce

Issues RiskChange

managementWillingness of WFF workforce to accept the staffing levels solution

Unionised workforce may not accept proposed solution

Protest action by workforce unless demands are met 13/01/2010 Tfl/Halcrow Retired 19/04/2013 2 2 1 TfL


6.02Planning &

Outline DesignInterfacing

infrastructure RiskThames Tideway

Tunnel

Tunnel may be affected by the proposed solution (eg. piles in

river)

Failure to understand interaction between tunnel and terminal

foundationsDelay/cost from re-design.

Possible cost of compensation 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 3 3 TfL

Early liaison with Thames Water and Thames Tideway Tunnel project team 3

6.03Planning &

Outline DesignInterfacing

infrastructure RiskThames flood

defencesEffect of proposed solution on

defence wallsProposed solution may not be

acceptable to EA Cost and delay from re-design 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 1 1 TfL

Retired:Outline design to take account of flood defences 1

7.02Planning &

Outline DesignDesign

parameters RiskLarge capacity infrastructure

Design brief requires consideration of

loading/unloading up to 6 lanes of traffic simultaneously

Difficult to achieve without uneconomically/impractically

large infrastructure. Associated problems with connection to

lower capacity highway network

Increased construction cost, land take and navigational

obstacle in river 19/04/2013 Tfl/Halcrow Open 19/04/2013 1 5 3 TfL

Proposed to discount this suggestion at outline design stage due to impracticalities 5

Design to avoid encroachment into

7.03Planning &

Outline DesignDesign

parameters RiskSize of

infrastructure

Larger than anticipated terminals encroach into navigational

envelope considered in previous risk assessment

Further investigation of required geometry and increased

capacity parameters Delay/cost from re-design 19/04/2013 Tfl/Halcrow Open 5 1 2 TfL

encroachment into navigation envelope where possible. Navigational risk assessment to be revisited if necessary 10

8.01Planning &

Outline Design Political Issues Risk Political changesGeneral, local & mayoral elections & tolling regime

Change of scope or cancellation of scheme

Delay/increased cost or cancellation 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 0 0 TfL

Cancellation becoming less likely as workable options are developed

potential cancellation

9.00 NOT USED 19/04/2013

10.01 ProcurementUnanticipated

charges Risk Costs

Increase in scheme costs affecting viability of business

caseHigher cost of materials than

anticipated Possible cancellation 13/01/2010 Tfl/Halcrow Open

Note cancellation scenario not reflected in

risk values 2 5 0 TfLAllow contingency in cost estimate 10


charges Risk Costs


caseDisposal of more waste than

anticipated Possible cancellation 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 4 0 TfLAllow contingency in cost estimate 8


charges Risk Costs


case Lead-in times Possible cancellation 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 0 4 TfL

Investigate procurement of long-lead items 8


charges Risk Costs


caseTender prices higher than

anticipated Possible cancellation 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 5 0 TfLCarry out market testing 10

11.01 ProcurementProgramme alterations Risk

Co-ordinated procurement

Costs of civils works unknown at time of ordering vessels (two

different contracts for civils and vessels)

Costs increase to fit civils design (eg. Affected by ground conditions) to vessels already

ordered. Scheme may be cancelled due to increased

costs

Increased costs, possible delays. Unwanted vessels

delivered 13/01/2010 Tfl/Halcrow Retired 19/04/2013 TfL

Retired:Outside scope of Gallions Reach Marine Aspects outline design. Parameters for ferry provided by TfL following consultation with renowned expert

12.01 Detailed Design Design

Solutions RiskProposed solutions

Design solutions not acceptable to TfL

Unclear brief / requirements of Transport & Works Act cannot

be met within budget Cost and delay from re-design 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 4 4 TfL

Retired:Brief defined by TfL from consultation following feasibility studies 4

13.01 Detailed DesignEnvironmental

issues Risk Water qualityWater quality affected by

proposed solution

Possible polution/turbidity from proposed solution causes

objections from EA Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 3 4 TfL Mitigate through design 8

14.01 Detailed DesignDesign

Assumptions RiskDesign

parameters Change to parameters required Initial assumptions not valid Cost and delay from re-design 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 4 4 TfL

Retired:Brief defined by TfL from consultation following feasibility studies 4Retired:Brief defined by TfL from consultation


Assumptions RiskDesign

parameters Traffic capacity requirements Initial assumptions not valid Cost and delay from re-design 13/01/2010 Tfl/Halcrow Retired 19/04/2013 2 4 4 TfLfollowing feasibility studies 8


Assumptions Risk Geotechnical Unknown ground conditionsAssumptions in design found to

be inadequate

Cost of additional ground investigation. Cost and delay

from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 3 3 TfLAvailable data being reviewed 3


Assumptions RiskTolling system

(M&E) Design of M&E components

Significant design effort required if electronic "free-flowing" tolling

system usedCost and delay from design and

negotiation with operators 13/01/2010 Tfl/Halcrow Open 19/04/2013 3 2 2 TfL

Early discussion of requirements between designer, client and operator 6


Requirements Opp/RiskChanging

requirementsConsideration of hazardous

goods provisionSavings through reduced specification for vessels Cost increase/savings 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 -2 / 3 -1 / 1 TfL

Explore opportunity with designer, client and operator

-2

3


Requirements OppChanging

requirements

Increase hazardous goods provision or size/weight of

vehiclesOpportunity to provide better

provision for hazardous goods Better service, higher usage 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 -1 -1 TfL

Explore opportunity with designer, client and operator -2

3






Total Risk Score

Owner Strategy



Requirements RiskChanging

requirements

Requirements for ferry operations change during design life (for example - larger vehicles, bendy buses, hazardous goods)

Ferry unable to comply with new requirements

Reduced effectiveness of service (conscious decision to

be made at design stage) 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 2 1 TfL

Ferry capacity increased in brief for outline design 2

15.04(was 2.09) Detailed Design

Consents & approvals Risk Sedimentation

Effect on sedimentation patterns -will affect adjacent riparian

facilities

Proposed solution may not be acceptable to EA/PLA/key

stakeholdersCost and delay from re-design (full hydraulic model required) 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 2 2 TfL

Early liaison with EA/PLA/key stakeholders and full hydrodynamic analysis during detailed design stage 2


Consents & approvals Risk

Coastal processes

Disruption to coastal processes caused by proposed solution

Proposed solution may not be acceptable to EA/PLA Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 2 2 TfL

Early liaison with EA/PLA and full hydrodynamic analysis during detailed design stage 2


Consents & approvals Risk Archaeology

Effect on known archaeology from proposed solution Objections by English Heritage Cost and delay from re-design 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 1 3 TfL

Review of available data on known archaeology and watching brief for developments 3( ) g pp gy p p j y g g y g p p


Interfacing infrastructure Risk Utilities

Change to utilities outside TfL control (eg. Unknown services)

Disruption to services or delay/cost from wayleaves or

diversions. Delay/cost 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 2 1 TfL

Ongoing review of available data and services searches 2

16.01 Enabling WksNavigation

Issues RiskPLA navigation

aidsUnknown extent of PLA

requirements Further design work required Delay/additional cost 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 4 4 TfL

Early and ongoing discussions with PLA assumed to be advancing with progress of design 4

17.01 Enabling WksEnvironmental

Issues RiskNoise & air quality

mitigationUnknown extent of EA & PLA

requirements Further design work required Delay/additional cost 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 3 2 TfL

Early and ongoing discussions with PLA assumed to be advancing with progress of design 3

17.02 Enabling WksEnvironmental

issues Risk Dredging

Dredging of river may be required to achieve necsesary

draft under vessels and/or pontoons

Position of ferry terminals in previous study may not be

compatible with larger vessels in outline design specification

Damage to habitats, additional construction cost and ongoing maintenance requirement (see

29.04) 19/04/2013 Halcrow Open 2 5 2 TfL

Outline design to consider re-positioning terminals as necessary to avoid dredging as far as possible - certainly aim to avoid ongoing maintenance dredging during life of scheme (see 29.04) 10Review all available d t t i i i

18.01 Construction Archaeology Risk ArchaeologyDiscovery of uncharted

archaeology during construction Work halted Delay/additional cost 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 2 2 TfL

data to minimise likelihood of unknown finds 4

19.01 ConstructionEnvironmental

Issues Risk PollutionAccidental pollution of river

during construction Water quality affected

Delay and associated cost. Cost of remediation. Possible cost of

compensation 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 3 1 TfL

Method statements for construction to include procedures to avoid pollution 3

20.01 Construction WW2 Ordnance RiskUnexploded

ordnance

Discovery of unexploded ordnance during construction - no previous construction works

in area Work halted Delay/additional cost 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 1 2 TfL

Review all available data to minimise likelihood of unknown finds 2

21.01 Construction Ecology Risk FishDisturbance to fish during

construction Ecology affected



Temporary works designed to avoid disturbance 6

22.01 Construction Site boundaries RiskExisting Woolwich

serviceMaintaining continuous service at

Woolwich during works

Issues with availability of land for construction (developer of

adjacent land demands payment/compensation for delay

to their own project)

Land taken from existing facility resulting in reduced service.

Possible delay from negotiation with adjacent landowners to

take temporary possession of their land 13/01/2010 Tfl/Halcrow Retired 19/04/2013 2 4 4 TfL


23.01 Construction Political Issues RiskExisting Woolwich

servicePolitical implications of stopping

Woolwich serviceCessation of service not

permittedConstruction cannot proceed as

planned 13/01/2010 Tfl/Halcrow Retired 19/04/2013 3 4 4 TfL

Retired:Outside scope of Gallions Reach Marine Aspects outline design 1223.01 Construction Political Issues Risk service Woolwich service permitted planned 13/01/2010 Tfl/Halcrow Retired 19/04/2013 3 4 4 TfL Aspects outline design 12

24.01 ConstructionOther project

interfaces Risk

Interface with other major

projects in the area

Crossrail, Thames Tideway Tunnel & Olympics, may result in conflicts during construction or

reduced ferry service not possible (during Olympics)

Construction may be interrupted/postponed Delay/additional cost 13/01/2010 Tfl/Halcrow Retired 19/04/2013 1 4 4 TfL

Retired:Others schemes no longer likely to impact upon construction programme 4

25.01 ConstructionGround

conditions RiskContaminated spoil removal

High likelihood of contaminated ground requiring specialist

disposal

More contaminated spoil than anticipated needing to be disposed of at high cost Additional cost 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 2 2 TfL

Review all available data to minimise likelihood of unexpected contamination 4

25.02 ConstructionGround

conditions Risk

Removal of unsuitable material

Impractical to remove alluvium deposits (which may be

contaminated)

Alluvial deposits will need to be removed to form suitable

foundation for solid chain ferry slipways

Additional cost - may make solution unviable 19/04/2013 Tfl/Halcrow Open 3 4 2 TfL

Review geotechnical data. If significant removal required, consider alternative option of piled slipway 12






Total Risk Score

Owner Strategy


26.01 ConstructionInterfacing

infrastructure RiskExisting

structures

Accidental damage to existing structures caused by construction methods

For example - flood defences, Northern Outfall Sewer, etc



Design takes account of existing structures.Method statements for construction to include procedures to avoid damage to existing structures 3

27.01 ConstructionInterfacing operations Risk

Construction in river

Impact on navigation during construction

Disruption to river services or collision with river users. Construction method not

accepted by PLACost and delay from revisiting

construction methods 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 3 3 TfL

Early and continuous liaison with PLA and river users in conjunction with navigational risk assessment 6

27.02(was 3.04) Construction

Local Authority Obligations Risk

Agreements with local authorities

Compliance with agreements not carried out in specified time

Delays in procurement & construction processes mean

deadlines are missed Delay / re-negotiation 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 1 1 TfL

Strategy to be developed and managed to ensure compliance during construction in time with set deadlines 1

28.01 ConstructionProgramme

Management Risk

Delivery of pontoons /

vesselsTowing from remote location and

negotiating river traffic Late delivery Delay 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 2 3 TfL

Allow enough time during procurement phase for elements to be fabricated and delivered. Method statements to be prepared (discussed with PLA for operations in Thames) 3

28.02 ConstructionProgramme

Management Risk LogisticsDelivery & installation of terminal

infrastructure Late delivery Delay 13/01/2010 Tfl/Halcrow Open 19/04/2013 2 2 2 TfL

Allow enough time for procurement of elements. Method statements for delivery to be prepared 4

30.01Testing and

commissioning Risk Test failureSite testing of systems is not

passedInadequate design brief or poor

manufactureDelay (possible re-design),

reputational damage 19/04/2013 Tfl/Halcrow Open 2 3 3 TfL

Full design speficiation required plus Factory Approval Tests before installation on site 6

30.02Testing and

commissioning Risk Incompatibility

Ferry and terminal systems/infrastructure do not

work together adequatelyDifferent designers for each

element Cost and delay from re-design 19/04/2013 Tfl/Halcrow Open 2 3 3 TfL

Close liaison between each design organisation at detailed design stage 6g p y g q y y g p g g

30.03Testing and

commissioning Risk Component failureFailure of components during

commissioningInadequate design/specification or poor manfacturing practices

Cost and delay from repair / re-design 19/04/2013 Tfl/Halcrow Open 1 3 3 TfL

Detailed design to specify required materials and approvals. Trial erection off-site recommended 3

30.04Testing and

commissioning Risk Inability to toll

Tolling systems are not operational in time for service

commencementProcurement / design / manufacturing delay Loss of revenue 19/04/2013 Tfl/Halcrow Open 2 2 1 TfL

Necessary approvals to be obtained in a timely manner and procurement timed to meet operational date 2

29.01 Operation Risk

Damage during operation

(responsibility of operator)

Accidental damage to infrastructure / vessel during

operation (eg. berthing collisions, beaching) Service failure

Suspension of service. Cost of repairs and possible

compensation to affected parties 13/01/2010 Tfl/Halcrow Open

Note operational risks to be passed onto operator -

contratual risk of unsuitable handover see

7.01(now 29.10) TfL

Operating procedures to be developed to minimise the likelihood of accidental damage


Potential conflict with other river

traffic

Promotion of greater river taxi use could cause

demand/operational issues (also consider wash from clipper vessels causing damage)

Changes in usage from that anticipated during design

development Costs outweigh revenue 13/01/2010 Tfl/Halcrow Open 19/04/2013 TfL

Discussion of strategy between designer, client and operator during design phase

29.03 Operation Opp River taxi

Opportunity to design for combined ferry and river taxi use

of infrastructureGreater flexibility in infrastructure usage

"Future-proofed" terminal design 13/01/2010 Tfl/Halcrow Retired 19/04/2013 TfL

Retired:Brief defined by TfL from consultation following feasibility studies

29.04 Operation Risk Sedimentation

Interference with operations, adjacent riparian facilities and

habitats Dredging required

Cost of dredging. Possible compensation to affected river

users 13/01/2010 Tfl/Halcrow Open 19/04/2013 TfL

Carry out full hydro-dynamic study during detailed design phase

29.05 Operation Risk Traffic levelsIncrease in road/river traffic

beyond expectations

Ferry unable to deal with new traffic levels - despite

allowances for extra capacity made at design stage

Reduced effectiveness of service 13/01/2010 Tfl/Halcrow Open 19/04/2013 TfL

If tolled, could control demand by setting price levels accordingly

29.06 Operation Risk Pollution Pollution of river during operation Water quality affectedCost of remediation. Possible

cost of compensation 13/01/2010 Tfl/Halcrow Open 19/04/2013 TfLDesign ferry to avoid pollution






Total Risk Score

Owner Strategy


29.07 Operation Risk MaintenanceMaintenance costs higher than

anticipated

More maintenance required than expected. Higher cost of

labour/materials than expected. Reduced service in operation if maintenance cannot be carried out due to budgetary constraints

Additional cost. Delay caused by disruption to service 13/01/2010 Tfl/Halcrow Open 19/04/2013 TfL

Maintenance procedures to be developed during design phase in discussion with current Woolwich operator (and other operators) to minimise the likelihood of unexpected cost increases

29.08 Operation Risk Tolling Revenue less than anticipated

Reduced service in operation if costs cannot be covered by tolling revenues (resulting in

reduced ability to recoup costs) Costs outweigh revenue 13/01/2010 Tfl/Halcrow Open 19/04/2013 TfL

Discussion of strategy between designer, client and operator during detailed design phase

Retired:Outside scope of


Possible bridge crossing at

Gallions Reach

Operation of ferry service not possible during construction of a

bridgeOperations ceased for up to 4

years

Loss of revenue. Possible cancellation of scheme at

planning stage 13/01/2010 Tfl/Halcrow Retired 19/04/2013 TfL

Outside scope of Gallions Reach Marine Aspects outline design - bridge option not being considered in this task

29.10(was 7.01) Operation Risk

Operational contractual

arrangementsOperational risk not sufficiently

managedLack of detailed thought in

developing operational contracts Operational costs increase 13/01/2010 Tfl/Halcrow Open 19/04/2013 1 3 3 TfL

Early discussion and negotiation during planning phases, but deemed to be operational risk 3

29.11 Operation RiskNon-motorised

usersSafety of foot passengers and

cyclistsInterface with traffic and exposure to elements Injury/illness 19/04/2013 Tfl/Halcrow Open 3 3 1 TfL

Design to include for non-motorised users to be segregated from traffic with adequate shelter provided 9

29.12 Operation Risk Staff welfare Facilities for ferry operations staffInsufficient welfare facilities /

shelter Injury/illness 19/04/2013 Tfl/Halcrow Open 3 3 1 TfL

Sufficient facilities to be included in design from the outset 9

Boarding and alighting to be controlled on the basis of slightly lower th it "b t h "

29.13 Operation RiskFrequency of

serviceDesired capacity is not achieved due to low frequncy of crossings

Frequency dictated largely by boarding/alighting times (linked

to size of vessel)Queuing or uneconomical

service 19/04/2013 Tfl/Halcrow Open 1 3 2 TfL

than capacity "batches" of traffic to eliminate delay caused by sending vehicles back to queuing area 3

29.14 Operation Risk Safety of slipways Slippery sloping surfaceAccumulation of

silt/algae/riverdeposits with tide Injury/accident 19/04/2013 Tfl/Halcrow Open 4 3 1 TfL

Maintenance procedures to be developed during design phase in discussion with other chain ferry operators to minimise the likelihood of silt/algae accumulation 12




Appendix F

Designer’s Risk Assessment




Stage: Preliminary Design

Likelihood Consequence Index Likelihood Consequence Index

1 Construction: Working near and over water Risk of drowning, particular hazard presented by large tidal range 3 5 15 Designer Prior to constructionRiver works minimised through use of land access and prefabricated elements as far as reasonably practicable

1 5 5Contractor to develop safe method of working and issue operatives with necessary safety equipment (including provision of a safety boat)

Disruption or damage to local residences and businesses. Few local recptors in area. It is suggested that contractor informs

No. HAZARD Risk Owner

Project: Gallions Reach Crossings - Marine Aspects River Thames, London

Next Formal Risk Review Date

Designer's Health and Safety risk assessment

Location:

ANTICIPATED MEASURE THAT COULD BE APPLIED BY THE CONTRACTOR (OR OTHERS)

CONSEQUENCE OF HAZARD (RISK)

RISK LEVEL BEFORE MITIGATION MITIGATION MEASURE TO BE TAKEN BY DESIGNER

RISK LEVEL AFTER MITIGATION

A CH2M HILL COMPANYThis is a Mandatory Form

2 Construction: Noise and vibration from piling operations Possible minor loss of structural integrity which could result in injury to building occupants from falling or broken materials

3 3 9 TfL Prior to construction None 3 3 9 affected residents and busineses in advance and restricts piling operations to normal working hours

3 Construction: Lifting operations Death/injury to operatives and/or damage to structures 2 5 10 Designer Prior to constructionDesign includes consideration of size, weight and shape of prefabricated elements to allow for relatively simple lifting operations

1 5 5 Contractor to develop a suitable lifting plan

4 Construction: Interface with existing structuresRisk of damage to existing flood defence walls, Northern Outfall Sewer and Tideway Tunnel (from piling)

3 4 12 Designer Prior to constructionInfrastructure has been designed to be sufficiently remote from known existing structures

1 4 4Contractor to carry out survey prior to works to ensure construction plant will not encraoch too clsoe to existing structures

5 Construction: Interference with other river usersRisk of collision between river vessels and marine construction plant resulting in death or injury

3 5 15 Designer Prior to constructionDesigned for a large proportion of works to be carried out from land access

1 5 5Contractor to establish navigational channels and provide suitable risk control measures in consultation with Port of London Authority as necessary

6 Construction: Contaminated landInjury/illness to operatives and local flora/fauna due to excavation in contaminated land, and subsequent disposal

3 4 12 Designer Prior to construction Excavation works minimised 1 4 4Contractor to establish suitable methodology for excavation, treatment and/or disposal of contaminated materials

7 Construction: Pollution of riverDamage/injury to river flora/fauna and/or significant penalties from Environment Agency due to hazardous construction materials entering watercourse

3 3 9 Designer Prior to constructionUse of hazardous materials (eg. protective coatings) on site miniimised by use of prefabricated elements

1 3 3Contractor to develop suitable method of working to avoid pollution during construction and deal with pollution incidents if they occur

8 Construction: Buried servicesDeath/injury to operatives from contact with unknown buried services, particularly gas and electricity

3 5 15 Designer Prior to constructionNo services charted in the vicinty of either terminal. Design only requires minimal excavation

1 5 5Contractor to conduct appropriate surveys to check before any excvavtion works

9 Construction: Unexploded ordnanceDeath/injury to operatives and/or damage to nearby property from discovery and accidental detonation of unexploded ordnance

2 5 10 TfL Prior to construction None 2 5 10Area is known to have been heavily bombarded during World War II. Contractor to conduct appropriate surveys and keep a watching brief during construction

10 Construction: Use of the river for deliveriesInjury of operatives or damage to equipment caused by large elements being transported upriver to site colliding with fixed obstacles or other river users

3 4 12 Designer Prior to constructionDesign includes consideration of size, weight and shape of prefabricated elements to allow for transport by river

1 4 4Contractor to develop a suitable methodology for transport of large elements by river

11 Operation: Working in river environmentRisk of drowning for operatives and/or public, primarily during ferry sailing activity

2 5 10 Operator Prior to operation Design includes barriers to prevent access to river at terminals 1 5 5Operator to provide safety equipment on board vessel and PPE (eg. life jackets) for operatives in combination with emergency plans

Injury to operatives or damage to property if local objectorsTfL i i i i k f h h d di i i

12 Operation: Locals object to tollingInjury to operatives or damage to property if local objectors become violent or abusive about paying for a ferry service which previously (at Woolwich) was free of charge

3 3 9 TfL Prior to construction None 3 3 9TfL to minimise risk of protests through targeted media campaign prior to commencement of operation

13Operation: Management of vehicles and non-motorised users

Death or injury to operatives and/or public (particularly non-motorised users) in clue proximity to live traffic

4 5 20 Operator Prior to operationDesign includes physical seggregation of non-motorised users from vehicles wherever possible

2 5 10

Operator to develop procedures for safe interaction between non-motorised users and vehicles where physical barriers are not possible (eg. on chain ferry slipway). Procedures to be developed for dealing with broken down vehicles on infrastructure.

14 Operation: Slippery sloping surfacesInjury to operatives and/or public due to slippery surfaces on proposed ferry access ramps. Possible damage caused by errant vehicles

4 3 12 Operator Prior to operationAnti-skid surfacing specified to sloping surfaces, particaulrly on linkspan and pontoon for propeller driven ferry

2 3 6Operator to ensure surface is kept clean for anti-skid surfacing to be effective, particualrly on chain ferry slipway which is regularly washed by tidal water

15 Operation: Pollution of riverDamage/injury to river flora/fauna and/or significant penalties from Environment Agency due to hazardous materials (eg. fuel oil from vessel or vehicles on board) entering watercourse

2 3 6 Operator Prior to operation None 2 3 6Operator to develop suitable procedures for quickly dealing with pollution incidents if they occur

16 Operation: Transport of hazardous goodsDeath/injury to operatives and/or public due to leakage of hazardous goods whilst being carried on the ferry, or waiting to board

2 5 10 TfL/Operator Prior to operation None 2 5 10TfL to determine whether hazardous goods are permissible on the ferry, and if so operator to develop emergency plans to deal with any incident

17 Operation: Interference with other river usersDeath/injury to operatives and/or public and damage to equipment caused by collision between ferry and other river users

3 5 15 TfL/Operator Prior to operationTerminals designed to be remote from navigation channels in the river meaning risk of collision is most likely during sailing of the ferry

2 5 10Operator to develop methodology in consultation with Port of London Authority for safe traversing of river. TfL to specify vessel design which incorporates all necessary marine safety systems

18 Operation: Accidental damage to infrastructureInjury/damage (and subsequent loss of service) caused by severe or misplaced berthing loads

4 4 16 Operator Prior to operationInfrastructure designed to accommodate a certain level of impact from berthing

2 4 8Operator to utilise highly competent crew (particularly for the propeller driven ferry option) and arrange for training if ncessary

19 Operation: Welfare of staffInjury/illness to operatives caused by working in exposed and remote location.

4 3 12 TfL Prior to operationDesign includes provision of welfare facilities for staff. No lone working to be permitted, allowing staff to take breaks and deal with the public as necessary

1 3 3Operator to develop suitable roster of shifts in consideration of staff welfare

Index:

16-25

Likelihood x Consequence (See also CIRIA SP125).Likelihood:

1 Improbable Extremely unlikely to occur in relevant period

Consequence:

5 Catastrophic Death or major loss; total systems failure Very High Risk - Unacceptable Re-examine activities to provide lower risk16-25

9-15

6-8

1-5

Mike Green 15 May 2013

Paul Bowerman 16 May 2013

Mike Green 16-May-13

Rev 2 - 07/2012 PRISM - DESIGNERS RISK ASSESSMENT

Approved by: Title: Project Manager / Asst CDM co-ordinator Date:

Reviewed by: Title: CDM co-ordinator Date:

1 - Improbable - Extremely unlikely to occur in relevant period2 - Remote - Unlikely to occur in relevant period3 - Occasional - Likely to occur in relevant period4 - Probable - Likely to occur several times in relevant period5 - Frequent - Likely regular occurrence in relevant period

5 - Catastrophic - Death or major loss; total systems failure4 - Critical - Major injury, major damage to property/infrastructure, or major environmental effect.3 - Serious - Lost time injury or illness; minor damage to property/infrastructure or significant environmental effect.2 - Marginal - Minor first aid incident, or requiring routine maintenance repair. 1 - Insignificant - Unlikely to have impact on works.

Low Risk - Broadly acceptable if all reasonably practicable control measures in place.

Medium Risk - Tolerable only if further mitigation is not reasonably practical and there is need to continue activity with identified controls.

Very High Risk Unacceptable. Re examine activities to provide lower risk.

Prepared by: Title: Project Manager / Asst CDM co-ordinator Date:

High Risk - Apply further mitigation measures and/or alter method of work to reduce risk further. Seek Project Manager approval if risk cannot be reduced.

Rev 0 (04/2012) Page 1 of 1 PRISM - DESIGNERS RISK ASSESSMENT



Appendix G

Cost Estimates




ESTIMATE SUMMARY SHEET

00001 Revision 2 GRIP 3

14-May-13 Anticipated Start Date TBA TBA

TOTAL

Section Code of Account Headings VALUE%age of

Sub-total D VALUE

Level 2 £ % £A Roadworks General N/A

Main carriageways

Interchanges

Signage & Communication

Landscaping

B Piling 4,040,400

Substructure - End Supports 2,067,441

Substructure - Main & Approach Spans 3,975,000

Superstructure 4,203,800

Finishings 992,283

C Main Construction N/A

Finishings

DStructures - Tunnels

Special prelims N/A

Cut & Cover - Main Construction

Bored - Main Construction

Immersed Tube - Main Construction

E Other Works (Inc Utilities) General 1,398,750

16,677,673 0.00% - Other Costs - e.g: % SAY

F 25% 4,169,418

G 5% 833,884

H 2% 333,553

J (incl in Design)

K 3% 500,330

L 1% 166,777

M 7.5% 1,250,826

Sub - Total B 7,254,788 0.00% -

Structures - Retaining Walls, Culverst, Subways,etc

Base Construction Cost : Sub-Total A

Spares

Other - Contractor's O/H & profit

Preliminaries & General Items

Design

Testing & Commissioning

Consultancy Charges

Training

Project Title / Location

Gallions Reach Ferry - Propeller Driven (2 lanes)

1

Structures - Bridges, Viaducts, etc

Estimate No. Level

Estimate Date Anticipated Finish Date

Project /Contract No. Gallions Reach Crossings - Marine Aspects

Cost Estimate - Propeller Ferry - 2 lanesMain Summary Job Nr:

Date:

Total Construction Cost C 23,932,461 0.00% - OTHER Client Costs % SAY

N (by TfL)

P Possession / Isolation Management (by TfL)

R Compensation charges (by TfL)

S TWA Charges (by TfL)

T Land / Property Costs (by TfL)

U Escalation (by TfL)

V Other ( State ) N/A

Network Rail Costs - 0.00% -

Sub - Total D 23,932,461 0.00% -

X01 Mean cost from QRA

PROJECT BUDGET 23,932,461 -

X02 Plus contingency @ - -

FIXED PRICE (If Applicable)

X03 QRA @ P80

AUTHORITY VALUE 23,932,461 -

01/05/2002

SCHEDULE 4 CHARGES

Name :-

Company :-

Position :-

Signed :-

Date :- 14/05/2013 14/05/2013

Halcrow Group Ltd Halcrow Group Ltd

Team Leader Project Manager

APPROVAL & ENDORSEMENT

Estimate Produced By :- Estimate Endorsed by :-

Tom Aikman Mike Green

Project Management


Date:

Gallions Reach River Crossings ‐ Marine Aspects

Infrastructure Implementation Cost Estimate (Propeller Driven Ferry)

Ref Description Qty Unit Rate Price

GENERAL ITEMS

Method Related Charges

Plant ‐ Establish and remove

A Pile driving 1 sum 1,500,000.00 1,500,000£

B Ground investigation 1 sum 300,000.00 300,000£

IN SITU CONCRETE

Provision of concrete, standard mix

A Grade C50 5399 m3 100.00 539,900£

Placing of reinforced concrete

B Bank seat and approach structure 4392 m3 50.00 219,600£

C Pile cap, dolphins 787 m3 50.00 39,350£

D Pontoon ballast 220 m3 50.00 11,000£

CONCRETE ANCILLARIES

Formwork, fair finish

Plane horizontal

A Width exceeding 1.22 m 4988 m2 60.00 299,292£

Plane vertical

B Width exceeding 1.22 m 2636 m2 45.00 118,599£

Reinforcement

Deformed high yield steel bars to BS 4449

C Bar reinforcement to bankseat @ 180 kg/m3 77 t 900.00 69,300£

D Bar reinforcement to approach structure @ 180 kg/m3 714 t 900.00 642,600£

E Bar reinforcement to dolphin type A @ 180 kg/m3 62 t 900.00 55,800£

F Bar reinforcement to dolphin type B @ 180 kg/m3 54 t 900.00 48,600£

G Bar reinforcement to dolphin type C @ 180 kg/m3 26 t 900.00 23,400£

Concrete accessories

H Finishing of top surfaces 4455 m2 2.50 11,138£

STRUCTURAL METALWORK

Fabrication of main members for linkspans

A Link span of approximate length 58 m (2 No.) 826 t 3,500.00 2,891,000£

B Link span flaps 72 t 3,500.00 252,000£

Fabrication of other members

C Steel floating pontoon 30 m x 30 m (2 No.) 1300 t 2,500.00 3,250,000£

D Walkways to dolphins 25 t 2,500.00 62,500£




Erection of members for linkspans

E Transportation and installation of link spans 826 t 800.00 660,800£

Erection of other members

F Transportation and installation of floating pontoons 1300 t 500.00 650,000£

G Transportation and installation of walkways to dolphins 25 t 500.00 12,500£

Miscellaneous metalwork

H Linkspan bearings 8 No. 50,000.00 400,000£

Off Site surface treatment

I Anti skid surfacing to floating pontoons 1350 m2 50.00 67,500£

J Paint protection system to link span bridges 2 No. 380,400.00 760,800£

K Protective coating to marine piling on approach structures 2100 m2 35.00 73,500£

(assume average 10 m length)

L Protective coating to dolphin type A (15 m length) 872 m2 35.00 30,520£

M Protective coating to dolphin type B (12 m length) 1046 m2 35.00 36,610£

N Protective coating to dolphin type C (12 m length) 349 m2 35.00 12,215£

PILES

Isolated steel piles

Mass 250 ‐ 500 kg/m

610 mm diameter 16 mm wall thickness

A Depth driven ‐ vertical piles on approach structures 2068 m 150.00 310,200£

(assume average bed level = 0 m CD)

B Depth driven ‐ raking piles on dolphins & bankseats 1512 m 200.00 302,400£

(assume average bed level = ‐4 m CD)

Approach structure

C Number of piles 32 m long (average length taken across 1:38 slope) 44 No. 8,500.00 374,000£

D Number of piles 31 m long 44 No. 8,000.00 352,000£

Bank seat

E Number of piles 28 m long 16 No. 7,500.00 120,000£

Dolphin type A

F Number of piles 34 m long 24 No. 9,000.00 216,000£

Dolphin type B

G Number of piles 31 m long 36 No. 8,000.00 288,000£




Dolphin type C

H Number of piles 31 m long 12 No. 8,000.00 96,000£

965 mm diameter 19.1 mm wall thickness

I Depth driven ‐ vertical piles on dolphins 216 m 175.00 37,800£


Dolphin type A

J Number of piles 35 m long 4 No. 17,000.00 68,000£

Dolphin type B

K Number of piles 32 m long 6 No. 15,500.00 93,000£

Dolphin type C

L Number of piles 32 m long 2 No. 15,500.00 31,000£

Ground anchors

M Ground anchors for all raking piles 84 No. 3,000.00 252,000£

MISCELLANEOUS WORK

Vehicle barrier

A Galvanised steel vehicle barrier 675 m 150.00 101,250£

Pedestrian barrier

B Galvanised steel pedestrian barrier 675 m 100.00 67,500£

Berthing fenders

C Provision and installation of marine fenders suitable for designated 8 No. 30,000.00 240,000£

ferry

Electrical services

D Provision and installation of electrical services for pontoon and link 2 No. 20,000.00 40,000£

span structure

Lighting

E Provision and installation of lighting for pontoon and link span 2 No. 50,000.00 100,000£

structure

Navigation markers

Including ducted services and power supply

F Navigation beacons and markings to pontoon and linkspan structure 2 No. 75,000.00 150,000£

SIMPLE BUILDING WORKS INCIDENTAL TO CIVIL ENGINEERING WORKS

Staff accommodation building

Including provision of all services and security measures

A Staff accommodation and maintenance building 2 No. 200,000.00 400,000£

Propeller Driven Ferry Infrastructure Total 16,677,673£




TOTAL


Sub-total D VALUE


Main carriageways

Interchanges


Landscaping

B Piling 5,196,600




Finishings 1,076,920


Finishings


Special prelims N/A






F 21.1% 4,179,450

G 4.2% 835,890

H 1.7% 336,733

J (incl in Design)

K 2.5% 501,138

L 0.9% 168,366

M 7.5% 1,485,587

Sub - Total B 7,507,164 0.00% -

Estimate No. Level





1




Spares



Design


Consultancy Charges

Training


Date:


N (by TfL)








Sub - Total D 27,314,984 0.00% -





X03 QRA @ P80


01/05/2002

SCHEDULE 4 CHARGES

Name :-

Company :-

Position :-

Signed :-

Date :-

Project Management




14/05/2013 14/05/2013




Date:




GENERAL ITEMS





IN SITU CONCRETE


A Grade C50 10798 m3 100.00 1,079,800£







Plane horizontal


Plane vertical


Reinforcement



D Bar reinforcement to approach structure @ 180 kg/m3 1428 t 900.00 1,285,200£

















E Transportation and installation of link spans 826 t 800.00 660,800£








J Paint protection system to link span bridges 2 No. 380,400.00 760,800£






PILES


Mass 250 ‐ 500 kg/m






Approach structure

C Number of piles 32 m long (average length taken across 1:38 slope) 88 No. 8,500.00 748,000£

D Number of piles 31 m long 88 No. 8,000.00 704,000£

Bank seat


Dolphin type A


Dolphin type B





Dolphin type C





Dolphin type A


Dolphin type B


Dolphin type C


Ground anchors


MISCELLANEOUS WORK

Vehicle barrier


Pedestrian barrier


Berthing fenders


ferry

Electrical services


span structure

Lighting


structure

Navigation markers











TOTAL


Sub-total D VALUE


Main carriageways

Interchanges


Landscaping

B Piling 6,352,800




Finishings 1,956,108


Finishings


Special prelims N/A






F 14.0% 4,184,855

G 2.8% 836,971

H 1.2% 358,702

J (incl in Design)

K 1.7% 508,161

L 0.8% 224,189

M 7.5% 2,241,887

Sub - Total B 8,354,764 0.00% -



Spares



Design


Consultancy Charges

Training



1


Estimate No. Level




Date:


N (by TfL)








Sub - Total D 38,246,587 0.00% -





X03 QRA @ P80


01/05/2002

SCHEDULE 4 CHARGES

Name :-

Company :-

Position :-

Signed :-

Date :- 14/05/2013 14/05/2013






Project Management


Date:




GENERAL ITEMS





IN SITU CONCRETE


A Grade C50 16197 m3 100.00 1,619,700£







Plane horizontal


Plane vertical


Reinforcement



D Bar reinforcement to approach structure @ 180 kg/m3 2142 t 900.00 1,927,800£

















E Transportation and installation of link spans 1652 t 800.00 1,321,600£








J Paint protection system to link span bridges 4 No. 380,400.00 1,521,600£






PILES


Mass 250 ‐ 500 kg/m






Approach structure

C Number of piles 32 m long (average length taken across 1:38 slope) 132 No. 8,500.00 1,122,000£

D Number of piles 31 m long 132 No. 8,000.00 1,056,000£

Bank seat


Dolphin type A


Dolphin type B





Dolphin type C





Dolphin type A


Dolphin type B


Dolphin type C


Ground anchors


MISCELLANEOUS WORK

Vehicle barrier


Pedestrian barrier


Berthing fenders


ferry

Electrical services


span structure

Lighting


structure

Navigation markers











TOTAL


Sub-total D VALUE


Main carriageways

Interchanges


Landscaping

B Piling 3,197,250

Substructure - End Supports


Superstructure

Finishings 35,200


Finishings


Special prelims N/A






F 25% 3,481,573

G 5% 696,315

H 2% 278,526

J (incl in Design)

K 3% 417,789

L 1% 139,263

M 7.5% 1,044,472

Sub - Total B 6,057,936 0.00% -



Spares



Design


Consultancy Charges

Training


Gallions Reach Ferry - Chain Ferry

1


Estimate No. Level



Cost Estimate - Chain FerryMain Summary Job Nr:

Date:


N (by TfL)








Sub - Total D 19,984,226 0.00% -





X03 QRA @ P80


01/05/2002

SCHEDULE 4 CHARGES

Name :-

Company :-

Position :-

Signed :-

Date :- 14/05/2013 14/05/2013


Slipway Designer Project Manager



John McLaren Mike Green

Project Management

Cost Estimate - Chain FerryMain Summary Job Nr:

Date:


Infrastructure Implementation Cost Estimate (Chain Ferry)


GENERAL ITEMS





Temporary Works ‐ Establish and remove

C Cofferdams 4 sum 1,000,000.00 4,000,000£

D Pumping 4 sum 100,000.00 400,000£

IN SITU CONCRETE


A Grade C50 11680 m3 100.00 1,168,000£


B Slipways (inc crossheads) 10170 m3 50.00 508,500£

C Concrete bearing slab (inc retaining walls) 1510 m3 50.00 75,500£



Plane horizontal


Plane vertical


Reinforcement


C Bar reinforcement @ 180 kg/m3 2102 t 600.00 1,261,200£


D Finishing of top surfaces 14080 m2 2.50 35,200£

Earthworks

E Earthworks 1 sum 200,000.00 200,000£

F Sub‐base for on‐shore slabs 3688 m2 15.00 55,320£



A Protective coatng to marine piling (assume average 5m length) 1640 m2 35.00 57,400£


Infrastructure Implementation Cost Estimate (Chain Ferry)


PILES


Mass 250 ‐ 500 kg/m


A Depth driven ‐ vertical piles (assume average bed level = 0.3m CD) 3905 m 150.00 585,750£

B Number of piles 25m long (average length taken across 1:8 slope) 171 No. 6,500.00 1,111,500£

MISCELLANEOUS WORK

Fences

A Galvanised steel two rail safety handrail 320 m 75.00 24,000£

Lighting

B Provision and installation of lighting for slipway approach 2 No. 50,000.00 100,000£

Navigation markers


C Navigation beacons and markings to slipways 2 No. 35,000.00 70,000£

Water supply

D Provision and installation of water and fire hydrant supply for slipways 2 No. 50,000.00 100,000£

Chains and tensioners

E Troughs for chains 264 m 300.00 79,200£

F Chains 4 sum 100,000.00 400,000£

G Chain anchorages / tensioners 4 sum 60,000.00 240,000£

Stabilisation works

H Stabilisation of northern flood defence wall (provisional) 1 sum 250,000.00 250,000£





Chain Ferry Infrastructure Total 13,926,290£



Appendix H

Outline Construction Programmes




ID Task Name Duration Start Finish

1 TfL Strategic Review of Crossing Options 8 wks Mon 29/04/13 Fri 21/06/13

2 TfL receipt of preliminary design reports 0 wks Mon 29/04/13 Mon 29/04/13

3 TfL review of all Thames crossing options 8 wks Mon 29/04/13 Fri 21/06/13

4 TfL selects a ferry crossing at Gallions Reach 0 wks Fri 21/06/13 Fri 21/06/13

5 Planning and Orders 182 wks Mon 29/04/13 Fri 21/10/16

6 Resolution of current legal position 52 wks Mon 29/04/13 Fri 25/04/14

7 Preparation of illustrative design 52 wks Mon 29/04/13 Fri 25/04/14

8 Prepare information for SoS to consider TWA Order 26 wks Mon 28/10/13 Fri 25/04/14

9 SoS decides to pursue TWA Order 0 wks Fri 25/04/14 Fri 25/04/14

10 TWA Order drawn up 26 wks Mon 28/04/14 Fri 24/10/14

11 TWA Order in Force (planning permission 'granted') 0 wks Fri 24/10/14 Fri 24/10/14

12 Enactments amended / repealed under TWA Order 104 wks Mon 27/10/14 Fri 21/10/16

13 CPO & Land Acquisition 84 wks Mon 24/06/13 Fri 30/01/15

14 CPO approved 0 wks Fri 24/10/14 Fri 24/10/14

15 Identify landowners 52 wks Mon 24/06/13 Fri 20/06/14

16 Notice of Intention published 0 wks Fri 24/10/14 Fri 24/10/14

17 General Vesting Declaration executed 0 wks Fri 23/01/15 Fri 23/01/15

18 Title transferred 0 wks Fri 23/01/15 Fri 23/01/15

19 Take possession of land 1 wk Mon 26/01/15 Fri 30/01/15

20 Procurement 191 wks Mon 24/06/13 Fri 17/02/17

21 Prepare Business Case 52 wks Mon 24/06/13 Fri 20/06/14

22 Business Case review by GoL/DfT 6 wks Mon 23/06/14 Fri 01/08/14

23 Business Case Review by Treasury 6 wks Mon 04/08/14 Fri 12/09/14

24 Initial Business Case approved 0 wks Fri 12/09/14 Fri 12/09/14

25 Business Case revised 8 wks Mon 25/07/16 Fri 16/09/16

26 2nd review of Business Case 8 wks Mon 19/09/16 Fri 11/11/16

27 Final Approval of Business Case 0 wks Fri 11/11/16 Fri 11/11/16

28 Preparation of procurement strategy 52 wks Mon 29/07/13 Fri 25/07/14

29 TfL approval of procurement strategy 0 wks Fri 25/07/14 Fri 25/07/14

30 Market testing 13 wks Mon 28/07/14 Fri 24/10/14

31 OJEU Notice and Prequalification 29 wks Mon 04/08/14 Fri 20/02/15

32 Preparation of OJEU Notice and PQQ 12 wks Mon 04/08/14 Fri 24/10/14

33 Issue OJEU Notice and PQQ 0 wks Fri 24/10/14 Fri 24/10/14

34 OJEU Notice Period 9 wks Mon 27/10/14 Fri 26/12/14

35 Evaluation of Prequalification submissions 8 wks Mon 29/12/14 Fri 20/02/15

36 TfL confirmation of selected candidate list 0 wks Fri 20/02/15 Fri 20/02/15

37 Tender 116 wks Mon 24/02/14 Fri 13/05/16

38 Preparation of ITT documents 52 wks Mon 24/02/14 Fri 20/02/15

39 Issue ITT to selected bidders 0 wks Fri 20/02/15 Fri 20/02/15

40 Tender period (incl. preliminary design) 52 wks Mon 23/02/15 Fri 19/02/16

41 Tenders returned 0 wks Fri 19/02/16 Fri 19/02/16

42 Tender evaluation 12 wks Mon 22/02/16 Fri 13/05/16

43 Announce shortlist 0 wks Fri 13/05/16 Fri 13/05/16

44 BAFO 26 wks Fri 13/05/16 Fri 11/11/16

45 Issue BAFO 0 wks Fri 13/05/16 Fri 13/05/16

46 BAFO preparation 10 wks Mon 16/05/16 Fri 22/07/16

47 BAFO returned 0 wks Fri 22/07/16 Fri 22/07/16

48 BAFO evaluation 4 wks Mon 25/07/16 Fri 19/08/16

49 BAFO negotiations 4 wks Mon 22/08/16 Fri 16/09/16

50 Confirm Preferred Bidder 0 wks Fri 11/11/16 Fri 11/11/16

51 Preferred Bidder 14 wks Mon 14/11/16 Fri 17/02/17

52 Final negotiations with preferred bidder 12 wks Mon 14/11/16 Fri 03/02/17

53 TfL Board Approval 2 wks Mon 06/02/17 Fri 17/02/17

54 Concession Award 0 wks Fri 17/02/17 Fri 17/02/17

55 Financial Close 0 wks Fri 17/02/17 Fri 17/02/17

29/04

21/06

25/04

24/10

24/10

24/10

23/01

23/01

12/09

11/11

25/07

24/10

20/02

20/02

19/02

13/05

13/05

22/07

11/11

17/02

17/02

Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Se2014 2015 2016 2017 2018

Gallions Reach Ferry - Outline Programme for 'TWA Order' PFI Procurement Route

Page 1 of 1 Appendix G1


1 Implementation 149 wks Mon 23/02/15 Fri 29/12/17

2 Design and Approvals 26 wks Mon 20/02/17 Fri 18/08/17

3 Finalise permits, consents and approvals (outside TWA) 26 wks Mon 20/02/17 Fri 18/08/17

4 Detailed design and drawing production 25 wks Mon 20/02/17 Fri 11/08/17

5 Advance works 129 wks Mon 23/02/15 Fri 11/08/17

6 Environmental baseline monitoring 104 wks Mon 17/08/15 Fri 11/08/17

7 Procurement and construction of PLA RCMs 104 wks Mon 23/02/15 Fri 17/02/17

8 PLA Risk Control Measures operational 0 wks Fri 17/02/17 Fri 17/02/17

9 Construction 45 wks Mon 20/02/17 Fri 29/12/17

10 Mobilisation and site clearance 8 wks Mon 19/06/17 Fri 11/08/17

11 Surveys and investigations 4 wks Mon 20/02/17 Fri 17/03/17

12 Topographical survey 4 wks Mon 20/02/17 Fri 17/03/17

13 Site investigation 4 wks Mon 20/02/17 Fri 17/03/17

14 Environmental & archaeological monitoring 28 wks Mon 19/06/17 Fri 29/12/17

15 Construction on land 20 wks Mon 14/08/17 Fri 29/12/17

16 Road diversions / traffic management 20 wks Mon 14/08/17 Fri 29/12/17

17 Utility diversions 4 wks Mon 14/08/17 Fri 08/09/17

18 Earthworks 4 wks Mon 11/09/17 Fri 06/10/17

19 Drainage 4 wks Mon 09/10/17 Fri 03/11/17

20 Roadworks 8 wks Mon 06/11/17 Fri 29/12/17

21 Construction in river 2 wks Mon 11/09/17 Fri 22/09/17

22 Temporary access 2 wks Mon 11/09/17 Fri 22/09/17

17/02

Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan F2016 2017 2018

Gallions Reach Ferry - Outline Programme for Common Implementation Tasks

Page 1 of 1 Appendix G2


1 Implementation of Propeller Driven Ferry 198 wks Mon 17/08/15 Fri 31/05/19



4 Mobilisation for river works 9 wks Mon 25/09/17 Fri 24/11/17

5 Install piles for dolphins 22 wks Mon 27/11/17 Fri 27/04/18

6 Construct dolphins 39 wks Mon 30/04/18 Fri 25/01/19

7 Float pontoons into position 2 wks Mon 28/01/19 Fri 08/02/19

8 Connect linkspans 2 wks Mon 11/02/19 Fri 22/02/19

9 Construction of land-based concrete deck 52 wks Mon 29/01/18 Fri 25/01/19

10 Miscellaneous and finishing works 4 wks Mon 25/02/19 Fri 22/03/19

11 Landscaping 4 wks Mon 25/02/19 Fri 22/03/19

12 Road markings 1 wk Mon 25/02/19 Fri 01/03/19

13 Commissioning of infrastructure 6 wks Mon 25/03/19 Fri 03/05/19

14 Snagging and remedials 8 wks Mon 11/03/19 Fri 03/05/19

15 Demobilisation and cleanup 4 wks Mon 06/05/19 Fri 31/05/19

16 Ferry Procurement 198 wks Mon 17/08/15 Fri 31/05/19

17 Tendering process (traditional route by TfL) 26 wks Mon 17/08/15 Fri 12/02/16

18 Design of pontoons and linkspans 27 wks Mon 15/02/16 Fri 19/08/16

19 Construction of pontoons and linkspans 104 wks Mon 22/08/16 Fri 17/08/18

20 Design of propeller driven ferry 26 wks Mon 22/08/16 Fri 17/02/17

21 Construction of propeller driven ferries 52 wks Mon 20/02/17 Fri 16/02/18

22 Commissioning of propeller driven ferries 10 wks Mon 25/03/19 Fri 31/05/19

23 Commence operations 0 wks Fri 31/05/19 Fri 31/05/19 31/05

Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun2016 2017 2018 2019

Gallions Reach Ferry - Outline Programme for Construction of Propeller Driven Ferry (2 Lane Approach)

Page 1 of 1 Appendix G3a


1 Implementation of Chain Ferry 147 wks Mon 20/02/17 Fri 13/12/19



4 Mobilisation for river works 9 wks Mon 25/09/17 Fri 24/11/17

5 Install cofferdam for slipway (1st phase) 9 wks Mon 27/11/17 Fri 26/01/18

6 Install cofferdam for slipway (2nd phase) 9 wks Mon 23/04/18 Fri 22/06/18

7 Install cofferdam for slipway (3rd phase) 9 wks Mon 24/09/18 Fri 23/11/18

8 Install cofferdam for slipway (4th phase) 9 wks Mon 25/02/19 Fri 26/04/19

9 Remove cofferdams for slipways 4 wks Mon 29/07/19 Fri 23/08/19

10 Install piles for suspended slipways (1st phase) 4 wks Mon 29/01/18 Fri 23/02/18

11 Install piles for suspended slipways (2nd phase) 4 wks Mon 25/06/18 Fri 20/07/18

12 Install piles for suspended slipways (3rd phase) 4 wks Mon 26/11/18 Fri 21/12/18

13 Install piles for suspended slipways (4th phase) 4 wks Mon 29/04/19 Fri 24/05/19

14 Construction of suspended slipway decks (1st phase) 8 wks Mon 26/02/18 Fri 20/04/18

15 Construction of suspended slipway decks (2nd phase) 9 wks Mon 23/07/18 Fri 21/09/18

16 Construction of suspended slipway decks (3rd phase) 9 wks Mon 24/12/18 Fri 22/02/19

17 Construction of suspended slipway decks (4th phase) 9 wks Mon 27/05/19 Fri 26/07/19

18 Install piles for land-based slabs (1st phase) 4 wks Mon 26/03/18 Fri 20/04/18

19 Install piles for land-based slabs (2nd phase) 5 wks Mon 21/01/19 Fri 22/02/19

20 Construction of land-based concrete deck (1st phase) 17 wks Mon 23/04/18 Fri 17/08/18

21 Construction of land-based concrete deck (2nd phase) 17 wks Mon 25/02/19 Fri 21/06/19

22 Construction of ground slab (1st phase) 9 wks Mon 23/07/18 Fri 21/09/18

23 Construction of ground slab (2nd phase) 9 wks Mon 27/05/19 Fri 26/07/19

24 Miscellaneous and finishing works 2 wks Mon 26/08/19 Fri 06/09/19

25 Landscaping 4 wks Mon 26/08/19 Fri 20/09/19

26 Road markings 1 wk Mon 26/08/19 Fri 30/08/19

27 Commissioning of infrastructure 4 wks Mon 23/09/19 Fri 18/10/19

28 Snagging and remedials 4 wks Mon 23/09/19 Fri 18/10/19

29 Demobilisation and cleanup 8 wks Mon 21/10/19 Fri 13/12/19

30 Ferry Procurement 140 wks Mon 20/02/17 Fri 25/10/19

31 Tendering process (traditional route by Contractor) 8 wks Mon 20/02/17 Fri 14/04/17

32 Design of chain ferry 16 wks Mon 17/04/17 Fri 04/08/17

33 Construction of chain ferries 40 wks Mon 07/08/17 Fri 11/05/18

34 Commissioning of chain ferries 5 wks Mon 23/09/19 Fri 25/10/19

35 Commence operations 0 wks Fri 13/12/19 Fri 13/12/19 13/12

Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan2018 2019 2020

Gallions Reach Ferry - Outline Programme for Construction of Chain Ferry

Page 1 of 1 Appendix G3b

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