Transport Assessment

Transport Assessment Group 1

486469,501302,508295,608542

2014

This document includes a transport assessment for a redevelopment of the Southsea leisure park.

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Page 1 of 28 Transportation Engineering

Contents List of Figures .......................................................................................................................................... 2

List of Tables ........................................................................................................................................... 2

List of Abbreviations ............................................................................................................................... 3

1.0 Introduction ................................................................................................................................ 4

1.1 Background ............................................................................................................................... 4

1.2 Report Outline .......................................................................................................................... 5

2.0 Policies. .......................................................................................................................................... 6

2.1 National Policies. ...................................................................................................................... 6

2.2 Local Policies. ........................................................................................................................... 7

3.0 Existing Environment, Community and Site Conditions. ............................................................... 9

3.1 Existing Site. .............................................................................................................................. 9

3.2 Public Transport Assessment ................................................................................................. 10

3.3 Cycling and Walking: ............................................................................................................... 10

3.4 Accidents analysis ................................................................................................................... 11

3.5 Traffic Count ........................................................................................................................... 13

3.6 Mode split .............................................................................................................................. 13

4.0 Proposed Development .............................................................................................................. 16

4.1 Road Access ............................................................................................................................ 16

4.2 Parking Provision .................................................................................................................... 17

4.3 Character of the design .......................................................................................................... 18

4.4 Trip generation ....................................................................................................................... 18

4.5 Trips Distribution .................................................................................................................... 19

4.6 Alternate route “Rat Run” ....................................................................................................... 20

4.7 Junctions ................................................................................................................................. 21

4.8 Drainage ................................................................................................................................. 21

4.9 Pavement design .................................................................................................................... 23

5.0 Appraising the Impact of the Proposed Development. .............................................................. 24

5.1 Environmental ........................................................................................................................ 24

5.2 Economy ................................................................................................................................. 24

5.3 Safety ...................................................................................................................................... 24

5.4 Accessibility ............................................................................................................................ 25

5.5 Integration .............................................................................................................................. 25

6.0 Conclusion ................................................................................................................................... 26

Bibliography .......................................................................................................................................... 27

Appendices .............................................................................................. Error! Bookmark not defined.

1.0 Drawings ...................................................................................... Error! Bookmark not defined.

1.1 Site layout and General Arraingment ...................................... Error! Bookmark not defined.




1.2 Drainage ................................................................................... Error! Bookmark not defined.

2.0 Traffic Count ................................................................................ Error! Bookmark not defined.

2.1 Traffic Count ............................................................................ Error! Bookmark not defined.

2.2 Initial Traffic Count .................................................................. Error! Bookmark not defined.

2.3 Effect of Development on each junction ................................. Error! Bookmark not defined.

2.4 Total Traffic Flow at each junction after 5 years (with the development) .... Error! Bookmark not defined.

2.5 AADT with the development for each junction ....................... Error! Bookmark not defined.

2.6 Trips generated by similar developments ............................... Error! Bookmark not defined.

2.7 Ratio of trips generated at each junction due to the development ....... Error! Bookmark not defined.

2.8 AADT through the development .............................................. Error! Bookmark not defined.

3.0 Calculations .................................................................................. Error! Bookmark not defined.

3.1 Junction Calculations ............................................................... Error! Bookmark not defined.

3.2 Drainage Calulations ................................................................ Error! Bookmark not defined.

3.3 Pavement Calculations ............................................................ Error! Bookmark not defined.

3.4 Horisontal Allingnment Calculations ....................................... Error! Bookmark not defined.

List of Figures Figure 1, Road Assessment 1 .................................................................................................................. 9 Figure 2, Road Assessment 2 .................................................................................................................. 9 Figure 3, Bus Routes ............................................................................................................................. 10 Figure 4, Local Taxi Ranks ..................................................................................................................... 10 Figure 5, Cycle Routes (Transport routes in Portsmouth, n.d.) ............................................................. 11 Figure 6, (Crash map (n.d)) of the roads near the development .......................................................... 12 Figure 7, Accident map (Road Collisions, n.d) ...................................................................................... 12 Figure 8, Illustration of junctions affected by the development (Google, 2014) ................................. 13 Figure 9, Mode split for PM peak flow ................................................................................................. 14 Figure 10, Chart illustrating the most preferred mode of transport to work (values from Population Statistics, 2013) ..................................................................................................................................... 14 Figure 11 Melville Road Realignment ................................................................................................... 16 Figure 12, Sites used to estimate trips generated by houses and flats (Google, 2014) ....................... 18 Figure 13, possible rat run route ......................................................................................................... 20 Figure 14 Sustainable Drainage ............................................................................................................ 22 Figure 15, Pavement Design ................................................................................................................. 23

List of Tables Table 1, Information about means of transport to work, by people in Portsmouth (Population Statistics, 2013) ..................................................................................................................................... 14




List of Abbreviations

BRT - Bus Rapid Transport

CBR - California Baring Ration

EHDC - East Hampshire District Council

HDM - Heavy Duty Macadam

HGV - Heavy Goods Vehicle

HRA - Hot Rolled Asphalt

MfS2 - Manual for Streets 2

NPPF - National Planning Policy Framework

PCC - Portsmouth City Council

PCU - Passenger Car Unit

TFL - Transport for London




1.0 Introduction

1.0.1 This transport assessment has been prepared by a group of undergraduate civil engineers on

behalf of the University of Portsmouth.

1.0.2 A property developer has recently acquired the Southsea leisure park off Melville road. The

client’s intention is to develop the land for residential and office use only. The assessment

will include a redesign of the land and a travel plan to support the clients planning

application to Portsmouth City Council.

1.0.3 A transport assessment is an inclusive process that should cover all aspects of movement by

people and vehicles. It should be able to demonstrate how developments affect demands

for travel and how all travel demands and servicing requirements will be met (TFL, 2010).

The new development change of land will have some form of transport implication. This

assessment seeks to provide a better practise guide to help identify and deal with the likely

impacts.

1.0.4 Who should read this assessment?

1.0.5 This transport assessment is intended to ensure the satisfactory requirements are in place to

specify, assess, implement, monitor and review the impacts that development will have on

the local transport system. The target audience to read this assessment are as follows;

The developer

Local authority officers and councillors with responsibilities for development management

Portsmouth City Council

Public transport providers

Local residents

1.1 Background

1.1.1 The land is currently used as a caravan site, holding under 60 caravans. The development is

located south east of Portsmouth off Melville Road. Early considerations to take into account

is the visual aspect, the land offers an attractive view looking across the English Channel.

1.1.2 The client wants to develop the land according to the following requirements:

1. 8000m2 Offices blocks (8 blocks of 1000)

2. 40 (2 bed flats)

3. 50 (3 bed detached) houses

4. Pavement design

5. Outline of drainage design




1.2 Report Outline

1.2.1 This report is structured into the following chapters:

Chapter 2 provides an overview of the relevant national and local transport policies

Chapter 3 describes the existing conditions around the site including traffic flows, road

safety and provision for walking, cycling, public transport and accident analysis. It also

includes the traffic count and mode split.

Chapter 4 describes the proposed development, including parking provision, road access,

character of the design, trip generation, pavement and drainage design.

Chapter 5 appraising the impact of the proposed development, including the environmental,

economy, safety accessibility and integration.

Chapter 6 concludes that the proposed development would not have an adverse impact on

the local road network.




2.0 Policies.

2.0.1 This section will look into the policies in which this assessment has adhered to.

2.1 National Policies.

2.1.1 The main policy that has effected this assessment is the National Planning Policy Framework

(NPPF) (March 2012), stating; “All developments that generate significant amounts of

movement should be supported by a transport statement or transport assessment”. Below

are some of the key points of the policy (Communities and local Government, 2012);

2.1.2 The core of this policy revolves around sustainable development (economic role, social role

and environmental role), further stating this in paragraph 29.

2.1.3 One way in which this policy achieves these goals is through “actively manage patterns of

growth to make the fullest possible use of public transport, walking and cycling, and focus

significant development in locations which are or can be made sustainable.” As reflected

throughout this assessment.

2.1.4 From the section “Delivering sustainable development” within the NPPF. The government

concludes that meeting the twin challenges of global competition and of a low carbon future

should be at the forefront of the planning system. As shown within this assessment these

challenges have been encouraged through the use of public transport, cycling and walking

reducing carbon emissions. The introduction of new houses and offices will help develop the

economic growth within the local area.

2.1.5 Paragraph 35 of the NPPF has implemented that plans should protect and exploit

opportunities for the use of sustainable transport;

Accommodating the efficient delivery of goods and supplies. (turning circles and road

layouts)

Give priority to pedestrian and cycle movements and have access to high quality public

transport facilities.

Create safe and secure layouts which minimise conflicts between traffic and cyclists or

pedestrians, avoiding street clutter and where appropriate establishing home zones.

Incorporate facilities for charging plug-in and other ultralow emission vehicles.

Consider the needs of people with disabilities by all modes of transport. (Disabled parking

etc.)

2.1.6 Paragraph 69 of the NPPF states that a development should promote, “safe and accessible

developments, containing clear and legible pedestrian routes, and high quality public space,

which encourage the active and continual use of public areas.”




2.2 Local Policies.

2.2.1 The Portsmouth Plan is a document in which this assessments criterion is closely linked to

the policies within.

2.2.2 Portsmouth’s plan policy PCS17 “Transport” states that; the council will work with its

partners to deliver a strategy that will reduce the need to travel and provide a sustainable

and integrated transport network, which will include (Portsmouth City Council, 2012):

Encouraging development in areas around public transport hubs and along corridors where

there is good access not only to public transport but also to goods and services. Locating

development where there is the potential to improve accessibility for all through walking, cycling

and by public transport;

Continue partnership working within the sub region as part of Transport for South Hampshire to

enable the challenges affecting the sub region to be addressed effectively;

Safeguarding land for:

o A new interchange facility at Portsmouth & Southsea station (to be delivered as part of

Station Square development)

o Improved interchange facilities at The Hard

o Land for future stations at Farlington and Paulsgrove

o Land for Park and Ride facilities at Tipner, including a new junction on the M275 for access,

and Farlington

o All modes bridge between Tipner and Horsea Island

o A new road layout for north of the city centre.

Implementing highway improvements associated with the strategic sites;

Promoting walking and cycling and improved integration with other modes;

Creation of Bus Rapid Transit (BRT) routes in the short to medium term, with support for the

implementation of a sub-regional BRT linking Gosport, Fareham, North Fareham SDA and

Portsmouth (including Port Solent and Queen Alexandra Hospital) in the longer term;

Requiring travel plans from major new residential, business and retail development and schools.

2.2.3 This assessment is also closely linked to policies produced by the East Hampshire District

Local Plan, policies displayed below (East Hampshire (EHDC), 2006);

“Public Transport Provision and Improvement”

2.2.4 T2: Planning permission will not be granted for development likely to generate a significant

level of travel demand unless:

A It is, or arrangement are made for it to be, well-served public transport; and




B Its layout is designed to ensure that existing and/or future bus routes lie within easy walking

distance of the entire scheme with conveniently sited bus stops with shelters.

“Road Schemes”

2.2.5 T7: Planning permission will be granted for a road proposal only where it would mitigate or

overcome environmental problems, improve safety and/or convenience on the public

highway or provide access to a new development.

“Highway Issues – New Development”

2.2.6 T9: Planning permission for development requiring a new or improved access will be

permitted provided that it would not:

A. Cause danger or inconvenience on the public highway; or

B. Harm the character and appearance of the surroundings or cause any other environmental

damage.

2.2.7 T10: Development will only be permitted if:

A. The internal road layout is appropriate to the locality; and

B. Measures are incorporated to achieve safe traffic speeds which are in keeping with the

surrounding area and, where appropriate, provide for public transport.

“Parking Standards”

2.2.8 T12: Planning permission will not be granted for a proposal unless any parking of vehicles,

including cycles, is provided in accordance with adopted parking standards.




3.0 Existing Environment, Community and Site Conditions.

3.1 Existing Site.

3.1.1 The development site is located in Southsea, Portsmouth. It is bounded by Melville Road to

the north, Fort Cumberland to the east, sea to the south and Henderson Road to the west.

3.1.2 The site is currently located near Southsea Leisure Park just off Melville road.

3.1.3 The Leisure Park is mainly open planned with a few existing permanent structures. It has

sufficient parking and catering facilities for the guests. There is also an existing cycle path

that runs between Melville road and the junction on Fort Cumberland road.

3.1.4 The majority of the site has a sea view (increasing the properties prospects).

3.1.5 This site is situated near two schools within walking distance. Milton park Pre School

(0.8miles) and Milton Park Federated Primary School (0.9miles), giving sufficient schooling

options to any new families moving into the development. Other local facilities include

Bransbury Park (0.3 miles), Cockleshell community centre (0.1 miles) and Eastney swimming

pool (located adjacent to the existing site – on Melville Road).

3.1.6 The Road situated off Fort Cumberland is in need of repairs and is not suitable for the influx

of traffic that will occur due to the introduction of the new development (details shown in

figures 1 and 2)

3.1.7 It is suggested that the road be reconstructed with the development in accordance with T7

policy of the East Hampshire Local Plan (East Hampshire (EHDC), 2006).

Figure 1, Road Assessment 1 Figure 2, Road Assessment 2




3.2 Public Transport Assessment

Local bus routes:

3.2.1 As show in figure 3 there is one bus route

that runs near the new development. The

closest bus stop is stationed near the

junction where Fort Cumberland road meets

the old exit of Melville road. (council, 2014)

Local train station:

3.2.2 The nearest train station is Fratton station

which is located 1.7 miles away from the

proposed development. The local bus (as

shown above) stops near the train station.

Local Taxi ranks:

3.2.3 As shown in figure 4 the nearest taxi rank is located at number 25 (South Parade, north side

outside Bar Bluu complex. 5 cars, 1900-0600). (council, 2014)

3.3 Cycling and Walking:

3.3.1 In order to provide a sustainable development, it needs to be easily accessible through

walking and cycling. There is an existing cycle path, shown on figure 5 below. It allows for

more convenient transport around the development, encouraging cycling over driving. There

is also a very safe and well maintained cycle and pathway along the sea front stretching from

Figure 3, Bus Routes

Figure 4, Local Taxi Ranks




Clarence pier all the way to and around the purposed development location. As shown in the

figure 5 below, Portsmouth has very good cycle and walking routes.

Figure 5, Cycle Routes (Transport routes in Portsmouth, n.d.)

3.4 Accidents analysis

3.4.1 As shown in figures 6 and 7 there has been no recorded accedents at the junction 3 located

at melville roads entrence concluding that this junction is working efficiently.

3.4.2 Junction 4, where Fort Cumberland road meets the old exit of Melville road, has been a

seiries of slight accidents – on average one a year. As the development of the caravan site is

expected to increase the number of cars flowing through nearby junctions, it will also

increase the number of accidents. It is therefore essential that necessary measures to

prevent accidents are taken.

Proposed development site




Figure 6, (Crash map (n.d)) of the roads near the development

Figure 7, Accident map (Road Collisions, n.d)

3.4.3 By inspection of the site, it was noticed that there is not enough street lighting and signs

leading towards the junction 4 (shown in figure 8 below), warning the drivers about the

possible merging traffic. This is most likely the biggest cause of accidents in the area. It is

therefore proposed that the developer will take responsibility for introducing street lights

and placing additional signs on Fort Cumberland Road coming up to the junction, informing

drivers about it. In addition, due to accidents occurring near junctions 2 and 4, there will be

additional non-slip surfacing introduced, in order to reduce the risk of accidents in the

future.




3.5 Traffic Count

3.5.1 In order to measure the effect that the development has on the nearby junctions, a traffic

count was conducted. Traffic was measured at peak times in the morning (8-9AM) and the

evening (5-6PM) on Tuesday 15th of October 2013, at four junctions believed to be most

affected by the development.

3.5.2 Junction 1 is located where Ferry Road and Fort Cumberland Road meet, junction 2 is

between Handerson Road and Fort Cumberland Road, Junction 3 is located near the Eastney

Swimming pool; point where Driftwood Gardens and Melville Road cross Henderson Road.

Junction 4 is located north-east from the development site. All four junctions are shown

below in figure 8. Using the traffic flow data collected at each junction (shown in appendix

2.1), PCUs were calculated and results are illustrated in appendix 2.2.

Figure 8, Illustration of junctions affected by the development (Google, 2014)

3.6 Mode split

3.6.1 From the survey it was clear that most people commute by car, 89% of all PCUs counted that

day were cars. The second most common form of transport were bicycles, 170 cyclists were

counted, which had an equivalent of 34 PCUs (3% of total traffic). HGV1, Motorbikes and All

Bus types all ranged between 24 and 33 during the afternoon peak hour and no HGV2 were

counted.

Junction 1

Junction 2

Junction 3

Junction 4




Figure 9, Mode split for PM peak flow

3.6.2 A Census was conducted in 2013 by Hampshire City Council (Population Statistics, 2013). It

shows that 55% of people use cars and vans to travel to work, which is the highest out of all

other means of transport. Walking to work is second most preferred option, chosen by 18%

of employees. Cycling to work and using public transport are chosen with the same

frequency of 8%. Mopeds are the most rarely used, by only 1% of the workers. All results are

shown in table 1 and figure 10 below:

Means of transport 2013 (%)

Train 4

Bus, Mini Bus or Coach 8

Motorcycle, Scooter or Moped 1

Car or Van 55

Taxi or Minicab 6

Bicycle 8

On foot 18 Table 1, Information about means of transport to work, by people in Portsmouth (Population Statistics, 2013)

Figure 10, Chart illustrating the most preferred mode of transport to work (values from Population Statistics, 2013)

3.6.3 These findings suggest that although cars are the preferred method of transport for the

majority of employees in Portsmouth; walking, cycling and using public transport are very

important to the council’s agenda. By comparing these findings to results of current modes

13% 2%

81%

2% 2% 3% 1%

89%

3%

4% Cyclists

Morotbikes

Cars

HGV 1

HGV 2

All Bus types

4%

8% 1%

55% 6%

8%

18% Train

Bus, Mini Bus or Coach

Motorcycle, Scooter or Moped

Car or Van

Taxi or Minicab

Bicycle

On foot

PCU Count




of transport near the development (figure 9), it can be seen that the area is not as balanced

as the rest of Portsmouth.

3.6.4 This development will therefore aim to encourage other means of transport such as walking,

cycling and public transport through different means stated in the ‘Travel Plan’ section of

this report (Appendix 4).




4.0 Proposed Development

4.0.1 The overall layout of the proposed development is displayed in the drawings found in

appendix 1.1. The site has an area of 50,000m2 (5 hectares), the land uses as outlined by the

client include;

1. Office blocks: The site contains five office blocks, making a total floor space of 8000m2.

2. 2 -bed flats: There are five blocks of flats containing 40 dwellings of 2 bed flats each.

3. 3-bed detached: the site contains 50 detached dwellings comprising 3 bedrooms.

4.0.2 The access to this site is presently situated on Melville road. A preliminary discussion with

PCC coupled with an earlier scoping study concluded that the realignment of Melville Road is

the appropriate access and egress solution.

4.0.3 The site will be in operation between 16 - 24 hours daily; this is due to the nature of the

development plan for a site which includes housing development (Department for

Transport, 2007).

Figure 11 Melville Road Realignment

4.1 Road Access

4.1.1 The access into the site will be the proposed realignment of Melville Road, which will serve

as the main through road within the development. The road will link Fort Cumberland (north

of the development) to Henderson (west of the development). The site layout drawing is

shown in appendix 1.1.

4.1.2 The development will consist of minor roads as well as the realigned Melville Road which

will serve as the main link road to all the other minor roads within the development. These

roads will be designed to achieve a 20mph speed limit. The access road horizontal alignment

is designed to meet the manual for streets standard and the horizontal alignment

calculations which can be found in appendix 3.4. The width of the main access road is 7.3m,

Melville Road Realignment




in order to meet the design criteria for a 20mph speed limit in keeping with policy T10 (East

Hampshire (EHDC), 2006), the following have been introduced:

1. On-street parking (2m by 6m on both sides of the road)

2. A bus stop on both approaches conforming to the T2 policy from the East Hampshire Local

Plan (East Hampshire (EHDC), 2006).

3. Straights and bends meets manual for street 2 horizontal alignment standard for a 20mph

road.

4.1.3 Because a new priority junction will be introduced at each end of the new Melville Road,

visibility splays (x=2.4m and y=25) (MfS2) at both ends of the road is designed to meet the

manual for streets standards. All roads within the development will have adequate

provisions for pedestrians and cyclists in accordance with paragraph 35 of the NPPF

(Communities and local Government, 2012); all roads will be designed to have a minimum

footway width of 2.0m, (a cross fall of 1:40 or 2.5%), cyclists are encouraged to cycle on the

road (this is also aimed at keeping vehicle speed to the required limit), design of shared use

path will be provided wherever possible (although most of the minor roads are designed to

be quiet, therefore making it safe for pedestrians and cyclists). A bus stop will be provided

within the development to encourage a more sustainable mode of travel. (Cordwell, 2010)

4.1.4 All these provision will be designed in a way that integrates them into the existing and

surrounding transport infrastructure.

4.2 Parking Provision

4.2.1 The general arrangement drawing in appendix 1.1 shows 150 off street car parking spaces

(including disabled parking) with minimal on street car parking space. There will be more

emphases on sustainable modes of travel by providing cycle parking in accordance with T12

of the East Hampshire Local Plan (East Hampshire (EHDC), 2006). Each house within the

development will be allocated one car parking space. Offices will be provided with car

parking close to their office block with a limited amount of spaces, making it a requirement

for offices to encourage their staff to choose other modes of travel (such as cycling, public

transport and car pulling) for work (thereby reducing congestion within the development).

4.2.2 Safe parking and well lit spaces are also provided for cyclists and motorcyclists within the

development, this is aimed at encouraging residents to travel by sustainable transport

modes.




4.3 Character of the design

4.3.1 The local area around the site mainly consists of new build properties for domestic use;

housing, flats, community centre etc. This project has adopted the basic architecture of the

surrounding houses and flat complexes to help integrate the new development into the

surrounding area (Policy T9 (East Hampshire (EHDC), 2006)).

4.3.2 The existing sites location is situated next to the beach. Taking advantage of this natural

entity the location of most of the high rise buildings have been placed further away from the

beach or in a place that does not obstruct any smaller buildings giving the majority of the

new properties a sea view.

4.3.3 Already located on this site is a functioning cycle lane which has been integrated into the

proposed development.

4.3.4 This plan gives the local populace a clear layout of the network of streets. It also highlights

the natural assets of the development, such as the small park surrounding the sustainable

urban drainage pond and the beach giving the new development a welcoming and people

friendly environment.

4.4 Trip generation

4.4.1 In order to predict the amount of traffic introduced into the junctions by the development, a

count of trips from similar sites was conducted and scaled accordingly to match the size of

the development, results for which can be seen in appendix 2.6.

4.4.2 Sites used to estimate the trip generation of houses and flats were 24 detached houses on

Driftwood Gardens and 32 flats on Centurion Gate, shown in figure 12. Offices used to

estimate the trip generation were located on the corner of Kingston Crescent and Heathfield

Road and had floor area of 1800 m2. The survey was conducted on Tuesday 29th of October

2013, weekday during a peak month to represent the worst case scenario where traffic

movements are at their greatest.

Figure 12, Sites used to estimate trips generated by houses and flats (Google, 2014)

Detached houses

Flats

Development




4.4.3 The detached houses and flats were located within close proximity to the proposed

development and both were recently built. The offices had the most comparable attributes

to the offices proposed by the development. This means that trips calculated were a good

representation of what can be expected from the new site.

4.5 Trips Distribution

4.5.1 The proposed development has exits at two junctions; 3 and 4 (shown in figure 8). The ratio

of trips generated at each junction was assumed from the placement of buildings in the

development and can be seen in appendix 2.7.

4.5.2 Most houses are placed near junction 3 (can be seen from “site layout”, appendix 1.1),

hence it is expected that the trips generated at that junction caused by detached houses will

be higher. Ratio of 7:3 was therefore assumed. Similarly most flats are distributed near

junction 4; hence a ratio of 3:7 was adopted. As offices are scattered evenly throughout the

development, it is expected that they will generate equal number of trips at each junction.

By inspecting the ratio at which each junction distributes its’ flow, the additional trips

generated by the development were distributed consequently. The amount of trips

generated in each direction at each junction is shown in appendix 2.3.

4.5.3 To calculate the increase in traffic flow in 5 years, a factor of 1.043 for AM and 1.0442 for

PM (obtained using TEMPro (Department of Transport, 2013)) was applied to each value

(results shown in appendix 2.4). In order to calculate AADT, the PM values were multiplied

by 24 and divided by 2.63 (MacKay, 1997). The new development is expected to generate

the AADT at each junction, shown in appendix 2.5.

4.5.4 To accurately assume the AADT through the development, a number of cars going in at one

junction and out at the other has been calculated. There were four possible values for this,

as shown in appendix 2.8, and the highest value has been chosen as the design value to

ensure the design is viable at the highest flows.

4.5.5 The most traffic flow occurred during the afternoon peak flow, and the most traffic (AADT

equivalent of 913 PCUs) will travel through the development from junction 3 to 4 (west to

east).




4.6 Alternate route “Rat Run”

Figure 13, possible rat run route

4.6.1. Initial concerns were raised about the development being used as a shortcut to cut through

from Henderson road (A) to Fort Cumberland road (B). During traffic counts it has been

noted that around 37 PCUs use route 1 to travel from A to B during the evening peak time.

This gives an approximate 400 PCUs daily flow.

4.6.2. The risk of vehicles using route 2 as a shortcut was assessed by comparing the distance and

the speed limit of both routes. Route 1 has a distance of 4.9 km and speed limits of 30 mph

and 20 mph respectively, route 2 has a greater distance of 5.5 km and a constant speed limit

of 20 mph, which makes the development much less appealing to use as a “rat run”.

4.6.3. Additional factors discouraging drivers to use route 2 is the width of the road and number of

bends required to be executed. Due to on-road parking, the effective width of the road is

reduced to 3.3m, forcing the vehicles to stop in order to pass one another. Route 2 also

includes more bends and requires cars to stop at junctions 3 and 4 (A and B in figure 13).

This in effect lengthens the journey time of the route, and makes it very unappealing to non-

residents.

4.6.4. The risk of route 2 being used as a rat run is therefore very unlikely as it would increase the

journey time greatly as well as require additional stops and concentration throughout the

development.

A

B

1

2




4.7 Junctions

4.7.1 Due to increase in traffic flow, each of the 4 junctions was tested for flow capacity. They

were all modelled as T-junctions for simplicity of calculations, which can be seen in appendix

3.1. All junctions passed the requirements presented by the development and no further

action is required in order to increase their capacity.

4.8 Drainage

4.8.1 The city of Portsmouth is situated in a low lying area directly on the coastline off the English

Channel, where it faces a severe flood risk. The site has a detailed drainage system to ensure

a safe and habitable environment to live. Appendix 1.2 holds the overall layout of the storm

water drainage system showing the details of manholes, pipe levels and gulley positions. The

underground pipe network allows all the rainfall to run freely down the pipes into a SUDS

pond that retains the volume of water (situated south east of the development). If by

chance a freak flooding occurs, the SUDS pond includes a tidal flap which allows overflowing

water to transfer into the sea. This drainage method is aimed to provide an environmentally

friendly emergency procedure.

4.8.2 The idea of using the SUDS pond is to create a natural system that is cost effective with low

environmental impacts. The pond includes three vortex chambers allowing free flowing dirty

water to be collected through this unique design that controls and cleans the water whilst

transferring it into a pond. The vortex chamber has no moving parts so no maintenance is

needed, whilst the large cross-sectional area reduces the risk of blockage. The pond is one

metre deep preventing little risk of drowning for the local residents, with a sloped entry the

hazard is deemed nil with no boundary fence needed, however signs will be put in place not

to enter. The pond will also be decorated with reeves to create a wildlife habitat as well as

producing a pleasant asset for the development, encouraging the use of public areas as

stated in paragraph 69 of the NPPF (Communities and local Government, 2012).

4.8.3 The development has gully pots either side of the road and spaced no more than 25 metres

allowing the roads to be safe to walk, cycle and transport around without the risk of

flooding. The roads are constructed with a camber allowing a 1 in 40 cross fall directing the

rainwater into the closest gully where it connects into the main line.

4.8.4 Consideration of alternate drainage mechanisms was taken into account. The use of a

French drainage system also known as a filtration drain will be constructed in the car parks,

no kerbs surrounding the parking areas allows the cross fall camber to direct the rainwater

into the drains that link into the main line, shown in the drainage layout drawing in appendix

1.2. This drainage system is cost effective and low maintenance complimenting the




environmental aspect of this transport assessment. Both offices and flats will include green

roofs that are designed to create a free habitat for wildlife and clean the rainwater that will

transfer down the gully pipes into the underground pipe network. Whilst the office and flat

car parks have alternative drainage, the housing complex will use a forced system with the

use of swales, the grassed area depression which guides surface run-off overland from the

house towards the road where it falls into a nearby gully.

4.8.5 Appendix 3.2 holds the calculations and drainage specification using the Lloyd Davies

method. Each pipe run includes different gradients and pipe sizes to minimise costs for the

client.

Sustainable Drainage

Houses

Swales filter and transfer the

drainage systems around the

housing complex to the main

line

Offices

Green roofs are designed to

create a disturbance free habitat

for birds.

Car Park

French Drainage system

Filters water and low

maintenance

SUDS

SUDS pond with a max volume

of 440m3.

Installed tidal flap to allow

overflowing water to transfer

into the sea.

Clean and filtered water

Includes area for recreation and

disturbance free for wildlife

Figure 14 Sustainable Drainage




4.9 Pavement design

4.9.1 As discussed with the client a pavement design has been produced in order to help with

coasting. Below is the suggested pavement option;

4.9.2 The pavement consists of a HRA surface course with a standard thickness of 50mm

(Assuming the use of a HDM base and an optional binder course). The binder course should

be at least 50mm thick and must be of the same material as the base, the remainder is made

up of a 150mm HDM base (category A) and a 200mm class 2 foundation (200MPa stiffness)

over a subgrade with a 5% CBR. (Figure 15).

4.9.3 Due to the calculated msa equalling zero throughout the development this option is the

suggested solution for any road pavement design throughout the design.

4.9.4 For further details on the calculations and design of this pavement see appendix 3.3 and

drawing 1.1.

Subgrade (5% CBR)

200mm Class 2 Foundation (200MPa Stiffness)

150mm HBM base, Category A

50mm Asphalt, HDM binder course

50mm Asphalt, HRA surface course

Figure 15, Pavement Design




5.0 Appraising the Impact of the Proposed Development.

5.0.1 The government’s five objectives (Department for Transport, 2007) for transport include the

following:

5.1 Environmental

5.1.1 The development has been designed to be environmentally friendly. The development

encourages the use of sustainable mode of transport e.g. public transport, walking & cycling,

car sharing (Policy PCS17 (Portsmouth City Council, 2012)). It is hoped that this will have a

positive impact on the environment by reducing traffic noise and greenhouse gas emissions

resulting from car use. This will also improve local air quality and street liveability.

5.1.2 The newly realignment Melville road has been designed to (manual for street 2) standard

and does not encourage external traffic except traffic going in and out of the development.

The provision of on street parking on both sides of the road, bus services and tight

carriageway width will ensure that motorist do not consider this route as a ‘rat run’. This will

ensure that the development does not experience congestion from external traffic.

5.2 Economy

5.2.1 As part of the travel plan, the development will encourage the businesses and offices to

encourage their staffs & employees to travel to work in a more sustainable way e.g. cycling,

using public transport and car-sharing. It is hoped that this will improve the economic

efficiency of transport facilities within the development.

5.2.2 The development will invariably create employment for local residents. This should improve

the wider economy in Portsmouth. Public transport and taxies will be allowed to access the

side, this will form part of the travel plan to encourage the use of other transport modes.

5.3 Safety

5.3.1 The issue of safety is well addressed within the development. Road within the development

is well overlooked by houses. The entire development is designed to eliminate any obscure

areas. Street lights will be installed within the development to (MfS2) street lighting

standards. This should invariably improve security and eliminate perception of insecurity.

5.3.2 Road safety concerns as been significantly mitigated by proper design of road alignment to

(MfS) standards. The road design will achieve its design speed limit of 20mph; this will be

achieved through the different feature dotted along the highway. This should invariable

keep all road users safe and eliminate fears of accident (Policy T10 (East Hampshire (EHDC),

2006).




5.4 Accessibility

5.4.1 The development is well accessible for both pedestrians and cyclists. The development

consists of pedestrian footpaths (2.0m wide), quiet minor roads and shared use path (3.0m

wide). This can be found in the general arrangement drawing (appendix 1.1).

5.4.2 There are bus stops within the development which could be served by the first bus service

(No 15). The closest bus stop is located just off the Fort Cumberland road junction. The

closest train station is 1.7miles from the development, which is also accessible from the

development by bus services to Portsmouth City Centre. The development is also accessible

by cars & taxis for those who have essential use for automobiles.

5.5 Integration

5.5.1 The design of the development will address any integration issue by promoting integration

between all stakeholders within the development e.g. businesses, offices, motorists, non-

motorists etc.

5.5.2 The proposed development is well integrated into the wider National Planning Policy

Framework and the local policies. This ensures that this is a sustainable development.

5.5.3 The development streetscape also encourages social inclusivity, as the roads, houses and

other facilities are compactly positioned, all roads are properly linked together and are all

within reach. The grassed area within the development creates an atmosphere for social

inclusivity, where people of all ages can socialise. It is hoped that this will address any

integration issues within the development.




6.0 Conclusion

6.0.1 The development of the Southsea Leisure Park consists of residential housing and office

blocks provided with efficient parking.

6.0.2 The proposed development encourages smarter choices to travel into the development.

Influencing members of the public to use public transport by marketing transport

information of local bus routes, facilitating bike storage and shared car travel.

6.0.3 The development includes sufficient junctions that will not increase traffic flow proven in the

junction capacity calculations, plus junction 2 and 4 (shown in section 3.5.2, figure 8) with

new improved lighting and skid resistant surfaces and sign posts leading onto the junction

creating a safe approach into the new development. Using these methods is a cost effective

way to improve the safety of the existing junction.

6.0.4 The Road situated off Fort Cumberland is in need of repairs and is not suitable for the influx

of traffic that will occur due to the introduction of the new development. It is therefore

proposed that the developer will reconstruct the road to the pavement specifications

designated in this developments’ design.

6.0.5 The vision of this assessment is to provide a safe and sustainable environment for the

community to travel in and out with easy, efficient and cost effective methods of transport

with the use of well-designed streets and junctions to provide an easily navigated

development.

6.0.6 This transport assessment has been carried out thoroughly and it can be concluded that this

development will have a positive impact on the surrounding highway network.




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