Slane Traffic Management Study - County Meath50775,en.pdf · Slane Traffic Management Study ......

Slane Traffic Management Study Stage 1 Report

October 2012

Work in P

AECOM

Grand Canal House

Upper Grand Canal Street

Dublin 4

Tel (01) 2383100 Fax (01) 2383199

www.aecom.com

http://www.aecom.com/

AECOM Slane Traffic Management Study

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Slane Traffic Management Study

Stage 1 Report

Document No…….. 60275105

Made: ......................... Declan Keenan

Checked: .................. Shane Dunny

Approved: ................. Alan O’Brien

Document No. Revision Status Made Checked Approved Date

60275105 0 Final DK SD AOB 22nd

Oct 2012


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Executive Summary

AECOM has been requested by Meath County Council to undertake an analysis to assess the

impact of various levels of goods vehicle restriction through Slane Village. This report sets out

the results of the study. The analysis is based on collection of detailed origin and destination

data for goods vehicles through the locality, and is supported by a regional traffic model that

incorporates the M1, N2 and M3 corridors, in addition to all east-west connecting routes.

A total of seven possible scenarios for vehicle restrictions have been defined, which impose

restrictions on various roads in the vicinity of Slane Village, at levels ranging from 3 axle vehicles

up to 5+ axle vehicles.

In a review of similar projects, the study has concluded that a vehicle restriction in Slane would

likely operate in a manner that is similar to the Dublin City HGV Restriction. The scheme, which

was introduced primarily to address environmental and safety concerns, includes an online

permit system which ensures that necessary trips into the restricted area can be facilitated. The

review concluded that schemes for urban areas generally sought to shift large commercial

vehicle traffic to more suitable routes, or to encourage the use of smaller vehicles for access to

the restricted area.

The data analysis highlighted that approximately 20% of goods vehicle traffic across Slane

Bridge could be considered traffic that was using the N2 to avoid the M1. A further 25% was

legitimate N2 traffic travelling between Ardee/Monaghan and either Ashbourne or onwards to the

Greater Dublin Area. It is considered that a high proportion of this 25% could be encouraged to

transfer to the M1 under the right conditions. A further 49% of goods traffic is generated within

the broader Slane vicinity.

Following a detailed analysis of alternatives, it is concluded that the implementation of 5 axle

restrictions on Slane Bridge might represent the most manageable approach for implementing

vehicle size restrictions through Slane village. The proposal will generate slight safety benefits,

and an improvement in local air quality in Slane. It will reduce the volume of commercial vehicles

through Slane by approximately 42%, although the provision of a permit scheme for local access

will reduce this to below 40%. Nevertheless, this proposal brings with it a number of notable

adverse impacts:

It leads to an increase in goods vehicle traffic using the R152 and R153 as an alternative

to the N2 via Slane. The increase on the R152 is to the order of 300 vehicles per day,

with an increase on the R153 of approximately 100 vehicles per day;

It generates an increase in vehicle kilometres (and hence vehicle emissions), thereby

leading to a reduction in network efficiency as drivers seek longer routes to avoid the

restricted area; and

It reduces strategic accessibility between Ashbourne and the M1/Monaghan which is

currently available via the N2 corridor.

In light of the above impacts, it is questionable whether the traffic management proposals

presented in this report would yield a positive Business Case.

The previous N2 Slane Bypass scheme reflected an approach of delivering incremental

improvements along the N2, but within the ultimate frame of maintaining the N2 as a strategic

corridor. The proposal for vehicle size restrictions through Slane contradict the conventional

view of the N2 continuing to provide such a function, and would be more appropriately examined

in the context of a strategic plan for the M1, N2 and M3 corridors.


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Slane Traffic Management Study

Table of Contents

Page

1.0 Background .............................................................................................................................. 2

2.0 Existing Conditions .................................................................................................................. 4

3.0 Project Objectives .................................................................................................................... 5

4.0 Case Studies ............................................................................................................................. 6

5.0 Data Collection and Baseline Analysis ................................................................................ 10

5.1 Definition of a Study Area......................................................................................................... 10

5.2 Data Collection ......................................................................................................................... 11

5.3 Key Characteristics of Traffic Flows ......................................................................................... 12

5.3.1 Daily Flow Profile ...................................................................................................................... 12

5.3.2 Traffic Composition .................................................................................................................. 13

5.3.3 Vehicle Type ............................................................................................................................. 13

5.3.4 Average Weekday Daily Flow Calculation ............................................................................... 15

5.4 Analysis of Traffic Movements through Slane .......................................................................... 15

5.4.1 Total Matrix of Goods Vehicle Movements via Slane .............................................................. 17

5.4.2 Total Goods Vehicle Movements that could use N2 Slane Bridge .......................................... 18

5.4.3 Origin-Destination Patterns in Slane Village ............................................................................ 18

5.4.4 Extent of local trips using Slane Bridge .................................................................................... 19

5.4.5 Locally Generated 5-Axle Goods Vehicle Traffic ..................................................................... 19

6.0 Development of the Traffic Model ........................................................................................ 22

6.1 Conversion of AM and IP models to All Day ............................................................................ 23

7.0 Definition of Traffic Management Scenarios ....................................................................... 24

8.0 Scenario Testing .................................................................................................................... 29

8.1 Scenario 1: 5+ Axle Ban on Slane Bridge ................................................................................ 30

8.2 Scenario 2: 5+ Axle Ban on Slane Bridge, and on N2 between Slane and Collon .................. 31

8.3 Scenario 2a: 4+ Axle Ban on Slane Bridge, and on N2 between Slane and Collon ................ 32

8.4 Scenario 3: 3+ Axle Ban on Slane Bridge, and on N2 between Slane and Collon .................. 33

8.5 Scenario 4: 3+ Axle Ban on Slane Bridge, on N2 between Slane and Collon, and on N51 .... 34

8.6 Scenario 5: Southbound 3+ Axle Ban on Slane Bridge, and N2 between Slane and Collon .. 35

8.7 Scenario 6: 3+ Axle Ban on Slane Bridge, but in southbound direction only ........................... 36

8.8 Summary of Traffic Analysis .................................................................................................... 37

8.9 Multi-Criteria Assessment of Alternatives ................................................................................ 37

9.0 Implementation of Preferred Scenario ................................................................................. 39

9.1 Overview................................................................................................................................... 39

9.2 Extent of Restrictions ............................................................................................................... 39

9.3 Management of Access/Permits .............................................................................................. 39

9.4 Mitigation of Impacts ................................................................................................................ 39

9.5 Conclusion ................................................................................................................................ 40

9.6 The Role of the N2 as a Strategic Route ................................................................................. 40


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1.0 Background

The basis for the N2 Slane Bypass arose out of the high volume of goods vehicle traffic which

was transiting the town via the N2 and the resulting road safety problems on the N2 through

Slane Village. The problems in the town centre were broadly acknowledged; noise and air

quality issues resulting from goods vehicle activity, and exacerbated by the steep gradient

leading out to the north and the south of the town. The safety issue was particularly notable, with

a number of incidents occurring in the town centre in recent years.

In 2001, a Traffic Management Scheme was implemented in Slane to address the significant

road safety issues that existed. The scheme complemented the existing shuttle system across

Slane Bridge and included the implementation of advanced traffic signals which provided priority

to light vehicles, and associated signage. This scheme did lead to a safety improvement, but at

significant journey time cost to non-goods vehicles.

The N2 Slane Bypass was intended to act as a long term solution to the existing issues in

addition to the existing traffic management measures. By removing a large volume of goods

vehicle traffic from the town centre, the scheme would provide significant safety and

environmental improvements to residents of the town, in addition to journey time savings for road

users. Following the preparation of the N2 Slane Bypass Scheme and its submission for planning

approval, the scheme was refused planning consent by An Bórd Pleanála in March 2012.

In its report, An Bórd suggested that the need for a bypass of the town had not been

demonstrated, and that lower cost ‘management’ measures which would achieve the desired

outcomes had not been fully explored. The findings are summarised below;

Due to the location of the bypass in the viewshed of Brú na Bóinne, An Bórd Pleanála

considered that the proposed bypass would be acceptable only where it has been

demonstrated that no appropriate alternative is available. Following on from the

submissions received and the oral evidence given during the Oral Hearing, An Bórd was

not satisfied that alternatives to a bypass have been adequately explored. In this context,

they considered that:

“The proposed development would have a detrimental impact on the setting

of the Brú na Boinne archaeological complex which would be contrary to the

heritage protection provisions of the County Development Plan” and that

“The bypass would be contrary to proper planning and sustainable

development, as it would tend to undermine the investments that had been

made improving the M1 and M3 corridors, and would have negative

implications for the quality of the environment and road safety along the N2

route.”

Whilst it was accepted that the Slane Bypass would assist in alleviating the high traffic

levels in the village in a north-south direction it will not impact upon the east-west traffic.

An Bórd also reported that the scheme was:

“likely to attract additional traffic, including a substantial proportion of

additional heavy commercial vehicles onto the N2 including a substantial

proportion of heavy commercial vehicles, onto the single carriageway N2

along its length, and through the settlements of Collon and Ardee”


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An Bórd also reported its conclusion that the proposed Slane Bypass would undermine

public investment given the current configuration of the overall national road network in

the region, and that alternatives to a bypass had not been fully explored.

An Bórd went on to state that although it has no role in developing regional transport policy or the

implementation of a traffic management system they suggested that traffic management in the

form of a HGV ban merited more investigation. The Board stated that potential negative impacts

for local business would need to be considered as would potential improvements on alternative

routes to alleviate safety concerns. An Bórd concluded that traffic management alternatives

might align well with the principles of proper planning and sustainable development, and ought to

be given further consideration.

As a consequence of the refusal of the scheme, AECOM has been requested by Meath County

Council to prepare a study that would assess the impact of various levels of goods vehicle

restriction through Slane Village.

This report sets out a quantitative analysis of the impact of goods vehicle size restrictions

through Slane. It sets out the process of data collection to understand existing traffic patterns,

aggregates goods vehicle traffic into appropriate size categories, and performs a network-wide

analysis of the reassignment impacts of a size restriction on the road network. The following

tasks have been undertaken:

Establishment of project objectives, to support comparison of alternative solutions;

Case Studies of vehicle restrictions in other locations, and their means of operation;

A detailed discussion of existing travel patterns through the undertaking of

comprehensive traffic and travel surveys;

Development of an analysis tool (traffic model) to support the assessment of impacts;

Identification of alternative Traffic Management Solutions;

Appraisal of alternatives, and selection of an emerging preferred solution that best fits the

project objectives; and

An exploration of key issues to be considered in the implementation of such schemes.


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2.0 Existing Conditions

The N2 National Primary Route is a strategic corridor connecting Dublin with Northern Ireland

and the border counties. The National Spatial Strategy identifies Monaghan as a ‘Hub’ which is

defined as:

“An important local node in transportation and communication terms: (a) on the

national road and rail or bus networks, (b) with access to a national or regional airport

(c) having adequate, reliable, cost effective and efficient access to port facilities (d)

with effective and competitive broadband access”

In this regard, the N2 is obviously seen as key to supporting the intended function of Monaghan

as a designated Hub.

Nevertheless, the M1 runs almost parallel to the N2 between Dublin and Ardee. Furthermore,

the M1 is connected to the N2 by a number of east-west routes of varying quality, most notably

the N51 (Slane – Drogheda), the R169 (Collon – Dunleer), the N33 (Ardee – Dunleer), and the

N52 (Ardee – Dundalk). This connectivity between both corridors leads to a notable degree of

traffic mixing between corridors on trips between the Greater Dublin Area and areas to the north.

The M1 currently charges a toll of between €1.80 for cars and €5.90 for 5-axle goods vehicles.

Understandably, this toll reduces the attraction of the M1 for trips, particularly for those who

might be otherwise drawn from the parallel N2 corridor.

Surveys undertaken in May 2012 showed that Slane Village currently caters for traffic flows of

over 13,000 vehicles per day. The surveys found that over 9% of the vehicles travelling through

the village are Heavy Goods Vehicles (HGV) and a further 11% are Light Goods Vehicles (LGV).

Slane Bridge itself experiences a traffic flow in the region of 7,000 vehicles per day of which 12%

are Heavy Goods Vehicles.

The existing N2 route passes through Slane village in a north-south direction as it descends from

high ground adjoining Slane Hill to cross the River Boyne Valley at a much lower level. The

route descends some 80m over a short distance of 1km, which leads to an average gradient of

8%, which exceeds the maximum permissible gradient of 6% for a single carriageway road. The

steep road gradient is a significant contributory factor to the traffic safety problems in Slane.

Further major safety problems arise at Slane Bridge over the River Boyne, where the road

alignment involves very sharp corners at the bottom of steep hills at both ends of the bridge.

This bridge is too narrow for two-way traffic, and a shuttle traffic signal system manages the flow

in alternate directions. Inherent traffic hazards arise from the seriously deficient road layout at the

bridge, and this has led to frequent accidents due to loss of control mainly by trucks. Following

the most recent fatal accident at this location in 2001, a major road safety scheme was

constructed in 2002, which involves separate signal control of light traffic and trucks with a

holding point in a safer location further up the hill where there is enough width for a virtual

escape lane for runaway trucks. In 2009 non-skid surfaces were reapplied on various road

sections around Slane however residual safety issues still remain due to the layout and

topography of the area as evident by the occurrence of a multi vehicle accident in 2009.


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3.0 Project Objectives

Project Objectives set out the intended outcome of any scheme, and are a driving influence in

the selection and definition of alternatives. Through appraisal of alternatives against project

objectives, solutions which best fulfil the particular needs of a project can be identified, refined

and shortlisted to produce a small number of possible solutions. Through more detailed analysis

(such as traffic modelling) the impacts of each alternative scheme can be quantified and a

preferred solution chosen.

The objectives of the N2 Slane Bypass project as set out in the Project Brief were defined as

follows:

(a) To improve traffic safety;

(b) To improve the environment of Slane Village by removing a significant portion of

north/south through traffic;

(c) To obtain an improved level of service suitable for a National Primary route;

(d) To achieve the objectives of various national and regional policies for the national

road network.

(e) To achieve an objective of the Meath County Development Plan 2007 – 2013.

It is considered that these objectives might not be fully relevant to the assessment of a Traffic

Management Solution, in that they dictate the identification of a new corridor. As such, the

objectives of the current exercise have been identified as follows such that they facilitate the

identification of a broader range of management solutions:

(a) To improve traffic safety;

(b) To improve air quality in Slane Village and other populated areas;

(c) To reduce transport emissions;

(d) To maximise the efficiency of the transport network; and

(e) To protect the accessibility of rural areas to designated Gateways, including the

Greater Dublin Area

In order to assess the comparative impacts of alternative schemes, a series of indicators will be

used as in Table 3-1 below.

Table 3-1: Project Objectives

Objective Measured By

Traffic Safety Aggregate PAG collision estimates based on road type

Air Quality Volume of goods vehicles through populated areas

Transport Emissions Total Vehicle kilometres travelled on the road network

Network Efficiency Total Vehicle hours travelled on the road network

Accessibility Impact on routing of restricted vehicles


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4.0 Case Studies

There are a number of HGV charging schemes in place in Ireland and throughout Europe. An

overview of a number of such schemes is presented below.

Dublin City HGV Cordon

The Dublin Port Tunnel opened on 20 December 2006 providing direct access between Dublin

Port and the national road network for Heavy Goods Vehicles (HGVs). Dublin City Council (DCC)

introduced the HGV Management Strategy to ensure maximum use of the Port Tunnel by port-

related traffic and to enhance the city centre environment. In order to implement the measures,

revisions were made to the Road Traffic (Control of Traffic) Regulations 2006 (SI 639 2006).

These revisions remain in place, and allow for other such schemes to be implemented under the

same regulations. The regulations (operative from 15 December 2006) provide for “the

application of regulatory provisions which include the regulation of traffic lane control in a road

tunnel, the imposition of prohibitions and restrictions on the entry to a specified public road by

certain non-passenger vehicles e.g. goods vehicles (by reference to total number of axles) with

provision to provide for operative periods and exemptions through issue of a permit...”

The DCC HGV Management Strategy was introduced on the 19th February 2007. The HGV

Strategy provides for a ban on 5-axle vehicles during the hours of 07.00-19.00 seven days a

week from a designated cordon area. A limited permit scheme has been incorporated which

allows 5-axle vehicles to load/unload within the city centre area. Large fines are in place for

entering the cordon area without a permit or for delivering to unregistered premises.

Figure 4.1 – Dublin City HGV Cordon Area

http://www.dublincity.ie/RoadsandTraffic/HGV/Pages/HGVPermit.aspx


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The HGV Strategy has resulted in reductions of 5-axle vehicles within the city centre area of

between 80 - 94%. Dublin City Council issues an average of 200 permits per day for access to

the City Centre. Such permits are awarded for loading/unloading at a nominated site, or where

vehicles are not suitable for travelling through the Dublin Port Tunnel. Permits are obtained

through www.hgv.ie which was developed to allow for the expansion to other HGV permit

schemes throughout Ireland.

Enfield HGV Ban, Ireland

In 2006, Meath County Council implemented a HGV ban within the town of Enfield as outlined

below. The ban was enacted under the Local Government Act 1994 which gave Meath County

Council the powers to introduce a bye law, in this case referred to as the Enfield Traffic

Restriction Bye-Laws 2006. The ban restricts HGV’s with an unladen weight in excess of 3

Tonnes from travelling on certain links in the Enfield area to encourage use of the Enfield

Bypass. The banned links are highlighted in red below. The bye law exempts certain classes of

vehicles from the ban including emergency vehicles, public transport vehicles, vehicles based

within Enfield and vehicles with a specific delivery/collection in Enfield. Any person found on the

specified links not liable for an exemption will be subject to a €1,250 fine.

Figure 4.2 – Enfield HGV Ban Locations

London Lorry Control Scheme, United Kingdom

The scheme restricts the use of heavy goods vehicles to help minimise noise pollution in

residential areas during unsocial hours through restricted use of these roads. The Lorry Control

Scheme controls the movement of any heavy goods vehicles over 18 tonnes maximum gross

weight at night and weekends within the red boundary on the site map below.

During the restricted times, hauliers need special permits to be allowed to use their lorries on all

http://www.hgv.ie/


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but a very limited number of roads on a regulated basis. Permits can be obtained online or by

post/fax and are issued by the London Councils who manage the scheme.

Figure 4.3 – London Lorry Control Scheme Cordon Area

Liege City Centre HGV Ban, Belgium

A ban on HGV’s exceeding a defined length and weight was implemented in Liege, Belgium in

2006. Due to the city’s strategic location along a route between Germany and France, a

significant quantum of HGV traffic travelled through the city centre prior to the ban. This resulted

in significant noise pollution and congestion within the city centre. The ban was implemented in

order to ensure that HGV traffic utilised the nearby tunnel de Cointe provided for that purpose.

The HGV ban in Liege has proved successful with reductions in HGV volumes of approximately

45%. The scheme has resulted in benefits for the residents of Liege including reduced

congestion, noise and pollution within the city centre, in addition to a reduction in accidents.

Budapest Weight Limits, Hungary

A total truck weight restriction zone was implemented in 1996 in the city of Budapest. Freight

transport dedicated routes were also formed in order to control the delivery of goods within the

city centre. Various truck weight limits are applicable throughout a number of zones within the

city. Furthermore, the distribution of goods within the city centre is only possible with a permit

which has to be carried by each HGV.


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Goods Vehicle Restrictions, Monaco

All HGVs, regardless of their weight are banned from entering Monaco at various stages

throughout the day. The time restrictions are as follows: between 07.45 and 08.15, 11.30 and

12.30 and between 13.45 and 14.15. Furthermore, a permanent prohibition of vehicles

exceeding 8.5 tonnes is in place in Monaco, with these vehicles directed to an underground

facility within a shopping centre. It is noted that these measures help reduce air pollution and

noise within the city in addition to traffic congestion.

Conclusion

The case studies presented above represent a small number of a significant volume of similar

scenarios from across Europe. The evidence confirms that the application of restrictions on the

movement of large vehicles is a common mechanism for delivering environmental and safety

benefits in urban areas. The common feature of all schemes is that they seek to displace

commercial goods to more appropriate routes avoiding the restricted area, or to more appropriate

vehicles for accessing the restricted area.

Nevertheless, through the review of international experience it is clear that the majority of

locations do have some mechanism for facilitating access for specific circumstances, most

notably:

To facilitate deliveries or collections from nominated sites; and

Where vehicles are oversize and cannot travel on other routes (although this is perhaps

not relevant to Slane).

The experience in Dublin is particularly relevant, in that it has dealt with many of the legislation

and institutional issues which are required to implement commercial vehicle restrictions, and the

issuing of permits. Furthermore, the use of axles as a basis for restrictions has greatly simplified

enforcement, with visual inspection used to determine compliance or otherwise.

It should be noted that there are no examples of HGV ban’s on other National Primary Roads in

Ireland.


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5.0 Data Collection and Baseline Analysis

5.1 Definition of a Study Area

In undertaking the traffic analysis, it is necessary to define a Study Area within which the impacts

of any measures can be assessed. For the current project, it has already been noted that the

M1, N2 and M3 all play a significant role in providing for traffic flow through this area. In addition,

a large number of connecting corridors provide for traffic movements between these radial

routes.

The extent of the Study Area was defined based on the likely area of influence of any traffic

management measures in Slane as quantified by the National Transport Model (NTpM). The

resulting Study area is presented below in Figure 5-1. This area reflects the significant level of

competition between the M1 and N2 corridors and to a lesser extent between the N2 and M3

corridors. The study area extends as far north as Carrickmacross and Dundalk to account for any

long distance reassignment as a result of the proposed scheme.

Figure 5.1 –Study Area for Traffic Analysis


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5.2 Data Collection

A significant level of traffic data was collected in order to develop a full understanding of existing

traffic patterns and volumes through the Study Area. This data was collected in May 2012, and

included:

Goods Vehicle Origin-Destination (O-D) Surveys to understand vehicular routing through

Slane, the nature of goods being transported, vehicle types, and the extent of local traffic;

Automatic Traffic Counts (ATC) over 7 days, at sites across the Study Area; and

Journey time surveys were collected along key routes.

In specifying the Origin - Destination surveys, reference was made to the Inspectors Report from

the N2 Slane Bypass Oral Hearing, which outlined a need for more detailed traffic information.

The specification for the additional surveys was based on the following information requirements:

The definition of a series of screenlines and sectors which would allow the tracking of

goods vehicles through the region. This would allow longer distance traffic to be isolated,

and the origin and destination for more local traffic movements to be defined with

accuracy;

The collection of information on axle numbers for each goods vehicle, thereby allowing

the distinction between goods vehicles of different sizes. This would facilitate a more

detailed assessment of the impacts of HGV restrictions which would be targeted at

different vehicle sizes; and

The collection of data on vehicle type. Types include liquid tankers, retail palletised

transporters, construction vehicles, car transporters, buses and container vehicles. This

would support an understanding of the nature of goods movement through the area.

In specifying the surveys, it was important that the cordon for surveys was as closed as was

practicable – in other words, all routes that carry any reasonable volume of goods vehicle activity

were included in the survey to minimise leakage. The surveys were undertaken between 06:00 –

20:00 on an average weekday. The survey locations and the screenline/cordons are shown in

Figure 5.2.

In addition to the Origin Destination surveys, link counts using ATC’s were also undertaken at

each of the 22 sites over a 7 day period.


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Figure 5.2 – Survey Locations

Figure 5.2 – Survey Locations

5.3 Key Characteristics of Traffic Flows

5.3.1 Daily Flow Profile

In total, over 2,000 unique Goods Vehicles were found to access the survey area over the 14

hour period with each unique Goods Vehicle making approx 2.3 trips over the 14 hr survey


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period. The weekday flow profile of vehicles over Slane Bridge is shown in Figure 5.3, and

shows that the profile of Light Good Vehicles (2 axles) and Heavy Goods Vehicles (3 axles and

above) volumes over Slane Bridge are reasonably constant between 06:00 – 18:00 with volumes

dropping off outside those times.

Figure 5.3 – Traffic Flow Profile over Slane Bridge

5.3.2 Traffic Composition

Table 5.1 highlights the existing traffic composition on the approach routes to Slane village with

the LGV/HGV percentage significantly higher on the N2 than on the N51.

Table 5.1 – Slane Village Traffic Survey Findings

Location Cars LGV HGV

N2 North of Slane 75% 12% 13%

N2 South of Slane 76% 12% 12%

N51 West of Slane 86% 9% 5%

N51 East of Slane 88% 8% 4%

5.3.3 Vehicle Type

Examining the full study area, it was possible to develop a picture of the size and class of

vehicles using the road network in the vicinity of Slane. Table 5.2 outlines vehicle categories,

number of axles, and the contribution of each to total goods vehicle volumes.


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Table 5.2 – Origin Destination Survey - Vehicle Classification Results

Vehicle Category Axles

Total Daily Flows in Survey Area

Daily Flow through Slane Village

Daily Flow on

Slane Bridge

HGV1 – General LGV 2 26.2% 25.8% 23.7%

HGV2 – Retail LGV 3 1.9% 1.2% 1.8%

HGV3 – Construction/ Heavy Goods 3 1.0% 1.1% 0.7%

HGV4 – Other Vehicles 3 3.5% 1.9% 2.7%

HGV5 – Construction/ Heavy Goods 4 8.1% 9.0% 9.0%

HGV 6 – General Distribution/Retail Freight 5 47.2% 53.0% 52.1%

HGV 7 – Liquid Transporter (Non Fuel) 5 1.6% 0.5% 1.1%

HGV 8 – Liquid Transporter (Fuel) 5 0.4% 0.1% 0.2%

HGV 9 – Shipping Container 5 3.7% 1.1% 1.8%

HGV 10 – Automotive 5 0.1% 0.0% 0.0%

BUS1 – 2 Axle Bus 2 4.2% 4.1% 4.6%

BUS2 - 3 Axle Bus 3 0.1% 0.0% 0.0%

HGV11 – Other Vehicles 4 1.8% 2.2% 2.2%

The survey found that the most common type of Goods Vehicle in the survey area is the general

distribution 5-axle HGV (see HGV 6 in Figure 5.3 below) which accounts for 47% of Goods

Vehicles on a daily basis. Construction traffic accounted for over 9%, buses for a further 4% and

shipping container/liquid transport a further 5%. The remaining Goods Vehicles were smaller

general and retail Goods Vehicles. This highlights the dominance of large 5-axle Goods Vehicles

travelling through the Slane area.

Figure 5.4 – Goods Vehicles used in Survey Classification


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5.3.4 Average Weekday Daily Flow Calculation

The Goods Vehicle and Bus surveys were undertaken during daylight hours between 06:00 –

20:00. In order to factor 14 hr flows to average weekday daily flow a factor was ascertained from

the ATC counts undertaken at each survey point.

Table 5.3 –Conversion Factor

Location Site 24hr Flow 14 hr Flow

06:00 - 20:00

N33 East of Ardee 1 1355 1182

R171 North of Ardee 2 218 193

N2 North of Ardee 3 1981 1668

N52 West of Ardee 4 674 591

R165 West of the N2 5 149 134

R170 East of N2 and Ardee 6 87 79

R169 East of N2 7 529 470

N2 South of Collon 8 1403 1190

N2 North of Slane 9 1403 1195

N51 West of Slane 10 774 702

R163 East of R162 Kilberry 11 257 236

N51 North of Navan 12 723 652

N2 South of Slane 13 1311 1115

N51 East of Slane 14 445 411

N51 West of the M1 15 459 425

R168 South of Tullyallen 16 465 410

N2 North of R150 17 1541 1330

R150 East of N2 18 398 362

R153 West of Kentstown 19 663 595

N2 South of R153 20 1751 1505

N2 South of R152 21 2446 2118

R152 South of Duleek 22 771 704

TOTAL 19803 17267

14 hr to 24 hr Factor 1.15

Table 5.3 above outlines the calculation of the 14hr to 24hr factor used in converting the

following matrices to Average Weekday Daily flows.

5.4 Analysis of Traffic Movements through Slane

In order to present more detailed results, the Origin Destination matrices were compiled based

on a system of 15 zones (see Figure 5.4 below). Note that the zones at the periphery of the study

area are intended to represent external movements e.g. zone 1 includes traffic travelling onwards

via the N2 to Monaghan etc, whilst Zone 15 represents traffic travelling to/from Ashbourne and

Dublin via the N2.


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Figure 5.5 – Zones for HGV Traffic Patterns

Using the resulting matrix of goods vehicle movements, it was possible to undertake a number of

key analyses on the resulting dataset. These are presented below.


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5.4.1 Total Matrix of Goods Vehicle Movements via Slane

This analysis examines the total pattern of goods vehicle movement through the study area in

the form of a complete origin destination demand matrix.

Table 5.4 – Goods Vehicles - Daily Weekday Flows between Zones

Zone

To Zone

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Fro

m Z

on

e

1 50 343 59 9 1 13 15 43 12 0 8 2 38 6 178 776

2 386 21 102 1 1 2 0 7 3 0 6 1 1 1 8 541

3 56 101 29 3 14 2 0 3 3 0 5 0 2 0 12 231

4 38 0 1 13 23 10 8 40 8 0 6 1 15 2 78 244

5 12 1 10 7 20 9 6 91 17 0 5 0 33 2 120 333

6 53 2 1 22 37 8 3 15 9 0 2 0 12 0 41 206

7 38 0 3 10 22 7 13 56 10 5 17 1 8 1 15 207

8 31 6 5 18 94 7 35 44 3 5 73 2 18 0 20 360

9 35 0 0 17 43 13 10 9 12 1 6 1 33 1 89 269

10 2 5 2 2 1 0 5 28 1 0 22 0 6 1 5 79

11 13 6 14 5 6 1 3 75 7 20 59 5 6 1 13 231

12 5 1 2 0 3 0 2 0 5 0 1 31 7 13 164 234

13 54 1 3 23 40 13 3 24 23 0 3 10 130 90 167 586

14 1 0 0 0 1 0 0 5 0 0 1 6 76 18 90 198

15 195 6 14 61 152 8 23 17 26 2 15 120 84 98 115 936

967 493 246 192 458 93 127 457 140 32 228 181 470 235 1113 5434

The analysis highlights a number of findings;

There is a large demand (729 vehicles) between Zones 1 and 2. This highlights relatively

high volumes of Goods Vehicles travelling between the M1 and N2 via the Ardee Link

Road;

There is a high Goods Vehicle demand (373 goods vehs) between Zone 1 and Zone 15.

This traffic is travelling between the N2 (North of Ardee) and the Dublin/Ashbourne

Areas. This is legitimate N2 traffic which could, under the right conditions, be encouraged

to route via the M1;

There is significant localised demand (1219 vehs) between zones 12, 13, 14 and 15

which does not impact upon Slane;

Finally, there is a flow of approximately 272 vehicles between Zone 15 (N2 near

Ashbourne) and Zone 5 (R169 adjacent to M1). Much of this traffic is using the longer N2

corridor as an alternative to the M1.


Page 18

5.4.2 Total Goods Vehicle Movements that could use N2 Slane Bridge

This second analysis examines those origin destination pairs that involve logical routing via

Slane Bridge. This gives a measure of total goods vehicle activity across the bridge on a daily

basis.

Table 5.5 – Goods Vehicles (incl buses) Daily Weekday Flows

Zone To Zone

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Fro

m Z

on

e

1 12 2 38 6 178 236

2 3 1 1 1 8 15

3 3 0 2 0 12 17

4 8 1 15 2 78 105

5 17 0 33 2 120 173

6 9 0 12 0 41 62

7 10 1 8 1 15 36

8 3 2 18 0 20 44

9 35 0 0 17 43 13 10 9 1 6 134

10 1 0 6 1 5 13

11 7 5 6 1 13 31

12 5 1 2 0 3 0 2 0 0 1 15

13 54 1 3 23 40 13 3 24 0 3 166

14 1 0 0 0 1 0 0 5 0 1 8

15 195 6 14 61 152 8 23 17 2 15 493

289 8 20 101 239 33 39 55 75 3 26 13 139 15 489 1546

The analysis above suggests a total of 1,546 Goods Vehicles are likely to use Slane Bridge on

an average weekday. Further distilling of this data by vehicle size, it is possible to present this

potential demand as set out below.

Table 5.6 – Slane Bridge Demand by Vehicle Class

Vehicle Class Demand

Goods Vehicles (<= 2 axles) 406

Goods Vehicles (>= 3 axles) 1074

Buses 66

TOTAL 1546

Table 5.4 demonstrated a total of 272 Goods Vehicles using Slane as an alternative to avoid the

M1. The analysis suggests that such traffic represents only about 20% of the total commercial

traffic crossing Slane Bridge. When including the 373 vehicles that could be encouraged to

divert onto the M1, this suggests that 45% of goods vehicles crossing Slane Bridge are longer

distance movements that could be encouraged to transfer to the M1.

5.4.3 Origin-Destination Patterns in Slane Village

The patterns of Good Vehicles travelling through Slane on a daily basis were established using

the survey data. The results are presented in Table 5.7 below.


Page 19

Table 5.7 – Goods Vehicles (and buses) Daily Weekday Flows

Location N W S E

Northern Arm - 231 608 31

Western Arm 242 - 79 99

Southern Arm 691 94 - 30

Eastern Arm 56 111 44 -

As can be seen from above the main movements are north-south movements, representing

approximately 56% of all movements through the village. It is noted that approximately 20% of

goods vehicle traffic through Slane is associated with movement between the N2 North and the

N51 to/from Navan.

5.4.4 Extent of local trips using Slane Bridge

Table 5.8 – Daily Weekday Flows Goods Vehicle (and bus) to/from Internal Zones via Bridge

Zone To Zone

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Fro

m Z

on

e

1 12 38 50

2 3 1 5

3 3 2 6

4 8 1 15 2 78 105

5 17 33 51

6 9 0 12 0 41 62

7 10 1 8 1 15 36

8 3 18 22

9 35 0 0 17 43 13 10 9 1 6 134

10 1 0 6 1 5 13

11 7 6 13

12 0 0 2 0 0 2

13 54 1 3 23 40 13 3 24 0 3 166

14 0 0 0 0 0

15 61 8 23 2 94

89 1 3 101 83 33 39 33 75 3 9 2 139 5 139 756

*Internal zones comprise zones 4, 6, 7, 9, 10 and 13

Local traffic is therefore 756 vehicles per weekday, and therefore represents approximately 49%

of the 1,546 goods vehicles travelling across Slane Bridge on a typical weekday.

5.4.5 Locally Generated 5-Axle Goods Vehicle Traffic

The survey data has been interrogated to isolate the quantum of 5-axle HGV traffic that is

associated with the Slane area. For the purposes of this assessment it has been assumed that

trips with a destination in Zones 6, 7, 9 and 10 are classed are trips requiring local access. In

reality a significant proportion of these will not require access to Slane Village as they will be

travelling from an area on the same side as their delivery location. An analysis of origin and

destination patterns for 5-axle vehicles is provided in Table 5.9.


Page 20

Table 5.9 –5 axle HGV traffic matrix (Weekday Daily Flows)

Zone To Zone

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Fro

m Z

on

e

1 20 188 31 6 1 6 6 23 6 0 3 1 16 2 122

431

2 274 10 68 1 0 1 0 5 0 0 2 0 0 1 5

367

3 30 56 10 0 6 0 0 1 1 0 2 0 0 0 8

114

4 28 0 1 3 14 3 5 16 7 0 0 0 5 2 47

131

5 3 0 2 6 13 3 2 63 14 0 1 0 3 2 105

217

6 43 2 0 7 22 1 0 3 1 0 0 0 1 0 29 109

7 23 0 3 6 14 3 2 30 0 1 8 0 0 0 6 96

8 21 1 1 3 66 2 6 15 1 0 35 0 8 0 14

173

9 21 0 0 5 31 10 3 2 2 0 1 1 9 1 51 137

10 2 0 1 0 1 0 0 3 0 0 6 0 0 1 1 15

11 5 1 8 0 0 1 1 29 0 6 14 0 0 0 3

68

12 2 0 1 0 3 0 2 0 5 0 0 9 2 7 96

127

13 32 0 2 8 17 2 1 8 3 0 0 1 33 46 82

235

14 1 0 0 0 1 0 0 1 0 0 1 2 30 7 60

103

15 138 3 7 25 112 5 6 10 16 0 3 55 39 63 64

546

643 261 135 70 301 37 34 209 56 7 76 69 146 132 693

2869

There are in the region of 468 5-axle HGV’s with an origin or destination within the Slane area on

a daily basis. This accounts for approximately 12% of all 3, 4 and 5-axle goods vehicle activity.

Table 5.10 includes 4-axle HGVs in this assessment. This increases the daily local activity to

603 HGV’s per weekday, or 16% of all 3, 4 and 5-axle goods vehicle activity.

Table 5.10 – 4+ axle HGV traffic matrix (Weekday Daily Flows)

Zone To Zone

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Fro

m Z

on

e

1 22 203 38 7 1 7 12 32 7 0 6 2 17 5 126

485

2 287 10 74 1 0 2 0 5 0 0 5 0 0 1 5

390

3 36 67 15 0 6 0 0 2 1 0 3 0 2 0 9

141

4 32 0 1 7 20 7 6 20 8 0 0 0 5 2 53

161

5 5 0 5 7 17 6 2 67 15 0 1 0 16 2 107

250

6 46 2 0 13 22 7 1 7 3 0 0 0 3 0 32 136

7 32 0 3 7 16 3 6 36 6 1 9 0 1 0 8 128

8 23 3 1 3 71 3 9 26 2 0 38 0 8 0 16

203

9 21 0 0 7 32 10 3 2 5 0 1 1 16 1 64 163

10 2 0 1 0 1 0 0 5 0 0 7 0 0 1 3 20

11 5 3 9 2 0 1 1 36 2 9 22 0 1 1 3

95

12 2 0 1 0 3 0 2 0 5 0 0 20 2 7 106

148

13 39 0 2 9 22 5 1 12 6 0 0 3 75 55 93

322

14 1 0 0 0 1 0 0 2 0 0 1 2 44 14 66

131

15 150 5 8 30 115 7 10 13 20 0 5 70 51 73 82

639

703 293 158 93 327 58 53 265 80 10 98 98 241 162 773

3412


Page 21

Finally, Table 5.11 outlines the origin destination activity for all heavy goods vehicles, showing

those vehicles that have origins and/or destinations within the Slane area. The inclusion of 3-axle

vehicles increases the total to 683, or 18% of all 3, 4 and 5-axle goods vehicle activity.

Table 5.11 – 3+ axle HGV traffic matrix (Weekday Daily Flows)

Zone To Zone

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Fro

m Z

on

e

1 24 243 43 9 1 8 13 32 7 0 6 2 20 5 137

550

2 301 12 79 1 1 2 0 5 0 0 5 1 0 1 5

413

3 37 76 18 1 9 0 0 2 1 0 3 0 2 0 9

158

4 35 0 1 7 20 8 6 20 8 0 0 0 6 2 55

168

5 5 0 5 7 17 6 3 70 16 0 1 0 18 2 109

259

6 46 2 0 13 23 8 2 8 7 0 2 0 8 0 32

151

7 37 0 3 7 16 3 9 38 6 1 10 0 1 0 10

141

8 26 3 1 3 73 6 10 30 2 0 39 0 8 0 20

221

9 23 0 0 10 32 12 6 5 5 0 2 1 20 1 69

186

10 2 5 2 0 1 0 0 5 0 0 8 0 0 1 3

27

11 5 3 10 2 0 1 1 41 2 12 30 0 2 1 8

118

12 3 0 2 0 3 0 2 0 5 0 0 20 3 13 115

166

13 41 1 3 10 28 7 1 12 9 0 0 6 84 62 107

371

14 1 0 0 0 1 0 0 2 0 0 1 5 51 16 71

148

15 158 6 9 33 124 7 15 14 20 0 6 77 55 77 89

690

744 351 176 103 349 68 68 284 88 13 113 112 278 181 839

3767

.


Page 22

6.0 Development of the Traffic Model

A Traffic Model was constructed to support the assessment of traffic management alternatives

for Slane. The model was developed as a Local Area Model extracted from the National

Transport Model (NTpM), and has incorporated the extensive survey data collected for a base

year of 2012. The model development process followed the guidance set out in the NRA Project

Appraisal Guidelines, and was specifically developed to classify vehicles separately by axle

numbers in order to support testing of different vehicle restrictions. The traffic model also

included the M1 and M3 tolls such that the impacts of toll avoidance could be incorporated. The

Study Area for the Traffic Model is outlined below in Figure 6.1.

Figure 6.1 – Traffic Model Study Area

The development of the Traffic Models and the relevant inputs and assumptions is set out in full

in the Traffic Modelling Report which has been separately prepared for this project.


Page 23

6.1 Conversion of AM and IP models to All Day

A factor to allow the extrapolation of AM and IP period flows into Weekday Average volumes was

calculated using regression based on traffic data from 22 sites. A relationship was developed

based on regression analysis of local traffic data as set out in Table 6.1 below. The regression

analysis was based on weekday data and resulted in the following peak hour to Weekday

Average:

Table 6.2 – Regression Analysis Check

Location

Daily Flow

from

Surveys

Daily Flow using

regression % Difference

N33 East of Ardee 9717 9601 1%

R171 North of Ardee 2189 2111 4%

N2 North of Ardee 10096 9716 4%

N52 West of Ardee 5067 5531 -9%

R165 West of the N2 1394 1378 1%

R170 East of N2 and Ardee 953 918 4%

R169 East of N2 2962 3033 -2%

N2 South of Collon 6056 6104 -1%

N2 North of Slane 6413 6416 0%

N51 West of Slane 6595 6702 -2%

R163 East of R162 Kilberry 2174 2164 0%

N51 North of Navan 6107 6320 -3%

N2 South of Slane 6198 6205 0%

N51 East of Slane 4251 4426 -4%

N51 West of the M1 4623 4881 -6%

R168 South of Tullyallen 6172 6102 1%

N2 North of R150 7186 7325 -2%

R150 East of N2 3384 3458 -2%

R153 West of Kentstown 6371 6264 2%

N2 South of R153 10338 10320 0%

N2 South of R152 16418 16619 -1%

R152 South of Duleek 5937 6188 -4%

(5.33 * x) + (11 * y) = 5-Day AADT

Where,

x = AM Peak Period Flow

y = Inter Peak Period Flow


Page 24

7.0 Definition of Traffic Management Scenarios

A series of alternatives have been defined which seek to support the objectives set out in Section

3 of this report. During the identification of alternatives, it was considered that the existing

measures which have been implemented through Slane are targeted specifically at reducing the

safety risks associated with the passage of larger goods vehicles through the town. The

measures do not, however, lead to any environmental improvements, and in general lead to

increases in journey times for all vehicles.

The restriction of goods vehicles from the village brings obvious consequences for those who are

the subject of such restrictions. As such, the scenarios comprise a series of goods vehicle

restrictions which are applied across different locations, and apply to vehicles of different sizes.

In this way, the incremental impacts of the measures on goods vehicles, and on those living

adjacent to alternative routes can be understood.

Traffic Management Scenarios considered are outlined in Table 7.1 below. Note that the

terminology for vehicle restrictions is based on axle numbers, with 5+ referring to vehicles with 5

axles or greater.

Table 7.1 – Traffic Management Scenarios Tested

Scenario Description

1 Goods Vehicle 5+ Axle Ban on Slane Bridge.

2 Goods Vehicle 5+ Axle Ban on Slane Bridge, and on N2 between Slane and Collon

2a Goods Vehicle 4+ Axle Ban on Slane Bridge, and on N2 between Slane and Collon

3 Goods Vehicle 3+ Axle Ban on Slane Bridge, and on N2 between Slane and Collon

4 Goods Vehicle 3+ Axle Ban on Slane Bridge, on N2 between Slane and Collon, and

on N51 between M1 and R163

5 Goods Vehicle 3+ Axle Ban on Slane Bridge, and on N2 between Slane and Collon,

but in southbound direction only.

6 Goods Vehicle 3+ Axle Ban on Slane Bridge, but in southbound direction only.

The traffic management scenarios considered are presented overleaf.


Page 25


Page 26


Page 27


Page 28


Page 29

8.0 Scenario Testing

The impact of the different scenario options has been assessed using the both AM and IP traffic

models for a traffic flow year of 2012 (Base Year). The models have been run by applying

restrictions on relevant links in the model for the specific user classes. The model then reassigns

traffic from within those restricted user classes onto alternative routes as appropriate. The

following information is then extracted from the traffic model results:

The pattern of traffic reassignment, showing alternative routes travelled and the extent of

traffic flow increase on those alternative routes;

Goods Vehicle traffic flows on key links across the Study Area Road Network, including

on the roads through Slane;

Total vehicle km travelled by all vehicles in the study area – this provides a proxy of fuel

consumption and resulting vehicular emissions; and

Total travel time travelled by all vehicles in the study area – providing a measure of

network efficiency.

The results of the traffic modelling are presented below (figures show AM peak impact) with

green bands representing an increase in traffic as a result of the scheme and red bands

representing a decrease.


Page 30

8.1 Scenario 1: 5+ Axle Ban on Slane Bridge

Scenario 1 will lead to a reduction of 66% in heavy

goods vehicle traffic (3 axles or greater) across

Slane Bridge, with a 52% reduction in 3+ axle

goods vehicles on the N2 immediately north of the

village.

An increase in HGV traffic on the M1 is evident, as

are decreases on the R169 and the N2.

Furthermore the HGV ban results in some HGV

trips utilising the R152 past Duleek to travel

between the M1 and N2 corridors.

The reduction in volumes on the R125 and R169

is likely associated with goods vehicle traffic

rerouting onto the M1 as the most direct route (i.e.

a reduction in M1 toll avoidance). The increase in

N33 traffic is likely as a result of N2 traffic

switching to the longer, but more appropriate, M1

corridor.

It is noted that Heavy Goods Vehicle flows through

the M1 Drogheda Toll increase by 21% over a full

weekday.

Table 8.1 – All (3 and above axles) HGV Traffic across key links (Weekday - 2012)

Location Base Do Something % Difference

Slane Bridge 1201 412 -65.7%

Chapel Street (N2) North of Slane 1142 553 -51.5%

N51 East of Slane 282 288 2.0%

N51 West of Slane 716 689 -3.8%

M1 Dunleer 3255 3773 15.9%

M1 Drogheda 863 1047 21.4%

R169 674 457 -32.3%

N2 North of Ashbourne Bypass 1899 1600 -15.7%

N33 East of Ardee 1002 1292 28.9%

R150 East of the N2 376 376 -0.1%

R152 East of the N2 674 991 47.0%

R153 West of the N2 480 589 22.7%

R125 between N2 and M1 255 196 -23.2%

R147 between Kells and Navan 891 902 1.2%

R168 South of Collon 146 184 26.1%

N52 395 427 8.3%

R162 442 459 3.7%

R163 175 142 -18.9%

* The provision of HGV permits to facilitate local access to Slane will reduce the above traffic flow impacts

Option 1 has a significant positive impact upon Slane, albeit with some impact on local roads

which may require some mitigation measures. The majority of traffic is encouraged onto the M1

corridor, which provides a safer and less environmentally intrusive corridor for vehicles.


Page 31

8.2 Scenario 2: 5+ Axle Ban on Slane Bridge, and on N2 between Slane and Collon

This option again leads to an increase in goods

vehicle traffic using the M1, but introduces a

number of evident diversion routes, including the

N52, R162 and R168. The impact on the

N52/R162 is due to the restriction of the existing

movement between the N2 North and N51 Navan

Road through Slane, which as was shown earlier

accounts for approximately 20% of all heavy

goods vehicle movements through the town.

As such, the inclusion of a restriction to the north

of Slane Village leads to a more pronounced

reduction in goods vehicles than in Option 1, with

the reduction in heavy goods vehicles (3 axles or

greater) being to the order of 75% on Chapel

Street.

The impact on Slane Bridge, and on the M1

Drogheda Toll is relatively similar to Scenario 1.

Table 8.2 – HGV Traffic across key links (Weekday - 2012)


Slane Bridge 1201 412 -65.7%


N51 East of Slane 282 472 67.3%

N51 West of Slane 716 581 -18.9%

M1 Dunleer 3255 3952 21.4%

M1 Drogheda 863 1058 22.6%

R169 674 305 -54.8%


N33 East of Ardee 1002 1308 30.5%

R150 East of the N2 376 376 -0.1%

R152 East of the N2 674 996 47.8%

R153 West of the N2 480 589 22.7%

R125 between N2 and M1 255 196 -23.2%



N52 395 459 16.4%

R162 442 551 24.6%

R163 175 142 -19.1%


Option 2 therefore has a similar impact upon Slane Bridge as Option 1, but has a greater impact

upon the road network to the north of Slane particularly along N2 and R169. This option does

lead to higher level of rerouting via the N52 and R162 a result of the restriction on the north-west

movement through Slane Village.


Page 32

8.3 Scenario 2a: 4+ Axle Ban on Slane Bridge, and on N2 between Slane and Collon

Scenario 2a is an enhancement on Scenario 2, in

that the restrictions will additionally apply to 4 axle

vehicles.

The volume of 4-axle activity through Slane is

relatively low, at less than 60 vehicles per day.

This is significantly less than the number of 5-axle

movements across Slane Bridge on an average

day.

As such, the pattern of impacts of Scenario 2a is

similar to Scenario 2. The measures result in a

further reduction in traffic on the N2 at Chapel

Street and across Slane Bridge, with a moderate

reduction in traffic using the N51 west of Slane.



Slane Bridge 1201 310 -74.2%


N51 East of Slane 282 451 59.9%

N51 West of Slane 716 527 -26.4%



Page 33

8.4 Scenario 3: 3+ Axle Ban on Slane Bridge, and on N2 between Slane and Collon

The measures in Scenario 3 remove all goods vehicle

traffic of 3 axles or greater from the N2 to the north

and south of Slane. This suggests that residual traffic

will comprise solely of light vehicles, or goods

vehicles with only 2 axles.

The analysis presented earlier suggested that 2-axle

goods vehicles represent approximately 30% of all

commercial vehicles through the town. It would be

expected that much of this activity would be local,

relating to shop deliveries, refuse collections,

servicing of premises and agricultural vehicles.

The restrictions lead to traffic impacts that are similar

in pattern to Scenario 2 and 2a, with traffic increases

on the M1, and the various routes connecting the M1

and N2 (R152, N51, R168 and N33). The impact on

the N52, R162 and R153 via Navan is also evident.



Slane Bridge 1201 0 -100.0%


N51 East of Slane 282 494 75.1%

N51 West of Slane 716 494 -31.0%

M1 Dunleer 3255 4251 30.6%

M1 Drogheda 863 1183 37.1%

R169 674 152 -77.5%


N33 East of Ardee 1002 1416 41.3%

R150 East of the N2 376 392 4.2%

R152 East of the N2 674 1093 62.2%

R153 West of the N2 480 660 37.3%

R125 between N2 and M1 255 147 -42.3%



N52 395 497 25.9%

R162 442 643 45.4%

R163 175 125 -28.6%


As with previous scenarios, scenario 3 has a significant positive impact upon Slane as traffic is

reassigned to a number of local roads which may require some mitigation measures. The 62%

increase in commercial vehicle traffic past Duleek on the R152 is noted, and will comprise a

mixture of vehicles of varying sizes.


Page 34

8.5 Scenario 4: 3+ Axle Ban on Slane Bridge, on N2 between Slane and Collon, and on N51

Scenario 4 restricts all heavy goods vehicles (3

axles or greater) from all roads approaching Slane

Village. The traffic modelling demonstrates that

such measures will have quite substantial impacts

on roads through the study area as a larger number

of vehicles seek alternative routes to avoid Slane.

The analysis shows significant decreases on the N2

North and South of Slane, the R169 and the N51

between Navan and Drogheda. Nevertheless, there

are significant increases on the alternative routes

around Slane, most notably the N33, N52 and

regional roads including the R162, R153, R152,

R150 and R168.

HGV traffic past Duleek would be expected to

increase by 40%, or about 200 vehicles per day,

with an increase of approximately 340 HGV’s per

day on the R153 through Kentstown. In essence,

the R152 and R153 would operate as informal

bypass routes of Slane to the south, with traffic

travelling via Drogheda/Navan and returning to the

N2 further north.



Slane Bridge 1201 0 -100.0%


N51 East of Slane 282 0 -100.0%

N51 West of Slane 716 0 -100.0%

M1 Dunleer 3255 4017 23.4%

M1 Drogheda 863 1183 37.1%

R169 674 163 -75.9%


N33 East of Ardee 1002 1514 51.0%

R150 East of the N2 376 555 47.6%

R152 East of the N2 674 1115 65.3%

R153 West of the N2 480 817 70.2%

R125 between N2 and M1 255 147 -42.3%



N52 395 807 104.5%

R162 442 898 103.2%

R163 175 70 -59.8%


The results demonstrate the large reductions in goods vehicle movements through Slane, but

also the potentially substantial increases on other routes. Significant mitigation of impacts would

be necessary.


Page 35

8.6 Scenario 5: Southbound 3+ Axle Ban on Slane Bridge, and N2 between Slane and Collon

The safety concerns associated with southbound

traffic through Slane Village has been particularly

relevant in the development of the project

objectives. Scenario 5 seeks to remove the

southbound movement of all heavy goods vehicles

through Slane Village in order to address this

specific issue.

The results of the analysis show a range of

reassignment impacts for southbound traffic, with

the alternative routes being the N52/R162/R153,

R168/M1 and the N33/M1. The analysis also shows

an increase on the N51, which remains available as

an access route into Slane for local traffic.

Scenario 5 delivers a reasonable reduction in HGVs

over Slane Bridge with HGV flows decreasing by

approximately 50%. Total daily HGV traffic through

Slane Village decreases by 31% from 3,341 vehs to

2,313 vehs.



Slane Bridge 1201 603 -49.8%


N51 East of Slane 282 412 46.0%

N51 West of Slane 716 575 -19.7%

M1 Dunleer 3255 3711 14.0%

M1 Drogheda 863 1030 19.3%

R169 674 414 -38.7%


N33 East of Ardee 1002 1160 15.8%

R150 East of the N2 376 398 5.7%

R152 East of the N2 674 832 23.4%

R153 West of the N2 480 600 25.0%

R125 between N2 and M1 255 191 -25.3%



N52 395 449 13.7%

R162 442 524 18.5%

R163 175 109 -37.5%



Page 36

8.7 Scenario 6: 3+ Axle Ban on Slane Bridge, but in southbound direction only

The analysis of a southbound 3+ axle restriction on

Slane Bridge shows a broad rerouting of goods vehicle

traffic from the N2 onto the N1 corridor, with reductions

on the R169 and R125 suggesting a decrease in the

levels of M1 toll avoidance. Although there are

increases on the R152, R153 and N51, these are less

significant than in previous options.

The results of the analysis show a range of

reassignment impacts for southbound traffic, with the

alternative routes being the N52/R162/R153 and the

N33/R168/M1.

Scenario 6 delivers a reasonable reduction in HGVs

over Slane Bridge with HGV flows decreasing by

approximately 50%. Total daily HGV traffic through

Slane Village decreases by 27% from 3,341 vehs to

2,434 vehs.



Slane Bridge 1201 603 -49.8%


N51 East of Slane 282 293 3.9%

N51 West of Slane 716 668 -6.8%

M1 Dunleer 3255 3586 10.2%

M1 Drogheda 863 1030 19.3%

R169 674 500 -25.8%


N33 East of Ardee 1002 1155 15.2%

R150 East of the N2 376 398 5.7%

R152 East of the N2 674 821 21.8%

R153 West of the N2 480 606 26.1%

R125 between N2 and M1 255 191 -25.3%



N52 395 411 4.1%

R162 442 464 5.0%

R163 175 120 -31.2%



Page 37

8.8 Summary of Traffic Analysis

In order to support a comparative assessment of the alternatives, a summary of the findings are

presented below in Table 8.8.

Table 8.8 – Summary of Findings

Scenario

Parameter Base 1 2 2a 3 4 5 6

HGV Flow Slane Bridge 1201 412 412 310 0 0 603 603

Change % in HGV’s -66% -66% -74% -100% -100% -50% -50%

HGV Flow through Slane 3342 1942 1752 1451 988 0 2314 2434

Change % in HGV’s -42% -48% -56% -70% -100% -31% -27%

HGV Flow M1 Toll 863 1047 1058 ~1058 1183 1183 1030 1030

Change % in HGV’s +21% +23% +23% +37% +37% +19% +19%

HGV Flow on R169 674 457 305 ~305 152 163 414 500

Change % in HGV’s -32% -55% -55% -77% -76% -39% -26%

HGV Flow on N33 1002 1292 1308 ~1308 1416 1514 1160 1155

Change % in HGV’s +29% +31% +31% +41% +51% +16% +15%


8.9 Multi-Criteria Assessment of Alternatives

The analysis presented above demonstrates that the various scenarios can lead to substantial

reductions in goods vehicle traffic through Slane. Nevertheless, although this meets one element

of the project objectives, it is noted that the scenarios can lead to adverse impacts through other

populated areas, most notably Kentstown and Duleek. In addition, excessive restrictions can

lead to reductions in network efficiency as vehicles are required to route over longer distances to

access specific destinations. A broader assessment of the alternatives on the basis of project

objectives is therefore the relevant means for selecting the most appropriate solution. The

analysis methodology presented in Table 3.1 earlier in this report is therefore applied for the Multi

Criteria Assessment.

Safety The potential impact upon safety was accounted for by utilising accident rates for

each road type and vehicle kilometres on each road type extracted from the

various models. Benefits were calculated over a 10-year period.

Air Quality Reductions in goods vehicle movements through Slane are balanced against

increases through other populated areas – most notably Collon, Ardee, Duleek

and Kentstown.

Emissions Total kilometres travelled by all vehicles are extracted form the traffic models.

Efficiency Total hours travelled by all vehicles are extracted form the traffic models.

Accessibility The impact on accessibility between Dublin and Monaghan, and to/from Slane is

qualitatively assessed.

An Appraisal Summary Table is presented in Table 8.9 overleaf which summarises the key

impacts discussed above, and includes the network performance indicators as extracted from the

traffic models. Positive impacts are highlighted in green, with negative impacts in red.


Page 38

Table 8.9 – Appraisal Summary Table

Scenario Traffic Safety Air Quality Transport Emissions Network Efficiency Accessibility

1

Slight reduction in

accident costs due to

reassignment of larger

vehicles to M1. Benefits

exceed negative

impacts on local roads.

Slight reduction in HGV

traffic through

populated areas

Slight increase in

network vehicle km per

day resulting from the

reassignment.

Slight increase in

network HGV travel

hours per day resulting

from the reassignment

No significant impact on access to Slane for local

traffic as permit system will allow access. Access

to Monaghan available via the M1 and Ardee Link

(N33). Scheme will impact adversely on

accessibility between Ashbourne and the M1

Corridor/Monaghan. Overall Slight Impact

2

Slight increase in

accident costs, due to

increase in vehicle km

on non-motorway roads

Slight reduction in

HGV traffic through

populated areas

Slight increase in



reassignment.

Slight increase in

network HGV travel









2a

Slight increase in



on non-motorway roads

Slight reduction in

HGV traffic through

populated areas

Slight increase in



reassignment.

Slight increase in

network HGV travel









3

Slight increase in



on non

Moderate reduction in

HGV traffic through

populated areas

Strong increase in



reassignment.

Moderate increase in

network HGV travel



Moderate reduction in access to Slane for

service vehicles, and for general commercial

activity. Access remains available via N51. No

significant impact on access to Slane for local

traffic as permit system will allow access.

4




on non

Strong reduction in

HGV traffic through

populated areas

Strong increase in



reassignment.

Strong increase in

network HGV travel



Strong reduction in access to Slane for service

vehicles, and for general commercial activity. No

significant impact on access to Slane for local


5

Slight increase in



on regional roads

Neutral net impact in

HGV traffic through

populated areas

Strong increase in



reassignment.

Slight increase in

network HGV travel



Slight reduction in access, with onward access

to Dublin Area and areas north remaining via N51.



6

Slight increase in



on regional roads

Moderate reduction in

HGV traffic through

populated areas (Slane,

Kentstown, Duleek,

Collon)




reassignment.

Slight increase in

network HGV travel



Slight reduction in access, with onward access

to Dublin Area remaining via N51. No significant

impact on access to Slane for local traffic as

permit system will allow access.


Page 39

9.0 Implementation of Preferred Scenario

9.1 Overview

The analysis presented in Table 8.9 demonstrates positive and negative impacts associated with

all options. Examining the outputs, it appears that Scenarios 1 and 2 can best support to the

objectives of the project.

Regardless of the final solution adopted, there are a number of further issues which are

necessary as part of any plan to restrict goods vehicles from Slane. In this regard, the key

impacts are those associated with:

The legislation within which any restrictions can be delivered;

the need to manage access through the issuing of permits, and subsequent enforcement;

the impact of traffic rerouting to alternative roads, and the impact on those areas;

These issues are discussed below.

9.2 Extent of Restrictions

The implementation of an axle restriction is facilitated by the current Road Traffic (Control of

Traffic) Regulations 2006 (SI 639 2006). The implementation of Bye-Laws is a reserved function

of the Local Authority, and would require the specific area within which the restriction applies to

be defined. In defining the specific area, attention would be required to appropriate advance

signage on key routes, the facility for turn-back at entry points, the provision of lay-bys where

drivers may make arrangements for permits at the point of entry, and the means of enforcement

(manual or automated).

9.3 Management of Access/Permits

The analysis has recognised that the restriction of goods vehicle movement through Slane can

have an adverse impact on accessibility for local businesses.

As with other successful schemes, the implementation of restrictions can be supported by a

system of permits which will allow managed access to the restricted area. As the level of

restriction increases, so too does the need for permits. Although more detailed analysis and

consultation would be necessary to understand the exact demand for a permit scheme, it is

anticipated that the daily demand for access would be substantially less than the 200 daily

permits issued by the system operating in Dublin City. Our analysis suggests that the daily

requirement for permits would likely be no greater than 50 permits per day. Ultimately, the

demand for permits will be related to the basis upon which permits are granted.

The permit system would be a natural extension of the system already established by Dublin City

Council, and the cost of permits would be set to cover the costs of administering that scheme. It

is anticipated that the cost of a daily permit would be in the region of €5 to €10.

9.4 Mitigation of Impacts

The risk of increased traffic volumes using the R152 and R153 has already been noted in the

analysis. It is likely that some road safety mitigation works might become necessary prior to

implementation of restrictions through Slane, such that the impact on these diversion routes can

be managed. This could comprise local junction treatment/speed limit or streetscape


Page 40

improvements, or potentially further restrictions on HGV activity. More detailed analysis is

necessary to understand the extent of mitigation measures that might arise out of the solution.

9.5 Conclusion

It is therefore concluded that the measures presented within Scenario 1 (5+ axle ban on Slane

Bridge) and perhaps Scenarios 2 and 3, might represent the most manageable approach for

implementing vehicle size restrictions through Slane village. Nevertheless, the proposals bring

with them a number of notable adverse impacts:

It leads to an increase in goods vehicle traffic using the R152 and R153 as an alternative

to the N2 via Slane;

It generates an increase in vehicle kilometres (and hence vehicle emissions), and a

reduction in network efficiency; and

It reduces strategic accessibility between Ashbourne and the M1/Monaghan which is

currently available via the N2 corridor.

From the analysis, it is considered that the imposition of a 3+ axle restriction would lead to

excessive impact on local services.

The phasing in of a any restrictions would be subject to the normal rules of project preparation,

as it will likely require supporting mitigation measures along some select regional roads.

Nevertheless, in light of the impacts of the proposed measures on network efficiency, it is

questionable whether the traffic management proposals alone would yield a positive Business

Case.

9.6 The Role of the N2 as a Strategic Route

It is noted that with any vehicle restrictions through Slane, the N2 will cease to function as a

strategic corridor for commercial traffic. This will impact most significantly on Ashbourne, where

transport-dependant industry will suffer a reduction in accessibility to the Dublin-Belfast

Economic Corridor via Drogheda, or the Monaghan Hub via Ardee.

The N2 Slane Bypass scheme reflected an approach of delivering incremental improvements

along the N2, but with the ultimate objective of maintaining the N2 as a strategic corridor. The

proposal for vehicle size restrictions through Slane contradicts the conventional view of the N2

continuing to provide such a function, and perhaps should be more appropriately examined in the

context of a strategic plan for the M1, N2 and M3 corridors.

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