N11/M11 Junction 4 to Junction 14 Improvement Scheme · Arup has been appointed to provide multi-disciplinary technical consultancy services for the delivery of Phase 1-4 of the TII

Wicklow County Council

N11/M11 Junction 4 to Junction 14 Improvement Scheme

Scheme Feasibility Report

265455-ARUP-GEN-XX-RP-ZM-0003

Issue 4 | 28 November 2019

This report takes into account the particular instructions and requirements of our client.

It is not intended for and should not be relied upon by any third party and no responsibility is undertaken to any third party. Job number 265455

Ove Arup & Partners Ireland Ltd

Arup 50 Ringsend Road Dublin 4 D04 T6X0 Ireland www.arup.com

265455-ARUP-GEN-XX-RP-ZM-0003 | Issue 4 | 28 November 2019 | Arup

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ISSUE 4.DOCX

Contents Page

1 Introduction 1

1.1 Overview 1

1.2 Purpose of Scheme Feasibility Report 1

1.3 Scheme Background 1

1.4 Study Area 2

2 Policy Context 4

2.1 National Policy 4

2.1.1 Project Ireland 2040 (National Planning Framework) 4

2.1.2 National Development Plan (2018 – 2027) 4

2.1.3 Investment in our Transport Future – Strategic Investment Framework for Land Transport (SIFLT) 4

2.1.4 Smarter Travel – A Sustainable Transport Future (2009 – 2020) 5

2.2 Regional Policy 6

2.2.1 Greater Dublin Area Transport Strategy (2016-2035) 6

2.3 European Policy 7

2.3.1 Trans-European Transport Network (TEN-T) 7

2.4 Local Policy 8

2.4.1 Wicklow County Development Plan (2016 – 2022) 8

2.4.2 Dún Laoghaire – Rathdown County Development Plan (2016 – 2022) 9

3 Existing Conditions on the National Route 10

3.1 Existing Road Network 10

3.2 Existing Natural Constraints 11

3.3 Existing Human Environment 13

3.4 Existing Transportation Issues 14

3.4.1 N11/M11 Corridor 14

3.4.2 Existing Public Transport Provision 15

4 Existing Road Alignment 18

4.1 Overview 18

4.1.1 Existing N11/M11 Route Characteristics 18

4.1.2 Mainline Cross Section 19

4.1.3 Junctions and Accesses 20

4.1.4 Existing Junction Geometry and Capacity 23

4.1.5 Junction Merges and Diverges 23

4.1.6 Junction Separation and Weaving Lengths 26




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5 Journey Time Assessments 29

6 Traffic Volumes 31

6.1.1 Traffic Counts & Surveys 31

6.1.2 Origin – Destination Surveys 33

6.1.3 Future Forecasts 35

7 Safety Review 36

7.1 Assessment of Study Area and Existing National Route 36

7.2 Recommendations for Improvement to Safety Conditions 41

8 Feasible Transport Solutions 43

8.1 Possible Options and Alternatives 43

8.1.1 Overview 43

8.1.2 Potential Options 43

9 Cost Estimate 46

9.1 Feasibility Working Cost 46

10 Conclusions and Recommendations 47

10.1 Key Findings of Feasibility Report 47

10.2 Conclusions and Recommendations 47




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Page 1

1 Introduction

1.1 Overview

Arup has been appointed to provide multi-disciplinary technical consultancy services for the delivery of Phase 1-4 of the TII Project Management Guidelines for the N11/M11 Junction 4 to Junction 14 Improvement Scheme. The N11/M11 Junction 4 to Junction 14 Improvement Scheme is a proposed scheme to alleviate congestion and improve safety, journey time reliability and the strategic function of the N11/M11 corridor.

1.2 Purpose of Scheme Feasibility Report

The Scheme Feasibility Report has been produced as an output of the Phase 1 Scheme Concept and Feasibility studies. The purpose of phase 1 is to identify the project need, scope and extent and to set out a strategy and structure to progress the scheme delivery. Within this phase, the Scheme Feasibility Report has been prepared to gain a better understanding of the issues and challenges at hand, and to assist in planning the direction of further studies. It should be noted that the report has been prepared in advance of formal commencement of any planning or design. However, potentially feasible solutions to meet the scheme objectives are suggested, with a more rigorous appraisal of the viability of these options to be undertaken during phase 2 (Option Selection).

1.3 Scheme Background

The N11/M11 comprises of a motorway/dual carriageway for approximately 126km and runs along the east of the county connecting Dublin to Wexford. The N11/M11 forms part of the Trans-European Transport Network (TEN-T) providing access from Dublin to the south east of the country and a link between Dublin and Rosslare Europort.

The section under consideration for this commission is approximately 22km long and extends from the M11/M50 junction (J4) to the N11/M11 junction at Coyne’s Cross (J14). This section traverses two Local Authority boundaries, Wicklow County Council and Dún Laoghaire – Rathdown County Council. A Section 85 agreement has been put in place between the two local authorities which appoints Wicklow County Council (WCC) as the Lead Local Authority and Sponsoring Agency of the project. Kildare National Roads Office (KNRO) has been appointed by Transport Infrastructure Ireland (TII), acting as the Sanctioning Authority, to project manage the delivery of the scheme.

The N11/M11 has been in service since 1991 with the completion of the Bray Bypass. The section between M50 junction 4 and N11 junction 6 was upgraded in 2005 and the section between junction 14 and Gorey was designated motorway standard in 2009. This has highlighted deficiencies on the remaining section which has had limited intervention or upgrade and now sits between two sections of high quality motorway.




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Some sections of this portion of the N11/M11 corridor fall short in terms of current road design standards, with numerous direct accesses and at grade junctions. These deficiencies impact on traffic flow conditions and result in significant congestion during the weekday morning and evening peaks and ineffective levels of service. Consequently, this section of the N11/M11 fails to meet its primary function as a strategic road.

1.4 Study Area

The Study Area for the N11/M11 Junction 4 to Junction 14 Improvement Scheme is illustrated in Figure 1.3 below.




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Figure 1.3: N11/M11 Junction 4 to Junction 14 Improvement Scheme Study Area




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2 Policy Context

2.1 National Policy

2.1.1 Project Ireland 2040 (National Planning Framework)

The National Planning Framework and the National Development Plan (2018 – 2027) jointly present a ten-year strategy (Project Ireland 2040) for public capital investment of almost €116 billion to create a unified plan for development in the country. The plan establishes key objectives at national level which create a framework to guide regional strategies and local area plans.

A key strategic national outcome within the NPF is the enhancement of regional accessibility through continued investment in the national road network, ensuring that;

“all regions and urban areas have a high degree of accessibility to Dublin, as

well as to each other”.

In respect of Inter-Urban roads, the NPF sets the following objectives;

“Maintaining the strategic capacity and safety of the national roads network

including planning for future capacity enhancements”

“Improving average journey times targeting an average inter-urban speed of

90kph”.

2.1.2 National Development Plan (2018 – 2027)

As a companion document to the NPF, the National Development Plan (2018 – 2027) sets out the investment priorities that will underpin the successful implementation of the National Planning Framework.

In this context, the NDP identifies the ‘M11 from Jn 4 M50 to Kilmacanogue’ as a section of the national road network that will be progressed through pre-appraisal and early planning during 2018 to prioritise projects which are proceeding to construction as part of the NDP.

Furthermore, the NDP aligns with government policy in seeking to strengthen access routes to Ireland’s ports through investment to upgrade and enhance the road transport network to improve journey times. The plan quotes the, ‘ongoing

development of the M11’ in terms of improving connectivity to the Rosslare in the southeast as a key component in achieving this objective.

2.1.3 Investment in our Transport Future – Strategic Investment Framework for Land Transport (SIFLT)

In 2015, the Department of Transport, Tourism and Sport (DTTaS) published, ‘Investing in our Transport Future – Strategic Investment Framework for Land Transport (SIFLT)’. The document recognises that an effective transport network is central to the functioning of society and the economy.




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This framework provides a number of principles and priorities as criteria against which land based transport programmes will be drawn up and assessed. Rather than setting out a list of projects to be prioritised, SIFLT forms a filter of investment projects prior to their appraisal for suitability for inclusion in national and regional programmes. These priorities include:

• Priority 1: Achieve Steady State Maintenance

• Priority 2: Address Urban Congestion

• Priority 3: Maximise the Value of Existing Land Transport Networks

Investment in the section of the N11/M11 corridor under consideration is supported by a number of the priorities set out within SIFLT, in that any upgrade would likely address some urban congestion. Furthermore, the third priority of the SIFLT is particularly relevant in the context of proposals to upgrade the N11/M11. The underlying principles of this priority are that any further investment should be targeted to maximise the contribution of the land transport networks by enhancing the efficiency of the existing network, particularly:

• Through the increased use of Intelligent Transport Systems (ITS) applications;

• Through investments that improve connections to key seaports and airports or support other identified national and regional spatial planning priorities;

• In the case of roads, investment should provide access to poorly served regions, access for large-scale employment proposals, complete missing links or address critical safety issues.

2.1.4 Smarter Travel – A Sustainable Transport Future (2009 – 2020)

Smarter Travel – A Sustainable Transport Future (2009 – 2020), presents a transport policy framework for Ireland covering the period up to 2020. The policy, launched by the Department of Transport in 2009, sets out a vision, goals and targets to be achieved and outlines 49 actions that form the basis for achieving a more sustainable transport future. One of the key goals of the initiative is:

‘Improve economic competitiveness through maximising the efficiency of the

transport system and alleviating congestion and infrastructural bottlenecks’.

A key component of the plan is instigating behavioural change towards more sustainable transport modes and a reduction in car dependency by, “ensuring that

the alternatives to the car are more widely available, mainly through a radically

improved public transport service and through investment in cycling and

walking”.

The policy also promotes actions to improve the efficiency of motorised transport, with the following specific measures aimed at encouraging a more efficient and sustainable road network:

• Investment in modern technology for the road system aimed at improving information for road users.




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• Prioritising road space for public transport, reducing fuel consumption and emissions and optimising capacity for goods transport and business travel.

• Deployment of incident management technologies on key arteries with a view to limiting the development of traffic jams with their associated negative consequences for fuel consumption and emissions.

• Development of Intelligent Transport Systems.

The key goal as defined within the policy document, in relation to maximising the efficiency of the transport system and alleviating congestion and infrastructural bottlenecks, aligns entirely with the ambitions of the subject improvement scheme.

2.2 Regional Policy

2.2.1 Greater Dublin Area Transport Strategy (2016-2035)

The National Transport Authority’s (NTA) Transport Strategy for the Greater Dublin Area (GDA), adopted in 2016, provides a framework for the planning and delivery of the transport infrastructure in the GDA over the next two decades. The strategy presents a suite of transportation objectives to support the demands of substantial population growth within the GDA and sustained economic progression up to 2035. Measures listed in the strategy include provision of a range of additional public transport (heavy rail, light rail, bus and bus rapid transit facilities), cycling and pedestrian infrastructure.

Within the GDA Strategy, the study area is considered as part of Corridor F, incorporating Arklow, Wicklow, Greystones, Bray, Cherrywood, Dundrum, Dún Laoghaire to Dublin City Centre. Given the need to accommodate the anticipated growth in vehicular trip demand and improve road safety, the strategy envisages a number of specific developments to the national road network, including:

“Capacity enhancement and reconfiguration of the M11/N11 from Junction 4

(M50) to Junction 14 (Ashford) inclusive of ancillary and associated road

schemes, to provide additional lanes and upgraded junctions, plus service roads

and linkages to cater for local traffic movements”.

In addition to upgrades to the road network, the GDA Strategy also identifies considerable improvements to the public transport network, together with expansion of the cyclist and pedestrian infrastructure, to meet the growth in demand within the study area. Specific measures included within the Strategy are as follows:

• Substantial increase in peak-hour capacity on all existing rail lines, including to Greystones, delivered through the completion of the City Centre re-signalling programme, provision of a new train control centre to manage the operation of the network, enhancement of existing stations and provision of additional stations and an appropriate train fleet.

• Capacity enhancement on existing Luas Green Line by upgrading to Metro standard between St. Stephen’s Green and Bride’s Glen.




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From here, a new Luas line will be constructed to Bray, providing a second rail alternative with connection to a high frequency cross city rail corridor at the Metro terminus.

• Development of a Core Radial Bus Network (including along the Bray/N11 – UCD – Donnybrook route) with continuous priority for bus movement on these corridors, making bus transport a more attractive alternative for road users. This includes provision of a Bus Rapid Transit (BRT) system from UCD to Blanchardstown.

• Core Regional Bus Network serving longer distance buses from Wexford and regional buses from Arklow, Wicklow and the N11 corridor.

• Provision of sufficient on-street public cycle parking at key destinations such as bus and rail stations, schools, colleges, hospitals and large workplaces, particularly in urban areas.

• Development of a network of strategic rail-based park and ride facilities at appropriate points where rail services intersect with the national road network, with Woodbrook and Greystones identified among intended sites.

Furthermore, the GDA Strategy recognises that the provision of alternative public transport mode choices to the car must be complemented with travel demand management measures such as parking restrictions, multi-point tolling and ramp metering to reduce car dependency within the outer metropolitan area and incentivise public transport use.

The Strategy notes the importance of achieving a balance between the competing demands of strategic movement of high economic value and more locally based commuter traffic. This is particularly pertinent to the N11/M11 where the existing road space is shared between these competing needs, and the objective of protecting the capacity of this route through appropriate demand management is identified within the Strategy as follows:

“Implement, when appropriate, demand management measures on the radial

national routes approaching the M50 motorway (M1, M2/N2, N3/M3, N/M4,

N/M7, M11) to ensure that these routes retain sufficient capacity to fulfil their

strategic function, including freight movement”.

“Reduce the availability of workplace parking in urban centres to discourage car

commuting, where alternative transport options are available;”

“Implement, at the appropriate time, demand management measures to address

congestion issues on the radial routes approaching the M50 motorway, to ensure

that these routes retain sufficient capacity to fulfil their strategic function”.

2.3 European Policy

2.3.1 Trans-European Transport Network (TEN-T)

The N11/M11 road forms part of European Route E01 of the Trans-European Transport Network (TEN-T), commencing in Larne (UK) and terminating in Seville (Spain).




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The TEN-T networks is a European Commission policy directed towards the development of a Europe-wide network or road, rail, air, inland waterway and maritime links, consisting of the core network (primary connections linking nodes of greatest importance) and the comprehensive network (covering all European regions). The N11/M11 corridor is part of the comprehensive TEN-T road network, while Rosslare Europort forms part of the TEN-T comprehensive port network.

The ultimate objective of the TEN-T is to close gaps, remove bottlenecks and eliminate technical barriers that exist between the transport networks of EU Member States, strengthening the social, economic and territorial cohesion of the Union and contributing to the creation of a single European transport network. The policy seeks to achieve this aim through the construction of new physical infrastructure; the adoption of innovative digital technologies, alternative fuels and universal standards; and the modernising and upgrading of existing infrastructures and platforms.

Within Ireland, the majority of route E01 from the Northern Ireland border to Rosslare is of motorway standard, incorporating the M1, M50 and M11. From Junction 14 (Coyne’s Cross) to the south of Gorey, the route is also currently motorway status and the future completion of the M11 Gorey to Enniscorthy PPP Scheme, currently under construction, will extend the length of the motorway south by a further 26km.

2.4 Local Policy

2.4.1 Wicklow County Development Plan (2016 – 2022)

The Wicklow County Development Plan (2016 – 2022) supports the objective of developing the N11/M11 corridor as both a conduit for improved public transport provision and economically strategic traffic (e.g. freight and tourist journeys). Similarly, the plan encourages measures to improve the capacity and efficiency of the national routes, recognising the N11/M11 corridor as an essential means of access to the Dublin metropolitan area. The priority strategic road improvements within the plan comprise inter alia;

“the upgrade of the N11 in the north of the County, from the Dublin border as far

as Ashford, in particular improvements to the M50 / M11 merge which is deficient

in capacity, and all interchanges serving Bray”

Specific objectives regarding the N11/M11 corridor within the plan include;

• “Upgrading of the N11/M11 between the County boundary and Ashford

including road capacity and safety improvements to the main carriageway and

all necessary improvements to associated junctions;

• Improving the M11/M50 merge;

• Upgrading of the N11 to motorway status between Bray and Cullenmore;

• Upgrading the N11 interchange at the Glen of the Downs to facilitate the

provision of a northern link road from the N11 to Greystones;




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• Upgrade Ballyronan Interchange to facilitate improved access to

Newtownmountkennedy and a possible link road from Ballyronan to Kilcoole;

and

• The provision of a third interchange on the Arklow by-pass, linking the M11 to

Vale Road”.

2.4.2 Dún Laoghaire – Rathdown County Development Plan (2016 – 2022)

The Dún Laoghaire – Rathdown County Development Plan (CDP) sets out the framework for the development of the area over the next number of years. The CDP sets population targets for 2022 OF 240,300 based on the Regional Planning Guidelines – an increase of approximately 24% on the 2006 population recorded in the census. Furthermore, the CDP also sets a target for jobs within the council jurisdiction of 36,700 by 2022.

The CDP also contains a number of specific road objectives within policy ST25: Roads, with two objectives supporting improvement of the N11/M11 corridor:

• Upgrade of the N11 to motorway status as far as Fassaroe

• Junction 3 at Loughlinstown Roundabout to be upgraded to a grade separated junction in the longer term




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3 Existing Conditions on the National Route

3.1 Existing Road Network

The N11/M11 national road is the primary artery connecting Dublin to the south east of the country. In addition, the route provides access to international markets for freight and tourist traffic through Rosslare Europort as well as serving a high commuting demand within the Dublin metropolitan region. The overall length of the national route is approximately 126km from Dublin to Wexford, with the section under consideration for this study approximately 22km in length, commencing at the M11/M50 junction (J4) and terminating at the N11/M11 junction at Coyne’s Cross (J14).

Within this section, the route is designated as motorway for approximately 3.8km, commencing at junction 4 to a point just north of junction 6 (Bray, Fassaroe). The remainder of the route is a two-lane dual carriageway of varying geometric standard but generally consistent cross section. To the south of the study area, the route returns to motorway designation at junction 14 (Coyne’s Cross) and continues as far south as Gorey. The M11 Gorey to Enniscorthy PPP Scheme, currently under construction, will extend the length of motorway south by a further 26km.

The existing N11/M11 within the study area is an amalgamation of several separate construction projects and upgrades over a period of approximately 50 years. This piecemeal completion of the road is reflected in the geometric characteristics and operational effectiveness of the route. A timeline summary of the various construction contracts/upgrades making up the present-day route is presented in table 1.4 below.

Table 1.4: N11/M11 Construction Timeline

Section of Existing N11/M11 Route

Construction Contract / Upgrade Year of Opening

Junction 4 (N11/M50) to North of Junction 5

Constructed as part of M50 South Eastern Motorway Contract

2005

Junction 5 to Junction 6 M11 Bray Bypass (Loughlinstown to Valery’s Bridge)

1991

Junction 7 Kilcroney Dual Carriageway (Fassaroe to Kilmacanoge)

c.1970

N11 Kilmacanoge to Junction 10

N11 Road Improvement Scheme (Kilmacanoge – Glen of the Downs)

2003

Junction 10 Kilpedder Bypass c. 1972

Junction 11 N11 Kilpedder Interchange Design & Build Contract

2008

Junction 13 Newtownmountkennedy Bypass 1990

Junction 13 to Junction 14 Newtownmountkennedy to Ballynabarny Road Improvement Scheme

2004




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The specific geometric characteristics of the existing route are discussed in more detail in chapter 4.

The surrounding regional and local road network provides access to the N11/M11 corridor from the various towns and villages throughout the study area, including Bray (R767, R768, L152, L1596), Enniskerry (R117), Greystones – Delgany (R774, R762), Newtownmountkennedy (R772), Newcastle (L5050) and Roundwood (R765). The R761 does provide an alternative north-south route through the study area extending from Coyne’s Cross to Bray before joining the R119 at Wilford roundabout, however, this route varies in standard and traverses through consecutive congested urban areas as it links each settlement to the east of the N11/M11. In this regard, the regional road network can be viewed as serving the N11/M11 corridor rather than actively supporting it. For both strategic traffic and the majority of commuting traffic, the N11/M11 remains the only viable north-south corridor providing access to the Dublin metropolitan area. At the northern end of the study area, where traffic volumes are very high, it is noteworthy that the N11 is one of only two north-south crossings of the Dargle River across the entire width of the study area, the other being the R761 at Main St. in Bray town centre. The absence of a properly functioning supporting network of regional and local roads will have a major impact on the feasibility of options for appraisal during phase 2.

3.2 Existing Natural Constraints

The study area surrounding the existing N11/M11 corridor is physically constrained by the Irish Sea coastline to the east and the Dublin / Wicklow mountain region to the west. Along certain sections of the route, topography rises steeply in close proximity to the existing alignment, most notably to the west of Kilmacanoge at Sugarloaf Mountain and through the Glen of the Downs. A number of streams and tributaries, sourced in the mountain region, traverse the study area, with the most significant being the Dargle River. This river rises near Djouce Mountain to the west before flowing east and crossing under the existing N11 at St. Valery’s bridge, from where it flows through Bray and reaches the sea at Bray harbour.

A number of areas of notable environmental significance within the vicinity of the corridor include the following:

• Glen of the Downs Special Area of Conservation (SAC)

• Ballyman Glen (SAC)

• Bray Head (SAC)

• Carrigower Bog (SAC)

• Deputy’s Pass Nature Reserve (SAC)

• Knocksink Wood (SAC)

• Buckroney-Brittas Dunes (SAC)

• Vale of Clara (SAC)




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• Magherabeg Dunes (SAC)

• The Murrough Wetlands (SAC)

• Wicklow Reef (SAC)

• Kilmacanoge pNHA

Figure 3.2 below highlights the natural constraints and areas of environmental importance identified within the study area.

Figure 3.2: Existing N11/M11 Natural Constraints




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The wider Co. Wicklow area surrounding the N11/M11 corridor is highly scenic and environmentally sensitive, with several areas of outstanding natural beauty and high amenity value attracting both visiting tourists and the local population alike. The N11/M11 corridor serves as a distribution point from Dublin for onward journeys to the Wicklow Mountains, Glendalough Valley, Powerscourt Waterfall and Bray Head among others.

3.3 Existing Human Environment

The N11/M11 corridor is the primary artery connecting Dublin to the South East and serves a wide geographical area. The route traverses a region of high population density to the north of junction 10 (Delgany), with smaller settlements and villages to the south surrounded by mainly agricultural land use. The overall population of Co. Wicklow in 2016 was 142,425, a 4.2% increase on 2011 figures, with over 60% of this population resident within the study area. Bray, the fourth largest town in Ireland, had a recorded population of 32,600 in 2016. Other major population centres in the study area include Greystones-Delgany, Shankill/Loughlinstown and Kilcoole. The existing built environments sits in proximity to the N11/M11 corridor along substantial sections of the existing route. This is particularly the case between junction 4 and junction 7, where the environs of Bray town extend to the existing road boundary. However, this is also the case further south where the N11/M11 splits the village of Kilmacanoge, and at Kilpedder, where a mixture of residential and commercial development sits immediately adjacent to the existing route. Future developments, such as the major housing project at Fassaroe, will further expand the built environment within the N11/M11 corridor. The proximity of the built environment will present a major constraint to the development of feasible transportation options during phase 2.

While labour force participation within county Wicklow is high at 61.5%, the jobs ratio of 42% (2011) is significantly lower, forcing large numbers to commute to other regions, primarily the greater Dublin area, to work. 2016 census data records that 45.5% of persons at work and living in Bray commuted to Dublin city and suburbs for employment. The equivalent figures for Greystones-Delgany and Wicklow town were 48.4% and 28.5% respectively.

As outlined in the Wicklow County Development Plan 2016 – 2022, the populations of the county’s primary urban areas are targeted for further growth, as follows:

• Bray population targeted to increase from 29,339 in 2011 to 40,000 in 2028

• Wicklow population targeted to increase from 13,468 in 2011 to 24,000 in 2028

• Greystones-Delgany population targeted to increase from 17,208 in 2011 to 24,000 in 2028

Many of the smaller settlements within the southern part of the county, including Newtownmountkennedy and Kilcoole are also targeted for growth. These towns are typically located in areas not served by public transport where reliance on the private car is very high.




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In order to achieve the targeted population growths within the study area, a number of major future developments are proposed in close proximity to the N11/M11 corridor. These include the development of lands at Fassaroe to the west of N11 junction 6 and the Cherrywood Strategic Development Zone in Dún Laoghaire – Rathdown.

Outside of Dublin and the other major cities, Co. Wicklow is one of the most popular destinations for visiting tourists in Ireland, receiving over 275,000 overseas visitors in 2017.

3.4 Existing Transportation Issues

3.4.1 N11/M11 Corridor

The transportation issues within the N11/M11 corridor have been examined as part of the Scope and Pre-Appraisal of the project and are documented within the Project Brief. A summary of the key operational issues affecting the route are outlined below.

• In the 20-year period between 1998 and 2018, traffic volumes on certain sections of the N11/M11 route have more than doubled. Figure 3.3 below presents AADT data obtained from TII records over this timeframe for the M11 mainline just north of Junction 6 (Bray, Fassaroe). In that time, volumes have grown from 32,991 AADT to 69,989 AADT. A significant jump in traffic levels occurred between 2005 and 2007 in the years immediately following the completion of the M50 South Eastern Motorway and junction 4 interchange. The existing N11/M11 between junction 5 and junction 8 was not designed to accommodate such large volumes and in the absence of any intervention will remain heavily congested.

Figure 3.3: AADT on M11 between J5 and J6 (1997 – 2018)

0

10000

20000

30000

40000

50000

60000

70000

80000

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

2016

2017

2018

AA

DT

Year

AADT M11 at Fassaroe Between J5 and J6 (1997 - 2018)

AADT Level of Service D




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• Existing traffic volumes north of junction 8 significantly exceed the capacity corresponding to the provision of a minimum Level of Service D for the particular road type. TII standard DN-GEO-03031 specifies indicative AADT capacities of 52,000 for divided motorways and 42,000 for Type 1 Dual Carriageways to obtain this level of service. Volumes above this threshold instigate volatile operation with little or no gaps in the traffic stream, restricted freedom to manoeuvre and significantly reduced driver comfort.

• The regional and local road network surrounding the N11/M11 corridor is not sufficiently capable of supporting local access by providing alternative route options for short trips. This results in a proliferation of ‘hop-on, hop-off’ trips on the mainline route as well as vehicles utilising the N11 to perform U-turn manoeuvres as a result of direct access and left-in/left-out junction arrangements.

• Sections of the N11/M11 route were designed and constructed prior to the implementation of consistent and modern road design standards in Ireland. These geometric deficiencies along sub-standard sections of the route contribute to the operational inefficiency as well as posing significant safety hazards.

• Speed restrictions imposed the N11 mainline as a consequence of geometric deficiencies and propagation of access points seriously destabilises flow during AM and PM peak periods.

• The N11/M11 corridor is the dominant artery connecting Dublin to the South East and also traverses a heavily populated commuting belt within the metropolitan area of the city. As such, the route must serve the competing demands of freight transport, commuter journeys, local and tourist travel and cyclists.

3.4.2 Existing Public Transport Provision

The South – Eastern railway line, extending from Dublin Connolly (City Centre) to Rosslare Europort runs through the study area along the east coastline, providing an electrified DART service linking the City Centre as far south as Greystones, along with diesel Commuter and Intercity services further southwards, serving towns such as Bray, Greystones, Wicklow, Arklow, Gorey, Wexford and Rosslare. It should be noted that heavy rail capacity on the corridor is limited as all services south of Bray operate on a single line. The frequency of existing rail services along the corridor is as follows:

• Irish Rail: Operates 5 daily services (Mon-Fri) from Rosslare Europort to Dublin Connolly serving Arklow, Wicklow, Kilcoole, Greystones and Bray.

• DART/Commuter Services: Operates services from Bray to Dublin Connolly with frequency every 10-15 minutes. Services run as far as Greystones with frequency up to every 30 minutes.

There is a single dedicated park and ride facility within the study area located at Greystones train station.




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The existing Luas light rail green line terminates within the northern extent of the study area at Bride’s Glen in Cherrywood, providing a high frequency, high capacity service into Dublin with trams operating up to every 3 minutes at peak hours. While the service is regarded as frequent and reliable, its catchment area within the overall N11/M11 study boundary is very limited and the line is currently operating close to capacity.

At present, the population centres within the study area are also reliant on the bus network to a considerable degree, with a variety of routes served by Dublin Bus, Bus Éireann and private operators.

Reliance on the bus network, as a public transport alternative to the private car, is particularly evident away from the coastal areas and south of Bray, i.e. outside the catchment of the higher frequency and higher capacity rail services. A summary of the bus routes serving the study area is provided below:

• Dublin Bus Route 145: Operates from Ballywaltrim to Heuston Station via Herbert Road, Bray and Shankill with frequency up to every 10 minutes. A single morning service commences at Kilmacanoge on the existing N11 dual carriageway.

• Dublin Bus Route 155: Operates from Bray Railway Station to Ballymun (IKEA) via City Centre with frequency up to every 20 minutes.

• Dublin Bus Route 84/a: Operates from Newcastle to Blackrock via Kilcoole, Greystones and Bray with frequency up to every 30 minutes.

• Dublin Bus Route 84x: Operates from Newcastle to Hawkins St. (City Centre) via Kilcoole, Greystones, Loughlinstown with frequency up to every 10 minutes (up to 7.50am).

• Bus Éireann Route 133: Operates from Wicklow Town Dublin Airport with connection to Bray DART station and a single stop on the N11 dual carriageway at Kilmacanoge. Services operate hourly from 6.40am to 10.40pm.

• Aircoach Route 702: Operates 24hr hourly services from Greystones to Dublin Airport via Bray and Shankill.

• Wexford Bus Route 740: Operates hourly services from Wexford to Dublin Airport between 6.30am to 7.30pm with a single stop on the N11 dual carriageway at Kilmacanoge.

• Wexford Bus Route 740a: Operates services every 2 hours from Arklow to Dublin Airport between 6.30am to 7.30pm with a single stop on the N11 dual carriageway at Kilmacanoge.

• Go Ahead Ireland Route 184: Operates services from Newtownmountkenedy to Bray DART station via Greystones and Newcastle with frequency up to every 30 minutes.

• Go Ahead Ireland Route 185: Operates services from Enniskerry Golf Club to Bray DART with frequency up to every 30 minutes.




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• St. Kevin’s Bus: Operates 2 services per day (3 in July/August) from Glendalough to St. Stephen’s Green (City Centre) via Kilmacanoge, Bray and Shankill.

Accessibility to rail based public transport is an issue due to inadequate pedestrian and cyclist infrastructure and lack of availability of park and ride facilities. Bus services utilising the N11/M11 must negotiate the same traffic volumes as private cars and are subject to the same unreliability in journey time – this in turn disincentivises take up of public transport alternatives to the private car.

At present, the public transport mode share for all trip purposes within the study area varies between 7% at the southern end, to 11% at the northern end which is better served by DART. Existing public transport provision is not capable of serving demand within the corridor, forcing commuters to use the car.




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4 Existing Road Alignment

4.1 Overview

As noted in Chapter 1, the section of the existing N11/M11 under consideration is an amalgamation of several separate construction projects and upgrades over a period of approximately 50 years. As a result, significant portions of the current route were designed and constructed prior to the establishment of the National Roads Authority (now TII) in 1993 and the implementation of consistent geometric standards across the national road network. With limited intervention or improvements occurring since, the route is characterised by major and in some cases, abrupt variations in design standard and operational efficiency.

4.1.1 Existing N11/M11 Route Characteristics

From junction 4 (M11/M50) to junction 5 (Bray North), the M11 mainline consists of a two-lane motorway with a continuous auxiliary lane between the two junctions in both the northbound and southbound directions. The two-lane motorway continues south as far as junction 6 (Bray/Fassaroe), with the motorway then terminating to become the N11 dual carriageway. At this point, the speed limit of the road changes from 120km/h on the motorway to 100km/h on the dual carriageway. The geometric standard of the section of N11 dual carriageway between junction 6 (Bray/Fassaroe) and junction 8 (Kilmacanoge) drops considerably, and is characterised by numerous direct private accesses, inconsistent and reduced standard junction layouts and inadequate weaving lengths.

Additionally, there are a number of locations where the geometric alignment of the road does not meet the current TII design standards specified in DN-GEO-03031 (Rural Road Link Design). The mainline gradient in the vicinity of junction 7 (Bray South) reaches almost 5%, exceeding the permitted maximum of 3% (or 4% with relaxation) for a Type 1 Dual Carriageway. This gradient departure is also coincident with a horizontal curve less than the desirable minimum radius of 720m for a design speed of 100km/h. In the southbound direction, the steep uphill gradient presents a challenge for slow moving HGVs, which combined with mainline queuing stemming from junction 7 capacity problems, creates a significant safety and operational issue at this location.

South of junction 7, there is a further sub-standard horizontal curve at Jameson’s Corner just north of Kilmacanoge village. At this point in the southbound direction, the speed limit drops abruptly from 100km/h to 60km/h due to the proliferation of direct commercial and residential accesses through the village. This sharp reduction in speed limit acts as a major contributing factor to southbound congestion in the PM peak period. A speed limit reduction to 80km/h is in place along the adjacent northbound carriageway through this area.

Geometric deficiencies remain from junction 8 south, albeit traffic volumes are lower in comparison to the N11/M11 north of the junction. Nonetheless, the number, spacing and layout of direct accesses and junctions is not compatible with a safe and operationally effective strategic road.




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Immediately to the south of junction 9 (Glenview) and just north of the Glen of the Downs, there is a further sub-standard horizontal curve with a mainline radius of approximately 400m. This reduction in standards, coupled with the lack of adequate forward visibility to the Glen of the Downs Nature Reserve access, necessitates a reduced speed limit of 80km/h through this area in the southbound direction (the 100km/h speed limited is reinstated shortly after this access). To the south of the Glen of the Downs, there is a further sub-standard horizontal curve of approximately 455m radius coincident with a gradient relaxation. Beyond this point, the geometric standard of the mainline generally improves and junction spacing increases until the tie-in point with the M11 at junction 14 where the speed limit changes to 120km/h.

4.1.2 Mainline Cross Section

The required cross section for a standard Motorway / Type 1 Dual Carriageway as per TII detail CC-SCD-00007 is presented in figure 4.1 below.

Figure 4.1: Standard Motorway / Type 1 Dual Carriageway Cross Section

The existing lane and hard shoulder widths on the N11/M11 meet the required standard over the full length of the route. On certain sections of the route, lane widths exceed current requirements as a result of compliance with earlier standards. As outlined in Table 4.1, median widths vary significantly along the length of the subject section of the route.

Table 4.1: Existing N11/M11 Cross Section

Route Section

Hard Shoulder (m)

Carriageway (m) / No. of Lanes

Median (m) Hard Shoulder (m)


J4 – J5 3.0 10.95

(3 x 3.65)

9.0 3.0 10.95

(3 x 3.65)

J5 – J6 3.0 7.3

(2 x 3.65)

9.0 3.0 7.3

(2 x 3.65)

J6 – J7 3.0 7.3

(2 x 3.65)

Varies

(9.0 – 4.6)

3.0 7.3

(2 x 3.65)

J7 – J8 3.0 7.3

(2 x 3.65)

Varies

(9.0 – 6.0)

3.0 7.3

(2 x 3.65)

J8 – J9 3.0 7.3

(2 x 3.65)

Varies

(10.0 – 6.0)

3.0 7.3

(2 x 3.65)

J9 – J10 Varies

3.0 – 2.0

Varies

7.3 – 7.0

Varies

(10.0 – 3.0)

Varies

3.0 – 2.0

Varies

7.3 – 7.0




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Route Section

Hard Shoulder (m)


Median (m) Hard Shoulder (m)


(2 x 3.65 – 2 x 3.5) (2 x 3.65 – 2 x 3.5)

J10 – J11 2.5 7.0

(2 x 3.5)

Varies

(12.0 – 3.0)

2.5 7.0

(2 x 3.5)

J11 – J12 3.0 7.3

(2 x 3.65)

Varies

(9.0 – 3.0)

3.0 7.3

(2 x 3.65)

J12 – J13 3.0 7.3

(2 x 3.65)

9.0 3.0 7.3

(2 x 3.65)

J13 – J14 3.0 7.3

(2 x 3.65)

9.0 3.0 7.3

(2 x 3.65)

4.1.3 Junctions and Accesses

The number, type and location of each existing access point on the N11/M11 northbound and southbound carriageways between junction 4 and 14 is presented in Tables 4.2 and 4.3 below.

Table 4.2: Existing N11/M11 Access Locations Northbound (Major junctions in Bold)

No. Junction Ref.

Junction / Access Description Junction / Access Form

1 NB-4 Junction 4 M11/M50 (City Centre/Dún Laoghaire)

Freeflow Interchange

2 NB-5 Junction 5 R761 (Bray North) Grade Separated Junction

3 NB-6 Junction 6 R918 (Bray/Fassaroe) Grade Separated Junction

4 NB-6.1 Junction 6a (Enniskerry) Left-in / Left-out Junction

5 NB-6.2 Private Access (Dublin Oak Academy) Direct Access

6 NB-7 Junction 7 (Bray South) Grade Separated Junction

7 NB-7.1 Private Access (Woodlands Academy Direct Access

8 NB-7.2 Glencormack / Avoca Parallel Service Road with Merge / Diverge

9 NB-8 Junction 8 (Kilmacanoge / Roundwood)

Grade Separated Junction

10 NB-8.1 Access to 6 residential properties Parallel Service Road with Merge / Diverge

11 NB-8.2 Private Access (Kilmurray Grove) Direct Access



13 NB-8.5 Quill Road Left-in / Left-out Junction

14 NB-9 Junction 9 (Glenview) Compact Junction

15 NB-9.1 Private Access (Residential/Commercial) Direct Access

16 NB-9.2 Gated Access to Glen of the Downs (WCC lands)

Direct Access




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No. Junction Ref.


17 NB-9.3 One-way Access Road to Drummin Lane Left turn Access from N11 Mainline

18 NB-10 Junction 10 (Delgany / Drummin) Grade Separated Junction with diverge loop

19 NB-10.1 Killickabawn Single left-in merge

20 11 Junction 11 (Greystones / Kilpedder / Kilcoole)


21 NB-11.1 L5046 (Kilpedder) Single lane diverge

22 NB-11.2 Commercial Access Direct Access

23 NB-11.3 Private Access (Mount Kennedy House) Direct Access

24 NB-12 Junction 12 (Newtown Mount Kennedy / Roundwood)


25 NB-13 Junction 13 R772 (Newtown Mount Kennedy / Newcastle)


26 NB-14 Junction 14 R772 (Coyne’s Cross) Grade Separated Junction

Table 4.3: Existing N11/M11 Access Locations Southbound (Major Junctions in Bold)

No. Junction Ref.


1 SB-4 Junction 4 M11/M50 (Wexford/Bray Freeflow Interchange

2 SB-5 Junction 5 R761 (Bray North) Grade Separated Junction

3 SB-6 Junction 6 R918 (Bray/Fassaroe) Grade Separated Junction

4 SB-6.1 Access to Silverbridge Halting Site Left-in / Left-out Junction

5 SB-6.2 Dargle Lane L152 Left-in / Left-out Junction

6 SB-6.3 Herbert Road L1956 Left-in / Left-out Junction

7 SB-6.4 Kilcroney Church Direct Access

8 SB-6.5 Private Access (Residential) Direct Access

9 SB-7 Junction 7 R767 (Bray South/Greystones/Enniskerry)


10 SB-7.1 Gated Field Access Direct Access

11 SB-7.2 Gated Field Access Direct Access

11 SB-7.3 Garden of Ireland Direct Access

12 SB-7.4 Single Residential Access Direct Access

13 SB-7.5 Single Residential Access Direct Access

14 SB-7.6 Commercial / Residential / Wastewater Treatment Plant Access

Direct Access

15 SB-7.7 Commercial Access (Kelly Recovery / Oxygen Care)

Direct Access

16 SB-7.8 Commercial Access (Glen fuels / Circle K)

Direct Access




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No. Junction Ref.


17 SB-7.9 Residential Access Direct Access

18 SB-8 Junction 8 R755 (Roundwood/Kilmacanoge


19 SB-8.1 Kilmurray Cottages L5530 Left-in / Left-out Junction

20 SB-8.2 Gated Access Direct Access

21 SB-8.3 Twin Gated Access Direct Access

22 SB-8.4 Commercialp Access (Horkens Garden & Lifestyle)

Direct Access

23 SB-9 Junction 9 L1028 (Glenview) Left-in / Left-out Compact Junction

24 SB-9.1 Glen of the Downs Nature Reserve Direct Access

25 SB-10 Junction 10 R762 (Delgany/Drummin) Grade Separated Junction

26 SB-10.1 R762 Left-in / Left-out Junction

27 SB-11 Junction 11 R774 (Greystones / Kilpedder / Kilcoole)


28 SB-11.1 Kilquade L1042 Left-in / Left-out Junction

28 SB-11.2 Private Residential Access Direct Access

29 SB-12 Junction 12 R722 (Newtown Mount Kennedy/Roundwood)


30 SB-13 Junction 13 R722 (Newtown Mount Kennedy/Newcastle


31 SB-14 Junction 14 R722 (Coyne’s Cross) Grade Separated Junction

As noted in section 3.4.2, the existing N11/M11 corridor is also served by a number of bus services provided by both public and private operators. Bus stops are presently located on the route as indicated in table 4.4 below. While current TII standards do not make specific reference to the provision of bus stops on Type 1 Dual Carriageways, it is noted in TII standard DN-GEO-03031 that it is best practice to avoid bus stops on high speed divided carriageways and site these on alternative routes offline. As such, the provision and location of bus stops may influence the development of feasible options during phase 2.

Table 4.4: Existing Bus Stops on N11 Mainline

Ref. No Northbound Southbound

1 Junction 8 Kilmacanoge (Circle K Garage)

Junction 8 Kilmacanoge (Circle K Garage)

2 Kilmacanoge (North of Glencormack/Avoca Access)

Kilmacanoge (Kilmurray)

3 Kilmurray/Quill Road Junction 9 Glenview

4 Junction 9 Glenview Kilpedder

5 Timore (Between J13 and J14) Timore (Between J13 and J14)




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4.1.4 Existing Junction Geometry and Capacity

The piecemeal delivery of the existing N11/M11 over several decades is reflected in the geometric standard of the junctions along the route, which varies considerably. Few, if any, junctions along the scheme comply fully with current TII geometric standards. Furthermore, there is an absence of consistency in junction standard and design characteristics, which does not present drivers with intuitive and expected layouts.

The existing merges and diverges at junction 6 are sub-standard and have a direct impact on the operational efficiency of the N11 mainline. From a geometric perspective, the southbound diverge is particularly problematic as the absence of a near straight at the end of the diverge nose restricts the ability of approaching drivers to comprehend the junction layout and adjust their speed accordingly. Near straights are required at the downstream and upstream end of diverge and merge noses to provide a gradual transition in geometric standard between the mainline and connector road. Forward visibility across the diverge loop falls short of TII standard requirements as existing vegetation severely restricts sight distance on approach.

The layout of existing junction 7 also has a major impact on the capacity and operation of the mainline, with a similar loop diverge arrangement in the southbound direction, again without provision of a near straight or adequate forward visibility. A key issue is the existing conflict at the Killarney Road Roundabout in which vehicles accessing the N11 northbound exert a dominance at the roundabout and block vehicles exiting the N11 southbound – a particular contributor to PM peak congestion as the short diverge loop is insufficient to provide storage for queuing vehicles.

South of junction 8 as far as junction 14, there are no significant capacity issues at any of the junctions. Geometric deficiencies remain however in relation to junction layout, merge and diverge geometry and weaving lengths, as discussed in more detail below.

4.1.5 Junction Merges and Diverges

Junction merge and diverge layouts are typically not in compliance with current TII standards along the length of the route. The main geometric issues relate to the inconsistent and largely inadequate provision of entry/exit tapers, auxiliary lane lengths and widths, diverge and merge nose lengths at each junction. A summary of merge and diverge geometric parameters extracted from TII standard DN-GEO-03060, together with actual values measured on the existing route are presented in tables 4.5 to 4.8 below. Dimensions non-compliant with TII standard requirements are highlighted in red.




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Table 4.5: Geometric Design Parameters for Merging Lanes (extracted from DN-GEO-03060)

Road Class Length of Entry

Taper (m)

Nose Length (m)

Minimum Auxiliary

Lane Length (m)

Length of Auxiliary

Lane Taper (m)

Auxiliary Lane Width

(m)

Rural Motorway (120km/h)

Mainline 205 115 230 75 3.5

Type 1 Dual Carriageway (100km/h)

Mainline 130 75 160 55 3.5

Table 4.6: Existing Geometric Parameters for Merging Lanes on N11/M11

Location Entry Taper (m)

Nose Length (m)

Minimum Auxiliary

Lane Length (m)

Length of Auxiliary

Lane Taper (m)


(m)

Junction 5 – Motorway (120km/h)

NB Merge - 130 - - 3.5

SB Merge 155(1) 75 - - -

Junction 6 – Dual Carriageway (100km/h)

NB Merge - 75 280 55 2.5

SB Merge - 90 185 55 2.8


NB Merge - 80 - - 4.1

SB Merge - 25 245 80 3.0


NB Merge - 17 160 60 3.2-4.5

SB Merge - 75 160 40 4.1


NB Merge - 10 295 40 3.2

SB Merge - 19 260 45 3.5


NB Merge - 75 150 40 3.3

SB Merge - - 90 45 3.5


NB Merge - 115 165 60 3.8

SB Merge - 120 165 32 3.6

Junction 12 – Type 1 Dual Carriageway (100km/h)

NB Merge - 110 250 42 2.8

SB Merge - 35 105 20 2.8





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Location Entry Taper (m)

Nose Length (m)

Minimum Auxiliary

Lane Length (m)

Length of Auxiliary

Lane Taper (m)


(m)

NB Merge - 28 140 144 3.75

SB Merge - 150 140 215 3.80


NB Merge - 140 190 170 4.0

SB Merge - 170 140 230 4.0

(1) Note that the provision of a direct entry taper without auxiliary lane is not a permitted merging option in accordance with

Table 4.7: Geometric Design Parameters for Diverging Lanes (extracted from DN-GEO-03060)

Road Class Length of Exit Taper

(m)

Nose Length (m)

Minimum Auxiliary

Lane Length (m)

Length of Auxiliary

Lane Taper (m)


(m)

Rural Motorway (120km/h)

Mainline 180 80 200 75 3.5

Type 1 Dual Carriageway (100km/h)

Mainline 150 70 170 55 3.5

Table 4.8: Existing Geometric Parameters for Diverging Lanes on N11/M11

Location Exit Taper (m)

Nose Length (m)

Minimum Auxiliary

Lane Length (m)

Length of Auxiliary

Lane Taper (m)


(m)

Junction 5 – Motorway (120km/h)

SB Diverge - 120 - - 3.5

NB Diverge 230 90 - - -


SB Diverge - - 145 50 2.7

NB Diverge - 75 165 35 3.0


SB Diverge - 36 105 60 3.5

NB Diverge - 210 95 35 4.1


SB Diverge - 65 124 16 3.5

NB Diverge - 15 150 60 3.75


SB Diverge - 17 162 45 3.5




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Location Exit Taper (m)

Nose Length (m)

Minimum Auxiliary

Lane Length (m)

Length of Auxiliary

Lane Taper (m)


(m)

NB Diverge - 9 190 35 3.5


SB Diverge - 32 60 30 2.5

NB Diverge - - 20 45 2.7


SB Diverge - 95 165 100 4.0

NB Diverge 135 (2-lane) 100 - - -


SB Diverge - - 165 25 2.6

NB Diverge - 55 55 22 2.6


SB Diverge - 24 157 - 2.75

NB Diverge - 40 250 105 4


SB Diverge - 85 255 80 4.0

NB Diverge - 80 220 120 4.0

It should be noted that in the majority of the locations listed above, the mainline hard shoulder is typically used to provide the space for the merge and diverge tapers and auxiliary lanes, with the result that there is no hard shoulder or hard strip provided alongside the auxiliary lane. This is not in compliance with current TII standard DN-GEO-03060.

There are also a number of specific locations where junctions and accesses are sited directly on merge or diverge auxiliary lanes and tapers, with resultant hazardous conflicts with mainline traffic movements. These scenarios occur at the following locations:

• Junction 8 (Kilmacanoge) Southbound Diverge (access to Circle K off diverge)

• Junction 8 (Kilmacanoge) Northbound Diverge (access to single residential property off diverge)

• Junction 10 (Delgany/Drummin) Northbound Merge (left turn access off merge lane to Drummin Lane)

• NB-11.1 L5046 (Kilpedder) Northbound Diverge (access to single commercial property off diverge)

4.1.6 Junction Separation and Weaving Lengths

The provision of an adequate weaving length is a key criterion in the consideration of junction spacing on a grade separated road.




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A weaving section refers to the length of carriageway between a successive merge or lain gain and diverge or lain drop, where vehicles leaving the mainline at the diverge or lane drop have to cross the paths of vehicles that have joined the mainline at the merge or lane gain. In accordance with TII standard DN-GEO-03060, the desirable minimum weaving length shall be 2km on rural motorways and type 1 dual carriageway national roads. On the existing N11/M11 route, the junction separation distances provided are as shown in Table 4.9 below. Dimensions non-compliant with TII standard requirements are highlighted in red.

Table 4.9: Existing N11/M11 Junction Weaving Lengths

Junction / Access Weaving Length

Between Junctions (m) (Northbound)

Weaving Length Between Junctions (m)

(Southbound)

Junction 4 M11/M50 (Wexford/Bray) 890 1,100

Junction 5 R761 (Bray North)

900 1,450

Junction 6 R918 (Bray/Fassaroe)

N/A(1) 300

Access to Silverbridge Halting Site

N/A(1) 220

Dargle Lane L1522

N/A(1) 60

Herbert Road L1956

N/A(1) 600 Junction 7 R767 (Bray

South/Greystones/Enniskerry)

670

1,250 Glencormac L1019

220 Junction 8 R755

(Roundwood/Kilmacanoge)

720

2,200

MoorePark

340

Quill Road L5029

890

Junction 9 L1028 (Glenview) 1,750 1,900




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Junction / Access Weaving Length

Between Junctions (m) (Northbound)

Weaving Length Between Junctions (m)

(Southbound)

Junction 10 R762 (Delgany/Drummin)

1,150 460 Junction 11 R774 (Greystones /

Kilpedder / Kilcoole) 1,090 (From J 12)

1,100 L5046 720

Junction 12 R722 (Newtown Mount Kennedy/Roundwood)

3,000 2,750 Junction 13 R722 (Newtown Mount

Kennedy/Newcastle)

1,520 2,900 Junction 14 R722 (Coyne’s Cross)

(1) N/A means ‘Not Applicable’. This occurs where a junction or access is located on one side the carriageway only, i.e. northbound or southbound. For example, the accesses to Silverbridge Halting Site, Dargle Lane and Herbert Road are located on the southbound carriageway only, so have no impact on weaving lengths in the northbound direction.

It is evident from the table above that the majority of weaving lengths provided between the existing junctions is insufficient. This lack of weaving length provision is likely to be a significant contributor to flow instability and collision frequency on the N11/M11 corridor. Given the close spacing of existing junctions and accesses, the resolution of the weaving issues will impact on the feasibility of any on-line improvement options to the existing corridor.




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5 Journey Time Assessments

Journey time data for the N11/M11 corridor was collected using the Google maps distance matrix API 1. Figure 5.1 presents journey time durations in the northbound and southbound direction for each section of the N11/M11 over the 32km between M11 J15 (Ashford) and M50 J14 (Sandyford).

In the northbound direction during the AM Peak (08:00-09:00), the overall journey time was approximately 26 minutes and 21 minutes during the PM Peak (17:00-18:00), which equates to an average speed of 74km/h and 91km/h respectively. The average journey time in the northbound direction under free flow conditions was recorded during the morning was 19 minutes for the entire route, which suggests a delay of 7 minutes in the morning and 2 minutes in the evening during the weekdays.

Figure 5.1: Journey Times M11 J15 (Ashford) to M50 J4 (Sandyford) – Northbound

Figure 5.2 shows the journey times between M50 J14 (Sandyford) and M11 J15 (Ashford) in the southbound direction. For the southbound direction, the average journey time for the entire route is 21 minutes during the AM peak and 36 minutes during the PM peak which equates to an average speed of 91km/h and 55km/h respectively.

1 Source: Junction 4 M50 to Kilmacanogue – Junction 14 Project Appraisal Plan, prepared by Aecom Roughan & O’Donovan alliance.




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The average journey time in the southbound direction under free flow conditions was 19 minutes for the entire route, which suggests a delay of 2 minutes in the morning and 17 minutes in the evening during the weekdays. A PM journey time of 36 minutes represents an 89% increase on the free flow journey time experienced for the same section of road.

This is causing unstable flow breakdown in key areas on the approach to the M50 motorway. The impact of this high congestion is causing a shockwave effect with queuing extending back onto the M50 and is also having a far wider impact on the surrounding network as the junctions are not designed for this capacity.

Figure 5.2: Journey Times M50 J4 (Sandyford) to M11 J15 (Ashford) – Southbound

It should be stressed that the above journey times represent averages. The degree of saturation on the route means that such journey times can be highly volatile and unpredictable, particularly in the AM and PM peaks. Comparatively minor incidents along this sensitive corridor can compound congestion significantly with consequent increases in journey times. Furthermore, the journey time assessments are based on data acquired two years ago. Further journey time assessments will be undertaken as part of the detailed studies during phase 2.




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6 Traffic Volumes

6.1.1 Traffic Counts & Surveys

Transport Infrastructure Ireland’s (TII) Traffic Count Data website presents information on traffic volume and composition obtained via a network of traffic counters embedded in the road surface. Using this database, Annual Average Daily Traffic (AADT) volumes for the existing N11/M11 within the study area for the year 2018 have been obtained from TII Traffic Monitoring Units (TMU) located on the route and are presented in table 6.1 below. The TMU locations are shown in Figure 6.1.

Table 6.1: Existing N11/M11 AADT volumes

TMU Location AADT (2018) HGV %

M11 (between J15 – J16, Rathnew, Co. Wicklow) 34,235 4.0

N11 (between J8 – J9, Kilmacanoge, Co. Wicklow) 51,704 3.1

M11 (between J5 – J6, Fassaroe, Co. Wicklow) 69,427 2.8

M11 (between J5 – J4, Bray, Co. Dublin) 77,589 2.5

M50 (between J4 – M50 J17, Shankill, Co. Dublin 49,499 3.5

Figure 6.1: TMU Traffic Counter Locations2

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2 Source: Transport Infrastructure Ireland Traffic Count Data Website

(https://www.nratrafficdata.ie/c2/gmapbasic.asp?sgid=ZvyVmXU8jBt9PJE$c7UXt6)




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It is evident that traffic volumes on the N11/M11 have increased significantly in recent years, with AADT levels between junction 5 and junction 6 jumping from 63,352 in 2013 to 69,427 in 2018 – an increase of almost 10%. Further examination of the TMU traffic data located on the M11 between junction 5 and junction 6 illustrates the magnitude and concentration of flows around the AM and PM peaks. Figure 6.2 presents the daily traffic flow profile for the years 2013 and 2018 using averaged daily figures for weekdays (Mon – Fri) only during the month of October.

Figure 6.2: M11 Daily Traffic Flow Profile (2 Way Volumes) – 2013 / 2018

While the increase in overall traffic volume is clearly apparent, it is evident that the maximum traffic volumes experienced during the AM and PM peaks have not risen significantly. Instead, the duration of the AM and PM peak has broadened, with morning and evening congestion lasting longer than before, and inter-peak volumes have risen sharply. Figure 6.3 below presents the 2018 flow profiles individually for the northbound and southbound directions, again using averaged daily figures for weekdays (Mon – Fri) only during the month of October.

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Figure 6.3: M11 Daily Traffic Flow Profile (Each Direction) – 2018

Northbound throughput now exceeds 4,000 vehicles per hour during the AM peak, with mean spot speeds dropping as low as 40km/h south of junction 8 (Kilmacanoge). In the southbound direction, flow breakdown as a result of the capacity, weaving, direct access and geometric deficiencies between junction 6 and junction 8 is most evident to the north of junction 5 and the M11/M50 merge, where spot speeds reduce to approximately 25km/h in the PM peak.

It is noteworthy that the N11/M11 carries significantly lower volumes of Heavy Goods Vehicles (HGVs) by comparison to the other major inter-urban routes, with the daily proportion of HGVs on the M11 between Junction 5 and 6 standing at 2.8% in 2018. This compares with 10.6% on the N7 between Junction 5 and 6 and 8.6% at Maynooth on the M4 in the same year. Notwithstanding, the operational efficiency of the national route should not act as an impediment to growth in freight transport.

6.1.2 Origin – Destination Surveys

The origin and destination of all road trips on the N11/M11 northbound at junction 4 (M11/M50) has been assessed for the AM peak and is presented in Figures 6.4 and 6.5 below. It should be noted that the data is based on the National Transport Authority’s (NTA) 2012 Eastern Regional Model (ERM).

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Figure 6.4: Road Trips Origin on N11/M11 at Junction 4 (2012)




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Figure 6.5: Road Trips Destination on N11/M11 at Junction 4 (2012)

It is apparent from the above figures that the largest share of road trips are destined for the South Dublin region, an area which as part of the DART catchment is well served by rail transport for commuters originating from Bray and Greystones. However, it is also evident that a significant volume of road trips on the N11/M11 originate from the southern extents of the study area (Wicklow Town and environs) for which alternative transport options are very limited.

Further origin – destination surveys will be undertaken based on the revised 2016 ERM during phase 2. This will include more detailed studies within discrete local zones along the corridor and detailed junction capacity assessments.

6.1.3 Future Forecasts

During phase 2 of this project, a multi-modal model for the N11/M11 corridor and its surrounds will be developed for the purpose of assessing the relative transport merits of various transport options, and for subsequent appraisal of the economic and environmental benefits of the preferred set of recommendations. This multi-modal traffic model is capable of accurately testing alternatives which comprise a combination of public transport options with road-based options.

The NTA, in consultation with Wicklow County Council, will define the future forecasts at the outset of the options appraisal based on planning data and these will be fixed for use throughout the project.




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7 Safety Review

7.1 Assessment of Study Area and Existing National Route

The distribution of traffic accidents within the study area covering the period 1996-2013 is presented in figures 7.1 to 7.3 below. The resulting number of casualties for the wider study area and the N11/M11 corridor is listed in table 7.1. This data has been obtained from the Road Safety Authority’s collision statistics database and classifies accidents by severity, i.e. fatal, serious or minor.

Figure 7.1: Distribution of Fatal collisions across N11/M11 Study Area (1996 – 2013)




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Figure 7.2: Distribution of Serious collisions across N11/M11 Study Area (1996 – 2013)




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Figure 7.3: Distribution of Minor collisions across N11/M11 Study Area (1996 – 2013)




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Table 7.1: Collision Data Summary

Year Fatal Seriously Injured Minor Injury Injury of Unknown Severity

Study Area

N11/

M11

Study Area

N11/M11

Study Area

N11/M11

Study Area

N11/M11

1996 7 5 27 8 124 25 8 3

1997 3 2 19 3 137 29 6 2

1998 4 1 13 2 135 19 12 3

1999 3 1 13 0 107 7 12 7

2000 4 1 18 1 126 13 4 0

2001 6 0 12 1 122 25 2 2

2002 2 0 14 3 62 5 4 0

2003 2 2 12 4 112 18 9 2

2004 5 0 10 1 67 16 6 2

2005 3 1 7 2 69 13 8 6

2006 4 1 4 0 60 6 1 0

2007 3 2 11 5 20 4 0 0

2008 0 0 11 2 121 16 1 1

2009 1 1 3 0 129 27 2 0

2010 1 1 6 3 131 24 5 4

2011 0 0 3 0 117 11 3 0

2012 0 0 8 0 143 29 6 1

2013 0 0 8 2 110 22 2 0

Total 48 18 199 37 1892 309 91 33

Of the 18 fatal incidents occurring on the N11/M11 route, 13 of these occurred in the area from junction 4 to junction 8, corresponding to the highest traffic volumes, greatest concentration of junctions and accesses and sub-standard design elements. It is also noteworthy that approximately 20% of all collisions occurring on the N11/M11 route are classified as rear-end type collisions, indicative of the breakdown in levels of service on the route. Furthermore, 3 of the 7 fatalities since 2005 involved a direct interaction with pedestrians.

Congestion arising from traffic volume is further compounded by the erratic and ill-disciplined behaviour it encourages, which in turn increases the likelihood of incidents and accidents. The N11/M11 route exhibits behaviours typical of driver frustration, with motorists making swift lane changes and utilising junction ramps to queue jump. In addition, some drivers divert to ‘rat runs’ adjacent to the mainline, many of which traverse residential areas which are not suitable for large traffic volumes or high speeds, leading to an increased likelihood of collisions between vulnerable road users and vehicular traffic.




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TII have produced collision maps of the national road network which indicate which sections of the network experience collision rates above or below the national average for the particular road type. The collision map covering the period 2014 – 2016 for the existing N11/M11 corridor is presented in figure 7.4 below and indicates a number of sections along the route where rates exceed the national average. The highest collision rates on the route occur on the M11 motorway north of junction 5 (Bray North), coinciding with the heaviest traffic volumes on the corridor. Elsewhere along the route, collision rates fluctuate above and below the national average.

Figure 7.4: N11/M11 Average Collision Rates




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Reductions in the type and severity of collisions can contribute significantly to the overall benefit obtained from an improvement scheme. Table 7.2 sets out the costs of collisions depending on the accident severity, extracted from the TII Project Appraisal Guidelines Unit 6.11 – National Parameters Value Sheet.

Collision Type Value Per Casualty (€)

Fatal 2,310,500

Serious Injury 331,400

Damage Injury 31,100

Damage Only 2,500

Table 7.2: Collision Costs (Factor Costs, 2011 Prices)

As the scheme is currently at concept and feasibility stage, it is not possible to quantify the costs of any future accident savings, as the precise form of the transportation solution has not yet been identified. However, detailed projections of the safety benefits and resultant casualty savings will be analysed and compared for each option during phase 2.

7.2 Recommendations for Improvement to Safety Conditions

The distribution of collisions and incidents on the N11/M11 corridor closely matches the typical profile of the traffic along the route, with a significant spike in frequency during the AM and PM peak periods. This is evidence that a high proportion of incidents can be attributed to the impacts of congestion. It is important to note that capacity enhancement is not the sole means of reducing congestion difficulties – volumes could be eased through demand management measures or by achieving modal shift to public transport and a reduction in car-based commuting. Any solutions which ease congestion on the route are likely to improve safety for all road users.

As discussed in the review of the existing alignment, there are numerous geometric deficiencies along the N11/M11 corridor, resulting in abrupt changes in standard, inconsistency in speed limit and junction type and spacing. These characteristics of the route are not conducive to enabling drivers to predict and comprehend the road ahead and contribute to a hazardous environment. Furthermore, it is important to note that congestion relief will in turn enable increases in operational speeds, which may expose the danger of such geometric deficiencies to a greater degree than the present situation. Improvements in the junction layouts on the N11/M11 route, by bringing the merges and diverges to meet current TII standards, the provision of consistent and comprehensible junction layouts and the provision of adequate forward visibility will contribute to an improvement in safety conditions.

Grade separation of all junctions together with the removal of direct accesses is another potential solution to achieving the safety objectives of the project. The existing proliferation of accesses along the route, including individual residential accesses, is not compatible with the safe operation of a strategic road.




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The closure of sub-standard direct accesses and re-direction of these to segregated service or local roads would improve safety for mainline traffic and affected property owners alike. A consistent provision of grade separation for all access points along the route, with adequate space for weaving manoeuvres, is highly desirable from a safety perspective.

As outlined already, a key problem is that the existing N11/M11 route is the dominant artery connecting the south east to Dublin and as such, serves a multitude of journey types and modes. Security of road users improves once there is a separation of and separate provision for the various types of road users, i.e. strategic traffic, commercial traffic, commuters, public transport, cyclists and pedestrians.

Any of the potential solutions which improve safety along the N11/M11 corridor and wider study area are considered feasible options.




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8 Feasible Transport Solutions

8.1 Possible Options and Alternatives

8.1.1 Overview

The N11/M11 Junction 4 to Junction 14 Improvement Scheme is proposed to resolve the existing transportation issues identified in the previous chapters. The options identified within the feasibility study will be taken forward for more detailed appraisal during phase 2.

8.1.2 Potential Options

Numerous options can be considered as solutions to the transportation issues along the N11/M11 corridor. The public transport solutions recommended in the Transport Strategy for the Greater Dublin Area 2016 – 2035 combined with road-based options form the basis of the feasibility study for the N11/M11 Junction 4 to Junction 14 Improvement Scheme. These combinations may have the potential to relieve the problems outlined above and deliver on the goals, objectives and specific transportation problems identified in the Project Brief.

Potential options are outlined as follows:

• Do Nothing Option: This option assumes that there will be no other investment in the transport network (other than regular maintenance) during the appraisal period.

• Do Minimum Option: This option involves maintaining the existing infrastructure and constructing committed projects.

• Option 1: Implementation of demand management measures to address congestion and improve the efficiency of the N11/M11 corridor and ensure the sufficient capacity is retained for the strategic function of the route. This would be implemented in conjunction with public transport improvements within the corridor study area.

• Option 2: Combination of on-line improvements/interventions to the existing N11/M11 corridor, consisting of junction upgrades to meet current standards, closure of direct accesses onto and from the N11 to improve road safety and demand management measures. This would be implemented in conjunction with public transport improvements within the corridor study area.

• Option 3: Combination of on-line improvements to the existing N11/M11 corridor, consisting of junction upgrades to meet current standards, closure of direct accesses onto and from the N11 to improve road safety and capacity enhancement through provision of additional lanes. This would be implemented in conjunction with public transport improvements within the corridor study area.

• Option 4: Combination of offline N11/M11 routes with improved public transport provisions.




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Note that offline routes may be limited to certain sections of the route only where existing constraints indicate this to be feasible.

Options 1 to 4 are defined as ‘Do Something’ options. All of the Do Something options comprise an element of provision of public transport. However, once further work is carried out to develop a transport model for this scheme, the possibility of an option that solely comprises public transport only i.e. Do-Something Pubic Transport will be developed. This scenario would comprise a full build out of the public transport schemes as recommended in the Transport Strategy for the Greater Dublin Area 2016 – 2035, Bus Connects, plus those schemes listed in other plans and polices and any other viable public transport options that could contribute to the overall transportation solution. Traffic modelling work will be carried out to establish the feasibility of this public transport only option.

In conjunction with public transport improvements, options 1 to 3 would seek to utilise the existing asset as efficiently as possible through a series of incremental interventions aimed at relieving congestion, improving journey times and improving safety for all road users. This would initially focus on the implementation of demand management measures and thereby limit the provision of capacity enhancing infrastructure insofar as possible. It is important to note that the range of demand management measures available for consideration are varied and wide-ranging, but all with the intended purpose of reducing travel demand on the N11/M11, such that it operates without congestion for longer and improves safety and journey time reliability. Demand management polices seek to influence road user behaviour, to encourage individuals to make journeys off peak times, travel by a different mode such as cycling, walking and public transport, or avoid making the trip altogether. To achieve this objective, a range of both fiscal and non-fiscal measures can be implemented which serve either to reduce or divert demand or achieve a combination of both. Examples of fiscal demand management measures include:

• Road user charging – this may be variable, i.e. related to time of day, vehicle class, emissions class etc.

• Parking charges

• Public transport subsidies

• Fuel taxes

Non-fiscal demand management measures may include:

• Access control and restriction (e.g. ramp metering)

• Public transport improvements

• Traffic control measures (e.g. variable speed limits)

• Smarter travel measures (e.g. intelligent transport systems, incident detection)

• Traffic calming

• Road space reduction/travel restrictions




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Option 4 will investigate the feasibility of a road-based alternative to the N11/M11 corridor, however, it is unlikely that a wholly offline alternative will be viable in all locations due the proximity of the existing urban and human environment, topography and environmental constraints. The exact extent and location of these options is not developed at this stage and will be progressed during phase 2.




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9 Cost Estimate

9.1 Feasibility Working Cost

The N11/M11 Junction 4 to Junction 14 Improvement scheme is a complex and highly constrained project. At Phase 1, it is not possible to have sufficient detail on the scale and/or nature of the transportation solution, or the timetable of the project to ultimately be delivered. As such, it is not possible to accurately produce a Feasibility Working Cost (FWC) that could be used as a basis for assigning a scheme budget. Therefore, no FWC is available at Phase 1 of the project.




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10 Conclusions and Recommendations

10.1 Key Findings of Feasibility Report

It is clear from the information examined during the preparation of this Scheme Feasibility Report that there are significant transportation issues along the existing N11/M11 corridor. The existing route and junctions are congested, journey time is variable and unreliable, collision rates exceed national averages, non-motorised users are not effectively accommodated and there are inadequate public transport links to support the commuting demand.

The resolution of the transportation issues along this strategic corridor is compatible with the Government’s objectives in the National, Regional and Local policy documents. It is compatible with Project Ireland 2040, the National Development Plan, the Regional Planning Guidelines, The Wicklow County Development Plan and the Dún Laoghaire – Rathdown County Development Plan. The resolution of these issues is essential to allow the corridor to function as strategic and safe national route, whilst also ensuring that the objectives of the project are satisfied.

The key constraints identified within the feasibility study, such as the proximity of existing urban communities, designated environmental sites and the challenging topography, must not impede the progression of the scheme to phase 2, but rather will impact on and influence the development of a viable and sustainable transport solution for this corridor.

10.2 Conclusions and Recommendations

The transportation issues within the N11/M11 study area are significant and action to resolve them needs to be progressed. Further works need to be undertaken examining the problems in greater detail, identifying solutions and quantifying their merit and benefit.

The existing issues identified will not improve in the future without intervention to address the base problems. Feasible solutions identified in this report need to be further examined and fully appraised during phase 2. These solutions combined with recommendations from the Greater Dublin Area Transport Strategy 2016 – 2035, Bus Connects and other schemes need to be examined further. Transportation options which increase the mode share of cyclists, pedestrians and public transport users need to be examined such that a holistic solution accommodating all transport users is obtained.

The protection and enhancement of existing amenities and quality of life in the study area need to be protected and maintained when considering options and resolutions to the existing transportation issues.

Improving the transportation network to meet all the objectives outlined in the project brief is not at any cost.




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The total financial cost of the proposed project must represent value for money and realise sufficient benefit to justify costs, so that the project is deliverable in an appropriate timescale to prevent the collapse of the existing transport network.

Documents

N11/M11 Junction 4 to Junction 14 Improvement Scheme · Arup has been appointed to provide multi-disciplinary technical consultancy services for the delivery of Phase 1-4 of the TII