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Transport and Strategic Regeneration Welsh Assembly Government M4 Corridor
Enhancement Measures Strategy, Appraisal and Monitoring Black
DRAFT 2 WORKING DOCUMENT
1
Transport and Strategic Regeneration Welsh Assembly Government M4 Corridor Enhancement
Measures Strategy, Appraisal and Monitoring
May 2010
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Ove Arup & Partners Ltd Draft 2 4 May 2010
Contents
Page
1 INTRODUCTION 1
1.1 Background 1
1.2 Purpose of this Report 1
1.3 The Problem 2
1.4 The Need for a Strategy 2
2 STRATEGY DEVELOPMENT 3
2.1 Making Best Use of Existing Capacity 3
2.2 Improving the Resilience of the Network 3
2.3 Improving Public Transport 3
2.4 Conceptual Strategy 4
3 SCHEME APPRAISAL 7
3.1 Strategic Performance Indicators 8
3.2 Scheme Specific Objectives 11
4 IMPLEMENTATION AND MONITORING 17
5 SUMMARY 18
Appendices
Appendix A
Transport Planning Objectives
Appendix B
Problems with the Transport System in South East Wales
Appendix C
Results of Capacity Assessments of Existing M4 (J25a - J29)
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1 INTRODUCTION
1.1 Background
In December 2004, the Minister for Economic Development and Transport reported on the
outcome of his review of transport programmes, which he had undertaken to ensure a good
strategic fit with ‘Wales: A Better Country’ and the ‘Wales Spatial Plan’. One of the
conclusions of the review was that additional capacity was required on the M4 motorway in
south east Wales, in order to reduce congestion, improve resilience and remove an obstacle
to greater prosperity along the whole corridor through to Swansea and West Wales.
In addition to widening the motorway north of Cardiff, the Minister announced proposals to
develop a New M4 south of Newport between Magor and Castleton. At the same time, it
was announced that the existing route could include priority measures for public transport
and multiple occupancy vehicles. This resulted in investigations being undertaken as part of
the New M4 Project.
A WelTAG Stage 1 appraisal1 was undertaken as part of the New M4 Project. This has
shown that an option of corridor enhancement measures (CEMs) would make a contribution
to most of the transport planning objectives (TPOs) that had been drawn up at the WelTAG
Planning Stage. The TPOs are included for reference at Appendix A.
The National Transport Plan (NTP), which was published following consultation in March
2010, sets out the detail of how the Welsh Assembly Government will deliver the Wales
Transport Strategy ‘One Wales: Connecting the Nation’ over the next five years. This Plan
recognises that “for a long time there have been concerns about the section of motorway
around Newport, which falls well short of modern design standards. These centre on peak-
time capacity, safety and the resilience of the local network”. As part of the NTP, the
Assembly will:
“Deliver a package of measures designed to improve the efficiency of the M4 in south-east
Wales, including public transport enhancements, making the best possible use of the
motorway and improving the resilience of the network.”
In order to achieve the above, Arup was asked to investigate potential schemes to improve
the operation of the existing M4 around Newport, as part of the New M4 Project. Such
schemes are to be implemented as interim measures to:
• make best use of existing infrastructure and capacity;
• improve the resilience of the network; and
• improve public transport.
A strategy was thus required to embrace the above three themes and to ensure that any
measures put forward would contribute effectively to one or more of these themes.
1.2 Purpose of this Report
The purpose of this report is to outline the process of strategy development and the
conceptual strategy that has emerged from this process. It also describes how options for
individual measures/schemes are to be appraised by drawing up a set of Strategic
Performance Indicators as well as Scheme Specific Objectives. This report also outlines a
suggested methodology for monitoring progress with individual measures as well as post
implementation effectiveness.
1 New M4 Project, Magor to Castleton, WelTAG Appraisal Report Stage 1, Arup, January 2010
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1.3 The Problem
The M4 motorway in south east Wales is running close to capacity with traffic volumes
continuing to grow, causing increasing congestion. The motorway around Newport is
congested during weekday peak periods, resulting in slow journey times and stop start
conditions, with frequent incidents and accidents causing delay. The motorway does not
conform to current standards and has closely spaced junctions with sub-standard slip road
visibility. Heavy congestion occurs along the two lane stretch either side of the Brynglas
Tunnels. As traffic volumes increase over time, the situation will worsen, accidents and
incidents are likely to increase with journey times becoming increasingly unreliable,
hindering economic growth.
Recent improvement measures include widening the M4 from dual 2 lanes to dual 3 lanes
between Castleton (Junction 29) and Coryton (Junction 32) as well as ‘making better use’
work to improve traffic flow on the motorway. However, additional measures are required in
order to address safety and capacity issues on the motorway and the resilience of the
strategic road network around Newport.
A WelTAG Planning Stage Workshop in October 2007 identified the transport problems.
These are listed for reference at Appendix B.
1.4 The Need for a Strategy
There is a need to safeguard the capacity of the motorway for use by longer distance traffic
and especially freight vehicles. Local trips should be discouraged from using the motorway
around Newport. Improved access to the Newport Southern Distributor Road from the
motorway could provide an attractive expressway to those areas of Newport that lie to the
south of the motorway.
There is also a need to improve the resilience of the main road network around Newport.
This means making the network more capable of coping with events, incidents, accidents
and maintenance works as well as high traffic demand.
Improvement to public transport would increase travel choice.
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2 STRATEGY DEVELOPMENT
The adoption of a strategy for the M4 transport corridor through south east Wales that would
make better use of existing infrastructure and services would be likely to result in efficiency
gains. In particular, the aim is to improve operating conditions on the motorway around
Newport. A central plank of this strategy, therefore, will be to safeguard the capacity of the
motorway for use by longer distance/strategic traffic and especially freight vehicles. This
might involve closure of those junctions that link non-strategic routes to the motorway.
Conversely, those junctions that link strategic routes to the motorway may benefit from
improvement.
The following three themes have been adopted as a basis for the overall strategy:
• Making the best possible use of the existing capacity;
• Improving the resilience of the network; and
• Improving public transport.
2.1 Making Best Use of Existing Capacity
The Southern Distributor Road (SDR), which skirts the built-up area of Newport to the south,
distributes local traffic. It has frequent junctions along its length which, being roundabouts,
tend to disrupt through movements. As a consequence, the SDR is currently seldom the
route of choice for other than those drivers who have destinations immediately off it. When
there are significant delays on the motorway around Newport, the SDR currently provides
an alternative route, albeit of limited attractiveness.
If capacity on the motorway around Newport is to be safeguarded for through movements,
traffic accessing Newport needs to be encouraged to use the SDR. To achieve this,
consideration may need to be given to any sources of traffic delay along the route of the
SDR. These are likely to include Tredegar Park interchange (J28) and the Pont Ebbw
roundabout. Further consideration may also be given to the potential extension of the SDR
to the east (by upgrade to the Steelworks Access Road – Magor to Queensway Meadows).
The aim would be to create an expressway route into Newport from both east and west with
access from the south of the city.
2.2 Improving the Resilience of the Network
Within the existing motorway landtake around Newport, there may be scope to undertake
incremental widening and modification to existing junctions to maximise the roadspace
available to through traffic on the motorway. Consideration should also be given to the
development of an incident/event management plan that would maximise the capacity
available on alternative east/west routes temporarily should the need arise. This may
influence the form of junctions to be provided along the upgraded Steelworks Access Road
and SDR.
2.3 Improving Public Transport
During peak travel periods, there is a predominance of car driver commuters, often resulting
in single occupancy car use. Therefore, any measures that increase vehicle occupancy
would be likely to impact positively on operating conditions on the motorway during peak
periods. Increase in travel choice is necessary to create the potential for modal shift and
reduced dependence on driving a car for the complete journey. The provision of Park and
Share and Park and Ride facilities in strategic locations that give car drivers genuine choice
may impact positively. However, there is unlikely to be a sea change in travel behaviour in
the Newport area in the short to medium term. Thus, whilst investment in public transport
would be beneficial in increasing travel choice and accessibility, it is unlikely to have a
significant impact on congestion on the M4, at least in the short to medium term.
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2.4 Conceptual Strategy
The premise upon which the current corridor enhancement strategy has been based is that
available capacity on the motorway around Newport is to be safeguarded for longer distance
and strategic movements of people and goods. Furthermore, where it is practical and
politically, socially, environmentally and economically acceptable, the transport capacity of
the east/west corridor around Newport should be increased.
The physical constraints imposed by the River Usk Viaduct and the Brynglas Tunnels on the
section of motorway between Junctions 25a and 26 make on-line widening of this section of
the motorway impractical. Therefore, it has to be accepted that this section of the motorway
has a finite capacity, which must be seen as a vulnerable link in the strategic road network.
Whilst additional capacity could be achieved on other sections of the motorway around
Newport, the value of such measures must be weighed against the restriction in capacity on
the Junction 25a – 26 link. The concept must, therefore, be to manage/regulate demand for
use of the Junction 25a – 26 link, at least, as an interim solution. This might be achieved by
restricting access locally to the motorway, by providing acceptable alternative routes and by
the introduction of Managed Motorway principles including variable speed limits.
Previous work undertaken by Arup2 has highlighted that there are a number of measures
that have the potential to improve the efficiency of operation of the M4 transport corridor
through south east Wales. Many of the measures identified would complement each other,
whilst others may be classed as discrete initiatives.
Intelligent Transport Systems (ITS) may be called upon to support day to day management
of traffic movements on the motorway and the strategic transport networks and also to
assist with incident and event management.
Measures to increase driver choice aimed at encouraging mode shift away from private
vehicle motorway travel may also be deployed. These might include improvement to public
transport and provision of Park and Ride facilities.
The previous work has shown that there is scope to achieve incremental improvements to
operating conditions within the M4 transport corridor and the measures that have hitherto
been considered are aimed at efficiency improvements within the corridor. However, since
the available capacity on the motorway around Newport is limited and, at times, currently
causing restraint, there will be a limit to the relief that may be obtained from corridor
enhancement.
Measures such as the removal of the east facing slip roads at Junction 26 (impact of around
4% reduction in traffic flows through Brynglas Tunnels) and at-grade upgrading of junctions
along the Southern Distributor route (impact of around 3% reduction in motorway traffic
flows across the River Usk) would be likely to result in the greatest reduction in traffic
volumes using the Brynglas Tunnels. This suggests that around 7–8% would be a realistic
initial target for reduction to traffic volumes through Brynglas Tunnels. It is possible that the
introduction of further measures, including junction closures or restriction of access to/from
the motorway at selected junctions around Newport might lead to further reduction in
motorway flows. Conversely, on-line widening / hard shoulder running would encourage
motorway use. Research to date has shown that an upper limit of traffic flow reduction
through Brynglas Tunnels would be reached at around 11% and that an extensive package
of measures would be required to achieve this.3
2 New M4 Project Magor to Castleton, Corridor Efficiency Improvements Report WelTAG Stage 1, Arup, October 2009
3 M4 Corridor Enhancement Measures, Traffic Modelling and Road Network Impacts (Work in Progress), Arup, December 2009
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Other measures such as the provision of the Steelworks Access Road (SAR) would improve
access to the Newport Eastern Expansion Area. However, during normal operations, in
isolation the SAR is unlikely to impact upon the use of the motorway around Newport.
Nevertheless, when coupled with upgrading of the SDR and modification to Junction 28,
limited reduction in traffic flows on the motorway around Newport may occur, especially
during periods of congestion. During incidents/maintenance works on the motorway, the
SAR, SDR upgrading and J28 improvements would provide increased network resilience.
Traffic forecasting using a SATURN traffic model has indicated that, unless travel behaviour
were to change significantly, even with corridor enhancement measures in place, traffic
congestion and capacity problems could be expected to occur during weekday peak travel
times with increasing frequency some time during the period 2018 to 2024 on the
approaches to Brynglas Tunnels (see Appendix C).
The incremental development of an expressway route into Newport from the south would:
• increase east/west highway capacity;
• strengthen network resilience by offering an alternative traffic route to the motorway;
and
• provide access to new development including housing, employment, retail and park and
ride facilities.
Having regard to the aims stated above, a strategy for corridor enhancement for the
motorway around Newport is illustrated conceptually in Figure 2.1.
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Figure 2.1: Conceptual Strategy for Corridor Enhancement Measures
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3 SCHEME APPRAISAL
The Transport Planning Objectives (TPOs) (see Appendix A) developed through the
WelTAG process should form the basis on which any Corridor Enhancement Measures
(CEMs) are initially evaluated. However, to help focus on options that address the problems
on the existing M4 and deliver the intended benefits, a further set of Strategic Performance
Indicators have been developed.
The Strategic Performance Indicators aim to reinforce the proposed Newport Expressway
principle. Namely, the over-arching strategy is to safeguard the capacity of the motorway
around Newport for use by longer distance/strategic traffic and especially freight vehicles.
This may involve closure of those junctions that link non-strategic routes to the motorway.
Conversely, those junctions that link strategic routes to the motorway may need to be
improved. By upgrading the road links around Newport to the south that connect to these
junctions an Expressway will be created to the south of Newport. This will provide an
alternative means of access to the city, which will increase network resilience.
The TPOs and Strategic Performance Indicators should be used in tandem to help arrive at
an effective set of CEMs.
For each CEM, there may be more than one option. In order to choose between options,
Scheme Specific Objectives (SSOs) have been established. The appraisal process thus
comprises of two stages, namely:
• Strategic stage, at which proposed measures are either included or discarded,
depending on how effectively they perform against the TPOs (by appraisal against the
Strategic Performance Indicators). This appraisal may be qualitative or quantitative;
and
• Specific stage, at which schemes/options for individual measures are tested against
objectives set, bearing in mind site specific conditions and opportunities.
This appraisal process is illustrated in Figure 3.1.
Figure 3.1: Appraisal Process for Corridor Enhancement Measures
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3.1 Strategic Performance Indicators
Consideration of the TPOs and the proposed strategy for corridor enhancement has
enabled a set of Strategic Performance Indicators to be drawn up. The purpose of these
indicators is to identify those TPOs that might be met, in part or whole, by individual CEMs.
This facilitates the appraisal of the relative performance of individual measures and assists
in developing an effective package of measures in order to meet the TPOs.
The Strategic Performance Indicators developed for this purpose are as follows:
1. Encourages use of the SDR by traffic with an Origin or Destination in Newport
2. Improves access/egress between the M4 and Newport Expressway to the west (J28),
east (J23a) and from J24
3. Encourages the use of the M4 between J23a and J29 by through traffic via reduced
journey times and improved reliability
4. Discourages the use of the motorway around Newport for local/short distance trips
5. Minimises adverse environmental impacts
6. Encourages increased vehicle occupancy
7. Improves public transport services/infrastructure
8. Improves driver information and route choice
9. Improves network operating conditions
10. Provides a level of service compatible with demand
11. Increases size of workforce within 30 minute catchment
12. Improves access to development areas (housing etc)
13. Improves access to public services
14. Reduces risk of transport accidents
15. Increases resilience of transport network
16. Improves journey experience of transport users
In addition to the above indicators that may be related to specific TPOs, there is a further
indicator that, whilst not being directly related to any specific TPO, is a fundamental
requirement in order for any measure to go forward. This indicator is that any measure
being considered must meet affordability and deliverability constraints. This could be now
or in the future, so that some measures may need to be delivered during the later stages of
a phased implementation programme. Conversely, some measures may be deemed to
provide “quick wins” with immediate benefits resulting from modest investment and/or
minimal disruption.
The relationship between the Strategic Performance Indicators and the Transport Planning
Objectives is illustrated in Figure 3.2.
The CEMs previously brought forward have been appraised against the Strategic
Performance Indicators. The scoring is based on a -3 to 3 scale where:
3 = large positive 2 = moderate positive
1 = slight positive 0 = neutral -1 = slight negative -2 = moderate negative -3 = large negative
A summary of this strategic stage appraisal is provided in Table 3.1.
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Figure 3.2: Relationship between Strategic Performance Indicators and TPOs
Strategic Performance Indicators Transport Planning Objectives (see below*)
1 2 3 4 5 6 7 8 9 10 11 12
1. Encourages use of the SDR by traffic with an Origin or Destination in Newport � �
2. Improves access/egress between the M4 and Newport Expressway to the west (J28), east (J23a) and from J24 � � �
3. Encourages the use of the M4 between J23a and J29 by through traffic via reduced journey times and improved reliability
� � �
4. Discourages the use of the motorway around Newport for local/short distance trips �
5. Minimises adverse environmental impacts � � � �
6. Encourages increased vehicle occupancy �
7. Improves public transport services/infrastructure �
8. Improves driver information and route choice �
9. Improves network operating conditions � � � � � �
10. Provides a level of service compatible with demand �
11. Increases size of workforce within 30 minute catchment � � �
12. Improves access to development areas (housing etc) �
13. Improves access to public services �
14. Reduces risk of transport accidents � � �
15. Increases resilience of transport network � �
16. Improves journey experience of transport users �
Meets affordability and deliverability constraints
*Transport Planning Objectives:
TPO1 To improve connectivity within Wales and Internationally along the east-west strategic corridor in South Wales.
TPO5 To increase travel choice for all. TPO9 To improve air quality around Newport.
TPO2 To discourage the use of the motorway around Newport as a local distributor road.
TPO6 To improve accessibility to key centres and services. TPO10 To reduce the number of people subjected to high noise levels.
TPO3 To make better use of the existing highway asset.
TPO7 To improve the transport network management around Newport.
TPO11 To reduce greenhouse gas emissions per vehicle and/or person kilometre.
TPO4 To increase journey time reliability. TPO8 To improve travel safety on the transport network around Newport.
TPO12 To enhance the traveller experience through the gateway to South Wales.
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Table 3.1: CEM Scores against Strategic Performance Indicators
Measure Unweighted Score
Transport Planning Objectives Impacted Upon
2, 3 1, 3, 7 1, 4, 12
2 9, 10, 11, 12
5 6 7 1, 7, 8, 9, 11, 12
12 3, 5, 6 6 6 4, 8, 12
3, 7 12
Strategic Performance Indicators
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1. Incremental widening between Junctions 29 and 28 +7 -1 0 2 -1 0 -1 0 0 2 2 1 0 0 1 1 1
2. Hard shoulder running/incremental widening between Junctions 28 and 27
+5 -2 0 2 -2 0 -1 0 0 2 2 1 0 0 1 1 1
3. Incremental widening between Junctions 27 and 26 +5 -2 0 2 -2 0 -1 0 0 2 2 1 0 0 1 1 1
4. Increased length of westbound merge at Junction 29A +9 0 0 0 0 0 0 0 0 3 2 1 0 0 2 0 1
5. At-grade improvement to the A48 Southern Distributor Road (SDR)
+19 3 2 1 0 0 0 0 2 2 2 1 2 1 0 2 1
6. Upgrade to Steelworks Access Road +18 2 2 1 0 0 0 1 2 2 2 1 2 0 0 2 1
7. Improvement to B4245 junction west of Magor +12 1 2 0 1 0 0 0 0 2 2 1 1 0 1 0 1
8. Improvement to Junction 28 with associated works at Bassaleg and Pont Ebbw Roundabouts
+16 1 2 1 1 -1 0 0 0 3 2 2 2 0 1 1 1
9. Closure of Junction 27 +9 0 0 2 2 0 1 1 -1 1 0 1 0 1 2 -1 0
10. Removal of east facing slip roads and widening of west facing slip roads at Junction 26
+12 0 0 1 2 1 2 2 -1 1 1 1 0 1 1 -1 1
11. Removal of east facing slip roads at Junction 25 +6 1 0 1 2 0 1 1 -1 1 0 0 0 0 1 -1 0
12. Lane restriction with enforcement using ITS +6 0 0 1 0 0 0 0 0 1 0 0 0 0 3 1 0
13. Improvement to incident and queue detection using ITS +8 1 1 0 0 0 0 0 2 2 0 0 0 0 1 1 0
14. Traffic monitoring for incident management using ITS +7 0 0 0 0 0 0 0 3 2 0 0 0 0 1 1 0
15. Update to controlled motorway +6 0 0 1 0 1 0 0 0 2 0 0 0 0 1 1 0
16. Improved driver information +8 1 0 0 0 0 0 0 3 1 0 0 0 0 1 1 1
17. Park and Ride at Severn Tunnel Junction +9 0 0 1 0 0 1 2 0 1 0 1 1 0 0 1 1
18. Park and Ride at Magor +4 0 0 0 0 0 1 2 0 1 0 0 0 0 0 0 0
19. Park and Ride at Llanwern +9 1 0 0 0 0 1 2 0 1 0 0 1 1 0 1 1
20. Park and Ride at Rogerstone +8 0 0 0 1 0 1 2 0 1 0 1 0 1 0 0 1
21. Park and Ride at Coedkernew +7 0 0 0 0 -1 1 2 0 1 0 1 1 1 0 0 1
22. Reduction in traffic noise +2 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0
23. East/West Bus Rapid Transit +19 0 0 0 1 1 2 2 0 2 1 2 2 2 0 2 2
24. Re-branding of driver experience on motorway +5 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 3
25. Park and Ride/Parkway railway station at St Mellons +11 0 0 0 0 0 2 2 0 1 1 1 1 1 0 1 1
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3.2 Scheme Specific Objectives
As a result of the investigations previously carried out, possible measures for further
investigation are summarised in Figure 3.3.
Making the Best
Possible Use of the
Existing Capacity
Improving the Resilience
of the Network
Improving Public
Transport
• Upgrade Steelworks
Access Road (Magor
to Queensway
Meadows)
• At-grade improvements to the
A48 Southern
Distributor Road
(SDR)
• Improvement to Junction 28 (Tredegar
Park)
• Update to Controlled
Motorway between
Junctions 28
(Tredegar Park) and
24 (Coldra)
• Improvement to B4245 junction west of
Magor
• Widening between
Junctions 27 (High
Cross) and 26 (Malpas)
• Widening between
Junctions 29 (Castleton)
and 28 (Tredegar Park)
• Hard shoulder
running/widening
between Junctions 28
(Tredegar Park) and 27
(High Cross)
• Improvements to
A48(M) Junction 29A
(St Mellons)
• Modification to Junction
27 (High Cross)
• Modification to Junction
26 (Malpas)
• Modification to Junction
25 (Caerleon)
• Park & Ride/Share
Option East of Cardiff
• Park & Ride/Share
Option at Coedkernew
• Park & Ride/Share
Option at Llanwern
• Park and Ride/Share
Option at Severn
Tunnel Junction
Figure 3.3: Possible Measures for Further Investigation
As a result of the strategic stage appraisal, selected CEMs are currently being developed.
For each measure, broad options are being considered and a scheme or schemes are
emerging. To assist in this process of comparing options and developing schemes, a set of
Scheme Specific Objectives (SSOs) has been drawn up for each measure.
The measures currently being investigated further are as follows:
• modification to Junction 26;
• improvement to Junction 28 with associated works at Bassaleg and Pont Ebbw
roundabouts;
• upgrade to Steelworks Access Road (SAR);
• incremental at-grade improvements to the A48 Southern Distributor Road (SDR);
• improvement to B4245 junction west of Magor;
• improvement to Junction 29A; and
• strategic Park and Ride.
Proposed SSOs for options/schemes for the above measures are outline below.
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Modification to Junction 26
The presence of east facing slip roads onto and off the motorway at Junction 26 encourages
traffic with an origin or destination in Newport or Cwmbran to use Brynglas Tunnels. There
are alternative routes between Newport and Cwmbran and the motorway. The restriction of
use of the east facing slip roads at Junction 26 to emergency and maintenance vehicles
only would be likely to result in a reduction in traffic passing through Brynglas Tunnels. It
would also reduce turning movements at the junction and would enable bus priority
measures to be introduced at the junction and along A4051 Malpas Road.
Bearing in mind the above, the proposed SSOs for modification to Junction 26 are as
follows:
• To reduce traffic flows through Brynglas Tunnels;
• To provide directions to local traffic wishing to access the motorway;
• To improve operating conditions for all traffic using the junction;
• To minimise disruption to road users during implementation;
• To improve bus journey times and reliability through the junction;
• To enhance road safety at the junction; and
• To avoid adverse impact on the environment.
Improvement to Junction 28 with Associated Works at Bassaleg and Pont Ebbw
Roundabouts
Junction 28 is a key node on the local highway network in terms of access to the motorway
and to commuter routes. It provides access to west Newport, which is a major employment
area and hence a generator of peak period traffic. It also provides access to the motorway
and the SDR from the western valleys. During peak travel times, the approaches to the
interchange are congested with delays to all who use this junction. The provision of
additional capacity at this important interchange will improve network efficiency. However,
Bassaleg Roundabout to the north is linked to Junction 28 via the A467 Forge Road, which
is heavily trafficked at peak travel times. Further efficiency gains would thus be likely to
result from improved operations at Bassaleg Roundabout. Similarly, Pont Ebbw
Roundabout to the east is linked to Junction 28 via the A48 SDR. This junction provides
access to employment sites and is currently a source of traffic congestion during peak travel
times. This impacts upon through traffic using the SDR and is a source of delays. The
reduction in delays to SDR through traffic at Pont Ebbw Roundabout would improve the
efficiency of the distributor road.
In view of the impact on the local roads of the release of suppressed demand through the
provision of additional capacity at Junction 28, there would be merit in consideration of
appropriate modification to Bassaleg Roundabout and Pont Ebbw Roundabout in tandem
with improvement to Junction 28.
The proposed Scheme Specific Objectives for the improvement of Junction 28 are as
follows:
• To increase throughput at the junction;
• To increase use of the SDR;
• To reduce delays to movements between M4 (west)/A48 (west)/A467 and the SDR;
• To minimise disruption to road users during implementation;
• To enhance road safety at the junction; and
• To avoid adverse impact on the environment.
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Upgrade to Steelworks Access Road (SAR)
The provision of a public highway running east/west through the Llanwern Steelworks site
would link access to Junction 23A at Magor with the SDR at Queensway Meadows. This
route would be likely to be the preferred route to the Newport Eastern Expansion Area from
the east. Depending upon the standard of road provided, this route could offer an alternative
to the motorway as a means of access to Newport from the east. This would increase
east/west highway capacity. However, the effectiveness of this as an east/west route will be
dependent upon level of service provided. This will be influenced by the type and frequency
of junctions. For instance, the inclusion of roundabouts might reduce the attractiveness of
the route for through traffic.
The Scheme Specific Objectives for the upgrade to the SAR are as follows:
• To provide additional east/west highway capacity;
• To provide an alternative route into Newport from the east;
• To improve journey times between Junction 23A and south Newport;
• To provide a diversionary route during occurrence of accidents, incidents or
maintenance works on the motorway around Newport;
• To improve access to the Newport Eastern Expansion Area; and
• To avoid adverse impact on the environment.
Incremental Improvement to the Southern Distributor Road (SDR)
The motorway is generally seen as the most attractive route into Newport from the east and
west. Observation of existing traffic movements at the motorway junctions around Newport
shows strong movements onto the motorway (west) from the A449 at Junction 24, strong
movements onto and off the motorway (east) at Junction 25A, strong movements onto and
off the motorway (west) at Junction 26 and strong movements onto and off the motorway at
Junction 28. These movements are illustrated in Figure 3.4.
In order to increase the attractiveness of the SDR as an east/west through route and/or as a
means of access into Newport, the level of service provided requires to be raised. This
would require, where possible, unimpeded through movement. To achieve this, all sources
of delay to main line traffic on the SDR need to be identified and minimised. This is likely to
require the re-modelling of some existing junctions. The approach to be adopted may be
incremental, such that those junctions where delays are greatest may be tackled as a matter
of priority. Where conditions at existing junctions are unlikely to impact upon drivers’ route
choice, no action would be required.
The proposed Scheme Specific Objectives for the incremental improvement to the SDR are
as follows:
• To reduce the average journey time end to end on the SDR;
• To improve journey time reliability;
• To eradicate significant sources of delay to main line traffic;
• To provide direction via the SDR for traffic with an origin or destination in Newport;
• To provide additional capacity for east/west movements around Newport; and
• To avoid adverse impact on the environment.
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Figure 3.4: 2005 AM Peak Hour Traffic Movements at Motorway Junctions 24 – 28 Key:
Peak Hour Flow (vehicles per hour)
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Improvement to B4245 Junction West of Magor
The junction between the B4245 and the steelworks access road to the west of Magor
currently results in traffic queuing back into Magor during the AM peak period. Residents of
Magor have voiced their concerns about this situation. Increased use of the access road
would exacerbate the situation. As part of the corridor enhancement package, potential to
improve the situation and to achieve network efficiency improvements is under investigation.
The proposed Scheme Specific Objectives are as follows:
• To facilitate access to the motorway at Junction 23a;
• To provide direction via the SAR for traffic with an origin or destination in Newport;
• To minimise delays to traffic using the B4245;
• To enhance road safety at the junction; and
• To avoid adverse impact on the environment.
Improvement to Junction 29A
The A48(M) terminates immediately to the east of the westbound merge from the A48 at
Junction 29A. The existing junction is a taper merge, the dimensions of which are sub-
standard compared with the requirements of current guidance (TD 22/06). In practice, traffic
flows inbound to Cardiff on the main carriageway are disrupted during peak travel times by
merging vehicles from the minor road (the A48) joining the inside lane without sufficient
distance for speeds to adjust and efficient merge operations to occur.
The proposed Scheme Specific Objectives for improvement to Junction 29A are as follows:
• To provide a layout that conforms to current design standards;
• To avoid the need to acquire land beyond the existing highway boundary;
• To enhance road safety at the junction; and
• To avoid adverse impact on the environment.
Strategic Park and Ride
The National Transport Plan4 states that the Welsh Assembly Government will “create a
series of strategic modal interchanges where people can park and ride or park and share,
by 2014.”
The M4 corridor would appear to be a candidate for the location of strategic modal
interchange. However, the impact that public transport has in limiting demand for motorway
capacity around Newport is currently small and previous studies5 have indicated that the
potential to reduce future demand for private transport use of the motorway is likely to be
limited. Nevertheless, the provision of Park and Ride facilities and improvement in service
levels of local public transport would have the potential to increase accessibility and travel
choice.
A number of candidate sites for strategic Park and Ride have previously been identified from
a combination of previous studies, policy documents and inspection of arising opportunities.6
The proposed Scheme Specific Objectives for option development for strategic Park and
Ride are as follows:
• To identify a site or sites with high potential to achieve significant patronage to impact
positively on congestion and sustainable travel along the M4 corridor;
4 National Transport Plan, Welsh Assembly Government, March 2010
5 New M4 Project Magor to Castleton – Assessment of Rail Measures in CAF Hybrid 2, Final Report, Arup, March 2008
6 Strategic Park and Ride, Technical Note (Draft), Arup, March 2010
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• To maximise access to interchange between transport modes at strategic locations
along the M4 corridor;
• To provide information on travel choice, using ITS and other methods, and to provide
clear direction to Park and Ride and Park and Share facilities;
• To provide attractive, user friendly parking and transfer facilities to ensure sufficient
capacity to accommodate likely demand;
• To offer a good level of service (including tariff structure, opening hours, security,
frequency of transfer etc) so as to attract patronage; and
• To avoid adverse impact on the environment.
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4 IMPLEMENTATION AND MONITORING
As has been referred to previously, a strength of the corridor enhancement approach is that
measures can be introduced in a phased manner. This enables flexibility so that
implementation programmes can be developed based on likely available funding. There is
also the opportunity to gain “quick wins”, where measures can be introduced in a short
timescale and can deliver immediate, tangible benefits.
Where land acquisition is necessary or statutory processes need to be followed, timescales
to implementation may be longer, or even indeterminate at the outset. Such considerations
must be taken into account in developing implementation programmes.
It will be important to monitor progress with implementation and the effect that individual
measures have as they are introduced. This monitoring process is particularly important in
this case, as the impact of individual measures may influence the implementation
programme of other measures.
To assist the monitoring process, when designing schemes, the expected outcomes as a
result of a measure should be clearly identified. When implemented, the degree to which a
measure achieves the outcomes expected will be testament to the effectiveness of the
measure in practice. Some measures may exceed expectations, whilst others may be less
effective. Either way, the knowledge of the effectiveness of performance will be useful
information to the Assembly when considering other situations.
It is recommended that an M4 CEM Monitoring Review Panel be established. This might
include representatives of the main stakeholders. Each of the involved parties would be
expected to take ownership of the proposed programme and thus to work positively towards
its successful delivery. The approach to monitoring should be “open book” to the Review
Panel, if the process is to be fully effective.
The Review Panel should meet on a six monthly basis to review progress during the early
years. It is possible that, as a result of changing circumstances, programmes may need to
be accelerated or re-scheduled and the input of the Review Panel would provide valuable
feedback to aid political, financial or technical decision-making.
Monitoring criteria7 put forward for the National Transport Plan could be used directly to
monitor the effectiveness of CEMs. These include:
• % modal share;
• Greenhouse gas emissions;
• % use of sustainable resources during construction;
• Emissions of air pollutants, number of pollution incidents, number of AQMAs;
• Accessibility to health, education, employment, retail, key settlements, visitor attractions;
• Travel time variance;
• Accidents; and
• User satisfaction.
7 National Transport Plan: WelTAG Assessment, AECOM, February 2010
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5 SUMMARY
Arup has developed a strategy for the M4 transport corridor through south east Wales which
aims to make best use of existing capacity, improve the resilience of the network and
increase travel options. A number of Corridor Enhancement Measures (CEMs) have been
considered and an appraisal process has been developed. Each measure under
consideration has been scored against an identified set of Strategic Performance Indicators
(SPIs). These indicators have been cross-referenced against the Transport Planning
Objectives (TPOs), which were established at the WelTAG Planning Stage. The appraisal
summary table (see Table 3.1) gives an indication of the relative performance of individual
measures and, overall, indicates that a package of measures will, to a degree, address each
of the TPOs.
Based on a seven point scale (-3 to +3), each measure has been scored against 16 SPIs,
which has resulted in an aggregate unweighted score for each measure. The list of
measures in score order is shown in Table 5.1.
It is recommended that the Welsh Assembly Government give consideration to the
unweighted scores of individual measures in order to identify priorities for implementation. It
should, however, be noted that the scores quoted make no allowance for political,
economic, social or environmental weightings.
On points of detail in respect of Table 5.1, the following should be noted:
• East/West Bus Rapid Transit forms part of a citywide transport strategy for Newport and
is included in the Unitary Development Plan8 for the city; and
• Park and Ride/Parkway railway station at St Mellons is a development proposal which is
currently being promoted by a private development company. This proposal would
need the support of the rail industry. The affordability and deliverability of this proposal
will need to be established.
A number of measures are currently being investigated further and a set of Scheme Specific
Objectives (SSOs) has been drawn up for each measure being investigated. For each
measure the SSOs form the basis for appraisal of scheme options.
Finally, recommendations are made regarding the establishment of an M4 CEM Monitoring
Review Panel to assist the process of monitoring implementation of measures. It is also
suggested that the monitoring criteria put forward for the National Transport Plan could be
used to monitor the effectiveness of CEMs.
8 Newport Unitary Development Plan 1996 – 2011, Adopted, Newport City Council 2006
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Table 5.1: CEMs in Strategic Appraisal Stage Unweighted Score Order
Measure Unweighted Score Against SPIs
At-grade improvement to the A48 Southern Distributor Road (SDR) +19
East/West Bus Rapid Transit* +19
Upgrade to Steelworks Access Road +18
Improvement to Junction 28 with associated works at Bassaleg and Pont Ebbw Roundabouts
+16
Removal of east facing slip roads and widening of west facing slip roads at Junction 26
+12
Improvement to B4245 junction west of Magor +12
Park and Ride/Parkway railway station at St Mellons** +11
Increased length of westbound merge at Junction 29A +9
Park and Ride at Severn Tunnel Junction +9
Park and Ride at Llanwern +9
Closure of Junction 27 +9
Improvement to incident and queue detection using ITS +8
Improved driver information +8
Park and Ride at Rogerstone +8
Incremental widening between Junctions 29 and 28 +7
Traffic monitoring for incident management using ITS +7
Park and Ride at Coedkernew +7
Removal of east facing slip roads at Junction 25 +6
Lane restriction with enforcement using ITS +6
Update to controlled motorway +6
Hard shoulder running/incremental widening between Junctions 28 and 27 +5
Incremental widening between Junctions 27 and 26 +5
Re-branding of driver experience on motorway +5
Park and Ride at Magor +4
Reduction in traffic noise +2
* Included in Newport Unitary Development Plan 1996 – 2011
** Private sector development proposal
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Appendix A
Transport Planning Objectives
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A1 Transport Planning Objectives
The TPOs shown in Table A aim to provide a framework within which to test the relative
effectiveness of a series of possible measures that follow themes, such as:
• Public transport;
• Increasing the capacity on the motorway;
• Improving network resilience and network choice; and
• Environmental improvement/mitigation.
Table A: Transport Planning Objectives for Improving Corridor Efficiency, April 2009
Objectives Definition
TPO 1 To improve connectivity within Wales and Internationally along the east-west strategic corridor in South Wales.
TPO 2 To discourage the use of the motorway around Newport as a local distributor road.
TPO 3 To make better use of the existing highway asset.
TPO 4 To increase journey time reliability.
TPO 5 To increase travel choice for all.
TPO 6 To improve accessibility to key centres and services.
TPO 7 To improve the transport network management around Newport.
TPO 8 To improve travel safety on the transport network around Newport.
TPO 9 To improve air quality around Newport.
TPO 10 To reduce the number of people subjected to high noise levels.
TPO 11 To reduce greenhouse gas emissions per vehicle and/or person kilometre.
TPO 12 To enhance the traveller experience through the gateway to South Wales.
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27
Appendix B
Problems with the Transport System in South East Wales
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B1 Problems with the Transport System in South East
Wales
Problems with the Transport System in South East Wales
Problems Definition
P1 There is a lack of resilience* in the road network around Newport.
P2 There is a mismatch between demand and available capacity on the motorway
around Newport.
P3 Problem P1 and P2 will worsen over time.
P4 The existing transport system acts as a constraint to economic growth.
P5 There will be capacity restrictions during essential major maintenance on the existing M4 within the next 5-10 years.
P6 HGVs do not operate efficiently on the motorway around Newport.
P7 There is an air pollution problem associated with the motorway around Newport.
P8 Traffic congestion on the M4 around Newport contributes to emission of greenhouse gases.
P9 The transport system is at increasing risk from extreme weather events.
P10 There is an environmental noise problem associated with the motorway around Newport.
P11 The existing transportation system does not meet the Wales Spatial Plan aspirations as a gateway to Wales.
P12 The existing transportation system does not meet the aspirations of the local development plans.
P13 The current accident rate on the existing M4 is higher than average.
P14 The existing M4 is a barrier to intra-regional travel.
* Resilience is the ability of a network to cope with sudden changes in demand or operation, e.g. traffic throughput could be maintained during periods of temporary disruption
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Appendix C
Results of Capacity Assessments of Existing M4 (J25a - J29)
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Appendix C. Results of Capacity Assessment of Existing M4 J25a-J29
Motorway Capacity between Junctions 25a and 26
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2005 2007 2009 2011 2013 2015 2017 2019 2021 2023 2025 2027 2029 2031
Peak hour flow
Do minimum On-line widening between J29-J24 Corridor efficiency improvement *
New M4 Practical Capacity Practical Capacity (On-line Widening)
Peak hour flow over
capacity by 2024
Congestion Reference Flow between Junctions 25a and 26
0
20000
40000
60000
80000
100000
120000
2005 2007 2009 2011 2013 2015 2017 2019 2021 2023 2025 2027 2029 2031
AADT
Do minimum On-line widening between J29-J24
Corridor efficiency improvement * New M4
85% of Congestion Reference Flow 85% of Congestion Reference Flow (On-line Widening)
Demand flow exceeds
congestion threshold by 2018
* Measures include:
Corporation Road link; Hard shoulder running between Junctions 29 and 28; Hard shoulder running between Junctions 28 and 27; Hard shoulder running between Junctions 27 and 26; Increased length of westbound merge at Junction 29A; Increased capacity of eastbound merge and westbound diverge at Junction 29; At-grade improvement to the SDR; Upgrade to Steelworks Access Road; Improvement to B4245 junction west of Magor; Improvement to Junction 28; Closure of Junction 27 with associated works at Bassaleg Roundabout; Removal of East facing slip roads and widening of West facing slip roads at Junction 26; and Removal of East facing slip roads at Junction 25.
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Appendix C: Results of Capacity Assessment of Existing M4 J26-J29 (continued)
Motorway Capacity between Junctions 26 and 27
0
1000
2000
3000
4000
5000
6000
7000
8000
2005 2007 2009 2011 2013 2015 2017 2019 2021 2023 2025 2027 2029 2031
Peak hour flow
Do minimum On-line widening between J29-J24 Corridor efficiency improvement *
New M4 Practical Capacity Practical Capacity (On-line Widening)
Peak hour flow remains
under capacity in 2031
Congestion Reference Flow between Junctions 26 and 27
0
20000
40000
60000
80000
100000
120000
140000
160000
2005 2007 2009 2011 2013 2015 2017 2019 2021 2023 2025 2027 2029 2031
AADT
Do minimum On-line widening between J29-J24
Corridor efficiency improvement * New M4
85% of Congestion Reference Flow 85% of Congestion Reference Flow (On-line Widening)
Demand flow remains under
congestion threshold in 2031
* Measures include:
Corporation Road link; Hard shoulder running between Junctions 29 and 28; Hard shoulder running between Junctions 28 and 27; Hard shoulder running between Junctions 27 and 26; Increased length of westbound merge at Junction 29A; Increased capacity of eastbound merge and westbound diverge at Junction 29; At-grade improvement to the SDR; Upgrade to Steelworks Access Road; Improvement to B4245 junction west of Magor; Improvement to Junction 28; Closure of Junction 27 with associated works at Bassaleg Roundabout; Removal of East facing slip roads and widening of West facing slip roads at Junction 26; and Removal of East facing slip roads at Junction 25.
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Appendix C: Results of Capacity Assessment of Existing M4 J26-J29 (continued)
Motorway Capacity between Junctions 27 and 28
0
1000
2000
3000
4000
5000
6000
7000
8000
2005 2007 2009 2011 2013 2015 2017 2019 2021 2023 2025 2027 2029 2031
Peak hour flow
Do minimum On-line widening between J29-J24 Corridor efficiency improvement *
New M4 Practical Capacity Practical Capacity (On-line Widening)
Peak hour flow remains
under capacity in 2031
Congestion Reference Flow between Junctions 27 and 28
0
20000
40000
60000
80000
100000
120000
140000
160000
2005 2007 2009 2011 2013 2015 2017 2019 2021 2023 2025 2027 2029 2031
AADT
Do minimum On-line widening between J29-J24
Corridor efficiency improvement * New M4
85% of Congestion Reference Flow 85% of Congestion Reference Flow (On-line Widening)
Demand flow remains under
congestion threshold in 2031
* Measures include:
Corporation Road link; Hard shoulder running between Junctions 29 and 28; Hard shoulder running between Junctions 28 and 27; Hard shoulder running between Junctions 27 and 26; Increased length of westbound merge at Junction 29A; Increased capacity of eastbound merge and westbound diverge at Junction 29; At-grade improvement to the SDR; Upgrade to Steelworks Access Road; Improvement to B4245 junction west of Magor; Improvement to Junction 28; Closure of Junction 27 with associated works at Bassaleg Roundabout; Removal of East facing slip roads and widening of West facing slip roads at Junction 26; and Removal of East facing slip roads at Junction 25.
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Appendix C: Results of Capacity Assessment of Existing M4 J26-J29 (continued)
Motorway Capacity between Junctions 28 and 29
0
1000
2000
3000
4000
5000
6000
7000
8000
2005 2007 2009 2011 2013 2015 2017 2019 2021 2023 2025 2027 2029 2031
Peak hour flow
Do minimum On-line widening between J29-J24 Corridor efficiency improvement *
New M4 Practical Capacity Practical Capacity (On-line Widening)
Peak hour flow remains
under capacity in 2031
* Measures include:
Corporation Road link; Hard shoulder running between Junctions 29 and 28; Hard shoulder running between Junctions 28 and 27; Hard shoulder running between Junctions 27 and 26; Increased length of westbound merge at Junction 29A; Increased capacity of eastbound merge and westbound diverge at Junction 29; At-grade improvement to the SDR; Upgrade to Steelworks Access Road; Improvement to B4245 junction west of Magor; Improvement to Junction 28; Closure of Junction 27 with associated works at Bassaleg Roundabout; Removal of East facing slip roads and widening of West facing slip roads at Junction 26; and Removal of East facing slip roads at Junction 25.
Congestion Reference Flow between Junctions 28 and 29
0
20000
40000
60000
80000
100000
120000
140000
160000
2005 2007 2009 2011 2013 2015 2017 2019 2021 2023 2025 2027 2029 2031
AADT
Do minimum On-line widening between J29-J24
Corridor efficiency improvement * New M4
85% of Congestion Reference Flow 85% of Congestion Reference Flow (On-line Widening)
Demand flow remains under
congestion threshold in 2031
35