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 Latest News

7th August 2013

Participation Report added

19th November 2012

Equality and Health Impact Assessments added

5th November 2012

Environmental and
Habitats reports added

8th May 2012

Extended period for responses and additional public exhibitions

19th April 2012

Exhibition boards and documents available

6th March 2012

Consultation Launch

Now available

M4 CEM Newsletter no.2

28th Feb 2012

Consultation website
goes live

28th Nov 2011

The Second Deliberative Meeting of the M4 CEM Stakeholder Forum

14th Nov 2011

Ryder Cup -
Learn't Talk

25th Oct 2011

Wales leads on UK's
biggest push to
cut car use

26th Sept 2011

Providing a new route
from the M4 motorway
to the South East
of Newport

26th Sept 2011

Drop-in exhibitions
report (English version)

 Popular Downloads

M4 CEM newsletter no.2 "Easing the flow"

Brochure 2006

M4 CEM newsletter no.2 "Easing the flow"
(Welsh version)

Newsletter no1 Welsh

M4 CEM Timeline





Overview of the M4 Corridor Enhancement Measures Programme (M4 CEM)

What’s this all about?

The National Transport Plan for Wales, Published in March 2010, has some targeted proposals for south-east Wales which aim to continue development of the most appropriate, and sustainable, solutions to transport issues in south-east Wales.

Travel and traffic in south east Wales

South-east Wales is densely populated, with significant conurbations at Cardiff and Newport and smaller urban areas nearby. Local and long-distance traffic converge in this region, particularly around the M4 motorway. The M4 itself has brought major economic benefits to south Wales by improving domestic connectivity as well as access to the south of England. However, for a long time there have been concerns about the section of motorway around Newport. The primary concerns are about:

  • the capacity of the M4 here to meet high demand, especially at peak travel times

  • safety, and

  • resilience – the motorway and local road network does not cope well with sudden changes in demand or operation.

The most obvious problems experienced by local and longer-range (including freight and international) users of this section of the M4 around Newport for many years are journey time unreliability due to increased congestion and an inability to cope when incidents change the “normal situation” – say, as a result of accidents, extreme weather or popular events.
A detailed study of the problems of the transport system in SE Wales investigated these and other significant failings. To address these issues, the idea of a relief motorway was explored but, in July 2009, the Welsh Government announced that this option was now unaffordable; other methods of addressing the safety and capacity issues affecting travel in the area needed to be found to make important improvements to the existing transport network.

M4 CEM – The Story so far

The Welsh Government acknowledges that congestion and unreliable journey times have been a fact of life on the M4 around Newport for many years. Associated problems affect other roads and residents within the corridor area too. So, the M4 Corridor Enhancement Measures Programme was set up to solve travel-related problems caused by growing use and outdated-design of the M4 here. The M4 CEM need to address the importance of the M4 for strategic traffic movements and recognise local access needs in the whole corridor area.

What’s wrong with the Motorway?

The M4 motorway in South East Wales is running close to capacity and traffic volumes are continuing to grow with increasing congestion. Widening the M4 from dual 2 lanes to dual 3 lanes between Castleton (Junction 29) and Coryton (Junction 32), undertaken since 2006?, has helped ease the flow West of Newport.

However, the motorway around Newport does not conform to today’s motorway standards. It lacks continuous hard shoulders, has closely spaced junctions with sub-standard slip road visibility and narrows to a restricted two lane section through the Brynglas Tunnels. Heavy congestion occurs along this stretch and either side of it at peak hours. Traffic data show that the motorway is already approaching, and at times exceeds, capacity, while traffic forecasts indicate that if nothing is done, congestion and traffic related problems will increase.

What has been done so far around Newport?

Practical measures to make travel safer and easier on the M4 between junctions
23a and 29 began in 2008. This work includes replacing sections of steel central barriers with concrete ones, the introduction of Variable Speed Limit systems and the deployment of traffic officers. To ease congestion, improvements have been made to the roundabout at Junction 24 at Coldra and there are plans to create a link through Llanwern steel works between Junction 23a and the Newport Southern Distributor Road.

These measures alone aren’t going to solve the longer term issue of increasing demand for capacity on our travel networks. So, before embarking on a major programme to tackle the longer-term issues, the Welsh Government talked and listened to people at the beginning of the year – organisations and elected representatives speaking for the interests of the general public, businesses, the voluntary sector, as well as ordinary people and residents of the area – to find out exactly what problems people experience.

Working with people to decide upon the best way to ease the flow

The Welsh Government has tried to encompass a wide range of people and organisations to help shape the M4 CEM Programme up to this Formal Consultation stage.

In order to understand what people think about transport within the M4 Corridor around Newport, we have undertaken a series of public exhibitions in Newport City Centre, Lliswerry and Duffryn, and two half-day workshops for Local Authorities, Government and other key stakeholders. We also created a Stakeholder Forum, a group of individuals with both a strategic interest and detailed experience of addressing travel related issues, who informed the development of a number of different options, some of which are presented in the M4 CEM Formal Consultation Document.

You can download all published reports associated with the exhibitions and workshops from the Reports & Newsletters page.

Establishing what the problems are

Building on the research already undertaken by the Welsh Government, people attending the drop-in exhibitions and workshops were asked what they thought the travel related problems in the M4 Corridor: Magor to Castleton are. Using the responses and feed-back received the Welsh Government has established that there is a need to address the following problems, grouped here under four principle themes:



  • A greater volume of traffic uses the M4 around Newport than it was designed to accommodate, resulting in regular congestion at peak times over extended periods.

  • The M4 around Newport is used as a convenient cross town connection for local traffic, with insufficient local road capacity.

  • HGVs do not operate efficiently on the motorway around Newport.

  • There is insufficient capacity through some of the junctions (eg 3 lane capacity drops to 2 lane capacity).

  • The 2-lane Brynglas tunnels are a major capacity constraint.

  • The M4 cannot cope with increased traffic from new developments.


  • Difficulties maintaining adequate traffic flows on the M4 and alternative highway routes at times of temporary disruption; alternative routes are not able to cope with M4 traffic.

  • The road and rail transport system in and around the M4 corridor is at increasing risk of disruption due to extreme weather events.

  • When there are problems on the M4, there is severe disruption and congestion on the local and regional highway network.

  • The M4 requires essential major maintenance within the next 5-10 years; this will involve prolonged lane and speed restrictions, thus increasing congestion problems.

  • There is insufficient advance information to inform travel decisions when there is a problem on the M4.


  • The current accident rates on the M4 between Magor and Castleton are higher than average for UK motorways.

  • The existing M4 is an inadequate standard compared to modern design standards.

  • Some people’s driving behaviour leads to increased accidents (eg speeding, lane hogging, unlicensed drivers).

Sustainable Development

  • There is a lack of adequate sustainable integrated transport alternatives for existing road users.

  • Traffic noise from the motorway is a problem for local residents in certain areas.

  • The existing transport network acts as a constraint to economic growth  and adversely impacts the current economy.

  • Traffic levels are forecast to continue to increase therefore capacity and resilience issues will worsen over time.

  • The high volumes of congested, slow moving traffic on the motorway around Newport add to air pollution problems and greenhouse gas emissions.

  • The existing transportation system does not meet the aspirations of national and local government planning policies.

Developing the brief for Measures to tackle these Problems

Having asked people and key stakeholders, like the relevant Local Authorities, business organisations and others, about the Problems, the Welsh Government asked, what should be the Aims for this Programme of Improvements, and what Goals should we be aiming to achieve. Again, having reviewed the responses, here are the Aims and Goals for the M4 CEM:


  • Make it easier and safer for people to access their homes, workplaces and services by walking, cycling, public transport or road.

  • Deliver a more efficient and sustainable transport network supporting and encouraging long-term prosperity in the region, across Wales, and enabling access to international markets.

  • To produce positive effects overall on people and the environment, making a positive contribution to the overarching Welsh Assembly Government goals to reduce greenhouse gas emissions and to making Wales more resilient to the effects of climate change.


When the M4 CEM programme is concluded we will benefit from:

  • Safer, easier and more reliable travel East-West in South Wales.

  • Improved transport connections within Wales and to England, the Republic of Ireland and the rest of Europe on all modes on the international transport network.

  • More effective and integrated use of alternatives to the M4, including other parts of the transport network and other modes of transport for local and longer distance journeys around Newport.

  • Best possible use of the existing M4, local road network and other transport networks.

  • More reliable journey times along the M4 corridor.

  • Increased level of choice for all people making journeys within the transport corridor by all modes between Magor and Castleton, commensurate with demand for alternatives.

  • Improved safety on the M4 Corridor between Magor and Castleton.

  • Improved air quality in areas next to the M4 around Newport.

  • Reduced disturbance to people from high noise levels, from all transport modes and traffic within the M4 corridor.

  • Reduced greenhouse gas emissions per vehicle and/or person kilometre.

  • Improved travel experience into South Wales along the M4 Corridor.

  • An M4 attractive for longer distance journeys that discourages local traffic use.

  • Improved traffic management in and around Newport on the M4 Corridor.

  • Easier access to local key services and residential and commercial centres.

  • A cultural shift in travel behaviour towards more sustainable choices.

Any possible solutions which are proposed as part of the M4 CEM Programme will be judged against how well they deliver the goals outlined above.

Possible solutions

Having listened to the feedback given by the public and other bodies, and building on much work undertaken already by the Welsh Government and others, the Welsh Government is appraising a wide range of possible solutions. These fall into four categories:

  • Highways infrastructure This is about building and improving highways networks so that they work more efficiently for travellers and cause less problems for people living near them.
  • Road network management This is about managing our existing roads better, and includes ideas about how to minimise peak-time congestion, traffic associated with popular events and improve the response to accidents or bad weather so that there is less disruption for everyone.
  • Alternative travel modes This is about getting more people to travel and access services, homes, work and leisure without driving a car.
  • Smarter Sustainable Choices and Promoting Well-being This means thinking of ways of organising our lives so that we can prevent further travel-related problems. This might be achieved through:
    • government policy  (better strategic land-use planning , linking travel and access plans to  health, economy and  environment agendas);

    • action by organisations and individuals (flexible working hours, reducing travel by working from home, car sharing).

What happens next?

The Formal Consultation is open from 6 March to 6 July. After the 17 week consultation period has ended, the Minister will decide which measures should be progressed as the best strategy aimed at addressing the problems of capacity, resilience, safety and sustainable development on the M4 Corridor between Magor and Castleton – taking into account all responses to the Formal Consultation.


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