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M4 Junction 41 Port Talbot

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Ken Skates, Cabinet Secretary for Economy and Infrastructure
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We are undertaking a study of traffic on the M4 at Port Talbot in order to improve traffic on the road.


Project status: current
Region/county: south east
Start date: August 2014
End date: March 2015
Cost: to be confirmed

Why we are doing it

There is a significant drop in average speeds during peak hours around Junction 41. Data from 2012 shows that:

  • eastbound average speed drops to about 30mph during morning peak hours
  • westbound average speed drops to about 25mph during evening peak hours.

We need to improve traffic flow on the M4 to improve journey times.

Current progress

We have completed a trial closure of the westbound on slip during peak hours. A report of the trial can be downloaded below.

Scheme details

The scheme included:

  • trial closure of the westbound on slip during peak hours
  • funding allocation of £521,000 to Neath Port Talbot County Borough Council (NPTCBC) for local road improvements prior to the trial
  • funding allocation of £500,000 to NPTCBC to speed up of improvements to the local road network, including:
    • construction of a bridge linking the western and eastern sections of Baglan Energy Park
    • improvements Wharf Road link at Briton Ferry
  • monitoring of:
    • traffic flow on the M4 and local road network
    • foot fall in Aberafan Shopping Centre
    • parking ticket data
    • air quality through data collected by NPTCBC
  • average speed enforcement cameras installed with start of enforcement in  January 2015 – we have collected data to determine the effect of both the speed enforcement system alone and the combined effect of the closure and the speed enforcement.

We have used the Department for Transport’s market values of journey times and accidents to measure the financial benefit of improved journey times on the M4 compared to the monitory benefits or costs associated with local roads.

Measurement of parking tickets and foot fall has helped us determine what effect the closures have had on the town centre.

How we consulted

The closure of Junction 41 was recommended in NPTCBC’s 2009 public inquiry into the Port Talbot Peripheral Distributor Road Stage 2. Since then we have been working with the council to analyse these and other options, which included a number of closure options and allowing traffic to use the hard shoulder. We discounted hard shoulder running on the grounds of safety and value for money.

The Minister for Economy, Science and Transport met with the leader of NPTCBC, businesses and public representatives prior to the trial. A number of meetings between Welsh Government and NPTCBC officials and a group of public representatives took place during the trial.  

Formal consultation on the Experimental Order for the trial closure took place with the Police.  Discussions also took place with the Fire Service and Ambulance Service as non-statutory consultatees.

Next steps

The Minister for Economy, Science and Transport has decided to lift the part time closure of the M4 junction 41 westbound on-slip whilst officials conduct further analysis to inform a decision as to whether to proceed to a full consultation on closures.