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The Welsh Government’s traffic information service for motorways and trunk roads in Wales

A465 Dowlais Top to Hirwaun (Sections 5 and 6)


Start Date: Spring 2021 | End Date: Mid 2025

A465 Heads of The Valley Dowlais Top Junction

The A465 will be converted to two lanes in each direction from Dowlais Top to Hirwaun. 

For more information regarding this project, please see Welsh Government links on the right, for information on traffic management see details below.


This work is taking place on a 17km section of the A465 road, between Dowlais Top, Merthyr Tydfil and Hirwaun. The existing A465 was built in the 1960s and a traffic study identified the need to improve the road by:

  • making the road safer, especially around junctions and areas with poor visibility
  • improving traffic flow and make it safer to overtake

To complete these complex and long term roadworks, at times, the contractor will need to

  • reduce the carriageway from 3 lanes to 2.
  • close sections of the carriageway overnight or over weekends
  • use traffic lights to control traffic flow during the works.

From May 2021 the speed limit will be reduced to 40mph to protect the safety of road workers on site and the public. This will be enforced in the same way as the existing speed limit using average speed cameras. Free recovery will be available for vehicles breaking down with the works.

Every effort is made to minimise disruption 24hour working during full road closures to reduce the number required. 

June 15th Closure Diversion Route

Overnight Closure Locations

Start Date & Time** End Date & Time**

Hirwaun Roundabout to Cefn Coed Roundabout in both directions for 2 nights

15/06/21 20:00 17/06/21 06:00

Glynneath Interchange to Hirwaun Roundabout in both directions for 1 night

22/06/21 20:00 23/06/21 06:00

**Please note this programme may be subject to change. Further closures updates to follow.

The Welsh Government appointed Future Valleys Construction as their partner to help deliver the scheme. From May 1st, 2021 the South Wales Trunk Road Agent will no longer be responsible for the maintenance of this part of the network.

We will continue to work closely with the contractor to update this page and @TrafficWalesS with the latest traffic management measures but all enquiries about the works will be directed to the Future Valleys team. 

To report incidents or issues on the network, please call the A465 control room on 0787 287 1702. The line is available 24 hours a day, seven days a week.

For community queries or complaints please call 0776 245 1850 or email: [email protected].The Future Valleys, Public Liaison Team operate during normal working hours weekdays and will respond in the following working period.

Call the Traffic Wales information line
0300 123 1213
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