Start Date: 09/06/25 End Date: 30/11/25
Work to carry out essential bridge maintenance to five structures on the M4 between junctions 37 and 38 –will commence on 09/06/2025 and continue over a duration of six months.
The work will be carried out over a six month programme in four main phases, with works continuing to phases two and three.
Preparatory works to switch the contraflow system's direction.
24 July 20:00 - 29 July 06:00
- Overnight closures over five nights in both directions between junction 37 Pyle and junction 39 Groes.
Phases two and three - Contraflow works
29 July - 21 November
- Phases two and three - Bridge works with contraflow system in place and traffic flow reduced from three lanes to two lanes in each direction
- A 50mph speed limit will be in place during this time for safety.
- Further details on later phases of works will be published closer to the time.
For Phases 1 to 4, no diversion route will be necessary with all traffic, with junctions 37 and 38 remaining operational.
During the isolated full closures to install traffic management measures, a diversion route will be implemented utilising the A4229 and A48.
Westbound, traffic will be directed off the M4 at Junction 37 and via the A4229 and A48, re-joining the M4 at Junction 39.
For further information, please contact Traffic Wales on 0300 123 1213 or via X @TrafficWalesS and Facebook @TraffcWalesS.