Start Date: 09/06/25 End Date: 16/12/25
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 6 month programme in four main phases, with works continuing to phases 2 and 3 as outlined below
Phases 2 and 3 - Contraflow works
29 July (06:00) – 12 December
- Phases 2 and 3 - 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.
30 November (20:00) – 1 December (06:00)
- Overnight closures for 1 night in both directions to switch contraflow phases
- Westbound between J37 Pyle to J39 Groes
- Eastbound between J38 Margam to J37 Pyle
Phase 4 – Central Reserve Work
13 December (06:00) – 16 December
- Phase 4 central reserve works to close the contraflow crossovers
- A 50mph speed limit will be in place during this time for safety.
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.