National Highways Closes M48 and M4 Bridges for Maintenance

National Highways announced the closure of the westbound carriageways of both the M48 Severn Bridge and the M4 Prince of Wales Bridge to facilitate essential structural maintenance. According to the agency, the M48 closure occurs between Junction 1 slips from 9 p.m. to 5 a.m., while the M4 Prince of Wales Bridge is closed between Junctions 21 and 23 from 9 p.m. to 6 a.m.

These overnight closures are part of a broader maintenance program. National Highways stated that the M48 Severn Bridge has been subject to a 7.5-tonne weight restriction for heavy goods vehicles since May 2025. This measure was implemented due to concerns regarding the condition of the main cables and is expected to remain in place for 12 to 18 months.

Further disruptions are planned for the M48 starting August 1 through September 27, 2026. The agency confirmed a resurfacing trial during this period that will involve contraflows, lane restrictions, and full weekend shutdowns.

These combined restrictions and closures are expected to significantly impact regional traffic flow. National Highways is directing drivers to follow marked diversion routes to avoid delays, particularly for heavy goods vehicles that are already barred from the M48. The agency emphasizes that these works are critical to ensuring the long-term safety and structural integrity of the crossings between England and Wales.