Welsh Government Proposes M4 Junction Closures and New Menai Crossing
Plans aim to alleviate congestion on two major Welsh transport routes, though concerns remain about cost and impact on alternative roads.
The Welsh government is considering closing some M4 junctions in Newport and initiating plans for a new bridge across the Menai Strait as part of a strategy to tackle persistent traffic congestion. These proposals are the latest in a series of efforts to address bottlenecks on key Welsh roads.
M4 Corridor Improvements
An 18-month study will examine "road-based solutions" for the M4 in South Wales, a process that could include the construction of a new motorway south of Newport or the expansion of the Brynglas Tunnels, a significant source of congestion. Previous plans for an M4 Relief Road were abandoned in 2019. Ministers have ruled out the "black route" previously proposed, but a new motorway remains a possibility. Other options involve improving how the motorway is operated and managed, with the aim of delivering shorter-term benefits. Potential closures or partial closures of three junctions in and around Newport—junction 27 (High Cross), and east-facing slip roads at junction 26 (Malpas) and junction 25 (Caerleon)—are being considered by 2028. Deputy Transport Minister Mark Hooper stated that such measures could offer quick opportunities to improve traffic flow and resilience on the M4. However, final decisions have not been made, pending consideration of the impact on local roads and consultation with Newport council.
A review by transport consultants ARUP flagged potential downsides to junction closures, including increased congestion and noise on alternative routes, and a risk of redistributing economic costs rather than reducing them. The review estimated that closing these junctions could cost approximately £14 million and lead to a 3% reduction in traffic, with potentially limited long-term value. ARUP's report evaluated eight options, including new railway stations and bus rapid transit schemes. Widening the Brynglas Tunnels could cost an estimated £1.7 billion but carries engineering risks and the potential for major construction disruption. Alternative proposals like changes to the A48 and A4810 (the "Blue Route") are estimated to cost £1.8 billion, take eight years to complete, and reduce M4 traffic by 6%.
Menai Strait Crossing
The government also intends to recommence development work for a third crossing over the Menai Strait. Although formally scrapped three years prior, the proposal resurfaced a year later. Officials estimate a new crossing could cost around £670 million, with development work taking up to two years, and construction taking eight to ten years. The A55 currently uses the Britannia Bridge over the Menai Strait, which is a single carriageway unlike the rest of the A55. The Menai Suspension Bridge has been restricted to vehicles under 7.5 tonnes since October 2022 due to ongoing repair works. A review concluded against a three-lane tidal-flow operation on the Britannia Bridge, citing significant safety and operational concerns.
Deputy Minister Hooper emphasized the public's desire for action, stating, "people want action, not endless discussion." He added, "They want reliable journeys, less disruption and confidence that government is getting on with improving things and making a difference to people's lives." The 18-month study for the M4 will run concurrently with measures aimed at reducing peak-hour traffic by up to 10%.