M4 Relief Road: A Decades-Old Debate Rekindled in Welsh Politics

The question of whether an M4 relief road south of Newport will ever be given the green light has resurfaced as a prominent issue in the lead-up to the Senedd election on 7 May.

This proposed motorway, intended to alleviate daily traffic congestion caused by the M4's Brynglas Tunnels, has been a recurring topic on the political agenda for over three decades. The scheme was last abandoned in 2019 by former first minister Mark Drakeford.

Several parties are now championing the relief road. Reform UK and the Welsh Conservatives have pledged to build the road that Drakeford axed. Plaid Cymru, while favouring a "road answer" to congestion, suggests developing a new plan, as older schemes are now considered outdated.

However, significant opposition remains. Concerns about the environmental impact on the Gwent Levels persist. The Welsh Liberal Democrats, Wales Green Party, and Welsh Labour are all opposed to the relief road, favouring alternative solutions.

A government finance expert warned that while building the project might not be unfeasible, it could necessitate "difficult trade-offs," such as budget cuts. Former Labour first minister Mark Drakeford echoed these concerns, stating that the costs today would be "entirely prohibitive."

Traffic data from 2024 indicates an average of 81,578 vehicles passed eastbound daily between the junctions flanking the Brynglas Tunnels. This figure, though lower than the 2019 estimate of 85,379, is higher than the 2005 count of 72,540.

Residents in Newport express mixed views. Liz Thorne, 67, who uses the M4 at least five times a week, supports a relief road to help workers facing nightly traffic jams. She described the experience of traffic grinding to a halt and taking a significant amount of time to reach the next junction.

Andrew Lightbown, 59, a priest who frequently uses the M4, agreed about the frequent traffic jams but dismissed the relief road as a "cheap electoral promise." He believes smooth traffic flow through the area is "logistically almost impossible" and that the issue has been "explored to death."

Reform UK and the Tories propose building the road, but with different funding strategies. Reform UK's leader Nigel Farage has mentioned private funding and a potential toll road, with their manifesto also suggesting funding from a "Reform-instituted British Sovereign Wealth Fund" if they win a UK Parliament election. Reform's Dan Thomas suggested diverting funds from UK government rail projects, citing a £14bn Labour estimate, arguing that many proposed train stations are not needed.

However, railway spending is largely controlled by the UK government, while motorways fall under the Welsh government's remit, meaning they are funded from separate budgets. Labour's £14bn figure has also been questioned, with only £445m in spending announced.

The Tories' manifesto does not detail funding for the relief road, but a spokesperson indicated cost-sharing with a "future UK government" and opposed tolling.

Plaid Cymru's leader Rhun ap Iorwerth supports a "road answer" and stated that a Plaid government would develop a plan. He did not commit to a specific route, noting that previous plans, like the "black" route, are now outdated, especially with strengthened environmental protections on the Gwent Levels. A spokesperson for Plaid emphasized considering feasibility, affordability, sustainability, and environmental impact.

Despite a public inquiry finding the case for the road "compelling," former first minister Drakeford cancelled the scheme in 2019 due to its cost and environmental impact. At least £114 million had been spent on the project before cancellation.

Since ending support for the relief road, the Welsh government has focused on traffic flow improvements and public transport, including funding new railway stations.

Drakeford explained his decision by stating the plan's demerits outweighed its merits, citing concerns about cost and its impact on investment in other priorities. He maintained his assessment, believing current costs would be "entirely prohibitive."

Estimates for the project's cost in 2026 vary. Tory Senedd leader Millar suggested £1.8 billion, while Reform's Thomas estimated £1.5 billion to £2 billion.

David Phillips from the Institute for Fiscal Studies (IFS) noted that while building the road is not infeasible, it would require "difficult trade-offs" given the Welsh government's £3 billion capital budget is already committed to social housing, schools, hospitals, rail, and other road schemes.

Phillips speculated on Reform's proposals, suggesting a "mutual investment model" where the private sector finances upfront costs, repaid by the Welsh government over time. Alternatively, funding could come from increasing taxation, with a penny on income tax potentially raising around £400 million annually, though he questioned if this would be favoured in North Wales without similar investment there.

Welsh Labour reiterated its stance against building the M4 relief road, preferring sustainable public transport and active travel interventions.

Environmentalists have consistently opposed the relief road due to its potential impact on nature sites along the Gwent Levels. Haf Elgar of Friends of the Earth Cymru argued that new roads increase carbon emissions and air pollution, diverting focus from essential public transport improvements.

Catherine Linstrum, a former Green candidate involved in the campaign against the road, highlighted the Gwent Levels' numerous Sites of Special Scientific Interest (SSSIs), warning that a new motorway could irrevocably damage this unique landscape. She anticipates renewed opposition, viewing the proposal as an outdated solution from the 1960s and 1970s that failed to ease traffic.

Additional reporting by Elis Sandford.