Reform says a 15 per cent rise since 2011 strengthens the case for a new motorway, but the Welsh Government has ruled out the Black Route and is preparing alternative proposals
NEW population figures showing Newport has gained more than 22,000 residents since 2011 have reignited the political battle over how to tackle congestion on the M4.
Office for National Statistics estimates put the Newport local authority population at 167,899 in 2024, compared with just over 145,700 at the time of the 2011 Census.
That represents growth of approximately 15.2 per cent in 13 years.
Between 2011 and 2021 alone, Newport’s population rose by 9.5 per cent, the largest percentage increase recorded by any Welsh local authority during that census period.
Reform Wales says the figures strengthen its argument that the city and the wider south-east Wales economy have outgrown the existing motorway infrastructure.
Jason O’Connell, Reform’s Shadow Minister for Transport and MS for Pontypridd Cynon Merthyr, said the increasing population was adding to pressures on a road network already struggling with congestion and disruption.
“These figures confirm what drivers already know: Newport has outgrown the M4,” he said.
“The Brynglas Tunnels have become one of the biggest transport bottlenecks in Britain, holding back commuters, businesses and economic growth.
“Newport is growing, south Wales is growing and our economy is growing. It is time our infrastructure caught up.”
Motorway narrows through tunnels
The M4 is reduced from three lanes to two in each direction as it passes through the Brynglas Tunnels between junctions 25 and 26.
Official assessments have repeatedly identified the tunnels as the principal capacity constraint on the motorway around Newport. Welsh Government documents have previously estimated that approximately 80,000 vehicles pass through the corridor each day, although traffic levels vary significantly between sections and counting points.
The South East Wales Transport Commission, established after the previous relief road was cancelled, described the section incorporating the tunnels as one of the most congested stretches of urban motorway in the UK.
When an accident, vehicle fire or other incident closes a lane or tunnel, queues can spread rapidly along the M4 and onto roads through Newport.
The problem is not limited to commuters. The motorway is the principal east-to-west road link for freight, tourism and businesses travelling between south Wales, the Midlands and southern England.
Black Route abandoned in 2019
Plans for a new three-lane motorway south of Newport, commonly known as the Black Route, were abandoned by the Welsh Government in June 2019.
The proposed road would have bypassed the tunnels and existing motorway between Magor and Castleton, crossing the Gwent Levels and the River Usk.
The project had been estimated to cost at least £1.4 billion by the time it was cancelled, with concerns about rising costs and the environmental impact on the internationally important wetlands of the Gwent Levels. The scheme’s official status remains withdrawn.
Supporters argued that the new road would improve journey reliability, attract investment and provide an alternative when the existing motorway was blocked.
Opponents warned that building additional road capacity would generate more traffic, increase carbon emissions and cause lasting damage to protected habitats.
What did the economic studies find?
Mr O’Connell said previous Welsh Government assessments had demonstrated that a relief road could produce billions of pounds in economic benefits.
Historic assessments did identify substantial benefits, principally through shorter and more reliable journeys, lower vehicle-operating costs and fewer accidents.
The central economic appraisal produced in 2014 estimated benefits of approximately £2 billion over a 60-year assessment period, with more than £2 of calculated benefit for every £1 spent under its central assumptions.
Those figures do not represent £2 billion arriving directly in government accounts. Transport appraisals place a monetary value on factors such as time saved by motorists and businesses, accident reductions and changes in operating costs.
They were also calculated more than a decade ago, using historic construction prices, traffic forecasts and economic assumptions. Any revived motorway proposal would require a new route assessment, environmental examination, business case and cost estimate.
Welsh Government rules out original route
The new Plaid Cymru Welsh Government has acknowledged that the motorway is operating beyond capacity at peak periods, but has ruled out reviving the Black Route.
Deputy Minister for Transport Mark Hooper told the Senedd in June that the Government did not consider the route to be a credible option because of environmental and cost concerns and the time it would take to deliver.
However, he said other road options remained under consideration alongside rail, bus and traffic-management improvements.
“The solutions are public transport focused, the ultimate solutions, and that will be where we put a lot of effort,” he said.
Mr Hooper has also declined to rule out changes or closures at some motorway junctions, prompting concerns that additional traffic could be pushed onto already congested roads through Newport.
He is expected to return to the Senedd in the autumn with what he described as a balanced package of practical and deliverable measures.
£810 million alternative network proposed
The programme developed following the cancellation of the relief road has concentrated on creating alternatives to travelling by car along the M4.
A 2024 prospectus produced by the Burns Delivery Board set out an estimated £810 million package involving new railway stations, more frequent services, rapid bus corridors and improved walking and cycling connections.
The proposed network included six new stations, 23 miles of rapid bus lanes and 20 miles of cycle routes. Its authors estimated that the rail proposals could generate 1.5 million additional train journeys and remove 13 million car kilometres from the roads each year.
However, several elements still require detailed approval, construction funding or agreement between the Welsh and UK governments.
Pressure for an updated answer
Population growth does not, by itself, determine whether a motorway, rail investment or another combination of measures is the best solution.
The effect on traffic also depends on where new homes are built, where residents work, the availability of public transport and the proportion of journeys made by car.
But the increase of more than 22,000 residents since 2011 strengthens calls for transport plans to be based on up-to-date population, employment and travel data.
The political divide is now clear. Reform wants a relief road revived, while the Welsh Government has ruled out the original route and is developing a mixture of public transport and more limited road interventions.
For motorists and businesses facing repeated delays around Newport, the central question will be whether either approach can move beyond studies and consultations and deliver a lasting solution.
