Labour's Welsh leader has called on the Plaid Cymru administration to start work on an M4 relief road around Newport, seven years after his party axed the project in government.
Ken Skates told BBC Wales there was "no other option on the table" to solve congestion in Newport, and has backed a version of the original plan with changes. Labour will table a vote in the Senedd on Wednesday calling for an "appropriate relief road" to be built.
The previous proposals were cancelled in 2019 by the then first minister Mark Drakeford, on the grounds of cost and the impact on the environment. All three opposition groups in the Senedd, Reform, Labour and the Conservatives, now favour a relief road.
The call follows a report published earlier in October, which set out a number of alternatives to a new motorway and said a relief road could cost around three billion pounds.
Skates said the report "shows that no single or combined solution will adequately alleviate congestion on the M4 around Newport". He went on: "That means that there is no other option on the table other than a relief road if we wish to solve the problem of congestion on that route."
He favours an amended version of the black route, the proposed motorway south of Newport examined and backed by a public inquiry in 2019, and said the blue route alternative, which would use existing roads in part, was not appropriate. "In reality, the black route remains the only appropriate route," he said, adding that further work would be needed to make sure environmental concerns were met.
The Welsh government has commissioned an 18-month project to assess possible roads-based solutions, while ruling out the black route. The options it has set out for Newport include closing junction 27 at High Cross and the eastbound slip roads at junctions 25 and 26.
The October report also carried a warning about the land itself. The route is no longer safeguarded through the planning system, and it noted that "over time, new development or other land use changes may occur within parts of the former corridor, making it progressively more difficult or expensive to deliver the same highway alignment in the future".
Deputy Transport Minister Mark Hooper made the same point in a Senedd debate on 29 September. "The protected route status went when it was cancelled," he said. "So, we're talking about decades of work to even get that off the ground."
Plaid Cymru's position is that smaller measures can do the job. Peredur Owen Griffiths, who represents Casnewydd Islwyn, said: "Plaid Cymru is clear that doing nothing isn't an option... the action we're considering could reduce traffic by 10% in just four years."
Skates, who served as transport minister under four Labour first ministers, said the financial circumstances of 2019 were not those of today, and that it was right not to proceed then because of the cost.
Set out in order, the sequence the two reports describe has a quality that deserves recording. A corridor of land was protected by the planning system because a road might one day be built on it. The road was cancelled. The protection, having nothing left to protect, lapsed. Land use in the corridor is now free to change, and each change makes the road more expensive. The cost of the road therefore rises in proportion to the length of time it is not built.
This newspaper draws the obvious conclusion. The cheapest possible moment to build the M4 relief road was the instant before the decision not to build it, and that moment is now seven years in the past and receding at the usual rate.
The mechanism is worth admiring on its own terms. Safeguarding is how the planning system preserves a road by not building it. It is the only form of construction that works in reverse, and it stops the moment anybody decides it is not needed, which is the moment it becomes necessary.
Wednesday's motion cannot restore it. A Senedd vote may call for an appropriate relief road, but only a protected route can hold the ground still, and the ground has been moving since 2019.
The Department of Unnecessary Research has examined the corridor and reports one asset along that stretch of the M4 in sound condition and fully preserved. It is not safeguarded by any committee, it requires no capital allocation, and it has survived a cancellation, a change of administration and the commissioning of an 18-month assessment. Of everything on the road at Newport, only the congestion has enjoyed continuous protection since 2019.