Welsh Government open to M4 Brynglas tunnel widening

A congestion plan for the M4 will come from Plaid Cymru in the autumn, Wales' transport minister has said

19:24, 01 Jul 2026Updated 20:46, 01 Jul 2026

A method to expand the Brynglas tunnel without closing it is being looked at by Welsh Government officials(Image: John Myers)

The Welsh Government is open to exploring idea of widening the existing Brynglas tunnels to try to resolve congestion on the M4[1].

Deputy transport minister Mark Hooper told Senedd Members on Wednesday that he had asked officials to look at ways of widening the tunnels, which act as a bottleneck on the M4 at Newport which reduce the motorway to two lanes in either direction.

Mr Hooper had been asked by Conservative MS Natasha Ashgar if he would consider a method of tunnel expansion which allows tunnels to be widened while keeping them fully operational, by constructing a larger structure around the original bore.

Mr Hooper said: "The point you mentioned about the tunnelling methods I think is of interest, and it is something where we've had some references in Government already.

I've got officials looking at that currently.

"It looks like it's something that's on the outer edge of what you can do, and I think some of these things haven't been proven as a point yet, but they're things that we'd be keen to look at."

Conservative Casnewydd Islwyn Senedd member Natasha Asghar said the method, known as the Nazzano method, is used in Italy,.

She also asked him to rule out closing motorway junctions. For our free daily briefing on the biggest issues facing the nation, sign up to the Wales Matters newsletter here[2]

To that request, he responded: "I think when you start to change things like closing motorway junctions, it's a likely thing that will happen if there's change, whether they are permanent closures or they're temporary closures.

"What we've got to recognise is what's important is that we consult and we recognise."

Mr Hooper said in the autumn the Welsh Government[3] will have a plan for the M4 at Newport which he hopes to get "broad support" for.

He said: "I understand people's concerns in Newport[4], and Newport is probably the area that you'll see me spending most time in over the next few months, because I think it's important that I get to understand the issues from the community's perspectives, from the leaders in those areas' perspectives, and also to make sure that we do something that reflects those concerns as well.

"So, we're going to be coming back in the autumn with what I think will be quite a balanced suite of measures, and, hopefully, those will be things that will get some broad support, which is what I'm looking for."

Before May's election, Plaid Cymru said that it was open to a road solution to dealing with congestion on the M4, something which had been ruled out by the last Welsh Labour government when it axed the plan for a GBP1.6bn new M4 south of Newport, known as the Black Route.

Mr Hooper said that the M4 black route has been ruled out by the Plaid Cymru[5] administration.

During the election campaign, Rhun ap Iorwerth said he thought a solution was needed.

He reiterated those comments after his election.[6] Mr ap Iorwerth said previous Labour[7] administrations had "wasted" GBP150m on plans for the scheme, only to scrap it.

The First Minister has told the Senedd the tunnel was an "economic constraint for Wales".

References

1. ^ the M4 (www.walesonline.co.uk)
2. ^ For our free daily briefing on the biggest issues facing the nation, sign up to the Wales Matters newsletter here (www.walesonline.co.uk)
3. ^ Welsh Government (www.walesonline.co.uk)
4. ^ Newport (www.walesonline.co.uk)
5. ^ Plaid Cymru (www.walesonline.co.uk)
6. ^ reiterated those comments after his election. (www.walesonline.co.uk)
7. ^ Labour (www.walesonline.co.uk)