Conservative AMs will force a vote in the Senedd today on whether there should be a review of the Welsh Government's plan to build a new motorway south of Newport to relieve pressure on the existing M4.
The £1 billion project is highly controversial, both because of its cost and because of the environmental impact on the Gwent Levels wetlands. Some business groups prefer the idea of upgrading the existing Southern Distributor Road to a motorway, arguing that it would be a cheaper and quicker solution.
That's angered residents who live near the distributor road who fear the noise and pollution that might be caused by a motorway. Now the Conservatives' transport spokesman, Byron Davies, says he's not convinced that a full motorway is required and that more modest improvements might be enough to relieve pressure on the M4.
That's roughly in line with what the Liberal Democrats have been arguing, while Plaid Cymru oppose spending such a major part of the transport budget on just one road scheme.
There's also been opposition from some Labour AMs, including two former ministers. So it would appear that most Assembly Members at least have doubts about the project. The Welsh Government has already conceded that construction work won't get the go-ahead before the 2016 Assembly election.
There are strong winds on the M4 Briton Ferry Bridge in both directions between J42 (Earlswood Roundabout/Fabian Way) and J41 (Baglan/Pentyla). There's a 40mph speed limit.
One lane is closed and there's very slow traffic after a five vehicle accident on the M4 Westbound between J39 (Margam) and J40 (Port Talbot / Taibach).
There's congestion to congestion to J37 (Pyle / Porthcawl).
Strong winds on the M4 Briton Ferry Bridge between J41 (Baglan/Pentyla) and J42 (Earlswood Roundabout/Fabian Way) mean there's a 40 mph speed limit.
One lane is blocked and there's queueing traffic after an accident on the M4 Eastbound at J41 Baglan/Pentyla. There's congestion six miles long to J44 Llansamlet.
There are reports of a christmas tree in the road on the M4 Westbound near J36 A4061 / A4063 (Bridgend / Sarn Service Area).
One is lane blocked and there's queueing traffic because of a broken down car on the M4 Eastbound between J29 A48(M) and J28 (Tredegar Park).
There's congestion to J32 (Coryton Interchange).
One lane is closed and there's slow traffic because of a spilled load of hay on the M4 Westbound between J30 A4232 (Cardiff Gate) and J32 A470 / A4054 (Coryton Interchange).
There's queueing traffic after an earlier accident on the M4 Eastbound between J24 A48 / A449 (Coldra) and J23A B4245 (Magor Services). There's congestion on the M4 to J28 A48 / A467 Forge Road (Tredegar Park). All lanes have been re-opened.
Two lanes are closed and there's queueing traffic after an accident on the M4 Eastbound between J24 A48 / A449 (Coldra) and J23A B4245 (Magor Services).