THE Welsh Assembly will debate whether or not to call for a rethink on the M4 relief road proposals on Wednesday.

The Plaid Cymru sponsored debate will focus on whether the case has been made for proceeding with the ‘black route’ to the south of Newport, and whether “committing the entirety of new Welsh borrowing powers to one project will limit investment elsewhere”.

Assembly members will be asked to vote on a motion calling on the Welsh Government “to fully consider the 'blue route' on economic, traffic management, environmental and financial grounds.”

The £1 billion ‘black route’ was settled on in July, with a proposed opening date of 2022.

Running between Junctions 23 and 29, the selected route was one of three put forward in the Welsh government’s consultation.

But Plaid Cymru said the the ‘blue route’, upgrading the Southern Distributor Road and the former steelworks road, would have been preferable.

The motion also asks AMs to vote on whether the Assembly “believes that congestion on the M4 in the Newport area is detrimental to the Welsh economy, and that a sustainable and affordable resolution is required.”

The debate, proposed by Ceredigion AM Elin Jones, will take place at around 5pm on Wednesday at the Senedd in Cardiff Bay.

This follows news that a judicial review has been launched into whether the road is lawful.

We reported last week that Friends of the Earth Cymru (FotEC) say the plans to build the road through the Gwent Levels wetlands, one of Wales’ most important wildlife habitats, could be unlawful.

A judge will now examine whether the Welsh Government unlawfully limited the range of reasonable alternatives by only considering a new motorway south of Newport and two similar variations. They will also consider if the plan’s substantial damage to protected wildlife sites is permitted by law.

Edwina Hart AM, minister for economy, science and transport, defended the choice of the black route earlier this month: “The blue route would be in very close proximity to local residents and industry. Its introduction may require demolition of residential housing and the relocation of some significant industry. Higher traffic levels on the blue route may mean air quality and noise issues for neighbouring properties. There’s no guarantee that that it is a simple solution.”

A Welsh Government spokesperson said: “We are committed to this infrastructure project, which is of vital importance to the economic prosperity of Wales."