The commission is working on plans alongside the Welsh Government’s independent reviewer of road user charging Derek Turner, who helped to introduce London’s congestion charge in 2002.

Last summer the Welsh First Minister scrapped a proposal to build a 23km, dual three lane relief road south of Newport and the Welsh Government appointed the Commission to recommend alternative solutions.

In its new ‘emerging conclusions’ report, the Commission sets out a ‘network of alternatives’ to travelling on the M4 which includes a new local rail line from Cardiff Central through Newport to the Severn Tunnel Junction. A final report is expected to be published by the end of the year.

Commission chair Lord Burns said: “Overall, our view is that the region needs an integrated network of alternative transport options that do not depend on the motorway. Our focus is now on deciding the transport services that should form part of this transport network, in particular new rail stations, reliable bus services and new cycling routes.”

In the Welsh Parliament last week the Minister for Economy & Transport Ken Skates was asked by Conservative member Laura Anne Jones if he did not agree that “unclogging the main artery into south Wales” and delivering on an M4 relief road would provide “the much needed lifeblood to our Welsh businesses and tourism” that they “so desperately need”.

Ken Skates replied: “I don't think a single member in this chamber would disagree with what you said about the need to ensure that congestion is addressed, and that's why we are taking forward the initial recommendations of the Commission. I'd like to place on record my thanks to Lord Burns for leading this important piece of work.”

Photograph: Arup