Improving public transport between Cardiff, Newport and Bristol would be the best way to stop congestion on the M4 motorway, a report has suggested.
The South East Wales Transport Commission (SEWTC) has proposed a 'network of alternatives' designed to give people travel options to reduce the use of cars.
The new recommendations follow earlier fast-tracked proposals from the Commission that suggested the introduction of an average 50mph speed limit.
It comes after plans for a relief road near Newport were scrapped by the Welsh Government last year.
The report recommends upgrading the existing four tracks of the South Wales Main Line but also suggested building six new rail stations between Cardiff and the River Severn.
The commission also recommended a number of improvements to bus and cycle lanes.
If the proposals are followed through, it would see more than 90% of Cardiff and Newport’s population living within one mile of a rail station or a rapid bus corridor.
The commission was chaired by Lord Burns who said that the area needed a number of improvements to transport to "fulfil its potential".
“The area around the M4 is a very important economic corridor for Wales," he said.
"It is expanding and becoming an attractive place for people to work and live. Just like similar regions in the UK and other European countries, it needs a range of attractive, affordable and coordinated transport options to fulfil its potential."
"Many people have little choice but to use the motorway, given the lack of public transport options. We believe that a competitively priced, efficient and reliable public transport network could become the first choice for many travellers."
He also said that the suggested changes in the report would help generate extra capacity for the region's transport systems.
“Even a moderate reduction in the number of cars travelling on the M4 could result in a significant improvement to the travel flow," he added.
The report suggestions include:
New ways to organise transport services, speeding up interchange, coordinating timetables and integrating ticketing.
Improve internet connections so people can work better remotely reducing the need to travel
Local authorities to consider introducing fees for parking cars on site once changes have been made to improve public transport
A transport-focused approach to planning, ensuring developments are built around the public transport network rather than the motorway
Previous proposals for a second road, south of Newport and parallel to the existing M4 motorway between certain junctions, were ditched by Mark Drakeford in June 2019.
He said he did not see a ''compelling case in the public interest'' for the scheme, citing environmental concerns and a "substantial adverse impact on the Gwent Levels".
Despite the idea of a second road being shelved, the UK Government had revived the concept in recent months.
Boris Johnson told ITV Wales that that a relief road would "certainly be one of the things" he looked to "take forward".
Road building in Wales is the responsibility of ministers in Cardiff but the Prime Minister had also repeatedly said that he would try to find a way to bring back the project.