Sustrans Cymru - an organisation that promotes greener transport - has condemned the potential M4 Toll as "poor value for money".
A spokesman said that a "more cost effective way to reduce congestion would be to invest in shifting these journeys to public transport."
"The Welsh Government acknowledges that 40% of journeys on this stretch of the M4 are local trips of under 20 miles," he added.
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It is the model and actress’s first daughter.
The baby’s full name is Neve Te Aroha Ardern Gayford.
The first LNER service will be the 7.54am departure from Newcastle to London King’s Cross.