We have seen with the M6 Toll that drivers can be turned off by the imposition of charges. There is already a toll to get into Wales on the Severn Crossing but no toll to get out.
There is no doubt that the M4 around Newport needs improving. At the moment if there is a bad accident and the road is closed there is no real alternative for drivers.
But if the road is tolled it reduced its economic effectiveness as a lot of people will be put off using it and will simply avoid it.
More top news
There will be sunny spells, with temperatures peaking at 23 Celsius (73F). However, Northern Ireland will experience frequent showers.
Scottish X-Men star Alan Cumming under fire for 'offensive' comments blaming Brexit vote on 'stupid English people'.
The Australian government said Russia's participation in the Rio 2016 Games risks damaging the reputation of the Olympic movement.