In January, the transport operator increased the toll that applies to traffic headed towards the city centre from €13 to €14 while leaving the outbound toll at €12.

In internal discussions, Transport Infrastructure Ireland (TII) said the volume of tollable traffic using the tunnel to dodge heavy morning traffic was rising by more than eight per cent a year.

On the M50, all categories of vehicles will experience an increase, except for unregistered motor cars without a tag or video account.