The Dublin City Council and the NRA have released a statement, dismissing a new proposal for the Dublin Port Tunnel.
The Transport Umbrella Group today presented a plan to resolve the long-running row over height restrictions to a Dáil committee.
The group claims that by simply widening the footpaths in the tunnel, large trucks will be able to use it as they would be forced to drive closer to the centre; where the walls are a third of a metre higher.
The TUG says that if changes are not made, up to 900 large trucks a day will not be able to use the facility when it opens and will remain on city streets.
But the DCC and the National Roads Austhority have said the plan is based on a 'complete misunderstanding' of the tunnel layout.
In a joint statement the two bodies said the plan ignores constraints posed by mechanical and engineering services in the roof space. They also said the narrowing of the carriageway would compromise safety in the tunnel.
However, the Minister for Transport Séamus Brennan has indicated that he would be willing to study any new proposal in detail.