The National Roads Authority (NRA) and Dublin City Council unveiled the completed Dublin Port Tunnel yesterday - and were immediately accused of a lack of planning for 9,000 lorries which critics said will be "dumped on the M50".
The 4.5km tunnel, which is set to cost over €750 million, will open on December 20th.
The opening will be followed on February 19th by a ban on heavy goods vehicles of more than five axles in an area between the city's canals and including the Navan Road and Sandymount.
Announcing the official opening date yesterday, the NRA and the city council said they did not believe 21,000 vehicles - made up of 6,300 heavy vehicles and up to 3,000 smaller lorries among others - would impact significantly on existing traffic on the M50.
However, they were immediately contradicted by hauliers and members of the Oireachtas Committee on Transport, who accused the NRA of "an unbelievable lack of planning".
The Irish Road Haulage Association claimed roads authorities could be "at least 100 per cent off" in their predictions.
Haulage association spokesman Jimmy Quinn said a number of issues in relation to the tunnel and the related heavy goods vehicle ban in the city centre remained to be addressed.
These included safety issues in routing much of the State's petrol and hazardous-substance suppliers through the tunnel. He insisted this would not be accepted in France or many other European countries.
He predicted the cordon ban would cost hauliers €29 million annually, including the cost of using the West-Link bridge.
Mr Quinn also insisted a complicated traffic manoeuvre at the northern end of the tunnel "would require an awful lot of good manners from motorists and lorry drivers".
He said a one kilometre stretch of motorway would see lorries emerging from the tunnel and then moving to the left, crossing the M1 traffic coming from Dublin city centre. Yet because traffic cannot stop in the tunnel, the tunnel must close if this kilometre section becomes congested.
This kilometre was also pinpointed by Labour Party spokeswoman on transport Róisín Shortall, who said "the mind boggles" at the arrangements in place to accommodate displaced traffic from the city centre.
As well as the "2,500 lorries which will be dumped on the West-Link", existing roadworks on the M50 would combine with traffic from the proposed Ikea store to create an intolerable situation for road users.
Fine Gael spokeswoman Olivia Mitchell said much of the difficulty on the M50 was caused by a lack of planning to remove the West-Link barrier. She challenged the NRA to lift the barriers to see how traffic would perform.
NRA chief executive Fred Barry said planning for the tunnel had begun in the 1990s before many of the current problems with the M50 were envisaged. However, he defended the timing of the opening, saying: "As it is there you would open it."
On the question of the toll barriers, Mr Barry responded: "Would it be better if the electronic toll was in place, yes it would."
