Dublin Port Tunnel is taking its first HGV traffic this afternoon after its official opening this morning.
Up to 1,000 people attended the opening of the €751 million project including Santa Claus and Taoiseach Bertie Ahern who were among the first special guests to drive through.
But operators admitted the opening of the tunnel to traffic had to be delayed until after 3pm because of the time it had taken to clear the large volume of people from the plaza at the port end of the tunnel.
The delay left many hauliers backed-up for several hours.
The Port Tunnel is the longest urban motorway tunnel in Europe and largest ever civil engineering project in Ireland, stretching 4.5km in both directions under the city. Initially, it is expected to carry over 6,300 vehicles and buses a day from Dublin Port to the M1 and M50 in six minutes.
At the official opening, Mr Ahern pledged the tunnel would bring cleaner air and a better quality of life to the city centre.
He described the project as "a very significant step in the delivery of a much bigger plan for better infrastructure in Dublin."
"The removal of thousands of trucks from Dublin will greatly improve the environment for all those who live, work and visit the city," he said.
Minister for Transport Martin Cullen said: "The Tunnel will help reduce congestion in Dublin thereby facilitating improvements in public transport and for the general car user, while the upgrade of the M50 and the national motorway network will allow for better access to all parts of the country for Port traffic".
National Roads Authority chairman Peter Malone said: "The Dublin Port Tunnel will provide quick toll-free access to and from our capital city seaport to the modern motorway network servicing the entire country, with direct benefits to business and citizens alike".
More than 5,000 people worked eight million man hours during the course of the project, which started in June 2001.
The majority of the tunnel is between 21 and 23 metres — seven storeys deep — below ground level, through hard limestone.
The tunnel will open free of charge to heavy goods vehicles and coaches over 25 seats at lunchtime, and it is expected that over 98 per cent
of trucks leaving the port will be able to use the new roadway.
After the first few weeks of operations, when average truck numbers using the tunnel are known, it will be opened to cars with a toll of up to €12 depending on the time of day.
Drivers are advised to switch on dipped headlights, remove sunglasses, keep a safe distance from the vehicle in front, and stick to the 80kmph speed limit.
A dedicated, specialist fire tender has been imported for the tunnel and 200 Dublin firefighters have had specialist training in Switzerland if an emergency arises.
However, the development has come under some criticisms. Independent TD Finian McGrath has strongly attacked the Government for failing to tell the public the other side of the Port Tunnel story.
"We have had cracks, noise, disruptions, moving toilets, weeping walls, leaks and over €250 million over budget," the North Central representative claimed.