Dublin City Council has confirmed that the Port Tunnel, the largest infrastructural project in the history of the State, will open on 20 December.
The two-lane motorway, which is 4.5km in length, will connect the capital's port with Whitehall, close to the M50.
Dublin City Council hopes the €751 million tunnel will take 6,000 heavy vehicles off the capital's streets each day.
The underground journey will take six minutes to complete at a top speed of 80km/h.
While toll-free for trucks and buses, it will cost between €3 and €12 for cars, depending on the time of day.
The tunnel has been the subject of major rows over its cost, height and completion date.
The focus will now shift to whether trucks actually use it, whether it does ease congestion in the capital and, critically, whether it causes further traffic jams.