The tunnel is made up of 18 caissons and a traffic lane in each direction, a sidewalk on the north side, and three ventilation shafts (one air exhaust and two air intakes).
The two traffic directions are separated by a central support structure that forms the first ventilation shaft (the air exhaust).
The caissons lie directly on the bedrock.
In 1968, the tunnel was restored and resurfaced. Since then, maintenance work on the tunnel, such as pavement repairs, cleaning and painting of the walls, and restoration of the approaches, has been ongoing to preserve the structure’s integrity and to ensure users can use the tunnel safely and efficiently.