The Project

In the 80's the City of Marseilles decided to connect the two motorways, the A50 and the A55, via an underground path which would trace the route of the old Prado Carénage railway tunnel built in the 19th Century and then abandoned.

Opened in 1878, this tunnel enabled the transportation of merchandise between the Prado station and the Carénage basin; but it was only used for a few years, because the expansion of the port basins towards to the North caused all interest in this link to be lost and it was quickly abandoned.

Old Prado Carénage railway tunnel

  • The railway tunnel has been rebuilt as a road tunnel on two unidirectional levels, each with two 3-metre-wide lanes.
  • Its total length is 2,450m.
  • Heavy vehicles and vehicles higher than 3.2m are not allowed to use the tunnel.

Creation of the Prado Carénage road tunnel

Civil Engineering

The work took 33 months, from January 1991 to September 1993.

The upper carriageway corresponds to that of the existing tunnel but the tunnel had to be "deepened" to include the lower carriageway.


Deepening the Prado Carénage tunnel

The 2 road levels and their ventilation shafts

Adapting the railway tunnel

Stabilising and reinforcement of the existing tunnel, concreting of the abutments (1 and 2)
Deepening then concreting of the lower abutments and of the separating slab (3 and 4)
Concreting of the lower surface and creation of ventilation shafts (5)


Carenage interchange

This is a complex work comprising three levels of road in each of which all lanes are one-way.

The quality of the area (ranked) and its smallness led to the optimisation of the integration of this interchange and ventilation station with the building of a wall decorated with rocks and the creation of landscaped gardens.

Prado interchange

This is located at the East end of the tunnel, next to the old Prado station. In the year 2001, the 26th Centenary Park replaced this unused station.
The two toll stations were built on this interchange. Special care was taken with the toll area in terms of its architecture and acoustics.