Technical details

One-way traffic flow over 2 levels, one above the other

Motorists travel in two lanes going in the same direction. They can overtake but do not meet oncoming traffic.

There are escape stairways every 300 metres for the evacuation of pedestrians in the event of a serious accident, fire...

These pressurised stairways are protected by fire doors.

16 Safety recesses for each direction:

Every 150 metres, safety recesses are equipped with 2 fire extinguishers and an emergency telephone linked to the tunnel Command Post. Fire hydrants for fire fighters are also installed every 150 metres.


There are escape stairways every 300 metres for the evacuation of pedestrians in the event of a serious accident, fire...

These pressurised stairways are protected by fire doors.

Ventilation system

The tunnel has a semi-transverse ventilation system.
Three stations blow fresh air into the tunnel. Two of the stations are situated one at each end and the third, in a central position, also allows the extraction of used air when saturation linked to the intensity of traffic so requires.

The amount of air blown in can reach 500m3/second. This air is distributed through the ventilation shafts, through traps at 10m intervals all along the tunnel.

What happens in the eventof a fire?

Different scenarios have been anticipated depending on the location of the fire in the tunnel

In the event of a fire, the Command Post operator calls the Marseilles Marine Fire Battalion on a direct line. The operator also broadcasts warning messages on the FM radio waves rebroadcast inside the tunnel.

The CRS (French Republican Security Companies) and the Marine Fire Battalion take charge of the operation and decide upon the measures to be taken to protect the people and vehicles present in the tunnel.

Example of smoke extraction from lower tunnel section nº1:

The ventilators can be used to extract smoke by reversing their direction of rotation. The smoke can also be extracted using the central ventilation station. The ventilation and smoke extraction system is tested once a year during the annual security drill in collaboration with the Marseilles Marine Fire Battalion.

Instruments to measure pollution

Measuring instruments positioned throughout the tunnel monitor the levels of Carbon Monoxide (CO), the clearness of the air and the speed of the air flow at all times. They are linked to CTM which automatically regulates the in-flow or extraction of air based on the parameters observed.

Carbon Monoxide Anemometer Opacimeter
80 cameras linked to the command post

The entire length of the tunnel is monitored 24/7 by 62 cameras linked to the Command Post which provide the operator with information on the status of the traffic in the tunnel in real time.


Digital message boards

9 DMBs are distributed around the various tunnel entry points in order to communicate as much information as possible to motorists.

They mainly announce the open and/or closed status of tunnels in the City of Marseilles, potential work or accidents, and the time needed to get through the tunnel. These boards can also show warning messages if necessary, for example when pollution is at peak levels.

The Marketing and Communication service also has a 3x2m luminous screen on the upper toll level in the Marseilles-Aubagne direction. This screen is for advertisement but can be used as an information screen to show important evening events at the Vélodrome Stadium, or incidents on the A51 Motorway.

Control of oversized vehicles

Access to the tunnel is limited to vehicles with height less than 3.2m for obvious security reasons and due to the height of the inside of the tunnel. However, some motorists do not respect these necessary requirements for passage through the tunnel. Therefore, devices have been placed in the tunnel to prevent these vehicles from entering and redirect them.


If these measures are not sufficient to stop these oversized vehicles from entering the tunnel, a second, larger, louder, more visible system takes over to let the driver know that he should proceed no further.