Traffic management

To manage the traffic and provide users with more comfort, a large variety of equipment can be installed inside the tunnel. Signs and signals are some of the main devices available to the operator to perform this task.

For a given type of road, tunnels have the same signs and signals as in open air:

• Fixed signs (direction signs, danger signs, speed limits, etc.)
• Dynamic signs or signals (lane allocation signs, variable message signs).

The means available to the operator to manage the traffic on the route where the tunnel is located and inside the tunnel include:

• Tunnel lane control signs,
• Traffic signs and signals on approach roads,
• Portal message signs,
• Diversion signs and signals,
• Tunnel closure barriers.

This equipment could be located inside the tunnel, but also at the entrance to the tunnel and (if possible) at a distance sufficient for the user to be able to be diverted to an alternative route, if necessary. The main problem with regard to signage within a tunnel relate to the geometrical characteristics which must be optimised. Increasing the cross section will lead to significant extra costs. In practice, a compromise must be found between the need for good visibility of the signs (which must be sufficiently large) and the space available.

The different safety devices available to tunnel users (emergency telephones, extinguishers, emergency exits...) require additional specific safety signage (see page Monitoring and Incident detection and Evacuation aids).