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