In normal operating mode, the monitoring of a tunnel usually consists of a visual monitoring of traffic by means of video surveillance cameras (CCTV).
In the event of an incident in the tunnel, the alarm can be raised by video surveillance or by more specific means such as:
The ‘’quality” of the information provided by each of these devices is linked to the very nature of the device (an emergency call station makes it possible to locate and establish contact with users, whereas notification of the removal of a fire extinguisher may indicate the start of a fire, but does not provide more detailed information).
These devices therefore do not provide the operator with the same degree or ‘’quality” of information, although they provide an initial alert. The operator may use additional equipment to verify the alert or to obtain further information.