Road tunnel safety - Technical provisions

Fires in tunnels, whether caused by accidents or not, can have catastrophic consequences for people. The fire in the Franco-Italian Mont Blanc tunnel in March 1999, followed by the accident in the Austrian Tauern tunnel in May 1999, and finally the accident in the Swiss Gotthard tunnel in October 2001, unfortunately highlighted this risk.

What's more, among the multitude of minor incidents that can occur in tunnels, some can, through a chain of circumstances, have dramatic consequences. These incidents must be detected early enough to prevent them from degenerating into disasters.

The degree of tunnel supervision varies widely from one structure to another, ranging from no supervision at all to highly sophisticated supervision where the operator is able to act very quickly thanks to the information provided by automatic accident detection (AAD) and other systems:

• informing users and encouraging them to adopt the most appropriate behavior;

• alerting emergency services ;

• action on the equipment at its disposal (closing the tunnel, starting smoke extraction, etc.);

• trigger on-site intervention by specialized operating teams and, if necessary, the fire department.

This means that tunnel operators have to implement a real safety chain, starting from an incident. It is based on a set of equipment whose design, construction, maintenance and operation must be carried out in a systemic spirit.

This article deals with the provisions adopted to design and build this equipment in the case of tunnel construction. Upgrades to existing tunnels and operating and intervention measures will be dealt with in a later article.