Fire detection in the Mont Blanc Tunnel

The Mont Blanc tunnel is a road tunnel in the Alps connecting Chamonix of France and Courmayeur of Italy, beneath the Mont Blanc massif. At 11.6 km, the tunnel was the longest road tunnel in the world at the time of its completion in 1965.


The Mont Blanc Tunnel between France and Italy experienced a widely publicized fire disaster in March 1999, when a truck traveling through the 11,6 km long tunnel burst into flames 6 km into the structure. The resulting fire burned for 52 hours and ended 41 lives.

The damage to the tunnel was so severe that it took almost three years to complete the renovation and modernization of the entire tunnel infrastructure. For the consortium responsible for re-building the tunnel, a compromise was not an option: They had to employ the most modern, effective and reliable fire detection technology available to protect the tunnel. They chose LIOS LHD technology.

System configuration:

  • 8 OTS-100 LHD controllers linked via gateways and ODBC-Server.
  • Fully redundant layout.
  • 384 alarm and event zones.
  • Fire localization precision 6 m.
  • Almost 14 km of sensor cable, type HDPE 8 mm.
  • Centralized visualization in the French and Italian control rooms.
  • Ventilation, traffic signal, and barrier are controlled by the LHD system directly.

Commissioned end of 2001

In case of fire, the LHD system quickly provides precise information about the location of the fire and activates procedures in the ventilation system to slow down the natural tunnel wind at the point of the fire and extract smoke efficiently.


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