Mont Blanc Tunnel - The 1999 Fire

The 1999 Fire

On the morning of Wednesday, 24 March 1999, 39 people died when a Belgian transport truck carrying flour and margarine caught fire in the tunnel. After several km, the driver realized something was wrong as cars coming in the opposite direction flashed their headlights at him; a glance in his mirrors showed white smoke coming out from under his cab. This was not yet a fire emergency; there had been 16 other truck fires in the tunnel over the previous 35 years, always extinguished on the spot by the drivers.

At 10:53 CET, the driver of the vehicle, Gilbert Degrave, stopped in the middle of the tunnel to attempt to fight the fire but he was suddenly forced back by flames erupting from his cab.

At 10:55, the tunnel employees triggered the fire alarm and stopped any further traffic from entering. At this point there were at least 10 cars/vans and 18 trucks in the tunnel that had entered from the French side. A few vehicles from the Italian side passed the Volvo truck without stopping. Some of the cars from the French side managed to turn around in the narrow 2-lane tunnel to retreat back to France, but negotiating the road in the dense smoke that had rapidly filled the tunnel quickly made this impossible. The larger trucks didn't have the space to turn around, and reversing out wasn't an option.

Most drivers rolled up their windows and waited for rescue. The ventilation system in the tunnel drove toxic smoke back down the tunnel faster than anyone could run to safety. These fumes quickly filled the tunnel and caused vehicle engines to stall; they needed oxygen to run. Many drivers near the blaze who attempted to leave their cars and seek refuge points were quickly overcome.

Within minutes, two fire trucks from Chamonix responded to the unfolding disaster. The fire had melted the wiring and plunged the tunnel into darkness; in the smoke and with abandoned and wrecked vehicles blocking their path, the large fire engines were unable to proceed. The fire crews instead abandoned their vehicles and took refuge in two of the emergency fire cubicles (fire-door sealed small rooms set into the walls every 600 metres). As they huddled behind the fire doors, they could hear burning fuel roll down the road surface, causing tires to pop and fuel tanks to explode. They were rescued five hours later by a third fire crew that responded and reached them via a ventilation duct; of the 15 firefighters that had been trapped, 14 were in serious condition and one (their commanding officer) died in the hospital.

Some victims escaped to the fire cubicles. The original fire doors on the cubicles were rated to survive for two hours. Some had been upgraded in the 34 years since the tunnel was built to survive for four hours. However, the fire burned for 53 hours and reached temperatures of 1,000 °C (1,832 °F) mainly because of the margarine load in the trailer, equivalent to a 23,000-litre (5,100 imp gal; 6,100 US gal) oil tanker, which spread to other cargo vehicles nearby that also carried combustible loads. Slowly, everything became part of the inferno. It trapped around 40 vehicles in dense and poisonous smoke (containing carbon monoxide and cyanide). Due to weather conditions at the time, airflow through the tunnel was from the Italian side to the French side. Authorities compounded the effect by pumping in further fresh air from the Italian side, forcing poisonous black smoke through the length of the tunnel. Only vehicles below the inferno on the French side of the tunnel were trapped, while cars on the Italian side of the fire were mostly unaffected. 27 people died in their vehicles. 10 died trying to escape on foot. Of the initial 50 people trapped by the fire, 12 survived. It would be over five days before the tunnel cooled sufficiently for anyone to go back in, to start repairs.