On 24 March 1999, a transport truck caught fire while driving through the Mont Blanc Tunnel between France and Italy. When it stopped halfway through the tunnel, it violently combusted. Other vehicles traveling through the tunnel quickly became trapped and they also caught fire as firefighters were unable to reach the transport truck. 39 people were killed. In the aftermath, major changes were made to the tunnel to improve its safety.
Fire
On the morning of 24 March 1999, 39 people died when a Belgian transport truck carrying flour and margarine, which had entered the French-side portal, caught fire in the tunnel.
The truck came through the tollbooth at 10:46 CET. The initial journey through the tunnel was routine. According to the National Geographic documentary programme Seconds from Disaster, the fire and smoke appeared at around 10:49. Shortly after, 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 cabin. This was not yet considered a fire emergency. In fact, 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, the driver of the vehicle, Gilbert Degrave, stopped into the tunnel, in attempt to fight the fire but he was suddenly forced back when the payload violently combusted. Degrave subsequently abandoned his vehicle and ran to the Italian entrance of the tunnel.
At 10:54, one of the drivers called from refuge 22 to raise the alarm. 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 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 two-lane tunnel to retreat back to France, but navigating the road in the dense smoke that had rapidly filled the tunnel quickly made this impossible.
Between 10:53 and 10:57, the smoke had already covered half a kilometre of the French side. The larger trucks were stranded, as they did not have the space to turn around, and reversing out was not 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 restricted oxygen, disabling vehicles including fire engines which, once affected, had to be abandoned by the firefighters. Many drivers near the blaze who attempted to leave their cars and seek refuge points were quickly overcome due to toxic components of the smoke, mainly hydrogen cyanide.
At 10:57 and 10:59, two fire trucks from Chamonix responded to the unfolding disaster. Melted wiring had eliminated any possible light sources in the tunnel; in the smoke and with abandoned and wrecked vehicles blocking their path, both fire engines were unable to proceed, and were blocked at garage 17, from the burning truck. Without other possibilities, they abandoned their vehicles and took refuge in two of the emergency fire cubicles (fire-door sealed small rooms set into the walls every ).
Between 10:57 and 11:01, Italian firefighters had come within 300 metres of the truck, with two of them able to proceed to the garage 21. They were able to see the burning truck. However, burning fuel flowed down the road surface, causing tyres and fuel tanks to explode and sending deadly shrapnel in the air, thus spreading fire to other vehicles. This had forced Italian firefighters to retreat, and they rescued 12 people from Italian side.
At 11:10 six Chamonix firefighters entered the tunnel, but were blocked at the garage 17 from the truck. By 11:11, more Italian firefighters had come to tackle the fire. They were blocked at garage 22 and had also abandoned their vehicles, and searched for trapped groups of firefighters who had taken refuge in the fire cubicles. When it was realized that the cubicles were offering little protection from the smoke, they began searching for the doors that led to the ventilation duct.
By 11:30, 37 minutes after start of the fire, smoke had reached the French entrance of the tunnel, from the truck. At 11:39, another team of firefighters entered the tunnel from the French side but were blocked at the garage 5, from the truck.