Introduction
In the Alpine mountain range, under western Europe’s highest peak, the Mont Blanc Tunnel joins Chamonix, France, and Courmayeur, Italy. It is one gallery (level) with a two-lane, dual direction road and 11.6 kilometers (7.25 miles) long. The tunnel opened in 1965 and is a primary trans-Alpine transportation route; it transports about one-third of Italy’s freight to northern Europe.
Truck Set Ablaze
On 24 March 1999, 39 people died in what started as a Belgian transport truck fire in the Mont Blanc tunnel. One theory is that a lit cigarette tossed from another vehicle entered the engine induction snorkel above the truck's cab, setting the paper air filter on fire. Other theories blame a mechanical or electrical fault or poor maintenance of the truck's engine.
The truck was carrying flour and margarine bound from France to Italy. After driving several kilometers and noticing oncoming drivers flashing their headlights, the driver realized something was wrong. In his mirrors he saw white smoke streaming from under his cab. This was not yet a fire emergency; 16 other truck fires in the tunnel over the previous 35 years had all been extinguished on the spot by the drivers.
At 10:53 a.m., the truck driver stopped, halfway through the tunnel, to try to fight the fire, but suddenly erupting flames forced him away.
Dense Smoke Blocks Retreat
At 10:55, tunnel employees triggered the fire alarm and stopped any further traffic from entering. At least 10 cars or vans and 18 trucks had entered from the French side since the truck entered the tunnel. A few vehicles from the Italian side passed the truck without stopping. Although some cars from the French side managed to turn around to retreat, the dense smoke quickly made this impossible. Larger trucks 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, but smoke fumes quickly filled the tunnel and vehicle engines stalled from lack of oxygen. Many drivers near the blaze who tried to leave their cars and seek refuge points were quickly overcome. The tunnel’s ventilation system drove toxic smoke down the tunnel faster than anyone could run to safety.
Rescue Attempts
Within minutes, two fire trucks from Chamonix responded. In utter darkness (the fire had melted electrical wiring), in the smoke, and with abandoned and wrecked vehicles blocking their path, the large fire engines were stymied. The fire crews abandoned their vehicles for refuge in two of the emergency fire cubicles (fire-door sealed small rooms set into the walls every 600 meters).
Huddled behind the fire doors, they heard burning fuel roll down the road's surface, tires popping, and fuel tanks exploding. Five hours later a rescue crew reached them via a ventilation duct; 14 of the 15 trapped firefighters were in serious condition and one (their commanding officer) died in hospital. Another rescue worker perished after dragging several motorists to safety on his motorcycle.
Fate of Civilian Travelers
Some civilians escaped to fire cubicles. The original fire doors on the cubicles were rated to survive for two hours. Since the tunnel was built, some fire doors had been upgraded to survive for four hours. But, the fire burned for 56 hours, reaching temperatures of 1,000 °C (1,832 °F) mainly because of the margarine load in the trailer, equivalent to a 23,000 L oil tanker. The fire spread to other cargo vehicles that also carried combustible loads.
Slowly, the inferno grew. It trapped about 40 vehicles in dense and poisonous smoke (containing carbon monoxide and cyanide). The gradient (an inverted V) of the road turned the tunnel into a chimney—sucking cold air in one side with the intense heat and smoke leaving the other side. Authorities compounded the effect by pumping fresh air in from the Italian side, forcing poisonous black smoke through the length of the tunnel. Only cars on the upper side of the tunnel were trapped; cars on the other 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.
More than five days would pass before the tunnel cooled sufficiently for anyone to enter.
Conclusions
• The cause of the tragic loss of life was not commercial traffic, but the lack of coordination in the institutional and organizational operation of the tunnel and the insufficient equipment and construction features of the tunnel itself.
• The truck that caught on fire was carrying a particularly combustible load for a vehicle that was not designated for hazardous cargo; the smoke released by the combustion also was very toxic.
• From the time the truck entered the tunnel and the tunnel closure nine minutes later, a motorcycle, 10 passenger vehicles, and 18 trucks entered the tunnel. Four trucks passed the burning truck after it had stopped; 26 vehicles were trapped.
• The French fire detection system, which measures heat and gives alarm over 50 °C, had sensors located every 8 meters. They did not alarm while the vehicle was driving but set off much later. The Italian system worked differently, using sealed tubes containing a special gas that run for 70–80 meters each. This system was prone to giving false alarms and, for this reason, the tubes at #21 (where the truck stopped) were switched off the night before. The Italian system did not signal any fire.
• The strong air supply at the roadway level, the air flow at the ceiling, and the longitudinal air flow all contributed to feed the fire and destratify the smoke, which, instead of staying at the ceiling and clearing up at the motorists' level, filled the entire cross section of the tunnel.
• The hot, toxic smoke was not extracted in sufficient quantities because the exhaust capacity limitations of the tunnel and the use of exhaust ducts in supply mode.
• Vehicles stopped very close to each other, contributing to the rapid propagation of the fire and trapping motorists in the toxic smoke cloud.
• Tunnel traffic signals were every 1,200 m and turned to red several minutes after the alarm; they did not limit the losses because some were not working, they were hardly visible, or they were not obeyed.
• Safe refuges in the tunnel were inadequately spaced and the tunnel did not have a connected safety corridor. This would have allowed the approach of rescue teams and the evacuation of personnel.
• The tunnel was operated by two companies with two distinct control centers (one at the Italian portal; one at the French portal); coordination was poor.
• The operators did not know, even approximately, the number of motorists inside the tunnel.
• Although an upgrading program started in 1990, some tunnel equipment was outdated and safety requirements, from 1985, did not apply to fires. The slow upgrading was due partly to disagreement over capital investments between the tunnel’s two leasing companies.
• The number of fire drills performed was inadequate and no joint fire drills had been conducted for 10 years. According to the official accident report, this was partly due to “local personal conflicts.”
• The operators’ first response assets were inadequate: an Italian fire engine could not be used immediately for lack of qualified personnel.
Practical Lessons
• Proper hazard identification: It might not always be readily apparent what is a major hazard or what can cause a major accident event
• Comprehensive fire detection: Systems capable of detecting incipient fires and initiating early alarm should be provided where fire and smoke hazards and potential consequences are significant
• Adequate escape, temporary refuge and evacuation facilities: Do not underestimate the impact of smoke; whilst we generally ensure a diversity of escape routes on hazardous facilities, we also need to ensure that other facilities are adequately protected from fire and smoke ingress for sufficient duration and that people can safely evacuate from these areas.
• Proper coordination is required between stakeholders: Establish clear emergency control hierarchy and responsibilities, which is critical in areas where multiple facilities are in close proximity to each other and where ‘domino’ effects are possible.
• Test emergency response: Involve all stakeholders in testing emergency response capabilities with realistic major accident scenarios
• Impaired safety barriers: Safety systems are installed for good reason. If any such system becomes difficult to maintain, is unreliable, or does not function properly, do not bypass or remove it. Understand the role of the system in managing major hazards and provide an alternative that meets or exceeds the designers’ original intent.
References
- Bailey C. Infrastructural Fires. One stop Shop in Structural Fire Engineering by the University of Manchester. Online at http://www.mace.manchester.ac.uk/project/research/structures/strucfire/CaseStudy/HistoricFires/InfrastructuralFires/mont.htm. Accessed June 30, 2009.
- Kosaka H. (1999) Some Lessons from the Mont Blanc Tunnel Fire. Expressways and Automobiles. V 42 No 9 pp36–40. [Abstract online at http://sciencelinks.jp/j-east/article/199922/000019992299A0834674.php. Accessed June 30, 2009]
- Mont Blanc tunnel fire inquiry highlights safety problems. (02 March 2005) Euronews, International News. Online at http://www.euronews.net/2005/02/03/mont-blanc-tunnel-fire-inquiry-highlights-safety-problems/. Accessed June 30, 2009.
- Pierre Duffé, Inspector General, and Michel Marec, State Engineer of Bridges and Highways, Report of the Task Force for Technical Investigation of the 24 March 1999 Fire in the Mont Blanc Vehicular Tunnel, Minister of the Interior, Ministry of Equipment, Transportation and Housing, June 30, 1999. [English translation by Sergiu f. Luchian, P.E. Online at http://www.miliarium.com/Monografias/Tuneles/Mont_Blanc.htm. Accessed June 30, 2009.]
- Public Private Partnership Projects. Insurance Cover as part of the General Risk Management Strategy. ITA Conference Prague, May 8, 2007. Online at http://www.ita-aites.org/cms/fileadmin/filemounts/general/pdf/ItaAssociation/ProductAndPublication/OpenSession/OS_2007_Wannick.pdf. Accessed June 30, 2009.
- The Mont Blanc Disaster – 41 deaths, 52 hours burning. Online at http://www.landroverclub.net/Club/HTML/MontBlanc.htm. Accessed June 30, 2009.
Photo Sources
• Mont Blanc Tunnel: Deal reached on Mont Blanc tunnel (26 Mar 2002). BBC News. Online at http://news.bbc.co.uk/2/hi/europe/1895523.stm. Accessed 30 June 2009.
• Mont Blanc Tunnel Fire Damage: Mont Blanc tunnel needs new repair. (4 Feb 2002) BBC News. Online at http://news.bbc.co.uk/2/hi/europe/1800009.stm. Accessed 30 June 2009.
About IRC Risk and Safety
IRC
Risk and Safety provides practical answers to tough risk and safety
issues. We promise remarkable delivery and to always be
responsive.
We are based in Houston with an office in the Netherlands. Our speaking engagements receive outstanding feedback.
Copyright © 2009 IRC Risk and Safety, LLC |
|
