Tunnel designers and operators across the globe got a wake-up call in April 1999 when a lorry fire wreaked havoc in the 11.6km, single bore Mont Blanc road tunnel which links France and Italy.
Forty one people are officially said to have died, mostly from smoke inhalation, in an accident that highlighted design weaknesses and a catastrophic degree of complacency among those responsible for the tunnel.
The fire began in a lorry carrying margarine and flour, and quickly turned into an inferno just to the west of the tunnel’s mid-point, plunging operators at the French and Italian ends into chaos. Alarm systems failed to function properly, communications broke down, and fire fighters struggled to get close enough to the fire to fight it.
To make matters worse, Italian operators decided to direct ventilation towards the blaze, while their colleagues on the French side had already done the opposite, effectively turning the tunnel into a horizontal chimney pushing toxic smoke onto motorists close to the eastern side of the fire.
Within 10 minutes most of the victims were dead, 300m of the tunnel was ablaze, trapping 36 vehicles including 25 lorries. Temperatures soared to 1,000°C.
When NCE asked Remy Chardon, the French chairman of the operating company when the most recent fire drill had been, his shocking reply was that his organisation had neither refused nor authorised a fire drill.
“If we had had a request, we would have acted immediately,” he said. It turns out that there had been no fire drill since 1973.
Chardon was subsequently fined £11,000 and received a suspended prison sentence for his role in the disaster.
His head of security received a six month prison sentence, but more importantly the blaze made operators and designers of other tunnels re-examine fire risks.
When the Mont Blanc tunnel was built in 1965, the transalpine crossing was considered to be a significant engineering achievement, and indeed in terms of tunnelling it was.
But the design had failed to anticipate the traffic volumes of the late 1990s.
Fire escape routes were nonexistent as there was no parallel bore into which motorists could escape. Fire crews could not see in the thick smoke and rescue vehicles ploughed into the tunnel walls as a result.
Some motorists managed to get to fire shelters built into the tunnel wall at 300m intervals, but these were unsafe and two people died inside them after suffering the effects of smoke inhalation.
The blaze triggered new European tunnel safety regulations which have affected the design and operation of existing and new tunnels in Europe.
Mont Blanc tunnel was extensively refurbished with an escape route built into the under road ventilation system, improved signage and ventilation and an overhauled Franco/Italian management and communications structure.