A DECISION to reverse smoke extractors inside the Mont Blanc tunnel soon after fire broke out contributed to the intensity of the blaze which killed 41 people, according to the preliminary report on the disaster published on Tuesday.
As a result of the decision fresh air was sucked into the tunnel through the ventilation system at the Italian end, fanning the flames and spreading the fire.
The disaster happened on 24 March after a Belgian lorry carrying margarine and flour burst into flames close to the mid-point of the 11.6km tunnel. The blaze took 50 hours to control and destroyed 33 vehicles (NCE last week).
The interim report on the fire was published by government inspector Pierre Duffe and vice-president of the French Conseil Generale des Ponts et Chaussees Michel Marec.
It highlights a lack of co-ordination between operators at the French and Italian ends of the tunnel as a factor which worsened the tragedy.
At the French end smoke extraction fans capable of removing smoke at a rate of 150m3 per second were turned to full power within three minutes of fire breaking out. Eighteen minutes later Italian operators reversed smoke extractors, feeding the fire with fresh air without knowing what their French counterparts had done.
The report also highlights weaknesses in the design of air tight shelters inside the tunnel and says that personality clashes and commercial considerations undermined efforts to organise regular fire drills.