FAILED SMOKE control measures were responsible for the death of two truck drivers in a blaze in the FrÚjus Alpine tunnel last month, fire experts said.
They expressed surprise that smoke dampers installed three years ago in response to the 1999 Mont Blanc disaster failed to keep the 12.7km long tunnel clear of smoke.
The fire is believed to have started on the evening of Saturday 4 June evening in the engine of one HGV travelling from France towards Italy. The blaze spread to its cargo of tyres and then spread to at least three other HGVs, one apparently carrying coal and one loaded with epoxy adhesive.
Both dead men are believed to have got away from the immediate vicinity of the fire but died of smoke inhalation while making their escape.
Seventeen people were treated for smoke inhalation, including fi ve fire fighters.
Fire fighters took six hours to bring the blaze under control.
'This tragedy shouldn't have happened; nobody should have suffered from smoke inhalation, ' said Halcrow fire safety engineering director Fahti Tarada.
'Safety measures in the tunnel were upgraded in the wake of the 1999 Mont Blanc tunnel disaster. Smoke dampers were installed three years ago, and these should have kept all but the immediate area around the fire clear of smoke.' The dampers - essentially large remotely operated vents - were installed in the tunnel's false ceiling at 80m to 100m centres (see diagram). Under normal conditions these are left slightly open to allow vehicle exhaust fumes to be extracted. In the event of fire, one or two vents nearest the incident are fully opened while the rest are slammed shut, allowing the tunnel's existing ventilation system to suck the smoke away.
'Photos of the fire clearly show smoke pouring out of the Italian portal, ' said Tarada.
'If the smoke dampers had been working properly the smoke should have gone up the normal exhaust shafts.' Edinburgh University Fire Research Centre research fellow Ricky Carvel said that the fire may have been too big for the ventilation system to cope with.
'There have been two HGV fires in the FrÚjus tunnel since 1998, the last in February last year.
'Neither resulted in any injuries and the tunnel was closed for a couple of hours only, ' said Carvel.
Plans to drive a parallel 4.5m diameter escape tunnel alongside the tunnel were announced last year. But this is not due to be completed until 2011. In the meantime, investigators will focus on the performance of the tunnel's heat sensors and CCTV monitoring.
As NCEI went to press there were no reports of serious damage to the tunnel's lining, which was protected by calcium silicate boarding in 2003.