RECONSTRUCTION of the Mont Blanc tunnel after the fire which claimed 39 lives in March 1999 is nearing completion.
Linking France and Italy through the Alps, the privately owned single tube tunnel has been closed to improve safety. Work involved excavating more refuge niches, installing more exhaust ducts and building regular escape connections from the tunnel to the fresh air ducts beneath the road deck.
There will also be a large chamber at the tunnel midpoint designed to house an around-the-clock monitoring and fire emergency station. This will work in conjunction with the emergency stations at each tunnel portal.
Drill and blast techniques are being used to excavate the hard granite in the tunnel. Immediate support to the excavations is being provided by rockbolts and steel fibre reinforced shotcrete, applied using Aliva shotcreting equipment. A 450mm thick layer of non-reinforced cast insitu concrete lining provides the finish for the new structures.
Work is divided into two contracts split between the Italian and French halves of the tunnel. Safety has been a key issue; wet mix shotcrete was specified to reduce dust and maximise visibility.