Excavation has begun at the Mont Blanc road tunnel between France and Italy for fire safety refuges and emergency points, some 18 month after the horrific traffic fire disaster that claimed 39 lives (T&TI May 1999).
The civil engineering programme will be followed by an electrical and mechanical installation to give the tunnel a range of automated control and monitoring systems as well as new information and traffic control signalling systems. These will include closed circuit TV with incident recognition software, traffic flow detectors in the road bed and temperature detectors, which will monitor and track heavy goods vehicles entering the tunnel.
According to Laurent Samama, an engineer with specialist consultant Scetauroute in Paris: “No ‘state-of the art’ systems will be installed – they are all proven. But no tunnel in the world has so many systems working together.” The electronic contracts are still to be finalised but the civil engineering is designed and under way.
New and more frequent fire refuges will be built in 5m high vaulted rock chambers, carved alongside the road every 300m. There will also be a series of other excavations for new ventilation ducts at 100m intervals, emergency telephone and fire control “niches” along the tunnel and, at the tunnel midpoint, a 45m² fire station, which will be permanently manned by a three-man fire team and two fire appliances, one light and one heavy.
The tunnel previously had small refuges at 600m intervals and less frequent fire alert points. It had and will continue to have short sections with an additional lane every 150m, so called garages.
The civil works in the French sector were announced last month by the French side tunnel concessionaire Autoroute du Tunnel de Mont Blanc (ATMB). On the Italian side, SITMB, which operates the southern 5.8km long section, is carrying out similar works following repairs on the vault.
A section of the tunnel more than 1km long on the Italian side was badly damaged on 26 March last year when a lorry caught fire and burned out of control within the tunnel. Concrete from the 700mm thick lining has had to be replaced and the vault strengthened.
The new structures on the French side are being built in a crash civil engineering programme by a JV contractor comprising Bouygues, GTM-Dumez and Italian firm Impregilo.
The contract is worth euro25M ($21.5M) and lasts just 23 weeks, six for preparation and 17 for a round-the-clock programme of excavation and building. Work will be in three shifts over 24 hours, six days a week.
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Excavations to improve fire safety features at the Mont Blanc Tunnel have been started
