A 150m3 rock collapse closed the 1.3km long Chüebalm tunnel, between Brienz and Interlaken, in Switzerland last month, with more rock falls expected. Nobody was hurt.
Although a protective gallery had been constructed over the entrance of the tunnel, the amount of rock that fell onto the A8 highway was far greater than design limits, and crashed through the roof, extending 10m-15m inside the tunnel.
At the time of writing, engineers were keeping the entire site clear because of the risk of further falls. A spokesman for the Swiss federal road office said: “We are not repairing the tunnel yet. We are expecting another 400m3 to fall. If it doesn’t fall naturally in the next couple of days, then we will dynamite it.”
The nearby community of Iseltwald was also affected by the fall, and the inhabitants of 16 houses had to be evacuated.
Rehabilitation has been sidelined until engineers can concentrate on the selection procedure.
The cost of repairing the damage is also unknown. “We can’t estimate the cost of putting the tunnel and rock face straight, for two reasons,” Mr Schatzmann, head of maintenance for the Canton of Bern, said. “First is the construction aspect of putting the road and tunnel back into shape, and secondly, the cost of reinforcement, which could be quite extensive.”
