The construction of the world’s longest railway tunnel is to take a historic step forward in Switzerland on Friday with the breakthrough of the east bore of the Gotthard Base Tunnel.
The 57km long Gotthard Base Tunnel will provide high speed rail services between Zurich and Milan. The breakthrough of its east bore marks the end of 11 years of tunnelling. When completed, the twin bore tunnel will take the record for the world’s largest from the Seikan Tunnel in Japan.
A spokesman for the project’s lead construction company AlpTransit Gotthard, Maurus Huwyler, said that earlier this month the tunnelling - which is taking place in both directions - reached 10m to go, when work was then stopped to prepare for the landmark. The two will meet in the section of the tunnel between Sedrun and Faido – one of four sections that the tunnel construction has been divided into. Formal ceremonies that will take place at the town of Erstfeld.
The tunnel, which has been constructed between Swiss towns Erstfeld to Bodio, has used four tunnel boring machines, two of which remain in use. The west tunnel bore, which has around two kilometres to go, will be completed early in 2011.
Huwyler said that the project has faced challenges in tunnelling such a large tunnel through the Gotthard Alpine pass – at its peak, there is 2.5km of rock above. He said that due to the softer rock in the section between Sedrun and Faido, progress has been slower than 1m tunnelling a day – however there have also been peaks of 20m a day elsewhere. Near Sedrun, explosives have been used in the excavation as, Huwyler said, the tunnelling risk was high enough to raise the possibility that the machine could get stuck.
The rail tunnel will open in 2017, at a projected total cost of 9.83 billion Swiss Francs (£6.4bn). It will reduce journey times from Zurich to Milan from four hours 10 minutes to two hours 50 minutes, providing a faster route than the first Gotthard tunnel.