Eyholz Tunnel: North Bore broken through

The Eyholz Tunnel between Stald­bach and Grosshüs serves the A 9 motorway to circumvent Visp in the Canton of Valais/CH, passing in the south. It consists of 2 bores set some 30 m apart with 15 cross-passages given maximal 820 m overburden [1, 2]. The excavated cross-section amounts to roughly 125 m² and 190 to 280 m² in the 2 underground branch caverns. There are also 2 ventilation control centres. Each bore of the tunnel accommodates 2 driving lanes with 1 m wide shoulders at each side, a ventilation duct above the intermediate ceilings (also to remove smoke in the event of fire) and an accessible utility tunnel in the floor.

After the 4,255 m long south bore was broken through on August 31, 2012, the 4,231 m long northern one was accomplished in October. Driving the north bore commenced on May 23, 2009, 2 months after excavation of the southern one. The geology was sophisticated, primarily in the soft ground section. Furnishing the interior from Staldbach has already started. Apart from installing the inner shell, initial operations for equipping the tunnel with operating and safety technology have already got underway. It is planned to open the tunnel in 2015; the Tunnel is due to cost some 700 million CHF (560 million €).

The A 9 motorway in the Upper Valais runs some 31.8 km between Siders East and Visp East (Grosshüs Eyholz). Half of it passes through tunnels such as the Eyholz Tunnel and the 3.2 km long Visp Tunnel, and covered sections. The Canton of Valais acting on behalf of The Federal Roads Office (FEDRO/ASTRA) is the client. The opening is planned for 2016/17.⇥G.B.

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