Swiss rail operator to overhaul Jura mountains’ Hauenstein Base Tunnel

Swiss Federal Railways SBB has unveiled plans to renovate the double-track Hauenstein Base Tunnel, part of the Basel–Olten railway line, one of Switzerland’s leading rail routes for freight and passengers.

The 8km tunnel was built from 1912 to 1916 and crosses the Jura mountain range between Tecknau in the canton of Basel-Country and Olten in the canton of Solothurn. S-Bahn trains run on the line to the economic centre of Basel, long-distance trains to and from the largest Swiss centres, international passenger transport and national and international freight traffic via the Lötschberg Base Tunnel.

The last major renovation work on the Hauenstein Base Tunnel was carried out from 1980 to 1987 and since then, SBB has kept the route in working order through selective maintenance and renewal projects including the replacement of heavily loaded switch parts. However, the national operator confirmed that the service life of the track will be reached in the next few years.

“In order to be able to guarantee safe, trouble-free rail operations over the next 25 years, a ‘major service’, or a basic repair, is now unavoidable,” the organisation confirmed via a project outline on its website.

The project has been budgeted at approximately CHF140M (£125M), financed by a performance agreement between the Swiss government and SBB. It will commence this autumn and continue until 2028.

As part of the overhaul, SBB will repair the tunnel vault, renew or replace tracks including rails, sleepers and ballast and re-lay all cables. Track drainage will also be selectively adapted and improved. The tunnel floor, which had to be expanded during the last renovation from 1980 to 1987 will remain unchanged.

SBB is also adapting a key ventilation shaft for the project. The 134m vertical shaft outside the municipality of Zeglingen in the Basel region is located 3.6km from the tunnel’s north portal. It has a diameter of 5.6m and a cross-sectional area of 24.6m2 and has always been used for tunnel ventilation.

Since the shaft shell is in poor condition and is subject to water ingress and damage, it must also be comprehensively repaired. However preparatory work will see the shaft equipped to channel the supply and exhaust air associated with the underground work. After completion of the construction and repairs, the shaft's original function will be restored.

Installation sites for construction logistics are located in Tecknau, Trimbach and Zeglingen. In Tecknau, these will be located at the sidings south and north of the station during the entire construction period. In Olten, the existing track and loading facility between the SBB plant and the Olten–Basel railway line will also be used for material handling.

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