A total of 500 million Swiss francs will be invested in the reconstruction of the 3.2-km-long Bellchen Tunnel. The joint venture company composed of Marti Tunnelbau, Marti Basel and Marti Solothurn is responsible for the construction of the new subway on the Swiss A2 highway between Hägendorn in Solothon and Eptingen in Basel on behalf of the Swiss Federal Highway Administration. The new tunnel will be completed in 2022 and will be able to refurbish the two-lane pipeline separated in two directions from the Bellchen Tunnel before 1970 without restricting traffic. At present, the daily traffic volume of these four available lanes is no less than 55,000 vehicles.

After a lot of preliminary work, the largest TBM in Swiss history began operation in early February 2016 to build a new pipeline at a distance of 40 to 116 m parallel to the existing tunnel system. The single-shield TBM S-947 produced by Herrenknecht has a cutter head diameter of 13.97 m. The TBM is 75 m long and weighs about 2000 t. During the excavation process completed in May 2017, approximately 470,000 m³ of rock was removed.Editor/Luo Wentao