An important phase has been completed in the construction of the approximately 2 km long, two-track Rosshäusern Tunnel on the line from Berne to Neuchâtel. After the decision to change the method of construction, the last blast took place in the upper half of the tunnel (top heading) 181 m west of the tunnel middle at the start of June 2015. After the breakthrough, the upper half of the tunnel will be refinished in the following three to four months, before the excavation of the lower half, the bench and the invert, is started in the autumn. The tunnel should be structurally complete in the middle of 2017.
The Rosshäusern Tunnel is the key structure in the two-track widening of the line from Rosshäusern to Mauss and makes up about half of the section. It will replace the original 1.1. km long single-track tunnel, which is 110 years old and in need of refurbishment. Excavation of the new tunnel started in spring 2013. Due to the difficult geological conditions, the method of tunnelling was changed in January 2014. Instead of full-face excavation from the east, the top heading was advanced first from east and from west. The change of tunnelling method in fractured rock has proved successful according to the owner company BLS AG; the works have made better progress than originally expected. The construction project has suffered a delay of about 18 with an increase of cost by 65 to about 265 million Swiss francs. The first trains should be able to travel on the new two-track line from the middle of 2018. / G.B.