Construction will begin on the new SFr 350m 2.7km tunnel between Effingen and Schinznach on the Basle - Zürich line in spring 2016, with commissioning scheduled for 2020.

Implenia's contract includes the installation of track and some of the electrical equipment, as well as conversion of the existing 2.5km tunnel into a rescue and service tunnel. The old and new tunnels will be linked by five cross-shafts to provide emergency access.

Clearances are being increased in more than 20 tunnels as part of the 4m corridor project, which also involves alterations to 150 station platforms along the north-south route.