New Bözberg Tunnel: Structural Measures when Tunnelling in squeezing Rock

The new Bözberg Tunnel is part of the so-called “4-Metre Corridor” on the northern access route to the new Gotthard Base Tunnel. After the new tunnel has been completed, freight can be transported in combined mode with a corner height of 4 m on the Gotthard artery through Switzerland and in turn, on the important Rhine-Alps goods train corridor as from the 2020/2021 modified timetable. The existing Bözberg Tunnel dating back to 1875 is not capable of coping with the required clearance profile and is being replaced by a twin-track tunnel that runs parallel to it. This possesses a considerably greater clearance profile in accordance with EBV 4/S3. The existing tunnel will be converted for use as a service and evacuation tunnel and linked to the new structure by means of five cross-passages.

1 Introduction

The new Bözberg Tunnel with a total length of roughly 2.7 km is the longest single element among the structures on the 4-Metre Corridor, which were largely driven mechanically using a TBM. SBB-Infrastruktur for the first time invited tenders for the main project, the twin-track tunnel in keeping with the new “General Contractor Plus” award model and commissioned the Swiss contractor Implenia to implement it.

The project is located in the Canton of Aargau between Brugg and Frick and passes through the sophisticated geology of the Swiss Faltenjura. A particular challenge is posed by...

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