Pilot project: applying the Tunnel-in-Tunnel method on DB electrified routes

This report deals with the refurbishing of the Petersberg Tunnel. In this connection, for the first time within the scope of the pilot project, the tunnel-in-tunnel method was applied on an electrified line belonging to the DB. The tunnel cross-section was enlarged within the scope of the excavation. These activities were executed with the aid of a tunnel enlargement system (TES). Towards this end, the existing overhead line for electrification of the route had to be integrated in the excavation. Once the driving operations had been completed, the tunnel inner shell made of reinforced concrete was produced. Thanks to this project the spectrum of refurbishing tunnels has been performed