Numerous railway tunnels from the 19th and early 20th centuries need to have their tunnel cross-section adapted to current clearance profiles.
The Tunnel Enlargement System (TES) developed by Herrenknecht in collaboration with PORR enables the safe renewal and widening of old rail tunnels while rail operations continue, as it also acts as an enclosure to protect passing trains. The development earned the bauma Innovation Award for Mechanical Engineering. Â
The system simultaneously serves as a carrier for excavation and safety work as well as a protective enclosure for rail traffic using the tunnel-in-tunnel method.
The TES is based on experience with classic tunnel boring machines in hard rock and accommodates the necessary excavation and safety equipment in less than half the available space.
Watch the Tunnel Enlargement System
TES consists of three parts: The front machine section protects the tunnel and the railway from collapse and falling rock. The two rear sections form the working area.
The middle section carries the necessary equipment such as telescopic drill rigs, hydraulic hammer and shotcrete system for excavation and securing work. The gantry houses the production logistics with aggregates, compressors, ventilation and dust extraction systems, electrics and material storage.
Users benefit from an integrated system for drilling, loading, blasting, reprofiling and securing with shotcrete, mats, arches and anchors. With its coordinated equipment, the TES increases work safety and raises the level of mechanization.
Ergonomic features such as fixed working platforms improve occupational safety, while mechanized and remote-controlled equipment reduces manual work in potentially hazardous areas.
Since January 2024, PORR has been using two TES to renew two 160-year-old tunnels on the Lahn Valley Railway in Germany. The 426-metre-long Fachingen Tunnel and the 732-metre-long Cramberg Tunnel will be widened by about 2 meters in radius using the tunnel-in-tunnel method while rail operations continue, thus achieving a clearance profile that corresponds to current new tunnel construction.
The distance between the tracks will be increased to 4 metres. At the Fachingen Tunnel, the tunnelling work was successfully completed in November 2024 with the breakthrough.
