Espacially in Europe, hundreds of railway tunnels from the 19th and early 20th centuries need to have their tunnel cross-section adapted to current clearance profiles in order to facilitate the modernization of the railroad infrastructure. Two Tunnel Enlargement Systems (TES) widen tunnels at the Lahntalbahn in Germany.
TES enables the safe renewal and widening of old rail tunnels while rail operations continue, using the so-called tunnel-in-tunnel method. The system simultaneously serves as a carrier for excavation and safety work as well as a protective enclosure for rail traffic.
The TES is based on classic tunnel boring machines in hard rock and accommodates the necessary excavation and safety equipment in less than half the available space. In view of the stringent safety requirements during rail operations, the protective housing is a key system component. The 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. The system has a modular design and can be adapted to local conditions.
The TES enables tunnels to be widened while rail operations continue, as it also acts as an enclosure to protect rail operations. Line closures can be reduced to a minimum and the original alignment of the railway line is retained. Spatial planning is maintained and minimizes planning approval or plan amendment procedures. 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, two TES renew two 160-year-old tunnels on the Lahn Valley Railway. The 426-meter-long Fachingen Tunnel and the 732-meter-long Cramberg Tunnel will be widened by a good two 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 meters. At the Fachingen Tunnel, the tunnelling work was successfully completed in November 2024 with the breakthrough. In the Cramberg Tunnel, around half of the driving section has been completed in a complex geological situation with cavities in the rock.
