Tunnel enlargement system (TES)

The Tunnel Enlargement System (TES) developed by Herrenknecht makes it possible to renovate railway tunnels during ongoing rail operations. First, the two existing tracks are removed and a track is laid in the middle of the existing tube instead. Rail traffic continues to run safely on this track throughout the entire construction period. During the advance, the Tunnel Enlargement System (TES) moves forward step by step on auxiliary rails. At the same time, the machine serves as a protective enclosure and separates the construction work from ongoing rail traffic.

The TES is based on experience with classic tunnel boring machines in hard rock and accommodates the necessary excavation and stabilization equipment. In view of the high safety requirements during ongoing rail operations, the protective enclosure is an essential component of the machine technology. The Tunnel Enlargement System consists of three parts: the front part of the machine protects the tunnel and the railway tracks from collapse and falling rock and houses the ventilation and dust extraction system. The middle section carries the necessary equipment such as telescopic drill rigs, hydraulic hammers and shotcrete system for the excavation and support work. The production logistics with power and hydraulic units, compressors, electrics and material storage are housed in the back-up.

First, the old masonry is broken out. This is followed by the excavation and widening of the rock by chiseling or blasting. The excavated material falls to the side of the machine into the tunnel invert and is removed by separate conveying and loading facilities. After excavation, a shotcrete manipulator applies the temporary shotcrete support. The rock is also stabilized with anchors. Steel mesh and steel lattice arches together with the shotcrete and anchors form the initial support. The typical excavation section length is 1.0 - 1.75 m with a maximum of two sections per day. Once the tunnelling work with the TES has been completed, in a second construction phase the final lining of the tunnel is then carried out with in-situ concrete using a formwork carriage.

Thanks to enlargement during ongoing rail operations, line closures can be reduced to a minimum. The original alignment of the railway is retained. As a result, not only can planning approval or plan amendment procedures be minimized due to adherence to regional planning; the system can also reduce further impacts on protected assets such as people and the environment.

With the start of industrialization in the 19th century, the construction of railway lines and the associated tunnels began. In Austria, Switzerland and Germany alone, between 1850 and 1910 around 800 tunnels were built that are now getting on in years. In order to electrify the lines, accommodate larger track gauges and faster trains, comply with current safety standards or replace the tunnel lining due to age, it is necessary to enlarge the tunnel profile. The TES makes a significant contribution to the efficient, sustainable modernization of the infrastructure: with low maintenance requirements, the tunnel is fit for the next 100 years of operation.