TECHNICAL | LININGS


used to push the front Wurm section while the rear section is braked, or to pull the rear section while the front section is braked. The conveyor interface is followed by another


infrastructure deck, 27.6m-long, located in the middle section of the Wurm. This deck houses a workshop, a shelter, a staff room and toilets, drinking water tanks, generators and electrical installations, a small laboratory, concrete pumps, and the operator’s cabin. In the subsequent 27.6m-long section, the


reinforcement cages are temporarily stored and installed in the upper area by crane. A further, 51.4m-long, deck area follows. This is


where the formwork is stored and installed in two sections, as well as a 5m-long intermediate section for installing the ventilation pipes. Then, a 42.6m-long infrastructure deck houses various


facilities, such as the bentonite station for the formwork, logistical openings, compressors and pressure vessels, cooling plants, and service water tanks. Connected to this are a 15m-long deck for lower


lateral dewatering and a 7m-long deck for train unloading and intermediate storage. A 42.6m-long section follows, with hose reels,


a crane for pipe transport, a logistical opening and intermediate storage for pipes and grout, where the pipes are installed. The last section of the Wurm is 79m-long and contains extensive infrastructure facilities, such as cable drums, the belt conveyor, ventilation, fans, and logistical openings. In this deck, all connections are routed back into the tunnel with the final inner shell installed.


The first of the


Herrenknecht TBMs on Mont Cenis Base Tunnel: the 180m-long, 10.34m-diameter ‘Viviana’ for the approx. 9km-long tunnel between Saint-Martin-La-Porte and La Praz.


PHOTO CREDIT: TELT The approximately 126m-long infrastructure deck


is located in the first part of the Wurm, closest to the Gripper TBM. It is here that all installations from the front area of the tunnel drive are diverted into the Wurm, including ventilation ducts, tunnel cables, the belt conveyor and other supply lines. Here there is a cooling and desanding plant, dewatering, generators, fans, toilets and crew cabin, a workshop, intermediate storage, diverse logistical openings, and areas as well as various cranes. The following, approximately 60m-long, reprofiling


section is separated from the first part by a dust separation wall. Here, the rock face is worked on using excavators, milling units, and a shotcrete plant, among other things. Logistical openings for materials and equipment to and from the reprofiling areas are located here, as is a crane. Another dust separation wall protects the next


area, the 17m-long shotcrete handling area with associated equipment. This is followed by the 30m-long section for


dewatering the bottom area with material, entrances and exits and intermediate storage. The material storage area and the assembly


crane for sealing are located in the approximately 58.4m-long upper sealing section. Behind this section is a 3.6m-long interface: cylinders are mounted here, which can either be


28 | March 2026


4 - CONCLUSION AND OUTLOOK Long-distance mechanised tunnel drives, such as the completed or still-to-be-completed base tunnels in the Alps, pose particular challenges at all levels: from the reliable performance of the machine technology to the comprehensive planning and management of a multitude of large and small construction sections. For hard rock drives with Gripper TBMs, the


advantages of using an additional unit in the tunnel that is complex in design and execution, such as the Wurm, are clear: the lining of the tunnel interior can already be carried out in parallel 1km-2km behind the advance with the Gripper TBM; the requirements of the TBM drive on the one hand and the interior lining on the other can be specifically coordinated and the construction schedule optimised accordingly. Furthermore, use of the Wurm can be compared


to industrial production, as the same teams work continuously at the same location and only need to be trained once. Although the Wurm moves continuously, the work is more or less stationary. This contributes to increased work safety, quality of the work performed, and cost-effectiveness. Another factor is that the individual work processes in the Wurm are independent of each other, both within the Wurm and throughout the entire drive.


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