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Herrenknecht Returns to the Gotthard
Around 16,000 vehicles pass through the Gotthard road tunnel every day. That's 6 million cars and trucks per year. For 45 years, it has been a key structure for European north-south traffic through the Alps. It runs for 16.9 km between Göschenen in the Swiss canton of Uri and Airolo in the canton of Ticino. The Swiss Federal Roads Office (ASTRA) is tackling the necessary age-related repairs after long-term and careful planning. ASTRA has commissioned the construction of a second, parallel tube to ensure that traffic can continue to flow during the renovation and the necessary closure of the tunnel. Once all the work on both tubes has been completed, one tunnel with one lane (plus emergency lane) will be available for southbound and one for northbound traffic – a significant improvement in safety compared to the previous operation with two-way traffic in one tube. The companies commissioned with the tunnel excavation ordered one tunnel boring machine (TBM) for the northern and one for the southern construction section of the main tunnel. The representatives of the contractor Marti Tunnel AG together with the responsible Herrenknecht engineers successfully completed the technical acceptance of the machine for the southern construction section on July 30, 2024. The Single Shield TBM is 12,310 mm in diameter. Its cutterhead is driven by 16 electric motors, which have a total output of 5,600 kW (around 7,600 hp). The machine is built to drive through the hard rock of the Alps – granite, gneiss and slate – on the 7,77 km long southern tunnelling section. Following technical acceptance, the machine will now be dismantled and the components transported to the construction site in Airolo (Ticino). There, the TBM will be reassembled so that the miners from Marti Tunnel AG can start driving the main tunnel from the south as planned from March 2025. According to preliminary geological investigations, the tunnel builders expect a geological fault zone in both the north and south of the planned route for the main tunnel. Due to the rock characteristics, the decision was made to excavate the 2 fault zone sections using conventional blasting before starting the mechanized main tunnel drive. In order to reach the fault zones in the mountain, access tunnels were driven through the rock. For the access tunnels, mechanized tunnelling technology was also used. Marti Tunnel AG successfully completed the excavation of the southern access tunnel with a 7.4 m diameter Herrenknecht Single Shield TBM in August 2023. The machines for the main tunnel will later be pulled through the fault zones that have already been excavated. Herrenknecht supplied a 7.0 m diameter Gripper TBM and a 12.2 m Single Shield TBM to a consortium of the companies Implenia Schweiz AG and Frutiger AG for the 2 northern construction lots (main tunnel and access tunnel). The excavation of the northern access tunnel was completed in April 2023. Acceptance of the Single Shield TBM for the southern section of the main tunnel took place in Schwanau on July 8, 2024. Construction consortia used 4 Herrenknecht machines at the Gotthard from 2003 to 2011 to excavate a total of 85 km of tunnel for the world's longest railway tunnel to date.
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