Around 16,000 vehicles pass through the Gotthard road tunnel every day. That's six 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 kilometers 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.
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 two 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. The excavation of the northern access tunnel by a a Gripper TBM (Ø 7,030mm) was completed in April 2023.The excavation of the southern access tunnel with a Herrenknecht Single Shield TBM (Ø 7,400mm) was successfully completed in August 2023. The machines for the main tunnel will, when they reach the fault zones during their drive, be pulled through the two fault zones that have already been excavated.
The tunnel boring for the northern and southern construction sections will each be carried out using a tunnel boring machine (TBM). For the 7,755-meter-long southern tunnelling section the diameter of the Single Shield TBM is 12,310 mm. The cutterhead is driven by 16 electric motors, which have a total output of 5,600 kilowatts. The northern section of the main tunnel with a length of is 6,885 meters is excavated by a Single Shield TBM (Ø 12,225mm), having a total output of 5,250 kilowatts. Single Shield TBM are specialists for driving through the hard rock of the Alps. Granite, gneiss and slate are the main types of rock to be expected.
On February 14, 2025, the two tunnel boring machines were started with the turning-on ceremonies in Göschenen and Airolo. The TBMs will excavate around 18 meters per day and reach their target in the approximate center of the tunnel in spring 2027. The ceremonial breakthrough is planned for fall 2027.
