Swiss Federal Railways (SBB) has officially begun construction on the four-track expansion of the railway between Zurich and Winterthur to increase capacity on one of Switzerland’s busiest rail corridors.
The project, known as MehrSpur Zürich–Winterthur, is being delivered by SBB on behalf of the Swiss federal government. Its central element is the 9-kilometre Brütten Tunnel, which is expected to remove a significant bottleneck in the national rail network and allow more passenger and freight trains to operate between the two cities.
The official groundbreaking ceremony took place in Bassersdorf on 2 July. Attendees included Swiss Federal Councillor Albert Rösti, Zurich cantonal government member Martin Neukom and SBB Chief Executive Vincent Ducrot, alongside representatives from federal, cantonal and local authorities.
The construction site in Bassersdorf sits near the centre of the 30-kilometre project area stretching from Zurich to Winterthur. It will serve as the main installation site for tunnel construction, with trains eventually running around 20 metres below ground through the Brütten Tunnel. An information centre is also planned to provide updates on construction progress.
The expanded route will increase rail capacity by around 30%, enabling approximately 900 trains to operate each day and serving more than 150,000 passengers daily. The additional capacity is expected to benefit Zurich’s suburban S-Bahn network, long-distance rail services across Switzerland and freight operations.
The project also includes upgrades to the stations at Wallisellen, Dietlikon, Bassersdorf and Winterthur Töss, together with improvements to connecting railway infrastructure.
SBB CEO Vincent Ducrot said:This project is the largest construction site in Switzerland and currently the SBB’s largest infrastructure project. Up to 1,000 people are working on the 30-kilometre perimeter. We are investing around 1 million Swiss francs per day during the ten-year construction period. With the Brütten Tunnel and the expansion of the four train stations Dietlikon, Bassersdorf, Wallisellen, and Winterthur Töss, as well as the access lines, we are increasing capacity on one of the busiest railway lines in Switzerland. The SBB is doing everything possible to minimise the impact of the extensive construction work over the next ten years.
Construction is expected to continue for around ten years. During this period, most rail services will continue to operate, although some timetable changes affecting S-Bahn services are scheduled from the December 2026 timetable update. Further timetable adjustments will be announced as work progresses.
The project will be completed in stages. Tunnel boring using tunnel boring machines is scheduled to begin in 2029, with the Brütten Tunnel currently expected to enter service in 2037.
Other planned milestones include the completion of accessibility improvements at Winterthur Töss station by the end of 2028, upgrades at Bassersdorf by summer 2030, a new single-track bridge west of Wallisellen station by 2031, and major station redevelopments at Wallisellen and Dietlikon by 2032. A new bridge in the Neumühle area is expected to be completed in 2034.
The project has an estimated cost of around 3.3 billion CHF, with an accuracy range of plus or minus 10%. It is being financed through Switzerland’s federal Rail Infrastructure Fund, which is supported by contributions from the federal government and the cantons.
