A groundbreaking ceremony on July 2 marked the start of civil works for the MehrSpur Zurich-Winterthur project, a major step toward a more direct rail link between the two Swiss cities. Federal Councillor Albert Roesti and Swiss Federal Railways Chief Executive Vincent Ducrot attended the event, according to railwaygazette.com.

The project is the largest element in the federal government’s Ausbauschritt 2035 rail investment programme. It includes a 9 km double-track tunnel, the Bruttener Tunnel, and grade-separated junctions to support more S-Bahn and long-distance passenger traffic while improving freight reliability.

A more direct alignment of approximately 15 km will avoid Effretikon, relieving bottlenecks in the corridor. The work builds on the eight-year Durchmesserlinie project, which ended in 2015 and eliminated the need for east-west trains to reverse at Zurich Hauptbahnhof.

Faster journey times are a key benefit. The new alignment will cut travel from Zurich Stadelhofen to Winterthur by 2 to 4 minutes, and from Zurich Flughafen to Winterthur by 3 to 4 minutes. The fastest services between Zurich HB and Winterthur will take 16 minutes.

Capacity will rise by 30%, allowing up to 900 S-Bahn and long-distance trains per day on the route. This supports a 15-minute interval S-Bahn service between the two cities and creates room for more long-distance services.

The total project cost is SFr3.3bn (EUR3.55bn), with a flexibility of plus or minus 10%. SBB obtained the construction permit in January, and preliminary works started on March 17. Financing comes from the Ausbauschritt 2035 programme, with contributions from the Canton of Zurich, developed with transport authority ZVV, SBB, and affected municipalities.

All six main civil work contracts have been let. The Bruttener Tunnel, along with works at Winterthur, Dietlikon, and Wallisellen, was awarded to a 50-50 joint venture of Implenia and Marti. The contract package is valued at SFr1.7bn.

The 9 km Bruttener Tunnel will start west of Winterthur. One branch will join the existing line east of Dietlikon towards Zurich Hauptbahnhof, while the other will end south of Bassersdorf, running towards Zurich Flughafen. The tunnel consists of two single-track bores with a diameter of 10 m on each branch, designed for 160 km/h operations. Tunnel boring machines will carry out most of the excavation. Civil works are scheduled to begin in August 2029, with opening planned for 2037.

Building information modelling is being used for both planning and construction.

The MehrSpur programme also includes station reconstructions in the Zurich conurbation. At Wallisellen, platforms will be widened and additional pedestrian underpasses built. A 580 m single-track flyover will be constructed west of Wallisellen, carrying trains over the existing line towards Zurich Oerlikon. This allows stopping trains that have called at Wallisellen to continue towards Oerlikon. Construction begins in 2028, with completion foreseen for the end of 2032.

At Dietlikon station, the existing two running lines will be moved to create room for a pair of running lines through the station area, providing access for trains using the Bruttener Tunnel. A 300 m dive-under will be driven as part of the grade separation works. Accessibility improvements include a pedestrian bridge with lifts and a step-free underpass. Station buildings will be expanded with new retail spaces, ticket vending machines, park and ride access, bicycle storage, and a car sharing point. A road underpass will replace the current level crossing over the line towards Effretikon. Works are scheduled to start in 2027, with principal elements due for completion by 2032.

At Winterthur Toess station, an additional track towards Winterthur will be added, along with a subway with step-free access.

The programme aims to increase capacity between Zurich and Winterthur by around 30%, giving daily throughput of 156,000 passengers or 900 trains. Swiss Federal Railways also hopes to deliver a more reliable railway in some of the most congested sections of the main line network. While primarily aimed at passengers, the programme should also benefit freight operators, with SBB Infrastruktur keen to reduce delays that these services often face around Zurich.