Implenia wins major contracts for new double-track line – cutting-edge railway infrastructure between Zurich and Winterthur

Glattpark (Opfikon), 8 January 2026 – Swiss Federal Railways (SBB) has commissioned a joint venture between Implenia and Marti (50% each) to build five of the six lots that make up the MehrSpur Zurich-Winterthur project: the Brüttener tunnel (Lot 240), Winterthur section (Lots 140 and 141), Dietlikon section (Lot 340) and Wallisellen section (Lot 540). The contracts for the five lots were awarded in stages over the last few months. This large and challenging infrastructure project focuses on the mobility needs of future generations and fits perfectly with Implenia’s strategy. The total order amounts to just under CHF 1.7 billion, of which Implenia’s share is around CHF 830 million. The construction phase of the project will take approximately ten years to complete. 

With the MehrSpur Zurich-Winterthur project the Federal Government and SBB plan to create a new double-track railway line through the Brüttener tunnel and to expand the Dietlikon, Bassersdorf, Wallisellen and Winterthur Töss stations. This will relieve the current capacity bottleneck in the rail service between Zurich and Winterthur and achieve the necessary upgrades.

The key to remedying the bottleneck is the 8.3 km Brüttener tunnel between Dietlikon and Winterthur, which also includes a 1 km long turn-off to Zurich Airport. Two single-track tunnel tubes with a diameter of around ten metres each will be built to carry the underground rails in each direction.

Most of the tunnelling will be carried out using a tunnel boring machine (TBM). Tunnel boring work is scheduled to begin in August 2029. BIM is being used for both planning and execution. In addition to the tunnel boring work, the construction project includes extensive special foundation and civil engineering works.

The Winterthur section extends from the Winterthur portal of the Brüttener tunnel to the platforms at Winterthur station; it also includes two additional sections of railway, as well as the refurbishment of Winterthur Töss station. The joint venture is also building supplementary over- and underground infrastructure, including the Neumühle railway bridge and the Storchen underpass, to ensure that services can run at the required frequencies and as flexibly as possible. 

The Dietlikon section includes the complete redevelopment of Dietlikon station, around 3 km of new track, extensive earthworks and embankments, several underpasses and the Dietlikon tunnel (approximately 300 m long). Construction for the Wallisellen section includes the Wallisellen West crossing, several new underpasses, platforms and bridges, as well as about 3 km of new railway tracks. 

This is an important project for Switzerland’s east-west rail connections, as Jens Vollmar, CEO of Implenia, emphasised: “We have an excellent railway infrastructure in Switzerland. We are pleased that Implenia, working with JV partner Marti, can harness its many years of experience and extensive expertise in infrastructure construction to upgrade this important part of the network, making it fit for increasing frequencies and future requirements. We’d like to thank SBB for their trust in Implenia and look forward to working together again.”