Implenia/Marti JV MehrSpur Zurich–Winterthur: design and risk notes for engineers
Reviewed by Joe Ashwell
First reported on Tunnelling Journal – News
30 Second Briefing
Swiss Federal Railways has awarded an Implenia/Marti 50:50 joint venture five of six MehrSpur Zurich–Winterthur lots worth just under CHF 1.7 billion, including the 8.3 km Brüttener tunnel (Lot 240) with twin 10 m diameter single-track tubes and a 1 km spur to Zurich Airport. TBM excavation will start in August 2029, with a roughly ten-year construction phase using BIM for planning and execution and extensive special foundations, earthworks and embankments. Additional works cover full redevelopment of Dietlikon station, about 6 km of new track across Dietlikon and Wallisellen sections, multiple underpasses, bridges and the Neumühle railway bridge and Storchen underpass near Winterthur.
Technical Brief
- Total order value is just under CHF 1.7 billion, with Implenia’s share about CHF 830 million.
- Five awarded lots cover Brüttener tunnel (240), Winterthur (140, 141), Dietlikon (340) and Wallisellen (540).
- Winterthur section runs from the Brüttener tunnel portal to Winterthur station platforms, including two extra track sections.
- Refurbishment of Winterthur Töss station plus Neumühle railway bridge and Storchen underpass are bundled into the Winterthur works.
- Dietlikon section includes full station redevelopment, ~3 km of new track, several underpasses and a ~300 m Dietlikon tunnel.
- Wallisellen section scope comprises Wallisellen West crossing, multiple new underpasses, platforms, bridges and ~3 km of new tracks.
- BIM is mandated for both planning and execution phases, implying integrated digital design–construction coordination across all lots.
- Extensive special foundations, earthworks and embankments indicate substantial ground modification and geotechnical risk management along surface sections.
Our Take
Within our 379 Infrastructure stories, very few rail contracts in Switzerland approach the nearly CHF 1.7 billion scale of the MehrSpur Zurich–Winterthur project, signalling that SBB is concentrating a decade-long pipeline of capacity upgrades into a single, highly integrated package.
The 8.3 km Brüttener tunnel with 10 m diameter single-track tubes implies use of large-diameter TBMs in a densely built corridor between Dietlikon and Winterthur, which will test Implenia/Marti’s ability to manage settlement and interface risks around assets like Dietlikon and Winterthur stations.
A 10‑year construction duration and tunnelling start only in 2029 suggest that early years will be dominated by complex permitting, design optimisation and utility relocation in Zurich/Winterthur, giving contractors a long lead time to lock in supply chains and specialist labour for Swiss underground works.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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