Strabag’s Pfaffensteig Tunnel contract: design and delivery notes for rail engineers
Reviewed by Joe Ashwell
First reported on Tunnelling Journal – News
30 Second Briefing
Strabag and Group company Züblin have secured the design-and-build structural works for the ABS Gäubahn Nord/Pfaffensteig Tunnel in south-west Germany, centred on an 11km twin-bore rail tunnel linking Stuttgart Airport station directly to the Gäubahn line towards Switzerland. About 9.8km will be driven by two TBMs, with conventional tunnelling for the A8 motorway undercrossing and airport connection, plus a 240m cut-and-cover section, retaining structures, railway underpasses and a grade-separated crossing. A 3km surface section will be upgraded and partially realigned for 200km/h operation, delivered under an integrated project delivery model with Ed. Züblin, Wayss & Freytag and Strabag AG sharing tunnelling, structural and earthworks packages.
Technical Brief
- Project split into two formal approval sections, separating main TBM drives from cut-and-cover and surface works.
- Ed. Züblin and Wayss & Freytag JV will execute Package 2 (tunnelling) and Package 4 (structural engineering).
- STRABAG AG is solely responsible for Package 3 earthworks, including formation for the 3km upgraded surface section.
- Conventional tunnelling is reserved for the A8 motorway undercrossing and underground airport station connection, avoiding TBM beneath critical assets.
- Above-ground scope includes retaining walls, multiple railway underpasses and a grade-separated crossing, integrating the new alignment into existing networks.
- The 240m cut-and-cover tunnel and links to Sindelfingen-Goldberg S-Bahn station form the core of the second approval section.
- Integrated project delivery model aligns contractors and designers from permitting stage to compress programme and reduce interface risk.
Our Take
Strabag’s role on the Pfaffensteig Tunnel sits alongside a run of UK-focused moves in our database – including its 2026 agreements to acquire Van Elle and Crofton Engineering – signalling a deliberate build-out of in-house ground engineering and structural capability that can be leveraged on complex rail tunnels like this one.
Among recent Infrastructure items, there are relatively few large rail-tunnel schemes in south‑west Germany, so this 11 km twin-bore project strengthens Strabag and Züblin’s reference list in a corridor that is politically important for Germany–Switzerland connectivity.
The combination of long TBM drives and a 3 km high-speed (200 km/h) surface realignment on the Gäubahn line means this contract will test Strabag’s ability to integrate underground works with operational rail interfaces, a capability that has also underpinned its recent UK dam and rail-related contracts in our coverage.
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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