B 31, road tunnel Waggershausen

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It will be quiet

connecting people

Federal highway B 31 between Immenstaad and Friedrichshafen was built as part of the new conception of the road network on Lake Constance’s north shore. The goal: to free the towns from transiting traffic. Due to town planning reasons, a 700 m tunnel with noise protection embankments and walls was constructed in the Waggershausen district. This ensures noise protection for the residents and reverses the separation of the neighbouring districts Waggershausen and Jettenhausen.

paving the way

Designing a tunnel is a complex matter. The great number of parties and disciplines involved requires intensive communication. The extensive operational equipment had to be integrated into the structure. What an advantage that GRASSL was also responsible for the design of the operational equipment! The tunnel width was optimised by carrying out a nonlinear structural analysis for fire safety. Not only technical aspects had to be considered; it was also important to minimise the environmental impact. We ensured this by developing a detailed construction logistics concept which also allowed traffic to continue flowing during construction.

creating construction culture

To limit changes to the surrounding environment, care was taken to maintain as much of the natural terrain as possible. Only the entrance areas with the tunnel portals are visible. Thanks to a clear design language and the harmonised materials of the noise protection cladding, the tunnel structure blends into the landscape. Conclusion: tunnels can be beautiful.

Year of completion


Type of intervention

New construction

Contracting authority




Type of structure

Road tunnel

Construction method

Dry construction pit

Total length

786,00 m

Construction width

21,40 m

Construction material

Concrete, reinforced concrete

Services Grassl

Basic assessment, preliminary design, detailed design, preparation of tendering, visualisation

Latest news about the project

Formal opening ceremony and opening to traffic of the Waggershausen Tunnel near Friedrichs

700 metres long, twin-tube cross section, 6,000 metric tons of steel, 34,000 cubic metres of concrete and thousands of square metres of mastic asphalt ...