The Haggen Bridge, which was built in 1937, links the village of Stein in the canton of Appenzell Ausserrhoden to St. Gallen. The intricate steel structure is an important example of 20th century civil engineering. Basler & Hofmann was given the task of carrying out the restoration due to the firm’s many years of experience working with riveted steel truss bridges.

Surveying the bridge at dizzying heights

Switzerland lists the 85 metre high Haggen Bridge as a cultural asset of national importance. The restoration work should help preserve the structure’s long term future. Basler & Hofmann initially carried out a comprehensive survey of the structure, which required the team to scale steep sections of the bridge. The structural examination in a 3-D model showed that the bridge is partly subject to high stress loads and is also prone to strong vibrations. 

Historically sensitive restoration

There are several aspects to this restoration project. Repair work will be carried out to the foundations. The heavy concrete slab of the bridge deck will be replaced by a lighter steel deck, providing significant relief for the delicate structure. During renovation works the bridge will not be fully enclosed in order to avoid additional wind loads to the pillars. New corrosion protection, the new bridge deck, improved drainage and vibration dampers all mean that the future of this impressive structure is secured.  

Clients:

The town of St. Gallen and the village of Stein AR