Viaducs de Chillon: complex anchor renovation

The A9 motorway passes above Lake Geneva along the Viaducs de Chillon, an over two-kilometre-long bridge structure from the 1970s. The elegant bridges are secured with numerous anchors on the steep slope, which have, however, reached the end of their service life. Basler & Hofmann developed a new anchor concept that will enable the bridges to be used in safety for decades to come.

Expertise involved

Geotechnical engineering


Federal Roads Office (FEDRO)

Unclear conditions in the ground

The anchor renovation process proved to be highly complex for various reasons – firstly, with the folding of the Alps having resulted in unclear geological conditions. In addition, the exact geometric location of the existing anchors could not be determined with sufficient accuracy. In order to avoid endangering them with the new anchors, the bridge foundations were reinforced with a concrete collar, thereby creating more space for the new anchors. Thanks to the new anchors, this roughly 40-year-old structure now complies with current standards and also fulfils all requirements in terms of earthquake performance.  

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