The Lignon footbridge crosses the Rhône River between Loëx and Le Lignon (GE). Commissioned in 1971, it carries a pipeline used to transport refined petroleum products to the Geneva region. The structure is also used by pedestrians and cyclists. It consists of a 136 m suspended ribbon deck supported by four prestressing cables anchored into reinforced concrete abutments founded on bedrock and stabilized by prestressed ground anchors.

As part of the rehabilitation project, investigations were carried out to assess the structural safety of the bridge and to define the strengthening measures required to ensure its long-term durability.

The works notably included strengthening the abutments through the installation of new instrumented prestressed anchors, enabling long-term monitoring of anchorage forces.

Carried out in a complex environment characterized by the presence of the Rhône River, a groundwater protection zone, demanding geotechnical conditions and a strategic pipeline that remained in operation throughout the works, the project required rigorous planning and adapted construction methods. These measures ensured continuous operation of the pipeline as well as uninterrupted use of the footbridge.

As part of the verification process and following completion of the works, a monitoring plan was implemented. Anchorage forces and cable deflections are continuously monitored, and operation is governed by predefined threshold values.

The completed interventions now ensure the safety and long-term durability of this unique structure while guaranteeing its continued operation.