As part of a rehabilitation project on the railway section between Visp and Zermatt, interventions were required on several bridges and tunnels towards Stalden.

The Mühlebach Bridge, designed by engineer Alexandre Sarrasin (1895–1976) and built in 1959, is characterized by its two inclined struts supporting the deck as if the entire bridge were cast in a single piece. This strut-type bridge follows the flow of forces and illustrates the importance of structural spanning; it is one of the few railway strut bridges in Switzerland.

After more than 60 years of service, the bridge showed a generally poor condition with several significant cracks related to alkali–silica reaction (ASR). Analyses revealed pathologically deteriorated concrete, particularly in areas exposed to water. Despite this deterioration, the project focused on rehabilitating the existing structure.

The selected solution consisted of a full jacketing around the foundations, struts and piers. Following hydrodemolition of ASR-damaged concrete, a new layer of ultra-high performance fibre-reinforced concrete (UHPFRC) was applied. Its strength enhances the existing structure, while its density halts degradation processes. The deck was strengthened and widened using a UHPFRC trough to meet regulatory escape walkway widths on the bridge.

The application of UHPFRC at the full bridge scale remains relatively uncommon. It required collective design efforts and highly precise execution to preserve the elegant appearance of a concrete strut bridge seemingly cast as a single piece.

The construction site took place in a specific geographical context, marked by steep gorges and limited access. It required the construction of a full temporary working platform, transport of materials by train and helicopter, and the maintenance of railway traffic during the works, except for an annual closure dedicated to track maintenance.