Haggen Bridge: Discreet safety for a historic steel bridge

Initial situation and concept

The Haggen Bridge provides a connection between the city of St. Gallen and the municipality of Stein in the canton of Appenzell Ausserrhoden and spans the Sittertobel gorge over a length of approximately 350 meters. With a height of over 100 meters, this steel truss bridge, built in the 1930s, is one of the most striking structures in the region. As part of a renovation in 2009 and 2010, measures to enhance safety were implemented in addition to repair work on the structure.

The planned protection barrier had to meet specific requirements. On the one hand, it was necessary to create effective passive protection; on the other hand, the appearance of the steel structure, which is a listed building, could not be compromised. Furthermore, the structural reserves of the bridge were limited, requiring a solution that had to be both lightweight and robust.

The concept developed by Jakob Rope Systems is based on a horizontal safety barrier using Webnet stainless steel mesh. The net’s transparent structure meets safety requirements without compromising the architectural impact of the delicate truss structure.

Construction and implementation

The safety barrier was installed below the bridge’s load-bearing structure. To this end, horizontal, cantilevered steel beams were mounted along both sides of the steel truss structure. Large-area Webnet stainless steel meshes are stretched between these beams and firmly connected to the structure using edge ropes. The total horizontal net area amounts to approximately 2,140 m².

Thanks to the high transparency of the nets, this safety measure is barely visible to pedestrians and cyclists crossing the bridge. At the same time, the design ensures a sustainable and low-maintenance solution for long-term operation. The combination of low weight, high strength, and corrosion resistance makes Webnet the ideal choice for this demanding infrastructure project.