At the site of the existing Obertor Bridge, a replacement structure is being built that does not adversely affect flood discharge and offers a high degree of flood resilience. The new bridge is designed as a shared facility for pedestrians and cyclists with two‑way traffic.
The core element of the concept is a hydraulic lifting system that raises the superstructure during flood events. This ensures compliance with the required minimum freeboard at the design flood HQ100 (100-year flood). Impacts from floating debris, blockage at the piers and water pressure due to flow against or over the deck can be excluded even during extreme flood events, as the lifted superstructure remains outside the flow.
In normal operation, the bridge is statically determinate and supported on elastomeric bearings. When a flood occurs, hydraulic jacks raise the superstructure and remove it from the action of water loads. This allows for slender cross‑sections, significantly reducing material consumption, costs and the CO₂ footprint of the superstructure.
At the same time, the full flow cross‑section is maintained in the bridge area: even in extreme floods, lateral discharge is not obstructed by ramp structures. This results in an economical and environmentally compatible solution for ensuring flood resilience.
During a flood event that requires lifting of the bridge, the crossing is temporarily closed and the abutment chambers are intentionally flooded. After the water has receded, these chambers can be drained and the superstructure can be returned to its functional position without damage.
