The images of the disastrous flood in Ahr Valley in the summer of 2021 have affected people in Germany and beyond. More than 800 m3 of water per second rushed through the valley. This corresponds to multiple times the amount of water measured during the until then recorded 100-year flood. The existing, mostly vault-type, bridges couldn’t withstand this flow – they were flooded and mostly destroyed. The pedestrian and cycle lanes next to the railway line are neither usable anymore.
Because those transport routes are important for the Ahr valley as a tourist region, the structures should be replaced as fast as possible. SSF has been contracted for final design of in total nine railway bridges as well as five foot and cycle bridges.
The new structures span lengths between 60 and 80 metres as supported continuous girders. For the railway lines, steel superstructures (steel trough with orthotropic slab) will be implemented according to our alternative offer, which reduces welding works on site. They will be assembled along the rail axis in front and behind the new structure and subsequently launched into their final position.
For the foot and cycle bridges, prestressed concrete as well as prefabricated composite (VFT®) superstructures are planned. The prefabricated single-span girders will be placed and then completed with reinforcement steel and cast-in-situ concrete to form a continuous system.
Important design principle is that the bridges withstand similar flood incidences in the future. So, in addition to regular loads, the structures are dimensioned for onflow and overflow compliant with data provided by the hydrological expert.
