Infrastructure project with impressive dimensions
The imposing bridge structure, which is up to 90 meters high, will carry the newly routed B32 federal road over the Neckar valley. With a total length of 677 meters, it is a key element of the Horb am Neckar bypass. In addition to the river itself, a state road, two railroad lines and a supra-regional cycle path have to be crossed. In order to bridge the required spans, the structure was designed as a six-span beam bridge braced with stay cables. In the middle of the bridge, two 157.5-metre-long bridge segments, each with five steel cables for horizontal load transfer, are braced on both sides between three V-shaped widened pylons.
These horizontal forces are transferred further into the foundations via the pylons. In addition to the five bridge piers, various auxiliary piers are being erected for the three advancing launching girders, from which the bridge superstructure will be constructed in 27 sections.
Demanding subsoil required comprehensive specialist foundation engineering expertise
As part of the “ARGE Hochbrücke Horb” consortium, PORR Spezialtiefbau is responsible for the structural and shoring foundations. This was mainly carried out using large bored piles with a diameter of 1.50 meters and a length of up to 44 meters. In the end, a total of 233 bored piles were embedded in the rock at depth. Holes up to 45 meters deep were drilled for the auxiliary piles, which were then reinforced and filled with concrete.
At Rauschbart, around 100,000 cubic meters of earth were brought in to create the working level for the northern abutment and to construct a total of seven platforms and a serpentine construction road. The construction site was then handed over to PORR by the Karlsruhe Regional Council. “Due to the challenging subsoil consisting of fillings, weathered rock and marl, we used two of the largest and most powerful rotary drilling rigs available in Germany. With an operating weight of well over a hundred tons, moving the equipment on the slope was a real challenge, as was delivering the reinforcement cages and ready-mix concrete up the serpentines. Thanks to a concerted team effort, we are still on schedule and were able to hand over 100 percent defect-free foundation piles,” says site manager Maximilian Mohn.
