Steel composite with prefabricated parts and a cast-in-place concrete supplement

After the steel construction work for the Nordbrücke bridge was largely completed in June 2024, the responsibility for the timely completion of the superstructure lies entirely with PORR. In about twelve months, the steel girder skeleton, which had been pulled over the Salzbachtal valley in four stages, has to be connected to the road surface structure. To this end, a total of 164 concrete parts of different types and lengths, up to 4.39 m, were placed on the substructure in the first step within three weeks.

After all the precast concrete parts had been placed, the in-situ concrete was added in 11 concreting sections using the pilgrim step method. In this process, the slabs in the field area are concreted first, followed by the slabs in the support area above the pillars. This proven method significantly reduces the risk of cracking. After the waterproofing has been installed underneath the caps, the caps themselves have been produced and the waterproofing installed between them, the final layer of the superstructure is a mastic asphalt covering.

30 seconds' drive instead of hours in traffic jams

The construction project began with a bang: due to an accident, both bridge sections of the Salzbachtalbrücke in the Wiesbaden district of Biebrich had to be blown up simultaneously in November 2021. PORR immediately began to replan the replacement construction, which was originally to be built in two construction phases, in close cooperation with the consortium partner as well as the client. While the excavators were still clearing away the rubble, construction of the first abutment began and the southern bridge was opened to two-lane traffic in the direction of Rüdesheim and Frankfurt shortly before Christmas 2023 after a construction runtime of just 20 months. There was collective relief in the city of Wiesbaden, as well as among the approximately 80,000 road users who depend on this important route within the Rhine-Main area every day and who had to struggle through Wiesbaden city centre for months.

‘A precision landing like this isn't something you can just pull out of your sleeve. Having a plan B up your sleeve at all times is one of the most important recipes for success for a major construction site,’ explains PORR project manager Salam Khuzandar. ’In the background, permanent fine-tuning is taking place so that the processes interlock like a well-oiled machine. We have to thank not only our construction site team for their tireless efforts, but also our suppliers. The 1,750 cubic metres of in-situ concrete per superstructure and the 350 cubic metres per superstructure cap, which have to be delivered just in time, alone require a sophisticated concept.’