The original Rethe lift bridge constructed in Hamburg, was originally built back to 1934 and was past its prime, meaning it was no longer able to meet modern infrastructure requirements. Hamburg Port Authority AöR therefore commissioned HABAU GROUP company MCE together with its consortium partners Hochtief, Bilfinger and Waagner Biro Bridge Systems to build the new structure – a double-leaf bascule bridge. The main objective was to increase the corridor width for shipping traffic by 20.0 m to 64.0 m and to simplify road and rail traffic flows. With a span of 104.2 m between the pivot bearings, it is one of the largest bascule bridges in the world.
The assembly itself was just as impressive: The four flaps were completely pre-assembled at a site in Wilhelmshaven, then transported as one piece to Hamburg on pontoons before being hoisted into position using a floating crane. Floating crane ‘Samson’ with a maximum lifting capacity of 900 t and a maximum lifting height of 67.0 m was used to assemble the four flaps (dimensions: length 67.1 m, height 14.5 m, weight approx. 650 t). Shipping was suspended for 14 days, allowing the team to finalise the assembly of the four flaps.
Innovative bridge finger joint
The project didn’t only need to be completed with the greatest possible precision, a considerable amount of innovation was also necessary, as project manager Günther Dorrer from MCE reports: “Given that the port railway also travels over the bridge via a fixed track construction, we needed to work with millimetre precision in the area around the track. This was an immense achievement for a bascule bridge this size.” Interdisciplinary collaboration between all fields, whether structural, steel, mechanical or control engineering, was critical in this regard. “The Rethe Bridge is unlike other bridges of its kind in that the tip of the bridge flap doesn’t feature a labour-intensive mechanical locking system. The flaps are automatically centred using what is known as a finger joint,” Dorrer continues. The German Chamber of Engineers and the Association of Consulting Engineers recently awarded the German Bridge Construction Prize for this locking mechanism, which is “one of a kind in Europe”.
Hubert Wetschnig, CEO of the HABAU GROUP, is also overjoyed with this achievement: “Not only MCE, but the entire group of companies is delighted about the award, for which we would like to express our sincere thanks. It speaks volumes as to our excellent engineering skills, our performance as well as our strength when it comes to innovation.”