Building with steel and concrete: Replacement construction of Aller bridge running full speed ahead

• Spesa executes replacement construction of Aller bridge in Verden together with Schachtbau Nordhausen
• 7,300 m³ of concrete and approx. 900 t of reinforcement steel will be installed during the shuttering and concrete works
• Start of superstructure assembly in December 2022
• Works planned to conclude in December 2025

Verden, Germany – Federal Highway B215 in Lower Saxony is a crucial traffic connection in the north-south direction for the region between Nienburg an der Weser and Rotenburg an der Wuemme. This section of the highway includes the Aller bridge in Verden, known as the “North Bridge”, which no longer can handle the existing volume of traffic. In addition, the outdated steel deck bridge now has a restricted load-bearing capacity and no longer meets the modern requirements for a bridge structure. And above all, there is a clear deficit when it comes to traffic safety, for example lane width or the required width of pedestrian and bicycle paths. Cost-intensive maintenance of the existing bridge structure would only have managed to restore the load-bearing capacity, but would not have improved traffic safety.

New bridge for more safety

After considering all aspects of traffic safety, environmental protection, noise reduction and flood protection along with feasibility of construction, the Lower Saxony Federal State Authority for Road Engineering and Traffic Development decided on a new replacement structure. For this purpose, a joint venture made up of SPESA Spezialbau und Sanierung GmbH along with SCHACHTBAU NORDHAUSEN GmbH was commissioned back in September 2021 with the execution of the new bridge structure for the Aller bridge on the B215 highway – a crucial step for maintaining traffic connections and ensuring the safety of all traffic participants.

Steel composite design

The new replacement structure will be executed using a six-pitch steel composite design in the immediate vicinity of the old bridge. Apart from the bored pile foundation for the substructures, comprising pillars and abutments, Spesa will carry out extensive shoring work and jet grouting injections. In total, roughly 7,300 m³ of concrete and approx. 900 t of reinforcement steel will be installed during the shuttering and concrete works. “In December 2022, the first of 30 components in total were installed on the 265 m long steep composite bridge,” explains Bernd Steudel, Project Manager at SPESA Spezialbau und Sanierung GmbH. “The construction components come from our joint venture partner Schachtbau Nordhausen.” The scope of service also includes the execution of bridge fixtures in the form of sealings, constructing the road surface and railings along with dewatering and media lines.

Dismantling the existing bridge

The completion and commissioning of the new Aller bridge is planned for December 2024. This will be followed by the demolition of the old existing bridge as well as the new building of a rain clarification basin made of reinforced concrete in the area of the old structure. Work is currently running full speed and is planned to conclude successfully in December 2025.