Hanover

B3 Südschnellweg

Rehabilitation of the B3 Südschnellweg as part of a joint venture

Road tunnel instead of a bridge

The Südschnellweg, with its two lanes in each direction, was built from 1954 onwards and has since served as an efficient, flood-proof east-west link in the south of Hanover.

As part of the rehabilitation works, the existing bridge over Hildesheimer Straße and Schützenallee in the Döhren district is to be replaced by an underpass. To this end, the consortium will first erect a 940-metre-long temporary bridge running parallel to the elevated road and then demolish the existing bridge. Subsequently, a 1,100-metre-long road tunnel with access ramps will be constructed to pass under Hildesheimer Straße and Schützenallee.

Preparations and special civil engineering works for the temporary bridge

In 2023, the first special civil engineering works commenced, including the construction of diaphragm walls over 1,100 m long on the north side of the Südschnellweg to serve as the foundation for the temporary bridge and part of the future tunnel. This work was completed in early 2024, enabling the special civil engineering team to hand over the site to the structural engineering team. Work also began on the retaining embankments, which will later form the access ramps to the temporary structure.

On-site wastewater treatment

An on-site wastewater treatment plant was constructed to treat the wastewater generated at the site. This enables the wastewater to be treated directly on site. Furthermore, a photovoltaic system was installed on the roofs of the containers to meet part of the site’s electricity requirements locally. The aim was to incorporate measures for energy supply and wastewater treatment into the site organisation from the outset.

Steel structure assembly for temporary bridge on a tight schedule

With the completion of the diaphragm wall works, structural engineering works began with the assembly of the steel structure for the 938 m-long temporary bridge, which was erected parallel to the existing bridge. The structure consists of 18 individually load-bearing sections and was assembled with precision using synchronised heavy-duty cranes. More than 40 bridge piers were constructed for this purpose; the steel components were supplied by two manufacturers producing in parallel. A highlight was the assembly at the junction of Hildesheimer Straße and Willmerstraße during tightly scheduled weekend road closures.

Seamless coordination through BIM

The large number of trades involved requires the coordination of different construction processes. BIM-based modelling is being used to support scheduling and planning, forming the basis for the implementation of this complex project. Health and safety and environmental protection are also integrated into the processes. Construction materials generated on site are recycled wherever possible. Amphibians and other animals are kept away from hazardous areas by protective fencing. Furthermore, measures to ensure the safe drainage of floodwater form an integral part of the project.

Opening of the temporary bridge to traffic

At the end of October 2024, the temporary bridge was officially opened to traffic. This commissioning created the necessary space to gradually dismantle the old Südschnellweg bridge and subsequently commence tunnelling.

Dismantling of the dilapidated existing bridge

In June 2025, the dismantling of the bridge over Hildesheimer Straße was completed. As dismantling by blasting was not an option due to the adjacent buildings and infrastructure, the bridge was dismantled in sections using heavy machinery. Six demolition excavators, fitted with concrete shears and hydraulic breakers, worked their way through the structure in synchronised fashion from both sides. The dismantling of the central section of the bridge – the so-called box girder – proved particularly challenging. Here, heavy-duty hydraulic breakers were used to create access points, through which concrete shears subsequently cut the bridge in half. The removed material – around 15,000 tonnes of concrete and steel – was roughly crushed on site. Once separated, it will be reused as a construction road, backfill or aggregate.

Second phase of diaphragm wall works

Following completion of the dismantling, the second phase of diaphragm wall works began in spring 2025 on the south side of the Südschnellweg. There, a further 1,100 m-long diaphragm wall, up to 30 m deep, is being constructed to prepare for the tunnelling work. Only once this has been completed can the excavation of soil between the parallel diaphragm walls begin.

Foundation for future traffic management on the Südschnellweg

The replacement of the existing bridge with a road tunnel will create a new section of transport infrastructure in the south of Hanover. The works on the Südschnellweg lay the structural foundations for future traffic management along the B3 federal roads and form part of the gradual modernisation of a key east-west link in the state capital.

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