Since 2023, the Südschnellweg in the state capital of Hanover has been undergoing extensive modernisation. The consortium consisting of PORR, PORR Spezialtiefbau and Hagedorn was commissioned by the Niedersächsische Landesbehörde für Straßenbau und Verkehr (Lower Saxony State Authority for Road Construction and Transport) to construct a temporary bridge, dismantle the existing bridge and build a road tunnel more than 1,000 metres long.
The commissioning of the Südschnellweg temporary bridge in October 2024 marked the start of construction work on the demolition of the old Südschnellweg bridge. Since 1960, the structure had been an indispensable part of the transport network in the south of the greater Hanover area. However, over the last 15 years, the bridge has become a cause for concern in Hanover's transport network. The constantly increasing traffic loads had led to considerable wear and tear. In order to maintain traffic safety, the state authorities had reinforcements installed at great expense – a necessary step to ensure that the bridge could continue to be used until the replacement structures were completed. In the end, traffic was only possible via the two central reservation strips, with steel cables supporting the load-bearing capacity.
Excavators ‘nibble’ the bridge away piece by piece
In an impressive team effort, the consortium removed 246 metres of the dilapidated structure within six days – significantly more than the 136 metres originally planned. This means that half of the dismantling of the 484-metre-long bridge has already been completed. Controlled demolition by explosion was not an option in the middle of the city – the risks of vibrations and dust would have been too great, and the surrounding buildings and infrastructure could have been damaged. Instead, the structure was dismantled section by section using excavators in a complex, precisely planned process. Six heavy machines are nibbling their way through the structure and will crush around 15,000 tonnes of concrete and steel until it is completely dismantled.
Successful dismantling and reopening of Hildesheimer Straße
The focus of the work was on the complex dismantling of the fields that ran directly over Hildesheimer Straße – a particularly sensitive area where not only Willmerstraße crosses the main urban thoroughfare, but also the routes of tram lines 1, 2 and 8. Both road and rail traffic were completely closed for the duration of the work. The tramway overhead lines were dismantled, a dam weighing more than 6,000 tonnes was built, 4,000 tonnes of bridge sections were removed and the dam was then dismantled.
On Easter Monday, the light rail system successfully completed a test run – traffic on Hildesheimer Straße was reopened at 10 p.m. on the same day, eight hours ahead of schedule. The tram ran for the first time over the reopened section – where the former Südschnellweg bridge had stood until recently. The track system was also completely restored.
Outstanding team performance under time pressure
‘We have impressively demonstrated how efficiently we work as a consortium – under high time pressure and with perfectly coordinated processes,’ emphasises site manager Timo Kögel, PORR Structural Engineering ARGE Südschnellweg Hannover. ‘The coordination between the dismantling of the overhead lines, the construction of the embankment and the demolition went smoothly. It was precision work.’ The measure was also well received by local residents, who followed the work with curiosity. The machines will continue to work for around two months until the old bridge has been completely dismantled.
With the successful demolition, the way is now clear for the next steps in this major project: Slurry wall work is already underway on the southern construction pit wall to enclose the first two tunnel docks. Once this has been completed, the anchoring work and underwater excavation of the construction pit for docks 1 and 2 are scheduled to begin in June 2025.
