General contractor for rebuilding the Düte Bridge

The Düte Bridge was rebuilt by the Düsseldorf branch of PORR Ingenieurbau over a construction period of five and a half years. The bridge is situated on the A1 between the Lotte/Osnabrück intersection and the motorway junction at Osnabrück-Hafen.

The new Düte Bridge was built using the steel composite construction method. A steel superstructure was mounted on new reinforced concrete columns and supports, and then the concrete bridge slab was built on top of it. The structure is supported by seven pier axes with two pairs of piers for each superstructure. A total of 11,480 cubic metres of concrete and 5,430 tonnes of steel were used in the 301-metre-long structure, which at first glance does not reveal how demanding the work that went into it was, especially the demolition of the existing bridge.

Sawing the existing bridge lengthwise in half  – in 60 hours

The 50-year-old existing structure was not built with the usual two separate superstructures. This ruled out the option of routing traffic over one half of the bridge while the other was demolished. The solution was to saw the concrete roadway, which is up to 65cm thick within the control range and reinforced with prestressing steel, in half lengthwise using concrete saws. Despite high levels of wear and tear, working on the existing roadway surface, and timed closure breaks for night-time rail traffic, this precision work was completed over the entire length of 300 metres over a period of 60 hours, during which the road had to be fully closed.

After the bridge had been sawn in two, traffic was routed over the remaining, western half of the bridge. Demolition from the ground was not possible due to the protected floodplains along the Düte River.

A 2,150t shoring structure for more stability during demolition

The old concrete superstructure was prestressed and, after it had been cut in half, its load-bearing capacity was no longer given. To remedy this, the entire bridge was underpinned with a full-surface scaffolding structure extending across not only the Düte River but also an ICE railway line and a municipal road. The 2,150-tonne shoring structure was driven into place with the aid of 479 hydraulic presses without closing the road beforehand. After the project was completed, the Düte River was renaturalised. Today, it winds its way under the bridge in loops, which are opening up new habitats for wildlife and vegetation.

None of this would have been possible without the reliable and cooperative collaboration with the project team of the Autobahn GmbH des Bundes, Westphalia branch, not to mention the experienced workmanship of all the trades involved. The PORR Spezialtiefbau was responsible for the pile foundation with in-situ concrete driven piles, while PORR Verkehrswegebau carried out the road construction work.