Railway overpass, Niedermoos

Steel pipe piles were safely used to construct the pile foundation for two bridge abutments of a railway overpass in Niedermoos, Bavaria. DIN EN 12699 steel pipe piles are particularly suitable for foundations in confined spaces, as the mandatory distances to existing buildings are relatively small. Because they are displacement piles, this pile system requires no soil extraction and is ideal for use in contaminated soils. It can also absorb horizontal loads and bending.

Safe execution immediately next to the railway line

The work was to be carried out right next to the railway line while the line was in operation. It was essential to keep a safe distance from the overhead line. PORR is pre-qualified for this work by Deutsche Bahn.

Smooth implementation with a compact device

The piles were safely produced using a tried and tested method: a starter pipe, sealed at the base, was driven into the ground by means of inner pipe ramming. Extension pipes can be attached and welded in place around the circumference, if required, so that the work can be continued. Once the final depth has been reached, a reinforcement cage is installed, and the pipe is concreted in place. A compact and powerful piling rig, the IHC Fundex CP25D, was used to safely construct the pile ­– 12 per abutment.

The Fundex CP25D was chosen because it was the perfect size for the project - it could be flexibly moved along the track, and reach depths up to the end of the hammer wire (35m). With a pile length of around 24m, each of the 406mm diameter steel pipes was butted and welded twice.

Working at night to avoid interrupting rail operations

The work was carried out from September to November 2020 with two crews, and sometimes involved night shifts. This was because the only time there were no trains on the line was between 0.40 am and 4.40 am. This time window allowed the team to transport material for the next day’s work from the station to the construction site with the two-way excavator. After the piling work had been completed, the team used the jet-grouting method to create a bracing and sealing floor slab on both sides of the abutment in order to protect the sheet piling box manufactured by Strabag Rail against water entering from below and to ensure that the shoring was stable.

The key to meeting DB AG’s requirements on site was a customised specialist civil engineering solution developed in cooperation with Strabag Rail’s planner. We would like to take this opportunity to thank the employer for the outstanding mutual collaboration.