Niedermoos

Railway overpass

Tubular steel piles for the foundations of a railway viaduct under continuous railway operations

Pile foundations for two bridge abutments

The abutments were founded on tubular steel piles, which were fabricated to transfer the loads from the bridge structure. The pile system is suitable for construction projects where space is limited and can be used in a variety of ground conditions. Tubular steel piles also enable the transmission of vertical loads as well as horizontal stresses and bending moments. The piles were driven without open-cut soil extraction whilst the pile tubes were being driven into the ground.

Work in the immediate vicinity of the railway line

The pile foundation work was carried out immediately adjacent to a railway line whilst rail services were in operation. In doing so, the operational constraints of the line as well as the required safety distances from the overhead line system had to be taken into account. The work was adapted to the local conditions and the requirements of the railway environment.

Tubular steel piles using internal pipe driving

To construct the piles, a starter pipe sealed at the base was first driven into the ground using the internal pipe driving method. Where necessary, additional pipe sections were added and welded together until the planned final depth was reached. A reinforcement cage was then installed and the pipe filled with concrete. The tubular steel piles produced reached lengths of around 24 m. The pipes used had a diameter of 406 mm and were each extended several times.

Compact pile driver for confined spaces

A compact pile driver was used for the work, enabling operation within the limited space available on site as well as in the vicinity of the railway line. The technical specifications of the machine allowed the required pile depths to be achieved and facilitated its delivery to and manoeuvring on the construction site. A total of 12 Tubular steel piles were constructed for each abutment.

Night-time work for site logistics

The works took place between September and November 2020. Part of the work was carried out at night, when there were no trains running on the affected section of track. During these time slots, material transport and site logistics were carried out using a road-rail excavator to prepare and support the work on the abutments.

DSV base for shoring and waterproofing

Following completion of the pile foundations, PORR special civil engineering constructed a DSV base on both sides of the abutments using the jet grouting method. The base complemented the sheet pile box constructed by STRABAG Rail. The DSV work served to waterproof the construction pits as well as to supplement the shoring system.

Foundation for the railway viaduct

The installation of the tubular steel piles and the DSV base created the conditions necessary for the construction of the two bridge abutments for the railway viaduct in Niedermoos. The foundation and shoring works formed the basis for the subsequent construction work on the bridge structure.