After PORR had already completed the construction of the approximately 9.5 km long two-tube Filder Tunnel, the approximately 5.7 km long two-tube Obertürkheim Tunnel heim, and a one-kilometre-long branch, the Untertürkheimer Kurve tunnel, as part of the Stuttgart 21 infrastructure project, the railway construction experts from the PORR headquarters in Vienna came into play. The FF PORR S21 consortium consists of PORR Austria and PORR Germany and has been commissioned to plan and execute 33 km of slab track system, as well as the electrical engineering and cable pulling.

Working shoulder to shoulder with the experts from PORR transport route engineering and A. Waggershauser Straßenbau GmbH & Co. KG, a subsidiary company of PORR, the project realisation has access to a wealth of expertise.

Slab Track Austria

Slab Track Austria is a joint development of PORR and ÖBB – the Austrian Federal Railways. The ÖBB-PORR slab track system was first built in Langenlebarn in Austria in 1989 and has also been used successfully in Germany for more than 20 years.

A slab track is a ballastless track superstructure. The main element of the sustainable Slab Track Austria system is the elastically supported track supporting slab, which consists of loosely reinforced concrete and integrated rail support points. An elastic separating layer is attached to both the base of the slab and the conical grouting openings, which serves to decouple and reduce vibrations and structure-borne noise. The track support plate is installed on a low-subsidence substructure, which, in accordance with the approval of the German Federal Railway Authority (EBA), consists of a concrete base layer as well as a hydraulically bound base layer, and is poured with self-compacting concrete after fine levelling.

Asphalt base layer reduces the number of layers of Slab Track Austria

The asphalt base layer planned by the FF PORR S21 joint venture is to replace the concrete base layer as well as the hydraulically bound base layer of the standard Slab Track Austria system. The new system structure is being used for the first time on line 4703 in the Obertürkheim branch on an earth structure as well as in the trough and tunnel structure. A special, temperature-reduced asphalt AC 22 T S 50/70 with a viscosity-modifying binder 30/45 is being used.

The special mix used was by no means chosen at random. The construction behaviour and the procedural handling of the construction material were thoroughly researched in advance on a separate test field. ‘This project fully exploits two of the benefits of our corporate philosophy of offering as many services as possible from a single source: our cumulative expertise and our local presence,’ explains Timo Wenning, project manager at PORR transport route engineering, and continues: ’The railway constructors benefit from our expertise in asphalt technology. In turn, our team received excellent support from our colleagues from the subsidiary company A. Waggershauser, who are familiar with the area, during various construction activities.’