Post-Tensioning Systems secure Railroad Bridges as Part of a High Speed Line

Due to its geographical position Belgium plays a vital role in the extension of the North European high-speed line (HSL). In Brussels the important European railroad lines of the Eurostar to London have always crossed with the lines from Paris to Amsterdam and from Paris to Cologne.

The European guidelines stipulate that new high-speed lines are designed for minimum speeds of 250 km/h (155 mph). As a result of the construction of such new lines European railroad connections are considerably shortened: For example, the travel time from Amsterdam to Paris is reduced by more than 1 hour, the distance from Amsterdam to London can be covered in 3-3/4 hours only and it takes only 7 hours to get to Barcelona by train. Hence, high-speed trains are a competitive alternative to road and air traffic and therefore are considered environmentally friendly.

In 1990 the Belgian authorities decided to build high-speed lines (HSL) in their country. For this purpose, 3 lines were deemed reasonable: the western line from the French border to Brussels, the northern line from Brussels to the Dutch border and the eastern line from Brussels to the German border. In total, the Belgian railroad project consists of 314 km of highspeed lines of which 200 km are to be new construction designed for maximum speeds of 300 km/h. The crossing of the plateau of Herve east of Liège with its new TGV station designed by Santiago Calatrava placed high demands on the construction work. Parallel to the E40 expressway, the line passes through many small valleys and crosses a number of important roads in a highly urbanized environment. Therefore, different structures were required, cut and cover tunnels, open tunnels and underpasses, and 4 viaducts with a total length of nearly 2.5 km: near José (422 m), near Herve (459 m), near Battice (1,226 m) and near Ruyff (312 m).

For the construction of these four viaducts, DYWIDAG-Systems International and Freyssinet set up a joint venture in late 2002. All viaducts consist of continuous beams and single span beams in turn and were built using precast prestressed concrete elements. First the cast-in-place concrete foundation of the V-shaped bridge piers was cast and anchored in the ground. Subsequently, the precast, post-tensioned V-legs were assembled thereon parallel in a row and continuously post-tensioned into the foundation. Two parallel V-shaped bridge piers were connected with two parallel, 2.6 m high and about 200 t heavy posttensioned U-girders each. Subsequently, the outer U-girders were lifted upon the V-legs and the continuous girder post-tensioned. These parallel placed continuous girders ultimately form the support for the 3.4 m wide concrete slabs for the railroad tracks. Post-tensioned single span U-girders were installed between the continuous girder spans.

This particular construction method demanded a great deal of discipline from all people involved. Since the components were precast in various factories and assembled on site, proper fitting accuracy had to be ensured. This was made possible through careful design and dimensioning as well as meticulous execution and quality controls.

The technical know-how of the experienced staff significantly contributed to the overall success of this project. Hence, this section of the new HSL connection from Brussels to Cologne was successfully completed on time in summer 2005. The commissioning of the entire HSL network in Belgium is scheduled for 2007.

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