Spunbonded polypropylene used under high-speed railtrack: Fid-Bau Portal

Spunbonded polypropylene used under high-speed railtrack

Short notice given only substantially as follows: Typar spunbonded polypropylene geotextile is being used to line ditches and provide drainage as well as layer separation beneath a new high-speed railtrack between France and Belgium, reports the materials manufacturer, DuPont of Luxembourg. The geotextile is being used as an anti-contaminant to protect drainage systems and ensure that small particles do not collect and clog them. New techniques have had to be developed to ensure adequate drainage in areas prone to flooding or which are particularly wet. The drains can often be as much as 15 m beneath the track level and they comprise a rigid corrugated core. They are entirely protected throughout their length by sheets of Typar. DuPont explains that the weight of the top soil compresses the wet earth creating a sponge effect which separates the water from the marshy ground. The faster the water is evacuated towards collectors, the faster will be the consolidation of the soil. Compaction can be reached in six to twelve months and occurs during construction of the new track. The Typar geotextile is now serving as an effective filter, allowing water to enter the pipe system and drain to the collectors. The gradual build-up of large and small particles above the Typar layer eventually creates a graduated filter which, in turn, reduces erosion at the surface. Water flows through it freely and clogging is avoided even in the presence of large hydraulic gradients. The high speed railway line is being constructed to link Lille in northern France directly to Brussels. Trains will travel on it at speeds of 160 to 220 km/h; but the track could support speeds reaching 300 km/h.