Czech train successfully runs on tensar trackbed

A new Pendolino Train was successfully tested at up to 237 kph (147 mph) on a track bed with the sub-grade stabilised by Tensar bi-axial geogrids, and laid over soft ground with low bearing capacity.

A new Pendolino Train was successfully tested by Czech Railways at up to 237 kph (147 mph) on a track bed with the sub-grade stabilised by Tensar bi-axial geogrids, and laid over soft ground with low bearing capacity.

Although the normal maximum speed for the Czech Railways is 160 kph, in November 2004 a test was authorised that took the train from 160 to 230 kph in three minutes, and then recorded a stopping distance of 1800 metres from 220 to 0 kph.

Tensar geogrids have been utilised to enhance the bearing capacity of soils on many sections of the 4th pan-European Corridor line between Ceská Trebová, Brno and Breclav.

With the standard maximum speed of 160 kph (99 mph), the track structure had to have an appropriate bearing capacity beneath the ballast layer.

However, the sub-grade stiffness modulus was as little as 15 Mpa in many sections, and the water table was also high.

Use of Tensar geogrids enhanced the bearing capacity and improved track geometry enabling the rail network to be modernised at minimum additional cost despite the poor ground conditions.

The Czech railway system has undergone extensive modernisation with the construction of the 4th and 6th pan-European Corridors; the work commenced in the mid-1990s and is scheduled for completion in approximately 2015.

The Tensar bi-axial geogrid manufacturing process produces a unique grid structure, consisting of full strength junctions and stiff ribs, which present a thick, square leading edge to the aggregate used in track bed construction.

This allows the aggregate particles in ballast or sub-ballast to grip the geogrid and forms an effective mechanical interlock.

The interlock prevents lateral movement and dilation of the aggregate particles, so that a very high effective angle of shearing resistance is mobilised, and the load bearing capacity of the aggregate layer is greatly enhanced.

This enables smaller volumes of aggregate to be used and avoids the requirement for heavy conventional solutions such as piling and rigid concrete structures.

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