TGV Track Construction - Finishing Construction

Finishing Construction

Now that the first track is almost complete, work begins on the adjacent track. This time, however, it is not necessary to lay a temporary track. Trains running on the first track bring the sleepers, and then the rail, which is unloaded directly onto the sleepers by dispensing arms that swing out to the proper alignment. The Nabla fasteners are secured, and the ballast is stuffed under the track as before.

The two tracks are now essentially complete, but the work on the line is not finished. The catenary masts need to be erected, and the wire strung on them. Once the catenary is complete, the track is given final alignment adjustments down to millimeter tolerances. The ballast is then blown to remove smaller gravel fragments and dust, which might be kicked up by trains. This step is especially important on high-speed tracks, since the blast of a passing train is strong. Finally, TGV trains are tested on the line at gradually increasing speeds. The track is qualified at speeds slightly higher than will be used in everyday operations (typically 350 km/h, or 210 mph), before being opened to commercial service.