21/07/2011
Track renewal train: modernising at top speed!
Like a veritable factory on wheels, a track renewal train can renew all rail components in a very short time, with the chief aim to disrupt commercial train traffic as little as possible.
Only two track renewal trains exist in France. These “factories on wheels” are several kilometres long, and consist of a number of machines strung one behind the other. Their aim: to renew all rail components in a very short time, the chief consideration being to disrupt commercial train traffic as little as possible. A veritable race against the clock that can take place in daytime or at night! A track renewal train is capable of restoring up to 1,000 meters of track in one day, while commercial traffic continues between the various operations. It is an industrial organisation that requires about 400 workers, technicians and engineers.
What does a track renewal consist of?
Track renewal consists of replacing all or part of the elements that make up a track: ballast, crosspieces, rails and brackets. The decision to renew tracks can be prompted by wear, or considerations such as comfort, efficiency or productivity. In fact, after a certain age, the state of a track no longer makes it possible to guarantee the resistance of structural components and adequate performance through the usual maintenance procedures. This entails heavy, costly works that need to be carried out every 30 to 50 years.
Track renewal trains regularly operate on the network. The Ile-de-France and Nord regions recently benefited from a full replacement of 27 km of track on the RER D line, and the renovation of the Hazebrouck-Dunkerque and Hazebrouck-Calais lines.
What does a track renewal consist of?
Track renewal consists of replacing all or part of the elements that make up a track: ballast, crosspieces, rails and brackets. The decision to renew tracks can be prompted by wear, or considerations such as comfort, efficiency or productivity. In fact, after a certain age, the state of a track no longer makes it possible to guarantee the resistance of structural components and adequate performance through the usual maintenance procedures. This entails heavy, costly works that need to be carried out every 30 to 50 years.
Track renewal trains regularly operate on the network. The Ile-de-France and Nord regions recently benefited from a full replacement of 27 km of track on the RER D line, and the renovation of the Hazebrouck-Dunkerque and Hazebrouck-Calais lines.
Track renewal in 4 stages
1. Clearing ballast: the machine lifts the tracks and removes old ballast. Reusable ballast is put back underneath the track, whereas the part that is not reusable is loaded onto the wagons strung in front of the machine.
2. Track laying: rail fasteners are removed in order to push the old rails away from the track. Old wooden crosspieces are removed and replaced by concrete crosspieces. Long new rails are gradually put in place, fastened to the crosspieces and welded together.
3. Re-railing: the track is restored by successive, precise re-railings of maximum 80 mm each. Ballast is poured and the track laid down to prevent the ballast from spreading.
4. Release: the rail is heated to a temperature of 20 to 32°C. This prepares it for the effects of dilation and traction that it will constantly have to endure due to temperature changes.
1. Clearing ballast: the machine lifts the tracks and removes old ballast. Reusable ballast is put back underneath the track, whereas the part that is not reusable is loaded onto the wagons strung in front of the machine.
2. Track laying: rail fasteners are removed in order to push the old rails away from the track. Old wooden crosspieces are removed and replaced by concrete crosspieces. Long new rails are gradually put in place, fastened to the crosspieces and welded together.
3. Re-railing: the track is restored by successive, precise re-railings of maximum 80 mm each. Ballast is poured and the track laid down to prevent the ballast from spreading.
4. Release: the rail is heated to a temperature of 20 to 32°C. This prepares it for the effects of dilation and traction that it will constantly have to endure due to temperature changes.
