Tour de force

Completed on 1 July 2017, the large-scale project „Ligne à Grande Vitesse Bretagne – Pays de la Loire” demanded a lot from man and machine. Since 2 July 2017, the French TGV runs at travelling speeds of 320 km/h to 350 km/h on the 214 km long high-speed line.

The metropolis, the bustle around the Eiffel Tower and the Champs-Élysées here; a small town with half-timbered houses in the picturesque Bretagne there. Paris and Rennes are worlds apart, separated by about 340 kilometres and around four hours by car. By train, this journey takes considerably less time: Until recently, it took two hours and four minutes. Now, it takes only one hour and 26 minutes thanks to the project called “Ligne à Grande Vitesse Bretagne – Pays de la Loire”, LGV BPL in short. The high-speed line connects Rennes with Connerré, east of Le Mans, completing the TGV line to Paris. The construction costs for the 214 km long line amounted to 3.4 billion euros. Since 2 July 2017, French high-speed trains run on the line. Building it was hard work, however.

25 years ago, the idea to build the line came up first. Following a lengthy procedure to select the route and the decision for a GPS based network, the Eiffage corporation won the contract in 2011. A testing phase followed in September 2014. Measuring, ballasting, track and tamping works were coordinated to ensure a smooth workflow and steady progress of the works. Aboard: Austrian high-precision machines.

Austrian precision in France

Plasser & Theurer’s SMD 80 laid rails and sleepers. Patrick Walke, project manager for surveying at the engineering office Herz­bruch, was impressed by the continuous action working train with a length of more than 600 m. “While the front part of the train, the crawler track, travels on the ballast bed, the installation unit, the sleeper wagons and material wagons for rail fastenings and long rails, travel on the newly laid track.” This is how the machine lays 1,500 m of track per day. In peak periods, it reaches outputs of even 2,300 m of track per day.

The machine places the concrete sleepers to a tolerance of 10 mm, which is an impressive level of precision for a heavyweight train, travelling with six rail wagons and up to 20 sleeper wagons.

For the project, seven levelling, lining and tamping machines were used, some of them with an integrated stabilising unit. The fleet included the Duomatic 09-32 CSM, 109-4X Dynamic Tamping Express and the 109-3X Dynamic Tamping Express. The machines carried out at least five tamping cycles and three stabilising cycles each. Like the SMD 80 track laying train, the machines produced in Linz ensure sustainability and safety.

Great logistical challenge

The distance and the varying conditions along the line were the biggest challenges. “It was a logistical challenge”, Patrick Walke explains. A separate railway bridge and two “Bases Travaux” were built in advance to ensure material supply.

The construction camps reached about 60 ha in size, which is as big as 130 soccer fields. The camps were used for parking machines and loading sleepers, rails and ballast. In addition, there were around 36 ballast depots along the line. Although the works had been well-prepared, a considerable number of staff was required.

“In mid-September 2015, when the SMD 80 was somewhere between line kilometre 175 and 180, close to Rennes, the trains for rail and sleeper supply were operated in three work cycles”, Patrick Walke explains. Immediately after the SMD 80 had laid the track, the trains supplying the material could already travel on it.

Since late 2016, test runs have been carried out on the „Ligne à Grande Vitesse Bretagne – Pays de la Loire“. In January 2017, a train reached the maximum speed of 352 km/h. It transports passengers from Paris to Rennes, two cities that are worlds apart, in one hour and 26 minutes (saving 37 minutes of time).

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Extract from “LGV BPL: La voie c‘est moi” part 1 and part 2, published in the magazine “Der Eisenbahn Ingenieur”, focussing on track measuring, January and February 2017 issues.