Heavy lorries rolled along the black asphalt strip that curved gently up and over the nearest hill. Its smooth surface needed only a white line to be complete.
Yet there was no paint to come. Instead, those lorries dumped their loads of heavy stone chips into the hoppers of pavers that spread it precisely over that black asphalt. For this was no road but a new high-speed railway line from Le Mans to Rennes, in western France.
Construction company Eiffage contends that the asphalt will result in a stronger trackbed that’s better able to carry the dynamic loads of trains running at up to 200mph (320kph). It’s one of the innovations the firm has brought to high-speed rail (HSR) to meet the needs of ever increasing train speeds.
Britain’s HS2 project will involve higher speeds than ever before on UK rails - 250mph (400kph) - and such innovations will become more important. French railway company SNCF ran a train at 357mph (575kph) under test conditions in 2007 and the latest European high-speed trains are designed for 225mph (360kph). As train speeds increase, it’s clear that track and formation design must match that capability. It must cope with the transition from earthworks to harder structures, such as bridges and viaducts. Ballast must withstand higher dynamic loads without fluidisation, which can cause the track to shift from its proper position. (The vibrations imparted by ballast tampers deliberately fluidise ballast so that it packs properly around sleepers.)
Eiffage is building the Le Mans-Rennes line under a project abbreviated to BPL - Bretagne-Pays de la Loire - reflecting the areas in which those cities stand. It’s a €3 billion French public-private partnership project with funding coming from national and local government and SNCF, a €1bn loan from 12 banks to special purpose company Eiffage Rail Express (ERE) and €129 million euros from Eiffage Group itself.
The deal lasts for 25 years, and includes six years of construction followed by 19 years of maintenance. Eiffage fully owns construction company CLERE and operating company OPERE.
The line itself will feature 214km of track, 182km of which is 320kph line, plus 32km of junction links to the existing French network. There are no stations, but eight junctions add to the complexity.
It has been a long time coming. Back in 1984, when SNCF built its second HSL, from Paris to Le Mans, it included provision (including bridges at Connerre junction, east of Le Mans) for the line that Eiffage is now building. A decade later work had been completed on the scope of the project and another decade passed before a public inquiry took place. This led to a tender in 2008 for which Eiffage was declared the winner. It signed its public-private partnership (PPP) deal with French railway owner RFF in 2011. Trains will be running from 2017, giving a Paris-Rennes journey time of less than 1 hour 30 minutes - 37 minutes less than today’s journey times.
Eiffage’s design, build and maintain contract gives it great incentives to build a railway based on best whole-life costs using systems engineering, rather than just building the system for the lowest cost and leaving other firms to cope with spending more to maintain it. According to Project Director Michel Oléo, the project also benefitted from SNCF allowing some flexibility with existing French High Speed Line (HSL) specifications. This allowed for innovation, he stressed.
A flatter management structure has been created, which, argues Oléo, allows for further innovation. Decisions can now be made at the correct place, rather than always being made at the top. For civil work, the Le Mans-Rennes HSL is divided into seven parts, each overseen by a manager who is responsible for everything in his or her section. These sections are sized so that the manager can easily cover the patch in a day. For BPL, each section is around 30km long.
Designers, builders and maintainers work together and have done from day one. This way, says Oléo, the best decision can be made between, for example, the length of earthworks and the length of a bridge.
Of these integrated teams, he says: “They have to be in the same place with the same boss and understand what others are doing in a clear and simple language. We need to have people together every day, in the same building. We normally don’t do this intense sharing of problems, but it works.”
Project Technical Director Imed Ben Fredj expands on this, saying that the integrated design team must consider ease of construction, planning, safety and costs. Integration allows those building the line to make decisions early in the design phase. “If we want to be successful, the team must work towards one target - the project,” he says, while recognising that each part of the team still has to make a profit.
Oléo adds: “With system engineering, if you can achieve your result with fewer interfaces then it will be more reliable and more efficient.”
Eiffage certainly has some interfaces to deal with. For example, the BPL line will have three signalling systems; TVM signalling for high speed, as well as ERTMS at Levels 1 and 2. Level 2 is needed as a result of European standards for interoperable railways while TVM is standard equipment for France’s fleet of TGV trains. ERTMS Level 1 is needed for freight trains using the eastern part of the line as a diversion around Le Mans. How many freight locomotives will be equipped with the necessary on-board kit for ERTMS remains to be seen but the facility for freight to use BPL came at the request of local government in Le Mans, which was keen to remove freight trains from the city centre. There is also provision for a local service between Laval and Sablé-sur-Sarthe to run (there is currently no direct railway between the two towns).
The two are some of the more surprising aspects of local consultation which is just as important a part of French life as it is in Britain. Elsewhere, bridges have been painted in colours according to local preferences, including the 300m viaduct over the environmentally protected valley of the River Courbe. Land temporarily used for building purposes has been returned to farmers according to their needs in an area famed for its agriculture. In some cases, it means that what might have been a gentle cutting slope is now steeper to maximise the usable land above it.
Eiffage encouraged the use of local workers. At the height of construction, 2,000 staff were employed, of which 800 were local while 15% of the total man hours were fulfilled by those who had been unemployed before the project. The company placed high emphasis on skills and learning
France takes a similar view to Britain when it comes to protecting wildlife and the environment. The route runs through the habitats of Marbled Newts, Common Parsley Frogs, Bechstein’s Bats, Hermit Beetles and Natterjack Toads, along with plants such as Soft Hornwort. Otters too were considered in the design of culverts carrying watercourses under the trackbed, with culverts made large enough to accommodate them.