When you open the small door of a pink Placo partition, in the distance, hidden by the dust from the construction site, they are there.
The platforms of the Haussmann-Saint-Lazare station of the RER E, and their passengers.
For the past few days, an annex tunnel (a “entonnement”), built as part of the extension of the line to La Défense and Yvelines, has joined the existing station to the future line under construction.
It will connect the current RER E to the new tunnel to Nanterre.
A symbolic advance.
But which announces the maintenance of the schedule for a commissioning of this portion in 2023.
These 170 essential meters could not have been excavated by the tunnel boring machine: “It is because of line 14 which passes above, explains Pierre Merand, project manager at Egis, pointing to the ceiling.
We do not have enough room to pass the tunnel boring machine 11 meters in diameter.
It was therefore necessary to drill in a “classic” way, that is to say with a “milling cutter” and a mechanical shovel. A titanic job that took almost four years. “In this hyper-dense area, the well that allows the equipment to pass is very narrow,” adds Matthieu Bachollet, operations director at SNCF Réseau. The machines had to be taken down in pieces to be assembled on site and used. “But at the start, there was no room to put them all,” says Pierre Merand. So we dig a meter, then we go up a machine to lower another which allows to put the hangers
(Editor's note: steel hoops)
to maintain the walls.
Then go up, to descend a third which throws concrete ... "All, as quietly as possible because of the apartment buildings nearby and as meticulously as possible because of the tunnels of the four metro lines (3,9,13 , 14) and the RER A nearby.
At the bend of a gallery, you can now see the four tunnels that will accommodate the trains.
It is also here that we will go from four to two lanes.
And that the automatic piloting system currently being deployed - Nexteo - will theoretically make it possible to maintain the interval of 108 seconds in rush hour between trains coming from or going to the east - Chelles and Tournan (77) - and from the west, Mantes-la-Jolie (78).
Or 28 per hour.
It remains to install ... cables, lights and of course the railway material (tracks and catenaries) while waiting for the final junction. Scheduled for 2022 but delayed due to the health crisis, the extension to Nanterre should be commissioned in mid-2023. The rest until Mantes-la-Jolie is planned before 2025.