discover behind the scenes in the technical backstage

HASnne-Laure Séménou is the 10,000^e annual TER subscriber in Nouvelle-Aquitaine. Every morning, she takes the train to work, having travelled from Cestas to Bordeaux for the past two years. To thank her for her loyalty, SNCF Voyageurs made a big splash. During the European Heritage Days this weekend, she and her family were able to visit the behind-the-scenes of the Saint-Jean train station, places rarely revealed to the public. “Sud Ouest” was able to slip into the group.

Exit the platform and the teeming halls, direction the central substations. This large room set up in the station unfolds an immense optical control panel (OCP). Electrical diagrams innervate this vast curved plan on a black background. At the top, names of cities (Coutras, Vayres, Saint-Macaire, etc.) indicate the 55 electrical substations scattered on a railway network as large as the former administrative region of Aquitaine. The PK, or kilometer point, provides information on the distance separating them from Paris.

Lower the tension

What is their function? Most trains run on electricity. To power them, we use the catenary, a set of electric cables located above the rails. When it rises, the locomotive’s pantograph will pick up the current.

“With each alert, my role is to find solutions: locate the fault, guide the field teams to the right kilometer point, secure the intervention by disconnecting the power to the sector concerned,” explains the regulator.

But before that, “there is a need to convert the electricity that arrives by lowering the voltage,” explains regulator Clément Trijasson. “That is the mission of the substations: these stations that line the lines will reduce it from 90,000 or 63,000 volts to 1,500 volts for all trains (TER, TGV and Intercités), he explains. They also rectify the alternating current into direct current.”

The Bordeaux switchboard allows the device to be controlled remotely. When the panel is off, everything is fine. If lights come on and an alarm sounds, there is a problem. Whether the problem is minor or major, the sound intensity is the same. A dangling cable, a catenary damaged by a falling tree, circuit breakers going crazy… “With each alert, my role is to find solutions: locate the fault, guide the field teams to the right kilometer point, secure the intervention by disconnecting the power to the sector concerned,” explains Clément Trijasson.

400 trains per day

The optical control panel is still equipped with pushbuttons and manually triggered switches. The old-fashioned way. In addition to emergency cuts, the Saint-Jean station control center intervenes on scheduled maintenance projects. The network of substations and the (almost) 2,000 kilometers of catenaries are constantly monitored seven days a week.

The blue lines are the rails. The red lines represent the trains present while the yellow lines trace the routes they will have to take.

A few corridors further on, the group of visitors arrives at the operational stopover centre (COE). They avoid speaking loudly. “It’s the equivalent of the control tower,” compares Cyril Chanu, regional director of the Nord-Aquitaine lines. There are the platform manager and the supervisors of the transporters (TER, TGV and Intercités). Like a hub, the 15 parking lanes of the railway site see around 400 trains pass through per day (all types combined), with connections to manage, “parasitic” traffic to insert between the passenger station and the technical centre (garage area).

Arbitrations

Based in a neighbouring building (the former postal sorting office), the signal box prepares the “theoretical score” for the day. The COE staff try to play it without a false note. Video surveillance cameras scan the traffic flow on the platforms and in the underground. A large control panel also allows traffic to be monitored entering and leaving the station. The blue lines are the rails. The red lines indicate the trains present while the yellow lines trace the routes they will have to take. When everything is running smoothly, the ballet is fluid.

But it is impossible to ignore disruptions: a train that is late or stuck on a platform, a copper theft, a driver who is absent, an evacuation following an alert, etc. So many incidents that lead to decisions, plan Bs: rushing a train out of the technical center, holding back the departure of a TER in favor of a TGV, transferring passengers to another train… All this is managed from the COE, in conjunction with the regional supervision center. Knowing that a flapping of wings in Limoges or Poitiers can cause repercussions in Bordeaux, and vice versa.

“We will weigh up the consequences of a delay on all carriers each time,” says Julie, who works on the TER component. “The crux of the matter in the event of a delay is providing information to passengers, whether at the station or on the app. We know that we have a lot of progress to make on this point,” acknowledges Cyril Chanu. Even if, year after year, the appeal of rail seems to be gaining more and more followers.