From the bridge of the D20 over the LGV, presentation of the components and systems of the high-speed railway infrastructure and the systems contributing to its operation. Then, visit the Vaumort signalling station, relay technology (PTS), and the various features present in the building built in 1979. Comments and visualization on site, of the present operating arrangements (banalization, emergency dock, operation of the post in "local control"...). Information on important work in progress (LGV+), which will see the replacement of these positions, which will have had 3 million high-speed trains, in November 2024, by electronic card stations (SEI). A little information on European signage (ERTMS) will be discussed. A brochure will be given to each participant.