TrainSim-Matt I’m not convinced that the TVM-430 system is working properly during the Bad Things scenario. My understanding of TVM-430 is that along the route there are flags (the yellow/white triangles on blue background). These flags represent signals and speed limit signs, which are signalled in the cab. When the train passes one of these flags, a transmitter tells the train whether to slow down, to speed up, or to stop. If you are told to slow down or stop, my understanding is that you must do so by the time you reach the next flag, which is usually positioned 1500 meters (1.5km) further down the track. When being slowed down, you are stepped down from 320, to 300, to 270, to 220, to 200, to 160, to 130, to 80, to 60, to 0 and then Red. Whenever you are about to be stepped down, the current speed flashes before the new speed limit takes effect. My understanding is that there are no transmitters between the TVM-430 flags. During the ‘Bad Things’ scenario the speed limit in the cab is constantly changing, even between TVM-430 flags. I don’t think it’s supposed to do that, but I’m happy to be corrected if I’m wrong. As a consequence you don’t really know where you are with the speed as it’s changing far too frequently during the run. Based on my understanding, each change in speed should only come at a TVM-430 flag and not between as there are no transmitters between the flags to tell the train what to do. TVM-430 was designed to reduce stress on the driver, but the very frequent beeping and speed changes are stress inducing during the Bad Things scenario. Also, on PS4 Pro when running the Bad Things scenario on PS4 Pro, I have twice turned TVM-430 safety systems on and have twice been emergency braked even though I was nowhere near the TVM-430 speed limit or track speed according to the HUD. On both occasions, this happened after leaving Avignon and before the scenario updates to tell you about the bad weather and problem train ahead of you. Also, leaving Avignon I get red triangles with zeros on them, but the HUD says all is good and I’ve got clear signals. - matjamca
TVM-430 is a continuous train protection system, just like LZB. This means that whenever the situation ahead improves (because the train ahead of you moves) this information will be relayed to your train immediately. This way traffic keeps flowing more smoothly, as you can stop braking when the TVM steps up to a better indication. The boards you see along the line are block marker boards, they indicate the boundary of each block.
I’ve used this site as reference material (see link below), it doesn’t mention more frequent speed changes ... AlexNL - where did you get the info about there being more frequent speed changes? Just so I can continue learning about the system. http://www.thuthuboutick.fr/bal/signaux4eng.html#2111
http://www.railfaneurope.net/tgv/signals.html Gives good info about the system and explains how it works.
From the page linked to by heardturkey: A detailed guide about how everything works was made by Link-Skywalker, available here: https://www.trainsimcommunity.com/guides/the-french-signaling-system-by-raph
So effectively, unless it’s an emergency the speed can only be restricted at a flag, but it can be increased between flags. So you might pass a flag and get told to reduce speed to 200 kph and a few moments later, allowed to increase to 220 kph, but you shouldn’t get a further speed restriction until you pass the next flag.
Seems like it's only a problem on that scenario, usually TVM works as described "So effectively, unless it’s an emergency the speed can only be restricted at a flag, but it can be increased between flags. So you might pass a flag and get told to reduce speed to 200 kph and a few moments later, allowed to increase to 220 kph, but you shouldn’t get a further speed restriction until you pass the next flag."
If a block has multiple track circuits, it is possible for speed changes to occur within the one block. See page 267 of Raph’s guide, linked above.
