Important note: this applies to city trains, which operate in a much more predictable environment than trains that cross large areas of the country.
A subway or city train stops every few minutes. This means that if somebody gets hurt, has a stroke, assaults somebody, starts shooting up… there is almost immediately a way to board more staff and handle the situation.
On a train with hours and tens or hundreds of kilometers between stops this is much less the case.
And yes, all the technology has been tested together. Before a train can enter a new region of authority, it must have permission from that authority, which means they must prove that the train can work with the local tech.
Not sure whether this means that the various signalling suppliers are waiting for a customer to take on the technical risk of being the first to deploy UWB CBTC, or that there were costs or disadvantages that make it unattractive.
What?
There’s one as far apart as you put them. The precision is what you make it.
I’m not entirely sure what you are trying to argue. Your original comment said you can’t know where trains are on underground subways because GPS doesn’t work underground, but that’s not the technology they use anyways, so it doesn’t make sense to reference it. The you seemed to argue that what might currently be in place is insufficient, but that wasn’t what this thread was talking about.
The only one showing ignorance here seems to be you suggesting subways use GPS.
Rarely used freight lines (aka branch lines) would never be automated, that wouldn't make sense. And some mainlines (I live near one) see as many as 4 100-car freight trains per hour. Those will never be less than one-man operation either, not least because at-grade crossings are everywhere.
All that means is that you design the system very robustly. And, of course, trains fail-to-safe. Cut a brake line? Train can't release its brakes. Signal out? Conductor can only move in GoA0 (manual), at reduced speeds, until the next signal is reached (and readable). Etc.