TCAS has solved this for airplanes. It wouldn't take much to modify the system for trains so that, in the least, it notifies when an unexpected train is nearby. A little more logic could allow it to verify which track each train is on.
Obviously it wouldn't be "just" GPS. In the simplest example - if I choose to add a friend to "Find my Friends" on iPhone, both our locations are visible to each other via GPS when our phones are on.
... via mobile data or WiFi, you mean. Whether it uses GPS, Galileo, track measurement points, or even "driver calls the control centre to update their position" doesn't have much to do with it. What I assume you mean is redundancy so that two or more systems can communicate train positions independently, where the more relevant problem is how to get the data across in a timely manner. The driver of the stationary train called in their position and it wasn't used: it's a communication problem, not a "where am I" problem. Idk why the focus on GPS and using GPS for communication (which GPS can't do, and newer systems only do at very low speeds for emergency communication) but finding one's position is usually not the problem
There is a system that does exactly that, its called ETCS Level 2: https://en.wikipedia.org/wiki/European_Train_Control_System But its not so wide spread unfortunately. Also if it fails then you are back to operators taking decisions
Because the issue is knowing where the other trains are, not yours.
TCAS has solved this for airplanes. It wouldn't take much to modify the system for trains so that, in the least, it notifies when an unexpected train is nearby. A little more logic could allow it to verify which track each train is on.
Obviously it wouldn't be "just" GPS. In the simplest example - if I choose to add a friend to "Find my Friends" on iPhone, both our locations are visible to each other via GPS when our phones are on.
> our locations are visible to each other via GPS
... via mobile data or WiFi, you mean. Whether it uses GPS, Galileo, track measurement points, or even "driver calls the control centre to update their position" doesn't have much to do with it. What I assume you mean is redundancy so that two or more systems can communicate train positions independently, where the more relevant problem is how to get the data across in a timely manner. The driver of the stationary train called in their position and it wasn't used: it's a communication problem, not a "where am I" problem. Idk why the focus on GPS and using GPS for communication (which GPS can't do, and newer systems only do at very low speeds for emergency communication) but finding one's position is usually not the problem
"Just put airtags on all the trains"... obviously simplistic but I get your point.