With respect to when the trains leave, the old way used to have a "block" system. The route would be divided up into segments long enough to allow a train halt when braking from full speed. A simple Ohm-meter told you if a train was in a block - the metal axles would allow electricity to flow from one track to another. If electricity flowed, it would turn on a red light on a post at either end of the block, and of the adjacent blocks. If a train saw a red light ahead, it would know that there was a train within the next few blocks, and would halt.
This was easy to set up without computers, but limited the number of trains you could run on the same length of track.
The UK then started switching over to a dynamic system which knows the precise location of the nose and tail of each train, and which calculates how much distance each train needs to stop based on its current speed. This automatically adjusts the minimum separation distance needed to avoid collision with the train ahead. This is more complicated, but lets you run more trains on the same track. If speeds are low and braking distances are short, you could have trains running within sight of each other.
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timeasmymeasure
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Date: 2026-02-10 01:08 pm (UTC)This was easy to set up without computers, but limited the number of trains you could run on the same length of track.
The UK then started switching over to a dynamic system which knows the precise location of the nose and tail of each train, and which calculates how much distance each train needs to stop based on its current speed. This automatically adjusts the minimum separation distance needed to avoid collision with the train ahead. This is more complicated, but lets you run more trains on the same track. If speeds are low and braking distances are short, you could have trains running within sight of each other.