NYC Subway is really hard-core about train stops. There's a trip cock on every subway car, near the right front wheel, and it works by directly operating an air valve to the brakes. The train stop lever alongside the track is raised by a big spring and lowered electrically, and the signaling system senses when it's physically up, ready to trip. Only then can the preceding train stop lower. There are always several train stops up between trains. A signaling failure or power cut will raise the train stops.
"The central principle of signal placement and engineering is that the control lengths of the signals be so designed such that when a train running at the highest possible speed under the worst weather conditions, with any semblance of functional brakes, is tripped, it will come to a halt before encountering the other train or obstruction that is causing the signal to be red."
Some signals have timers, for speed control. Go through a block too fast, and the signal ahead won't clear. Then the train stop will stop the train. This is common in downhill sections and ahead of curves.
Resetting a trip cock in NYC requires getting out of the cab and climbing down to the tracks. This is Not Fun.
Chicago has self-resetting trip cocks, which resulted in an accident in 2013.[1] A train parked in a service yard had a water leak into the control cables, which caused the train to move, slowly. The train hit a train stop, the brakes were applied, and the train stopped. But
the trip cock reset, and the train started again. This happened five times at five different train stops. Workers noticed, but were not able to stop the train. This continued until the train hit an occupied but stopped train just outside the yard.
This is why you want dumb train control.
[1] https://www.ntsb.gov/investigations/AccidentReports/Reports/...