MIG wrote:

Hitting someone who is getting on or off a train is likely to cause an
accident. Who knows how frail or surprised they might be. It doesn't
need to crush their bones to be dangerous.

/Likely/? I think you're exaggerating. At least around here, people
get hit by the doors all the time, and the vast majority of the time,
the only problems that ensue are train delays and black-striped clothing.

Again, why not have a sensor that will painlessly reopen the door if it
encounters an obstruction? Perhaps the sensor should be disabled if the
train is about to leave, but if the door is closing only due to
passenger request, there's no harm in reopening if necessary.
--
David of Broadway
New York, NY, USA