On National Rail, some of the latest stock like Class 450 on SWT have
passenger-openable doors which individually close (following the usual
warning bleeps) after a certain time has elapsed, about 30 seconds I
think. This is very useful at a terminus where otherwise the doors
could be open for a long time.

I'm not sure about that. At a terminus, boarding a train at leisure
which is not due to depart for five minutes, surrounded by all kinds of
noise and bleeping from adjacent trains, I have repeatedly had the
doors close on me with no effective warning just as I am getting on.

Maybe once they were going to do that, they should have given them
two-speed motors. After 30 seconds the door could close in leisurely
fashion, taking maybe 8-10 seconds to slide across; but on the guard's
command all doors not yet fully closed would close in the normal
manner. A two-speed flashing light would provide suitable warning.
--
Mark Brader "Remember, this is Mark we're dealing with.
Toronto Rationality and fact won't work very well."
-- Jeff Scott Franzman