Wow! What a slack-arse I have been! 4 days since I posted something. Isn't slack-arse a great expression?
Anyway, when we were in China we rode the very fast train from Shanghai to Nanjing. It travels at 100+mph and spends its day travelling back and forth between the two cities. It has an engine at both ends so that it doesn't have to be shunted around to face the other direction at each end.
The stations are so organised that when the train stops those exiting do so from the front of each car (there were 9 cars on our train). On the platform those waiting to board are standing in a neat line on a yellow square – exactly where the rear door of the car stops. There is a less than 5 minute stop at each station.