Today I was on the Hong Kong subway. The thing I like about this system is that there are no interconnecting doors between the cars and you can watch the train snake its way through the tunnels.
Those who campaign for female only subway cars make well-grounded arguments, but a woman alone in such a car late at night would be safer to move to a mixed car. If she is attacked in a female only car, then her cries for help would go unheard, largely due to the fact that passengers in adjoining cars would be focused on their mobile devices.
The time for women only cars, which can still be applied to the door-less systems, is the morning and evening crowded rush-hours. Other times, vulnerable passengers are safer in mixed cars where if attacked, there is a chance that someone will intervene.