I know this subject has come up a lot, but hopefully this will actually be considered. I think that in order to make the subway actually useful, the train should be present at every stop at all times and you should be able to choose what destination you want to go to. I think that people will actually use it then because it will be faster than walking, not slower like it is currently. I'm not sure if anyone has came up with this before, so sorry if it has.  

that could work quite well I guess.  

Then it wouldn't be a subway.

But era could make a taxi service though.  

This is a bad idea