One thing I often think about is what a metro rail network would look like if I was in charge. I created a metro rail network inside my head, didn't give it a name, but the way it works is very clear to me.
I would make the trains very small. This would allow space for extra tracks. The passengers would sit on the train in single file facing sideways and there would only be doors on one side of the train. The seats on the train would be made of hard plastic and would have a rounded bucket shape for comfortable seating. The small trains only have enough space for people to sit in single file and hold less people than normal trains, but they come more often and some of them go directly to busy hub stations. There is also over taking rail to allow trains to pass trains that are in the station. The trains would be driverless because there would be too many of them and trains are like lifts that go forwards and backwards instead of up and down. The jobs would be engineers that maintain all the trains. The trains themselves would be very bright and colourful and would have faces on the front of them.
When there are very few people using the network, the trains would use less power because some of the trains would not be running but the ones that are running are small and use less power.
In the station there would be two platforms one for passengers getting off the train and one for passengers getting on. The train would stop at the platform for people getting off the train then would move forward 100 meters to the next platform for passengers getting on. The train would move to the getting on platform as soon as a train ahead moves away so people won't worry about missing their train.
Like I said earlier, there is always at least 4 lengths of track along the network. Two for going from a to b and two for going from b to a. The outer tracks are for express trains that go past some of the stations the inner tracks are for trains that visit every station.
The parts of the network that are not underground would have a frame around them that holds solar panels and aluminum sheet walls to keep the trains enclosed inside and away from the wind and rain.
There are so many quirks to my imaginary metro rail network but I don't have the time to share them with you. If I wrote down all the things about the network it would fill the typical space of a book.