London? London has 13 major railroad stations and they're all dead ends.[1] Crossrail, with expensive tunnels, now provides some east-west through services.
[1] https://en.m.wikipedia.org/wiki/File:Major_railway_stations_...
[1] https://en.m.wikipedia.org/wiki/File:Major_railway_stations_...
e.g. today's 18:24 from Horsham to Peterbrough going through London Bridge at 19:31, Blackfriars at 19:37 and then St Pancras (for a triple!) at 19:46 https://www.thetrainline.com/live/departures/london-blackfri...
I literally posted a train going through London Bridge and north out of London!
This doesn't happen in London in my experience. Trains don't turn around, instead every train is double-ended. The driver gets out of the cab at the terminus, walks to the other end of the train and gets in the other cab. They can do it faster than the passengers disembark.