How to build an automatic Lego train system?
I think I'd use the ultrasound sensor instead of the touch sensor (or the brightness sensor with the light turned on in a dark tunnel). I haven't tried this but I'd worry about the touch sensor derailing or scratching the train. Otherwse, your system sounds pretty doable. The collision risk could be addressed by setting up the sensor a little further before the station and sending a stop signal to the second train if it triggers the sensor while the first train is still at the station.