Safe subway tracks
I've often seen videos of people who fall or are pushed onto tracks in a subway or other train tracks. They scramble to get back on the platform before the train comes and sometimes they make it and sometimes they don't. There is not always enough clearance for them to lay down between the rails and let the train pass over them. It should be made so. For the tracks along the platform they could be made differently than the simple rails on wooden ties. I imagine something like a concrete square U shape instead of ties that would create a space a few feet deep between the rails. This would ensure enough room to safely lay down while the train passes over so they can wait until it is safe to try and get off the tracks.