People have been using the trail at all hours of the day for ages. That was okay because it was they who were liable for whatever might happen, since they weren’t supposed to be there and no one made any representation about safety. Now, the municipality has paved the trail and is inviting people to use it, but there’s some risk (I’m sure there’s some) of something happening when the train goes by, so they put up the sign. Between the hours of 11:00 and 7:00, people use the trail but the municipality assumes no liability. Problem solved.
Edit: Just in case, I point out that the above was said tongue-in-cheek. But it is a case that someone wondered how safety could be guaranteed when trains are passing; since it can't, just say the trail is closed when trains are running, and the risk is the user's.
Edit: Just in case, I point out that the above was said tongue-in-cheek. But it is a case that someone wondered how safety could be guaranteed when trains are passing; since it can't, just say the trail is closed when trains are running, and the risk is the user's.