Why do trains sound their whistles in the middle of the night?

Train whistles, horns, and bells are warning devices which enhance railroad safety by giving motorists, pedestrians, and cyclists an audible indication of a train's proximity. The Federal Railroad Administration (FRA) requires that each lead locomotive in a train have an audible warning device. FRA does not specify when a train's audible warning device should be sounded. However, that agency is currently conducting a rulemaking proceeding to develop nationwide standards for the use of locomotive horns.

There are no Michigan regulations or state statutes pertaining to whistle blowing.