Union Pacific spokesman Mark Davis is reminding motorists to be careful at railroad crossings during the upcoming Labor Day weekend. Davis says because of their size, trains often appear to be moving more slowly than they actually are. He says by the time a locomotive sees a car on the tracks it's impossible for the train to stop in time to avoid a collision. Davis also reminds motorists that in Wyoming drivers who cross a closed rail crossing  are liable for a fine of up to $750.00.