A school bus approaches a railroad crossing and the driver can't see the train coming down the track-for parents, that's the stuff of nightmares. But the Minnesota Department of Transportation (MnDOT) has just finished a six-month trial of a "smart "system designed to keep kids safe at the crossing. MnDOT engineers installed communication antennas in railroad crossing signs and in the front license plate of each bus in one school district. As a bus approaches a crossing, the plate picks up a warning signal sent out by the sign. A dashboard display connected to the smart plate flashes and beeps to alert the driver that a crossing is coming up, and whether a train is near. Project manager Ben Osemenam called preliminary results from the experiment "very positive," and says the MnDOT is gearing up to test the system at crossings that don't have lights.