Did you know that things as small as leaves can delay trains? When leaves fall onto the tracks, they can cause wheels to slip and then the brakes may not work properly. In some areas, those leaves have to be removed by an army of cleaners. In spite of such efforts, trains are sometimes delayed for long periods of time. Some scientists suggest that a laser device fitted onto the front of a train might solve the problem. They claim that it could blast leaves away easily and quickly.