You might not see leaves as hazards, but train operators would beg to differ -- foliage on the tracks not only makes it harder for trains to stop, but also messes with anti-collision signals. The greenery might not be much of a danger for much longer, however. Dutch Railways is testing a laser system that zaps leaves (and other organic material) before it reaches the wheels, keeping the tracks clean. You can already use water jets and sand gels to do this, but they have limited supplies and sometimes damage the rails. The lasers run so long as the train has power, and they actually help the metal by drying it and preventing leaves from sticking.