Berlin-based street artist Dtagno has created a way to paint trains as they pass. His Morphogenetic Field Device Little Boy is a vertical pole with 22 spray cans that zebra-stripe passing vehicles. Dtagno has previously created similar painting devices like this one here which has a final product that looks like this. Check out the device at work below (skip to 3:35 for the train-painting action) and vote below if it's street art or simply vandalism.
Berlin Street Artist Dtagno Paints Trains With His Train Graffiti Device