Thrown Item Prevention Most people are decent and law bidding, but there are always those that do things that make one wonder about the brains of some.  Throwing things at a high-speed train or a Mag Lev train can be disastrous to the train and the person doing the throwing.  Hit a train doing 150 to 250 miles per hour with a rock and that rock will come flying back at 150 to 250 miles per hour, or if it hits glass or thin skin {train's skin} it can do major damage to the train. To help prevent this the BorderTransportationSystem suggests that in areas of predictable problems, i.e., urban areas, the track be protected by wire screening.   Index of ... Criminal rock throwing What are the security challenges for protecting rail systems?