To "hop" a train.
In some remote locations especially remote access Reservations, where there is no designated stop the travelers will tie a
white cloth further up the line to let the
Engineer know the want to board, give the train enough time to stop.
Also, train-Hop
To illegally board a box
car to ride across the country by 'hopping' onto a moving train.
Also;
Tight steering control and maneuvering at high speed