When Doc and Marty want to leave 1885 they realize that the DeLorean cannot reach 88 miles per hour (142 km/h) under its own power since commercial gasoline is not yet available. Doc devises a plan to use a locomotive to push the DeLorean up to the required speed. Doc and Marty explore a rail spur they intend to use and spot an out-of-control horse-drawn wagon.