This invention discloses a vehicle device moving on a cross roadway, which applies an independent driving structure of eight wheels of a motor and low voltage DC circuit supply to move in a limit region and finish specific operations, such as farming operation with farm tools in greenhouses and hoisting and carrying clogs in factories, in which, the method includes: installing four-pairs of drive and turning units under a car frame to drive the car to run on the roadway or switch between two roadways, setting a DC low voltage supply device to provide supply to the motor.