In strip mining, a haulage system in which the empty units enter the mine over one lateral and leave, loaded, over the lateral nearest the tipple. This system is utilized where laterals are built into the mine from the main road, whether outside the outcrop or on the high-wall side of the mine workings. This system reduces the haul on the coal surface to a minimum, except where there are only two laterals, one at each end of the workings.