In comparison to railroads, trucks have relatively small fixed investment in terminal facilities and operate on publicly financed and maintained roads. Although the cost of license fees, user fees, and tolls is considerable, these expenses are directly related to the number of trucks and miles operated. The variable cost per mile for motor carriers is high because a separate power unit and driver are required for each trailer or combination of tandem trailers. Labor requirements are also high because of driver safety restrictions and need for substantial dock labor. Truck operations are characterized by low fixed and high variable costs. In comparison to railroads, motor carriers more efficiently handle small shipments moving short distances