This book provides information concerning the costs of transportation on non-urban highways and the relationships between these costs and characteristics of highways such as surface roughness, and vertical and horizontal geometry. The sources of the information presented here are four major road user cost studies performed between 1970 and 1982 in Kenya, the Caribbean, Brazil, and India. In these studies road user costs were investigated in considerable depth. Surveys of commercial road users were performed, surveys on a far larger scale than had been conducted prior to the 1970s. Large scale experiments were undertaken, aimed at determining the fuel consumption of cars, buses and light and heavy goods vehicles under alternative highway conditions, and considerable effort was devoted to obtaining data on vehicle speeds and their responses to highway conditions. The resulting body of knowledge concerning road users' costs is enormous, spanning three continents, diverse highway conditions and radically different economic environments.