Steel Highway Accessory Structures

Highway accessory structures are essential for full utilization and continued service of modern highways. Culverts, retaining walls, bridge flooring and forms, guardrail, signs and lighting poles of steel have been developed since the coming of the automobile. Selection and control of steels for highway accessory structures are attained by means of ASTM and AASHO specifications developed jointly between representatives of the steel industry and highway organizations. Low carbon steels, which are strong, ductile and weldable, are available in hot and cold-rolled sheets, hot-rolled shapes, pipe and tubing. Zinc coatings are effective in prolonging life of steel both underground and in the atmosphere. Paint provides adequate atmospheric protection for steel. Certain high strength low-alloy steels of the weathering type may be used bare in the atmosphere. Steel's low cost and good workability along with its strength and durability provide a fine combination of desirable characteristics for highway accessory structures.