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a rail laid along track rails in order to guide the wheels of rolling stock. In curved track sections, guardrails reduce the wear of the outer track sides and prevent a lateral shifting of track rails. In the frog part of switches, guardrails guide the wheels of the rolling stock into the appropriate groove of the frog. Guardrails are made of pieces of standard rails. In switches both standard rails and rails of special cross sections are used.
a protective structure to prevent vehicles from running off roads. Guardrails are made of reinforced-concrete beams, metal strips, or masonry and concrete structures. The best types use metal strips and cables that are attached to supports by flexible components and permit elastic deflection when struck. Their height is not more than 0.8 m; the locations where they are compulsory in the USSR are regulated by the design standards for motor roads. During the night they serve to orient drivers, because light-reflecting units (catadioptric devices) are mounted on them. The reflectors on the right side of the traffic lane are red, and on the left side they are yellow or white.