Abstract: A guardrail assembly for use on an elevated work platform includes a plurality of pivotally interconnected rail sections mounted on each side of the open front end of the work platform for movement between a collapsed position against the sides of the platform and an extended position. In the extended position, the sections define an enclosure on an elevated work surface, e.g. the top of a railcar or the wing of an airplane, and latches releasably lock outer free ends of the rail sections together. Vertically movable feet on the sections stabilize the assembly on the work surface.