Rail Spanners W911S226U3919

Provide aluminum rail spanners meeting the following requirements: at least 72 inches long, 24 inches wide, and no more than 4 inches thick, with a rated capacity no greater than 50% of the failure strength (a 2-to-1 safety factor). Failure strength is defined by the weight causing permanent deformation of the aluminum; the spec notes that an 80,000-lb axle can be placed on a pair without permanent deformation.

Construct from structural tubes at least 3x3 inches and no more than 4x4 inches. The top surface must feature high-traction rungs up to 2 inches wide, spaced no more than 4 inches apart to allow tiedown chains or straps to pass between the rungs and over the tubes, while also permitting debris to fall through. Include a reinforced kickplate on one side to rest on a flat, unobstructed surface, and a minimum 12-inch reinforced stub toe on each end, tapering to a 2-inch blunt end (knife ends not acceptable). Each spanner must be etched with its part number and capacity. The spec also lists weight-related minimums per spanner and per pair, though the figures provided appear inconsistent.