This is an “Air Bridge” which is kind of a funny name, but it is used for heavy machinery to cross over an industrial gas line (or any buried utility) and provides an air gap between the pipe line and the equipment. Basically it keeps the machinery from “crushing” the pipe. These are temporary crossings, installed for a job and removed after completion. We supply this as a fully assembled kit ready to go. The gas company specifies how far away from the pipe the machinery has to be maintained, dependent on the depth the pipe is buried. This particular crossing is rated for all H-20 Highway Loading, 12 Cu Yard Dump Trucks, up to D-7 Cat and 561 Pipe Layer.