Each span has four steel double ribs of steel tubes butted and clasped by wrought iron couplings.
The top flange consisted of cast iron hollow castings butted end to end, and the struts were of cast iron.
Corners of signs and intersections of lines were first fixed by minute tube-drill holes, into which the hand tool butted, so that it should not slip over the outer surface.
At the back end, the lighter rear hub and butted spokes are carried over from the big ' un.