Railway Bridge Ties, Membrane Filters, Hydraulic Post Drivers, Bi-Planes

How It's Made – Season 23

Heavy timbers are cut, drilled and treated for use as railway ties on bridges. Selective membranes are formed and installed in filtration units; hydraulic mechanisms are assembled into machines that drive posts into the ground; and wooden or metal airframes, wings, control surfaces and engines are brought together to build biplanes.