Pieced steel (sometimes called sommerfield) planking is used by various
people (including the military) to provide a stable base for passage of
people and vehicles across soft terrain. It is visually similar (poss.
identical) to the type seen on the camel trophy vehicles, however I
suspect that is alluminium. It is possible to get this stuff cheaply in
the UK, however the aluminium stuff is more expensive (about 5x.)
As for availabilty in the states, I don't know, however I think K & J
Slavins have an US outlet, and they sell the alluminium type.
Regards,
Ralph.