A second regional test road was constructed by the Western Association of State
Highway Organizations (WASHO). Named the WASHO Road Test, two test loops were
constructed in 1952 near Malad, Idaho, each consisting of two 12-ft (3.7-m) lanes. All
pavement was comprised of asphalt concrete on a crushed aggregate base, constructed
on subbases from 0 to 16 in (406 mm) thick. Each lane of a loop carried only one loading
and axle configuration. Because of the limited number of sections constructed in
Maryland and Idaho, a rational design procedure could not be developed.