And while these works may seem ephemeral - often made from sandandmud rather than canvas and paint, their creators clearly expect them to survive beyond the next exhibition, leaving detailed instructions of how to recreate the work, and often rebuilding it themselves (as Turner nominee Karla Black did last week with her powder and make-up creation on the floor of Tramway).
The event is held every Memorial Day weekend in Ferndale, California, as artists race their bizarre wares across a 42-mile course over three days, including sections on land, sand, mudand water.