Over at the walden effect blog, they were looking for cheap creek crossing options that didn't require much infrastructure. My solution is a tensegrity arch bridge (or tied-arch bridge) that doesn't require elaborate abutments.
The glulam beams are loaded lostly in compression, because of their shape. According to NEN 6760 (see Sterktegegevens van hout, in Dutch), woods in the lower strength classes C14 to C18 are twice as strong in compression as in tension, and are stronger in compression than in bending. The wires on the underside prevent the need for abutments becaue they can carry tensile forces. Since they also prevent the ends of the arch from spreading, they also help eliminate bending in the arches.