NEW DESIGN CUTS WOODEN BRIDGE COSTS

The Lighthouse Bridge over the Clallam River in Clallam Bay, Washington, uses a new type of design and fabrication of wood glu-lam girders for bridge construction. Partially funded by a Timber Bridge Program grant, the new 162-foot, 7-inch, 2-span, HS-25 structure is believed to be the first publicly owned wooden highway bridge to incorporate aramid fiber-reinforced glue-laminated main girders. The project was initiated to replace an existing 100-foot glue-laminated pony truss with trestle approaches that was constructed in 1959, and was beginning to show significant deterioration on its exposed members. While all members in the original truss had been pressure-treated with creosote, the severe weather conditions of the area -- exposure to salt air and almost 100 inches of rainfall yearly --caused several of the truss members to prematurely deteriorate.