Glulam products, when manufactured with waterproof adhesives and pressure-preservative treatments, can be used in exposed applications such as bridges, utility poles and crossarms, and docks. Glulam beams are used in pedestrian and light vehicular applications, such as stream crossings on golf courses and in parks. They are also used in larger highway and railroad bridges. Designs range from straight girders to soaring arches. In all of these applications, the strength and stiffness of glulam give builders and designers more design versatility than they have with other structural products.
Glulam Timber Truss Bridge Spans Remote River
The Placer River Pedestrian Bridge, completed in July 2013, is the longest clear-span glulam timber truss bridge in North America. The 280-foot long camelback bridge is located in Chugach National Forest in Alaska at the Spencer Glacier Whistle Stop, one of five stops planned along a new railway in Alaska’s National Forests and Parks. Designed by Western Wood Structures, the bridge was constructed with preservative-treated Douglas-fir glulam trusses, Alaskan Yellow Cedar decking, and steel connectors.
The Placer River Pedestrian Bridge faced unique design challenges. Aesthetically, the US Forest Service wanted the bridge to evoke a look and feel reminiscent of an early 20th century railroad camp. At the same time, the backcountry bridge’s design had to not only withstand extreme weather, but also be placed high enough to avoid collisions with icebergs and ice floes from nearby Spencer Glacier. Sitting 25 feet above the waters of the Placer River, the bridge design meets every requirement for appearance, durability, and strength—and was achieved with cost-effective materials.
“People are pleased with the bridge—with the way it looks and with the way it fits in with the setting,” says Rod Dell’Andrea, a structural engineer for the USFS. “It’s truly a context-sensitive design and installation.”
Read more in the APA Case Study: Placer River Trail Bridge - Form Q110.