Summary of Glulam Trail Bridge Standard Plan

This is a U.S. Department of Agriculture Forest Service standard construction plan for glulam stringer trail bridges located at South Walker Creek and Boundary Trail on the Caribou Targhee National Forest, Westside Ranger District. The plan was revised on December 4, 2025, and consists of five detailed specification sheets covering bridge design, materials, and construction requirements.

The standard plan specifies construction of trail bridges using Douglas Fir (DF) glulam stringers with a 24F-V4 combination symbol rating. Bridge components include three stringers per structure (25 to 60 feet span depending on pedestrian load requirements), 3" x 8" minimum deck planks, solid sawn timber or glulam curb rails, and steel diaphragms. Decking, running planks, and railing systems require treatment with pentachlorophenol or copper naphthenate for exposed conditions. The specifications detail bearing shoe assemblies, timber sill or concrete sill connections, anchor bolt details with malleable iron washers, and gabion foundation basket systems. Materials must conform to American National Standards Institute (ANSI) 117 specifications for glulam members, ASTM standards for reinforcing steel, and Western Wood Products Association grading rules. Foundation designs include both timber sill connections on undisturbed soil and concrete sill options with standard gabion basket sizes ranging from 6 to 12 feet in length. All construction must comply with federal highway project specifications (FP-03) and current trail bridge construction standards.