Institute for Transportation

Interest in portable bridge systems has increased due to heightened awareness for reducing environmental impacts and costs associated with road stream crossings. To illustrate the effectiveness of timber bridges used in portable applications, this paper presents case studies of portable bridges constructed with longitudinal glued-laminated timber decks. Also, the paper discusses the need to account for dynamic loading effects in bridge design procedures. Longitudinal timber deck superstructures appear to be the most attractive option for use as portable bridges. The example glulam bridges performed well and were cost effective. Superstructure costs ranged from $347/m2 to $414/m2 with total costs ranging from $325 to $2,760 per site. Results from dynamic loading tests showed mean dynamic amplification factors ranged from 1.15 to 1.64 and 95th percentile values ranged from 1.31 to 1.88. Therefore, portable bridge design procedures need to account for dynamic effects from vehicle loads.