Institute for Transportation

An overview of wood preservatives currently used for timber bridges is presented through a series of case studies from different regions of the United States. New wood species and preservative treatment options for timber bridges have made choosing the appropriate preservative more complicated. The compatibility of wood species and preservative treatment is often overlooked but can be very important to the durability of timber bridge components. More technical guidance is needed for bridge designers who are not familiar with wood preservative treatments. The current trend is toward the use of waterborne preservatives and untreated decay-resistant wood species in opposition to current American Association of State Highway and Transportation Officials design specifications.