Eighteen timber bridges were inspected to assess their long-term performance. In general, they were in excellent structural condition with glued-laminated decks performing better than nail-laminated decks. Extensive moisture content readings indicated that wet-use stresses should be used when designing bridge decks, regardless of deck type or treatment. Dry-use stresses are appropriate for the stringers. A comprehensive program, including new technologies and demonstration projects, must be developed to address the repair and rehabilita tion of older nailed-laminated decks.

Many recent developments have increased the interest in timber bridges, such as new materials and manu facturing methods, improvements in preservative treatment, a systems approach to bridge engineering, alarm over needed bridge replacement and rehabilita tion, and improved technology (1, 2). A number of these developments reflect the advancement in knowl edge of the general behavior of wood as a structural material (3). The importance of these developments has been underscored in comprehensive state-of-theart reports and technical presentations and publica tions (4-7). Arecent workshop helped identify re search needs that are pertinent to timber bridge engineering (8)