Comparative Durability of Timber Bridges in the USA

IRG/WP 17-20615

J P Wacker, B K Brashaw

As engineers begin to utilize life-cycle-cost design approaches for timber bridges, there is a necessity for more reliable data about their durability and expected service life. This paper summarizes a comprehensive effort to assess the current condition of more than one hundred timber highway bridge superstructures throughout the United States. This national study was jointly administered by the Forest Products Laboratory and the Federal Highway Administration and relied on data from the National Bridge Inventory database. In-depth inspections were conducted using visual and non-destructive evaluation techniques to characterize the condition of the primary bridge components and detect any structural deficiencies. The most popular superstructure system studied in this project was the multiple sawn stringer and plank deck system. This system was evaluated in a number of wood hazard (climate) zones with numerous examples of 60 or 70 year service records. The durability of the timber bridges studied was predicated on use of pressure treated materials for the primary structural members as required by the national bridge design code.


Keywords: condition, inspection, bridge, service life, superstructure, durability, preservative

Conference: 17-06-04/08 Ghent, Belgium


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