|Project Name:||Long-Term Performance of Timber Bridges|
Office of Infrastructure Research and Development |
|Team:||Hazard Mitigation Team|
Infrastructure Research and Technology Strategic Plan and Roadmap|
|Project Description:||Timber bridges are a viable option for the U.S. highway system, mainly along secondary roadways in rural areas. Many of these structures have been in service for decades and have performed well structurally, but have been deemed deficient for functionality purposes. In addition, many bridge inspectors are not as familiar with timber as a bridge material and tend to downgrade their condition rating in the National Bridge Inventory (NBI). The net result is that many engineers hold the misconception that timber is a low-performance bridge material having an estimated service life of fewer than 20 years. There are a few good examples that support the long-term durability of timber bridge components. The Forest Service (FS) maintains nearly 3,000 timber road bridges in their transportation network. Many of them are sawn timber superstructures, which were installed in the post-WWII era, and are still in service after several decades. The FS also has a fairly large population of early glulam bridges built in the 1950s that are still providing vital transportation links in the Pacific Northwest. The railroads have used timber components for bridges for over 100 years and have several sawn timber structures, which have been in service for more than 75 years. However, what is lacking in the literature is a scientific study on the long-term performance of timber highway bridges in the United States.|
|Start Date:||October 15, 2008|
|End Date:||February 28, 2014|
The key project objective is to acquire precise data on the performance of timber highway bridges in the United States. A better understanding of the durability characteristics of timber bridge systems and components will improve comparisons to alternative bridge materials, improve bridge design details and practices, and provide for improvement in extension of service life. The primary objective of this study is to assess the condition and performance of a select number of existing timber highway bridges in various climatic regions in the United States and establish a baseline for evaluating future performance.
|Test Methodology:||The project is national in scope and will focus on the timber bridge structures located in the Pacific Northwest, the Arid South, the Midwest, the South, and the Northeast. Several cooperators will be involved in this effort, each focusing their efforts in one of the climatic regions. The project will be jointly managed by the Forest Service and the Federal Highway Administration (FHWA).|
|Other Information:||Funding: $315,681.66 (Federal Highway Administration) + $316,000 (Forest Service—Forest Products Laboratory).|
|Expected Benefits:||National scale project that provides more reliable data on the true longevity of timber bridges in the United States and allows for more accurate life-cycle cost comparisons.|
|Deliverables:||Name: Long-term performance of timber bridges.|
Product Type(s): Research report, Techbrief, Data
Description: The deliverable is a comprehensive final report and a database of performance characteristics of timber bridges.
Bridges and other structures|