Cost-Competitive Timber Bridge Designs for Long-Term Performance
Start date: 07/01/15
End date: 06/30/18
Iowa Department of Transportation
Iowa Highway Research Board
About the research
The objective of this work is to develop a series of design, contracting and construction options and strategies for cost-competitive (initial and life cycle costs), sustainable timber bridges in Iowa that meet American Association of State Highway and Transportation Officials (AASHTO) HL-93 load requirements and Load and Resistance Factor Design (LRFD) bridge design specifications. The project will incorporate standard plans for timber bridge superstructures that are currently under development by the United States Department of Agriculture (USDA) Forest Service and perhaps others. These plans will be evaluated and modified for Iowa and when coupled with best inspection and maintenance procedures, provide new opportunities for constructing innovative, long-lasting and cost-competitive timber bridges. In addition, several bridge construction projects have been identified with partnering counties in Iowa that will use the developed plans, allowing the project team to assess and validate the true initial costs of construction, predict life cycle costs and complete a life cycle assessment for these bridges. Companies and timber manufacturers that are local to Iowa provide a valuable resource which is currently underutilized. Cost information from two under construction timber bridge projects in Buchanan County, Iowa, as well as from 1-2 other potential bridge construction projects with partnering counties in Iowa utilizing the developed plans, will allow the project team to assess and validate the true initial costs of construction, predict life cycle costs and complete a life cycle assessment for these bridges. In addition, life-cycle cost information from several timber bridge construction projects in Minnesota, which are part of a sister Minnesota Department of Transportation (MnDOT) research project that Iowa State University (ISU) is a part of, will also be referenced to increase the database for the project.
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