University of Washington

25 2014-2015 Annual Report • Project: Safety of Idaho Rural Highways under 129k Trucks • PI: Ahmed Ibrahim (UI), aibrahim@uidaho.edu A significant number of local highway jurisdictions in Idaho lack the engineering expertise and financial resources to conduct detailed assessments when requests are received to increase weight allowances for local roadways beyond the current legal limit for gross load weight of 80,000 pounds. Idaho Code 49-1004A (1) states "the authority having jurisdiction may designate routes … for vehicles not exceeding … 129,000 pounds, utilizing criteria established by the board based upon road and bridge structural integrity and engineering standards" These higher load limits can enable private freight organizations to better compete in domestic and global markets by allowing them to distribute freight more efficiently. The Idaho Transportation Department has the engineering staff and database resources available to evaluate road and bridge capacities on state and federal highways; however, local highway districts may not have such resources. This limits the local districts' ability to expeditiously consider increased load requests, which in turn limits freight organizations' ability to operate more efficiently on rural highways resulting in less competitive Idaho industries. Additionally, many local roadways are not designed or constructed to accommodate any type of heavy load. This collaborative study between the Idaho Transportation Department and the Local Highway Technical Assistance Council would provide local highway jurisdictions guidance for conducting roadway assessment from review of available data and current condition to full engineering studies where appropriate. • Project: Rural Bridge Safety: Evaluation of Atypically Large Farm Vehicles • PI: Ahmed Ibrahim (UI), aibrahim@uidaho.edu The proposed study will determine how different types of FVs with different characteristics distribute their loads on bridge superstructures. These will be realized through actual load testing, computer simulation, and statistical analysis. At least two bridges, one in ID and one in OR, will be physically tested, subject to a variety of FVs. The structural behavior of the bridges will be monitored using wireless sensors to assess the behavior of bridges' superstructures and the corresponding load distribution factors for girders under the critical loading conditions will be determined. The selected bridges will be representative of rural bridges problematic for FV traffic in the region. The field investigation of the proposed bridges will be used to validate computer models in order to explore a broad number of bridges under various FVs. The research team will develop a FV profile that represents worst-case scenarios for use in determining load limits and distribution factors which will lead to increased infrastructure and operators' safety. With the information developed, unique traffic sign designs, that will include variations of tractor symbols and weight limits, will be developed and evaluated through an online comprehension survey of FV operators. The survey results inform supplemental traffic signage to be added to rural bridges to increase infrastructure and operator's safety. "A significant number of local highway jurisdictions in Idaho lack the engineering expertise and financial resources to conduct detailed assessments when requests are received to increase weight allowances for local roadways beyond the current legal limit for gross load weight of 80,000 pounds." — Ahmed Ibrahim (U I)

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