THE CONCRETE BRIDGE MAGAZINE

SUMMER 2012

ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.

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ASPIRE, Summer 2012 | 51 Overflow in Sabula, Iowa, which is functionally obsolete due to inadequate roadway width and clearance problems. The existing bridge is a 342-ft by 20-ft steel high-truss structure, for which the approach spans' deck was replaced in 1985. There was no rehabilitation option available, so the bridge is being replaced. The required data for this analysis was provided by the Iowa Department of Transportation. Two construction alternatives were compared: same alignment with detour (ABC) and shifted alignment (conventional). The AHP process was applied using the criteria shown in Figure 1 for these two alternatives. After completing the evaluation, the ABC alternative was preferred. The calculated overall priorities for the same and shifted-alignment alternatives were 0.727 and 0.274, respectively. Figure 2 summarizes the relative weighting of the five high-level criteria for this particular project. The size of each bar segment is based on the criteria weights resulting from the AHP analysis. Figure 3 presents a top-level summary of criteria weights for the project. The results indicate that Indirect Costs and Site Constraints criteria have the greatest impact on the decision to select the same alignment alternative as the best alternative. Additional detail is also available, as a result of the analysis, which indicates the relative weighting of the second level criteria within each criterion, as shown in Figure 4 for indirect costs. To date, the approach has been tested on projects in seven states (California, Iowa, Montana, Oregon, Texas, Utah, and Washington). It has proven to help decision makers clearly articulate the rationale for choosing an alternative by evaluating multiple criteria and diverse (sometimes opposing) perspectives. Using such a tool in a project's early stages can promote dialog and ultimately foster effective solutions. Reference Saaty, L. and Vargas, L. (2001). "How to Make a Decision," International Series in Operation Research and Management Science, vol 34, 1-25. _______ Benjamin Tang, P.E., is manager of bridge preservation for the Oregon Department of Transportation in Salem, Ore. Toni L. Doolen, Ph.D, Oregon State University, is the principal investigator of TPF 5(221) Pooled Fund Study for the AHP Decision Tool. Schedule Constraints Indirect Costs Site Constraints Customer Service Direct Costs Goal Figure 3: High-level criteria weights for Sabula Bridge. Road Users Exposure Livability During Construction Construction Personnel Exposure Freight Mobility User Delay Indirect Costs Revenue Loss Figure 4: Sub-criteria weights for indirect costs for Sabula Bridge. New Grouting Specification Available in hard copy and DRM Digital Edition at: www.post-tensioning.org/bookstore.php This specification provides minimum requirements for the selection, design, and installation of cementitious grouts and ducts for post-tensioning systems used in concrete construction. The 2012 edition includes significant updates in chloride test- ing, inclined tube testing, material certification requirements, prohibition of tendon flush- ing, pumping pressure, and personnel qualification. Editor's NotE For more information on the pooled fund study, visit www.pooledfund.org/Details/Study/449. ASPIREBook_Sum12_R02.indb 51 6/29/12 12:39 PM

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