Developing a Framework for the Prioritization of Infrastructure Improvements

The state of transportation infrastructure in the United States has reached a critical point. When the interstate system was constructed, beginning in the late 1950s, bridges were typically designed for a fifty-year lifespan; today, the average age of a bridge is 43 years old (AASHTO 2008). Further, freight tonnage on the highways has become much higher than was originally anticipated, and continues to increase. According to the American Society of Civil Engineers (2009), 26% of bridges in the United States are classified as either structurally deficient or functionally obsolete. With so many bridges in need of replacement and the cost of a new bridge so high, short-term fixes are often applied to defer the investment in a new bridge to a later date. At the same time, bridge inspections can only be so thorough, inevitably leading to failures, such as that on I-35W in Minneapolis in 2007, or unexpected closures. When such a failure occurs on such a crucial route, the transportation network suffers under the increased strain from reduced capacity, causing increased congestion and emissions. A lot of research has been done to identify critical infrastructure to protect and prevent potential security threats (Haimes et. al. 2002, Volpe National Transportation Systems Center 2003, Haimes et. al. 2004, U.S. Department of Homeland Security 2007), while other work has been conducted on infrastructure asset management (Dicdican, Haimes and Lambert, 2004). A study by Heaslip, Louisell and Collura (2009) created a methodology for testing the resiliency of a transportation network to identify areas for improvement, specifically during a disaster. Despite this work, no research has been found that sets a framework for prioritizing bridge repair and replacement based on structural need and economic importance for hauling freight traffic.