Bridges vary significantly in their size and use, including daily traffic volumes. In 2009, there were 602,977 bridges in the United States, which carried the nation’s passenger car, truck, bus transit, and commercial vehicle traffic over waterways, highways, railways, and other road obstructions. The number of bridges owned is fairly evenly split between states (48 percent) and local government agencies (50 percent). State agencies are responsible for 77 percent of the nation’s bridge deck area, which carry 88 percent of the average daily traffic crossings. The federal government owns less than 2 percent of the nation’s bridges, primarily on federally owned land. Bridge safety emerged as a high-priority issue in the United States in the 1960s, following the collapse of the Silver Bridge between Ohio and West Virginia, which killed 46 people. That collapse prompted national concerns about bridge condition and safety and highlighted the need for timely repair and replacement of bridges. Congress responded by establishing the National Bridge Inspection Program (NBIP) to ensure periodic safety inspection of bridges and what is now known as the HBP to provide funding and assist states in replacing and rehabilitating bridges. Both of these programs generally define eligible bridges as publicly owned, over 20 feet in length, and located on public roads. Although the NBIP and HBP are separate programs, they are linked by the data collected through bridge inspections. The NBIP establishes the National Bridge Inspection Standards, which details how bridge inspections are to be completed, by whom, and with what frequency. For example, state departments of transportation (state DOT) carry out the federal-level policies, procedures, and requirements for inventory, inspection, bridge load ratings, quality assurance, and reporting. Routine bridge inspections are generally conducted every 2 years by state bridge inspectors, but with FHWA approval, the inspection interval may be extended to 4 years on certain bridges. Bridges also may be inspected more often than every 2 years, when past inspection findings justify an increase. Inspectors must report bridge condition information to the NBI, maintained by FHWA headquarters. federal share of the costs, which is generally 80 percent of the project cost. Of the 602,977 bridges on the nation’s roadways, one in four is classified as deficient. Data indicate that the total number of deficient bridges has decreased since 1998, even as the total number of bridges has increased. From 1998 to 2009, the number of deficient bridges declined by over 14 percent, from 186,706 to 159,739, even with the addition of more than 20,000 new bridges to the NBI (see fig. 2). The decline in the overall number of deficient bridges—which includes structurally deficient and functionally obsolete bridges—is primarily attributable to a reduction in the number of structurally deficient bridges. Specifically, from 1998 through 2009, the number of structurally deficient bridg es decreased by 25 percent, from 96,263 to 72,388 (see fig. 3). During at same period, the number of functionally obsolete bridges decreased th by 3 percent, from 90,443 to 87,351. The reduction in the number of structurally deficient bridges may reflect state efforts to address deterioration or damage. Although reducing or eliminating structurally deficient bridges may not always be a state’s highest priority, structurally deficient bridges often require maintenance and repair to remain in service. In contrast, functionally obsolete bridges do not necessarily require repair to remain in service and therefore are unlikely to be state transportation officials’ top priority for rehabilitation or replacement. Additionally, in our prior work, we found that the average sufficiency rating of all bridges—including both deficient and not deficient bridges— also improved slightly. Specifically, the average sufficiency rating for all bridges increased from 75 to 79 on the sufficiency rating’s 100-point scale from 1998 to 2007. Further, while structurally deficient bridges generally have lower sufficiency ratings (average rating of 42 in 2007) than functionally obsolete bridges (average rating of 69 in 2007), the average sufficiency ratings of both types of deficient bridges improved slightly since 1998. In updating our prior work, FHWA officials indicated that bridge sufficiency ratings have continued to improve (average rating of 80 in 2009). In our Recovery Act work, a number of states have reported plans to use highway infrastructure investment funds to improve bridge conditions. Some of these plans include improvements to deficient bridges. F or example, Pennsylvania is using some Recovery Act funds to reduce t number of structurally deficient bridges in the state, in part because a significant percentage (about 26 percent, as of 2008) of the state’s bridges is rated structurally deficient. As of June 30, 2010, 29 percent of Recovery Act funds in Pennsylvania were obligated for bridge improvement and replacement. Nationally, about $3.2 billion of the $26.7 billion in highwa Recovery Act funds were obligated for bridge projects as of June 30, 2010. This includes funding for 61 new bridge construction projects ($719 million), 644 bridge replacement projects ($1.3 billion), and 554 bridge improvement projects ($1.2 billion). The impact of the federal investment in the HBP is difficult to measure in part because there are no comprehensive and complementary data for state and local spending on bridges. For example, while FHWA tracks a portion of bridge capital spending on a state-by-state basis, the data do not include (1) state spending on bridges located on local roads and (2) most local government spending on bridges, thus making it difficult to determine the HBP contribution to overall bridge expenditures. Also, while FHWA generates a single, national-level estimate for total bridge expenditures at all government levels, this estimate cannot be used to determine the impact of the HBP by state or by bridge. In addition, while two of the state DOTs we visited as part of our prior work had data on state bridge spending, none was able to provide comprehensive data on total state and local investment in bridges. Some officials we interviewed estimated that, in their states, such spending ranged from the minimum match amount—generally 20 percent of the HBP apportionment amount— to more than four times the state’s apportioned HBP funds. The lack of comprehensive information on state and local spending makes it impossible to (1) distinguish the impact of HBP funding from other funding to improve bridge conditions and (2) determine the extent to which states may be substituting increased HBP funding for state and local funds that they would otherwise have spent on bridges. Our previous w has shown that although the federal investment in HBP and other Federal- aid highway programs has increased over time, this investment has resulted in commensurate increases in the nation’s federal, state, and local government spending on the highway system. found in our previous work that as the level of federal funding has increased since the mid-1990s, states have not maintained their level effort in highway spending, and federal funds have increasingly been substituted for state funds. This suggests that increased federal highway e funding influences states and localities to substitute federal funds for stat and local funds they otherwise would have spent on highways and bridges. The impact of the HBP is also difficult to measure because available bridge condition data cover only some of the improvements funded by the program. As discussed earlier, states can and do use HBP funds for a variety of activities in addition to rehabilitating and replacing their deficient bridges. Therefore, simply measuring changes in the number of structurally deficient or functionally obsolete bridges does not reflec full impact of the program, since these measures do not capture the impact of the HBP investment in the other eligible activities—such as preventive maintenance—that do not necessarily result in an im reduction in the number of deficient bridges. Without quantifiable BP, it performance measures to track the full range of outcomes for the H is difficult to measure the program’s impact across the range of activities funded and determine the extent to which the program is serving its stat purposes. GAO, Federal-Aid Highways: Trends, Effect on State Spending, and Options For Future Program Design, GAO-04-802 (Washington, D.C.: Aug. 31, 2004). by the HBP—on the overall condition of the nation’s bridges. In o Recovery Act work, we have found that DOT is not currently assessing the impact of Recovery Act funds used on highway transportation projects— including funds that are being used to improve bridge conditions—but isconsidering ways to better understand and measure impacts. For example, the NBI could be used to help FHWA study the impact of Reco funds on the condition and performance of the nation’s bridges, including whether these funds improved the state of repair. As we reported in 2008, the HBP does not fully align with our principles for re-examining surface transportation programs in that the bridge program lacks focus, performance measures, and sustainability. These principles, which are based on our prior work and federal laws and regulations, include ensuring program goals are well defined and focused on the federal or national interest; incorporating performance and accountability into funding decisions; employing the best tools and approaches to emphasize return on targeted federal investment; and ensuring fiscal sustainability. First, HBP’s goals are not focused on a clearly identified federal interest. Over the years, the program’s statutory goals have expanded from improving deficient bridges to supporting activities like seismic retrofitt and preventive maintenance, thus expanding eligibility for HBP funds to include almost any bridge in the country. Our previous work has emphasized the importance of identifying clear areas of federal interest as a first step in determining program goals. For example, if mobility is determined to be a key federal interest and a primary goal, the HBP could be targeted toward heavily congested bridges or ones that are important for economic competitiveness and carry higher levels of freight than bridges that may serve relatively few people or businesses each day. If rehabilitating and reducing deficient bridges is determined to be a key federal interest, then the program could be further targeted toward that goal.