Transportation Infrastructure:

Better Data Needed to Rate the Nation's Highway Conditions

RCED-99-264: Published: Sep 27, 1999. Publicly Released: Sep 27, 1999.

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Pursuant to a legislative requirement, GAO provided information on federal and state efforts to assess the conditions of the nation's highways, focusing on: (1) the uses the Federal Highway Administration (FHwA), the states, and others make of the International Roughness Index to assess highway conditions; (2) the consistency and accuracy of state-reported data on highway roughness; and (3) FHwA's efforts to improve the data across states.

GAO noted that: (1) the International Roughness Index is used widely for federal and state purposes, as well as for independent analyses; (2) at the national level, where the index is the only available statistic on pavement conditions, FHwA uses it to assess changes in the overall condition of the nation's highways and to forecast future highway investment needs; (3) actual expenditures for highways by all levels of government in 1995 were about $29.2 billion, or about $41 billion less than FHwA had projected as needed to repair the deficiencies; (4) in addition, FHwA uses the index to measure progress toward a goal for ride quality in its strategic plan and publishes data from the index for use by the public; (5) at the state level, where other types of data on pavement conditions are available, reliance on the index varies; (6) while some states rely on it to make highway maintenance decisions, others do not consider it an important decision-making tool; (7) the states that rely on the index use it to project highway investment needs and report on pavement performance at the state or district levels; (8) in addition, some states use the index to set standards for construction projects; (9) independent analysts have used the data to compare pavement conditions across states and to develop scorecards of state performance; (10) critics contend that state comparisons based on the index are flawed because the pavement roughness data reported to FHwA by the states are not consistent or accurate; (11) these problems with consistency and accuracy have occurred for two reasons: (a) the states use different methods to gather data and compute results; the states differ in the devices they use to measure the pavement, the part of the road they measure, and their choice of an appropriate mathematical simulation; and (b) the type of surface asphalt or concrete influences the results; concrete roads may produce rougher readings than asphalt roads, even if the concrete road is of very high quality; (12) features such as joints between sections can contribute to the roughness of concrete highways; (13) while FHwA has tried to improve the data, these efforts have not been completely successful; and (14) the agency developed detailed guidelines for collecting the data and asked the states to apply these guidelines before reporting the data.

Recommendations for Executive Action

  1. Status: Closed - Implemented

    Comments: The Federal Highway Administration revised its Highway Performance Monitoring System (HPMS) field manual in December 1999 to achieve consistency with the American Association of State Highway and Transportation Officials' (AASHTO) protocols. The manual revision also excluded the use of profiling technologies known to produce significant errors. The agency's 2001 Performance Plan, issued December 2000, directed FHWA field office staff to evaluate their respective state's IRI data quality and the equipment and protocols used to gather that data for the HPMS. These revisions are responsive to the recommendations.

    Recommendation: To enable FHwA to reliably report on the condition of the nation's highways and accurately estimate the nation's highway investment needs, the Secretary of Transportation should direct the Administrator, FHwA, to revise the agency's guidelines to exclude profiling technologies known to produce significant errors and achieve consistency with the American Association of State Highway and Transportation Officials' protocols.

    Agency Affected: Department of Transportation

  2. Status: Closed - Implemented

    Comments: FHWA provided copies of GAO's report to each state DOT and each FHWA state division office. FHWA's 2001 Performance Plan directed FHWA field offices to assist states with implementing improved equipment and protocols for measuring pavement smoothness. FHWA arranged an October 2000 AASHTO meeting with profiler vendors and state agency staff to discuss collecting IRI data with standardized state profiling equipment. However, the meeting participants did not agree that a single standard profiler should be produced for all states to use when gathering IRI data. FHWA resolved its differences concerning IRI reporting with a "problem" state, after that state obtained new profilers and procedures. These actions respond to the recommendation.

    Recommendation: The Administrator, FHwA, should work with the states to implement the revised guidelines.

    Agency Affected: Department of Transportation: Federal Highway Administration


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