Long-Term Pavement Performance Compliance with Department of Transportation Information Dissemination Quality Guidelines

INTRODUCTION

On October 1, 2002, the Department of Transportation (DOT) issued Information Dissemination Quality Guidelines (IDQG) to implement Section 515 of the Treasury and General Government Appropriations Act for fiscal year (FY) 2001. The purpose of the guidelines is to ensure and maximize the quality, utility, objectivity, and integrity of information that is disseminated. This document presents the policies and procedures established by the Long-Term Pavement Performance (LTPP) program related to compliance with the DOT IDQG.

In the interest of brevity, this document does not recite all of the DOT IDQG specifications. Instead, each chapter on a specific topic covered in the DOT IDQG provides a general summary of the intent of the guidelines. A copy of the DOT IDQG can be found at http://www.thecre.com/pdf/20021026_dot-final.pdf.

Background

The LTPP program started as a States initiative in the early 1980s. Preimplementation research planning was conducted under a joint effort between the Federal Highway Administration (FHWA), Transportation Research Board (TRB), and the National Cooperative Highway Research Program (NCHRP). These plans were published by NCHRP in May 1986 in the report Strategic Highway Research Program: Research Plans. Implementation of the LTPP program was authorized under the Surface Transportation and Uniform Relocation Act of 1987. The 20-year LTPP program began operations under the 5-year Strategic Highway Research Program (SHRP) administered by the National Academy of Sciences. In 1992, the FHWA made a commitment to assume management and administrative responsibilities to continue LTPP and complete the baseline 20-year period of pavement performance monitoring. Continuation of LTPP under FHWA was formally authorized by Congress in the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA). In 1998, the Transportation Equity Act for the 21st Century (TEA-21) funded LTPP as a national program to 2003.

The LTPP Program received its foundational mission from a 1984 study entitled, America's Highways: Accelerating the Search for Innovation (Special Report 202), published by the TRB. The program's mission is to "increase pavement life by the investigation of the long-term performance of various designs of pavement structures and rehabilitated pavement structures, using different materials and under different loads, environments, subgrade soils, and maintenance practices." The strategic goals and objectives for LTPP were stated in the original LTPP work plan as follows:

• Evaluate existing design methods.
• Develop improved design methodologies and strategies for the rehabilitation of existing pavements.
• Develop improved design equations for new and reconstructed pavements.
• Determine the effects of loading, environment, material properties and variability, construction quality, and maintenance levels on pavement distress and performance.
• Determine the effects of specific design features on pavement performance.
• Establish a national long-term pavement database to support program objectives and future needs.

LTPP Data Quality Highlights

Data quality has been a prime concern in the development and operation of the LTPP program. Although the LTPP program started more than 14 years prior to the issuance of the Federal data quality guidelines, it is remarkable how many of the concepts and procedures contained in the guidelines were followed by LTPP. Some of the highlights of the LTPP data quality process include the following:

• Extensive peer review by experts and highway agency practitioners. A TRB committee was created in 1986 to monitor the status and progress of the LTPP studies and provides technical assistance to FHWA concerning courses of action and the future direction of the studies. The TRB LTPP Committee is supplemented with smaller Expert Task Groups (ETGs) created on specific subjects. Over the years, ETGs have been created on Experiment Design, Materials Testing, Environmental Data Collection, Profile Measurement, Falling Weight Deflectometer (FWD) Measurements, Traffic Data Collection, Pavement Distress Measurement, Construction Specifications, Data Analysis, Metrication, and Database Operations.
• Statistically-based factorial experimental designs were used to plan the studies. The experimental designs were prepared by nationally and internationally recognized statisticians and research engineers. These designs were reviewed by an ETG.
• LTPP has documented all phases of its activities. More than 300 documents have been prepared describing the details of the planning process, experiment design, construction guidelines, agency participation requirements, data collection procedures, data processing procedures, data evaluation checks, data collection equipment calibration procedures and checks, data analysis results, standard data release format and data user aids, and details of construction and instrumentation installation on specific test sections.
• Inclusion of an indicator of "data quality" on each record in the database was developed in the early 1990s and has been refined over time. This data quality indicator encompasses measures of identifying missing data, out of range data, inconsistencies in relational data structures between tables, and illogical data. The data quality indicator is disseminated with the data.
• In the design of the data collection plan, LTPP had to develop new procedures, protocols, and test methods. Some of these methods have been adopted as American Association of State Highway and Transportation Officials (AASHTO) standards.
• In 2000, LTPP implemented International Organization for Standardization (ISO) management quality standards in its data collection and processing activities. All data collection contractors developed management procedures for data quality control (QC). These procedures are audited by an independent source on a nominal 6-month cycle.
• Currently, LTPP data updates are released on a 1-year interval. Prior to data release, a central contractor, independent from data collection sources, performs a predistribution review of the data in order to identify, and if possible, corrects data problems not previously discovered.
• LTPP created a customer service and data problem feedback process in the early 1990s. A formal data problem and feedback mechanism was created in the late 1990s which allows data users, analysts, and others to submit problem reports. These reports and their resolution are now posted on the LTPP Web page http://www.fhwa.dot.gov/pavement/ltpp/index.cfm.

As a unique national research program whose operations model consists of providing research quality data for analysis to those who did not participate in the data collection process, all of the issues in recent Federal guides on data quality had to be addressed by LTPP. Improvements are continuously occurring to enhance LTPP's conformance to the new IDQG. These improvements are resource constrained and are dependent on budget allocation from Congress.

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