Accelerated Pavement Testing: Data Guidelines (2003)

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Over the years, more and more highway agencies have used accelerated pavement testing (APT) as a means of evaluating potential construction materials, pavement designs, and other pavement-related features. Of primary concern in APT is the appli- cation of a significant traffic volume in a reasonable length of time and at an acceptable cost to produce measurable deterioration. APT is generally defined as the application of wheel loads to specially constructed or in-service pavements to determine pavement response and performance under a controlled and accelerated accumulation of damage in a short period of time. The research being reported is concerned with APT in which full-scale wheel loads are applied to full pavement structures by machines or vehicles in a test facility, at a test track, or on an in-service pavement. APT facilities have several advantages over in-service pavements: • APT facilities provide a safer environment for the researchers and the traveling public (tests on in-service highways often involve safety hazards). • Tests can be conducted more quickly and in a more controlled manner. • The number of wheel load applications can be controlled accurately, and loads can be positioned at desired locations. • Different factors can be evaluated simultaneously. This research was conducted to (1) identify and develop definitions of data elements associated with APT and (2) recommend guidelines for data collection, storage, and retrieval. Pertinent national and international literature was reviewed to determine the state-of-the-practice in APT, with emphasis on APT facilities located in the United States. A questionnaire was then sent to APT facilities in the United States to gather information on facility administration, APT machine loading characteristics, pavement test programs, material characterization, environmental and climatic data, instrumen- tation installed, pavement response to load, pavement performance, construction and postmortem testing, and data documentation and storage. The survey showed that state departments of transportation operate six APT facilities, universities operate five, the U.S. Army Corps of Engineers operates two, the Federal Highway Administration operates one, and a private firm operates one. The survey was followed by visits to most of the APT facilities to supplement the collected information. SUMMARY ACCELERATED PAVEMENT TESTING: DATA GUIDELINES

The literature review results, the survey data, and information gathered during APT facility visits were used to identify and define data elements. The data elements were categorized as follows: • Administrative—administrative details of a particular APT facility or a particular study/experiment being conducted at the facility. • Load application—wheel loadings applied to a test pavement and the characteris- tics of the applied loads. • Pavement description—information on pavement type, pavement construction, and geometric details. • Material characterization—information about material type, composition, stiffness, strength, and test methods. • Environmental conditions—information (primarily temperature and moisture) about the “above” and “within” pavement conditions. • Pavement response—deflections, stresses, or strains measured at the pavement surface or within the pavement structure when subjected to a given load or when subjected to changes in temperature and moisture. • Pavement performance—information on various types of pavement surface dis- tress, pavement smoothness, and longitudinal and transverse (rutting) profiles. Data can be collected manually, semi-automatically (generated electronically or mechanically but recorded manually), or automatically (data generated and recorded electronically). Administrative data are usually collected manually, whereas pavement response data collection is more automated. The most common data storage medium is paper—written information (such as tables) filed in folders and stored in cabinets. Electronic storage devices range from simple floppy disks to more complex optical disks and flash memory cards. Electronic text files and spreadsheets are used for small data amounts, and dedicated databases are mostly used for large quantities of data. The method used for data storage and retrieval depends on the type and quantity of data. Storage capacity, cost, performance, reliability, and manageability must be considered when selecting a data storage and retrieval system. Finally, guidelines for APT were prepared to facilitate sharing of data among researchers. These guidelines delineate data elements related to APT and their defini- tions, describe information on state-of-the-art data storage and retrieval systems, pro- vide recommendations and specifications for a database, and propose data collection frequencies. 2