ASTM E2759-10(2018)

4.1.1 Traffic Monitoring Stages—Traffic monitoring truth-in-data describes how base data are treated at each traffic monitoring stage from field data collection through evaluation, acceptance, summarization, and reporting.

4.1.2 Benefits—Truth in data provides a means of addressing if and how missing or questionable data are modified as part of data acceptance and use. The benefit arises from understanding what data assumptions or adjustment factors, if any, were applied to reported traffic summary statistics. If an adjustment factor or factors were applied consistent with truth-in-data, the source and adjustment factor source characteristics are disclosed. With this type of information, the data user is in a better position to understand the data set and summary statistics, ask questions, and appropriately apply the data. Truth-in-data ensures that traffic data can be correctly interpreted and appropriately used to improve highway operations safety and efficiency.

4.1.3 Exceptions—Traffic monitoring truth-in-data does not address subsequent use of the data and summary statistics as in longitudinal studies. Traffic monitoring truth-in-data establishes the basis for appropriate current and longer-term use of base data and summary statistics. Critical use of traffic monitoring data, such as in safety analysis, depends on the data clarity and integrity identified by implementing truth-in-data. Traffic monitoring truth-in-data does not address data storage. Traffic monitoring truth-in-data describes the conditions leading to acceptance of data for storage and the reporting of data retrieved from storage. The metadata structure for archived data management systems (ADMS) recommended for traffic monitoring data is presented in Specification E2665. An ADMS is the information management system used to store traffic data with integrity over time.

1.1.1 Truth-in-data can be applied in all traffic monitoring programs at all levels of investment and development. Temporary manual field activities and permanent data gathering installations share a common interest in, and need for, the ability to check and confirm reported traffic statistics. This is the irreducible minimum for both sharing traffic data over time within an agency, and at a point of time and over time among agencies.

1.1.2 Truth-in-data also permits alternative assessment of the base data. The ability to recalculate traffic statistics from base data provides the opportunity to use different assumptions or to apply different adjustment factors. As understanding of traffic data proceeds, truth-in-data permits equivalent longitudinal assessment of traffic summary statistics through consistent adjustment and treatment of base data over a study period.

1.1.3 Truth-in-data is the foundation for all traffic monitoring programs because of its applicability to all traffic monitoring programs, its support of meaningful sharing of data among diverse programs, and its contribution to understanding and applying data for the improvement of traffic management.