1.1 This practice describes highway-traffic monitoring, which is the activity of collecting, summarizing, and reporting traffic volume, vehicle classification, and vehicle weight data. This practice is foundational and is not intended to be all-inclusive. Users of this practice are allowed, indeed encouraged, to exceed the practice.

1.2 Traffic monitoring results in traffic-volume, classification, and weight-summary statistics which are used in highway geometric and pavement design, alternative highway route selection, roadway demand and service assessment, and accident-exposure estimation.

1.3 Traffic-monitoring practices are based on the principle of truth-in-data. This principle involves providing the supplementary information required for appropriate use of traffic data and summary statistics.

1.4 To measure traffic for summary-statistic calculation, traffic-monitoring practices are also based on the principle of unedited base-data integrity. Missing or inaccurate unedited base data shall not be completed, filled-in, or replaced for any type of traffic measurement.

1.5 A limitation of this practice is traffic-data summarization. Traffic-data summarization procedures are hypotheses, particularly in the use of adjustment factors. These hypotheses shall be consistently calculated, but may also be expected to be challenged and to change across time. These changes will be important in improving the precision of traffic-summary statistics.

1.6 The inherent limitation of traffic-monitoring practice results in strict adherence to the principle of unedited base-data retention. Only with adequate historical unedited base data can alternative hypotheses be tested, the impact of the alternative hypotheses assessed, and standard practice refined.

1.7 The values stated in inch-pound units are to be regarded as standard.

1.8 The following safety hazards caveat applies only to the traffic data collection portion, Section 6, of this practice. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.