Average Annual Daily Traffic (AADT)

ADOT is introducing a new methodology for projecting future traffic volumes on the State Highway System. Previously, the traffic projections were based upon the linear regression of observed historical traffic data. However, this methodology does not account for greenfield development and other external considerations that may affect the location and intensity of future growth. The new methodology uses the Arizona Travel Demand Model (AZTDM) as the basis for future traffic projections. AZTDM is an econometric travel demand and network assignment model that considers the future location and density of population, employment, economic conditions, and network development and operations. The traffic projections derived from AZTDM are used in numerous ADOT and planning partner activities such as design concept reports, corridor studies, the Planning-to-Programming process, metropolitan planning organization Regional Transportation Plans, and the annual Highway Performance Monitoring System submittal. The web-based Transportation Data Management System, managed by the Traffic Monitoring Section, is the repository for Arizona traffic data including these future year traffic projections. 

- Keith L. Killough, AICP
  Director of Transportation Analysis

The annualized average 24-hour volume of vehicles at a given point or section of highway is called a traffic count. It is normally calculated by determining the volume of vehicles during a given period and dividing that number by the number of days in that period.

How We Obtain Traffic Counts

Automatic Traffic Recorder (ATRs)

The ATRs collect data 24 hours a day, 365 days annually, for each lane. The equipment records traffic volumes, speed and classification of vehicles. MPD uses this data to develop seasonal factors, daily factors, axle factors and estimate vehicle miles of travel (VMT). These factors are applied to all coverage counts.

Coverage Counts

Coverage counts are needed to ensure that adequate geographic coverage exists for all roads under the jurisdiction of the state highway authority. In simple terms, coverage counts are data collection efforts that are undertaken to ensure that at least some data exist for all roads maintained by the agency.

AADT Reports: Traffic Counts

This data is also available in the Traffic Data Management System.

View our interactive Traffic Database Map

References

Data Dictionary
This dictionary defines the column headings and code values used in these files.

Contact Us

For more information regarding traffic volumes, please contact the Traffic Monitoring Office:

Marissa Valenzuela
Multimodal Planning Division
Transportation Analysis Section
Phone: 602.712.8232
Fax: 602.252.8313