- Briefing Room
U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
Federal, State, Metropolitan Planning Organizations, Cities and local agencies rely on Annual Average Daily Traffic (AADT) values as a fundamental traffic element which is extremely important. Numerous methods of factoring and base line values are required to ensure AADT data are collected and reported correctly. The variability of these currently used methods were explored so that those in the traffic community will clearly know the limitations and the extent of each method used and how to properly utilize methods for their agency to obtain the necessary results. The Pooled Fund FHWA led, TPF-5(292), researched the AADT methods, both the estimation durations and frequencies of short term counts and the travel behavior at special events, holidays and recreational travel. A 14 year data set of continuous permanent volume traffic sites in the United States that all have 24/7 hourly volume data served as the reference dataset for this research for the four tasks. This research obtained a quantitative understanding on data quality (precision and accuracy) associated with differences AADT methods and the influence that traffic monitoring duration and frequency have when factoring portable counts to AADT’s. Aspects of this research were guided by the Pooled Fund Technical Advisory Committee.