Use of Readily Available Traffic Data for Adjusting AASHTO 2002 Pavement Design Guide Traffic Inputs: Alabama Case Study (05-1419)
Mary Stroup-Gardiner, Gardiner Technical Services, LLC
Rod E. Turochy, Auburn University
Alan Carter, Universite du Quebec, Canada

Readily obtainable traffic counter data from the Alabama Traffic Statistics website was used to determine when and how local traffic information can be used to adjust the default Level 3 AASHTO 2002 Pavement Design Guide traffic inputs. Data was randomly selected from a counter on 1 state route, 1 US route, and 1 Interstate (if applicable) for 27 of Alabama’s 67counties. Website traffic statistics can be used to adjust the percent distribution of percent trucks in the default truck distribution, estimate the average annual daily truck traffic (AADTT), and calculate the percent of growth in traffic (more critical when the annual average daily traffic (AADT) is less than 20,000). The default value of 4% annual growth may result in a substantially over-designed lower traffic volume road. Because of the wide range of the percent heavy trucks (three or more axles) in Alabama, it is important to adjust the default truck distribution per vehicle classification; it is more critical to adjust this distribution for lower volume roadways. A linear relationship between traffic and time (10 years) was found to be a valid selection for Alabama pavement designs.