Traffic volume is a primary design parameter in pavement design. This study focuses on evaluating the variability between field and projected traffic volume and its impact on asphalt pavement performance for various road sections in Canada. In this study, the Annual Average Daily Truck Traffic (AADTT) is considered as traffic volume. Baseline traffic is projected from the baseline year to the final year of field observation following the no-growth, linear growth, or compound growth technique allocated for different vehicle classes on the LTPP database. Projected and observed traffic was compared to observe variability. To determine asphalt pavement performance for field and projected traffic volume, the AASHTOware pavement mechanistic-empirical pavement design tool was used. To incorporate field observation traffic data in AASHTOware, the traffic growth rate is evaluated from the same projection technique used in projected traffic. The traffic growth rate is evaluated in such a way that projected traffic volume matches with field observation traffic. Traffic volume of baseline year with LTPP growth rate and evaluated growth rates are inputted into AASHTOware in case of projected traffic and field observation traffic, respectively. Other fundamental inputs in the MEPDG program are kept constant for individual sections. The results show that the projected traffic volume has a significant influence on pavement performance in terms of asphalt concrete (AC) bottom-up fatigue cracking, AC rutting, and total rutting on different roads. Equivalent AC layer thickness was also estimated in respect of observed traffic to minimize the additional impact of pavement distresses.

Contributors: Rana M, Hossain K.