Quantifying Lateral Displacement of Trucks for Use in Flexible Pavement Design (05-0935)**
Jeffrey J. Stempihar, Michigan Technological University
Ronald Christopher Williams, Iowa State University
Thomas D. Drummer, Michigan Technological University

Current flexible pavement design procedures in the United States are based upon the AASHO Road Test and subsequent updates and have not considered lateral displacement of vehicles across a pavement lane as a design input until the recent release of the 2002 AASHTO Pavement Design Guide for New and Rehabilitated Pavements. The lateral displacement of vehicles (wheel wander) has been identified by researchers around the world. As design methods are improved to better represent traffic loading in the field, wheel wander becomes increasingly important. This research has developed a model for wheel wander based on field data from highways. Data were collected using a developed reference system, which was painted on the pavement. Traffic was then video taped and the positions within the lane were recorded for 7761 tire contact points on 31 roadway sections. It was found that wheel wander on interstate highways can be modeled by a normal distribution with a mean of 110.6 inches (280.9 cm) with respect to the center pavement lane marking and a standard deviation of 12.1 inches (30.7 cm). The center pavement lane marking was determined to be the most consistent frame of reference for measuring wheel wander. The AASHTO 2002 Pavement Design Guide for New and Rehabilitated Pavements, which uses mechanistic-empirical pavement design procedures, will be able to take into account this lateral displacement of traffic loading and will require numerical values for mean wheel position and standard deviation. This research provides mean and standard deviation values that can be used in this design procedure.