Evaluation of Lateral Distribution of Heavy Vehicles on Multilane Roads Using a Strip-Based Approach

Abstract

Most highway agencies use the default values of the lane distribution factor (LDF) as suggested by their pavement design guidelines. However, the use of the default value of the LDF results in over- or underestimation of the number of standard axle repetitions, especially for multilane roads, which have a larger variation in the movement of vehicles across the entire carriageway compared with one- and two-lane roads. Therefore, this study focused on the accurate measurement of the LDF for multilane roads. Currently, the LDF is estimated as the ratio of the number of heavy vehicles in a design lane to the total number of heavy vehicles moving on the carriageway. However, in the case of multilane roads, the same vehicle can occupy more than one lane, which ultimately results in inaccurate measurement of the LDF. To overcome this issue, a strip-based approach is introduced for a microlevel analysis of the LDF of multilane roads. The vehicle damage factor (VDF) and LDF were obtained by extracting the traffic data collected through the video recording method. The results of the LDF indicate that the channelization of trucks occurred in the intermediate lane instead of the outer lane, which commonly is assumed for the estimation of the number of standard axle repetitions for flexible pavement design. A significant variation was observed in the number of standard axle repetitions estimated using actual LDF and the default LDF values suggested by the Indian Roads Congress. The study finding suggests that the estimation of the actual LDF from field study is essential for the estimation of the number of standard axle repetitions on multilane roads for the design of flexible pavement.