Critical assessment of the impact of vehicle wandering on rut depth measurement accuracy using 13-point based lasers

Accurate rut depth measurements have a substantial impact on the reliability of pavement performance evaluation, maintenance and rehabilitation (M&R) determination, and M&R funding allocation. To measure pavement rutting, China commonly uses 13-point based lasers. However, based on the 13-point lasers configuration, errors in rut depth measurement are inevitable if the vehicle on which the lasers are mounted wanders. Existing studies have not considered the impact of vehicle wandering on rut depth measurement accuracy and the relationship between rut shape and offset error. In this paper, 10 representative transverse profiles, including both symmetrical and non-symmetrical rut shapes with low and high severity levels of rut depths, were selected from 1100 actual transverse profiles (a 220-m rutting section from a 1.2 km roadway) that were acquired using a 13-point laser bar to simulate the impact of 5 different degrees of vehicle wandering on rut depth measurement accuracy. Results show that vehicle wandering could result in rut depth measurements error of the absolute and relative by as much as 6.4 mm and 29%, respectively. In-depth analyses show that the degree of rut depth measurement error is impacted substantially by the rut shape characteristics, including the position, slope, depth, and pattern of rut shapes (symmetrical and non-symmetrical), and the corresponding direction (right or left) of a vehicle's wandering. For example, a vehicle wandering in the direction opposite to the dominating/severe rut depth will result in a large rut depth measurement error. The contributions of this paper include quantifying the impact of vehicle wandering on rut depth measurement accuracy and identifying the factors, including the rut shape characteristics and characteristics of vehicle wandering, that might reduce rut depth measurement accuracy.