Detection vehicle lateral offset overestimation on asphalt pavement rut depth measurement accuracy

Abstract

The 13-point laser detection vehicle is widely used for the rapid detection of rutting on national and provincial trunk lines in China. Affected by the road alignment and drivers’ human factors, the inspection vehicle will inevitably shift laterally during the inspection process. Offset wandering of an automated measurement vehicle on the overestimation of rut depth was investigated and analyzed with the objective of determining the impact of this phenomenon on the accurate and timely selection of maintenance and rehabilitation (M&R) actions. For this purpose, three representative rut types commonly used in China with high and medium severity levels of rutting were selected from field surveys and studied. For each rut type, the cross sections with a rut depth between 10 and 15 mm were selected to study the impact of different offset distances on the measurement accuracy. The reliability of lateral offset detection was further validated by simulating different rut shapes. Finally, an error judgment parameter E was implemented and evaluated. The results showed that the overestimation could be observed only at an offset distance lager than 300 mm. The maximum percentage of overestimation could be as high as 86.0%, 93.3%, and 67.5% for Types 1, 2, and 3 rut shapes respectively. The presence of a central upheaval was a dominant factor which reduced the error parameter E. The calculation of the severity error judgment E indicated that the errors were mainly governed by the offset distance; the maximum ratio was 13.0% for 300 mm, and dramatically increased up to 61.3% for 500 mm. Therefore, the maximum acceptable offset within which reliable M&R decision could be taken was 300 mm.