PAVEMENT MARKING REFLECTIVITY EVALUATION THROUGH RADIOMETRIC CALIBRATION OF THE LEICA P40 TERRESTRIAL LASER SCANNER
Pavement markings serve as important traffic control devices, delineating traffic lanes and conveying regulations, guidance or warnings to roadway users. To ensure that pavement markings are clearly visible, especially at night, transportation agencies periodically assess the retroreflectivity of various categories of markings through manual approaches at discrete location. Because the radiometric information such as intensity in the lidar data cannot inherently be considered as a retroreflectivity measurement without additional processing, this study rigorously assesses the ability to determine pavement marking retroreflectivity from the Leica ScanStation P40 through radiometric calibration. For the evaluation, data were collected at a study site in Philomath, Oregon using the Leica P40, Leica Pegasus: Two mobile lidar system, and a handheld retroreflectometer as a reference. The results show that, with appropriate calibration, the lidar data can adequately assess the retroreflectivity of pavement markings. Additionally, while corrections have been proposed for range and angle of incidence, these corrections are not straightforward to apply for retroreflective materials, as will be discussed herein. While mobile lidar technology is ideal for a system-wide asset management framework, terrestrial laser scanning can be utilized for detailed investigations at sites such as intersections with highly variable wear where both can enable significant cost savings and applied for a variety of purposes simultaneously including asset management and project development.