Lidar for Maintenance of Pavement Reflective Markings and Retroreflective Signs

Pavement markings and signs are important traffic control devices used to guide and regulate traffic movement through visual information presented to motorists. Signs and markings are made with retroreflective materials to enhance visibility for motorists, particularly at night. Retroreflectivity evaluation of an extensive highway network for maintenance and asset management purposes is a critical, yet challenging task for DOTs. Visual evaluation can often be subjective while field measurement techniques can be time-consuming and dangerous. This project investigated the effectiveness of evaluating pavement marking and sign retroreflectivity with mobile lidar data. Oregon DOT currently captures mobile lidar surveys of the entire highway network within a two-year cycle for other purposes of asset management, utility location, engineering surveys, and more. The study found that mobile lidar point clouds can be used to additionally extract quantitative, accurate estimates of retroreflectivity for pavement markings, providing a safe, cost-effective, and reliable solution. Software was also produced to extract the pavement markings and perform the evaluation. Reliable retroreflectivity measurements of signs, however, was not possible due to sensor intensity saturation effects.