Utilization of LiDAR Technology for Highway Inventory

Collection of roadway inventory data is a basic task for most highway agencies. Maintaining upto-date information about roadways is essential for design, planning, maintenance, and rehabilitation purposes. For inventory, highway agencies typically rely on field data collection, which is time consuming and subject to limitations such as adverse weather conditions. Recent availability of new and emerging technologies has led to experimentation with these technologies for collection of roadway inventory. This paper is focused on the use of Light Detection And Ranging (LiDAR) technology for collection of roadway inventory. LiDAR uses the same principle as RADAR for collection of information. The LiDAR instrument transmits light beams towards a target and a receiver collects some of the reflected light. The time for the light to travel to the target and back to the receiver is used to determine the distance to the target. Placement of the LiDAR equipment onboard an airplane and directing the light beams at the surface of the Earth allows collection of the Earth’s surface profile. The resulting data can be used in obtaining information on certain roadway inventory elements. This paper describes experimentation with LiDAR data collected for Iowa 1 highway, passing through Linn and Johnson Counties, Iowa. Aerial imagery and LiDAR data for the study corridor were merged and analyzed to extract information on highway grade, side slope, and contours as well as stopping and passing sight distances. The results were verified in the field for accuracy by comparing information obtained from LiDAR to the ground truth. These comparisons showed that the information obtained from the LiDAR data closely matched conditions in the field. Overall, this research indicates that where available, LiDAR data can be effectively utilized to obtain certain elements of the roadway inventory. LiDAR is a relatively new and costly source of transportation data. Therefore, additional applications useful to transportation agencies must be developed to justify investment in LiDAR data collection.