Evaluation of LIDAR Track Measurement Systems in Car Body and Truck-Mounted Configurations

This study presents track alignment and curvature measurement results from a Doppler LIDAR (light detection and ranging) speed measurement system, a non-contact speed and distance measurement system comparable to encoders found on research geometry cars. The system has multiple mounting capabilities with the primary implementations being body-mounted and truck-mounted. Track speed is measured using the individual rails as reference targets, producing two speed signals. Curvature data is obtained from the measured speed differential as the train navigates tangent and curved track. The different dynamic behaviors of the truck and car body influence the motion of the LIDAR system, and thus the results vary depending on the mounting configuration. The curvature, speed, and distance data obtained from the LIDAR system has been compared with results from a geometry car and manual track measurements. The results indicate the LIDAR system has strong potential in serving as a highly precise, non-contact speed, distance, and curvature measurement device suitable for implementation in rail geometry applications.