Examination of LiDAR scanning for quantitative structural assessments of highway bridges

The use of LiDAR in the realm of bridge assessment has been primarily limited to measuring large-scale bridge dimensions (greater than 2m), which have been successfully captured with relatively small errors (< 1%). The objective of this paper is to explore the capability of LiDAR technology to estimate smaller dimensions such as flange thickness, flange width, and girder depth. To satisfy these objectives, an eleven-span steel girder bridge carrying a highly transited highway was subjected to a series of LiDAR scans under normal operating conditions. Various dimensional quantities were then extracted from the data both directly from the point cloud and through a standard plane-fitting approach. The direct point cloud approach resulted on percent errors of up to 30% (compared to bridge plans) while the plane fitting method resulted on percent errors of up to 17%. The ability of LiDAR sensors to accurately characterize geometric information opens up new opportunities for their use as a means for in bridge surveying and structural health monitoring.