Deformation Measurement of Highway Bridge Head Based on Mobile TLS Data

The precise leveling method is often used to monitor the uneven deformation of the highway bridge head, which requires manual contact, dangerous and heavy workload. In order to solve these issues, this paper proposes a method to extract deformation features of the highway bridge head based on mobile terrestrial laser scanning (TLS) point clouds. Firstly, an automatic data acquisition system is designed to analyze and determinate the scanning station spacing and scanning resolution. Then acquired road point clouds are denoised based on the plane fitting method, which usually sets the experimental threshold. The road dividing line information is used for point clouds coarse registration, and the weighted average elevation method is used for refined registration. Lastly, the elevation of the deformation monitoring point is the average elevation of all points in the selected grid surface, which will mitigate random errors in the elevation of a single point. Point clouds of three different roads were collected to verify the proposed method. The results show that the accuracy of the elevation repeatability is better than ± 1mm, and the accuracy of the elevation check with the TM50 total station is better than ± 2mm, which meets the requirements of deformation monitoring. In addition, it takes about 3-4 minutes to complete the data collection of a station on the highway bridge head. Therefore, the proposed method based on mobile TLS data can be suitable for highway bridge head deformation measurement.