New Method for Metro Tunnel Catenary Height Detection Based on Mobile 3D Laser Scanning Technology

Abstract

[Objective] The height of metro tunnel catenary is a crucial parameter for ensuring normal train electrification and requires regular inspection. In response to the significant errors and low precision associated with other height detection methods, a new method for detecting the metro tunnel catenary height based on mobile 3D laser scanning technology is proposed. [Method] Based on the above new method, the error sources are analyzed. The method of adding a rigid tilting component on the mobile 3D laser scanner is suggested to modify the incidence angle of the laser, thereby reducing the number of spikes in the point cloud model of the tunnel profile. Additionally, the use of isometric Lambert projection is recommended to obtain an accurate point cloud model of the tunnel. A comparison is conducted with the height gauge detection results to verify whether the accuracy of the height detection meets the relevant requirements. [Result & Conclusion] The presence of spikes in the tunnel profile point cloud model built on mobile 3D laser scanning technology is caused by the scattering and diffuse reflection of the catenary due to laser foot point vertical incidence. The addition of the tilting component effectively reduces the number of spikes in the tunnel profile point cloud model. A comparison of the height detection data between the mobile 3D laser scanner and height gauge indicates that the accuracy of the height detection based on mobile 3D laser scanning technology is generally within ±3 mm, thus meeting the precision requirements stipulated by the relevant regulations.

Keywords

• metro tunnel
• mobile 3d laser scanning technology
• catenary
• height detection inspection accuracy