LiDAR is the fastest, safest and most accurate way of collect information from underground spaces like tunnels and bridges to construct new structures or monitor and maintain old ones. One cannot survey them in any other means.
Active tunnel construction sites are non-traditional environments for LiDAR scanning and required unique and adaptable solutions.With correct data interpretation techniques, LiDAR technology provides a precise 3-dimensional tool for geo-mechanical assessment of exposed rock in the face and walls. LiDAR data may also be used retroactively for quality control of installed tunnel support.
Traditionally, deformation and change in an underground environment is measured using a series of five or more permanent control points installed around the profile of an excavation. Using LiDAR for profile analysis provides many benefits as compared to traditional monitoring techniques.
Due to the high density of the point cloud data, the change in profile is able to be fully characterized, and areas of anomalous movement can easily be separated from overall closure trends.
Furthermore, monitoring with LiDAR does not require the permanent installation of control points, therefore monitoring can be completed more quickly after excavation, and scanning is non-invasive therefore no damage is done during the installation of temporary control points.