Laser Scanning of the Harvey Tunnel
Successfully capturing accurate 3D as-builts of the entire Harvey Tunnel in Louisiana under a tight timeline required state-of-the-art technology, survey expertise and the vision to know it was possible.
Laser scanning was used to assist in the structural analysis and environmental remediation of the tunnel which is on a busy artery that serves traffic traveling between downtown New Orleans and the local communities. There has been little reinvestment in the structure, resulting in signs of deterioration, including concrete spalling and cracking on the tunnel walls and extensive leaking from overhead construction joints.
The scanners were equipped with 360-degree cameras with HDR that enabled the survey crews to quickly collect high-resolution panoramic photos in the low light conditions of the tunnel. Scanning was performed on the tunnel roadway, approaches, pedestrian walkway, ventilation shaft and ventilation buildings to completely map all the interior and exterior features. Scanning the ventilation shaft was a unique challenge due to its small size making it a confined space. At a height and width of four feet, crews used dollies to move the scanner through the shaft to collect scans of its interior.
The team developed multiple, user-friendly deliverables to provide the data needed for the project engineers’ structural and environmental analyses. The team generated 3D CAD basemapping and a mesh-based 3D model of all tunnel surfaces including the roadway, walls, ceilings, walkway and ventilation shaft. The firm also provided the final point cloud and 360-degree photos in web-based platforms that could be easily accessed and utilized by the engineers. A Potree web-viewer enabled the client to interact directly with the point cloud through a web browser to take measurements, cut cross-sections, and make visualizations as needed. High definition 360-degree photos were overlaid with the laser scan data in a second web-viewer called a TruView.