In the aftermath of Hurricane Helene, WithersRavenel worked with NCDOT to assess the extensive damage caused by flooding and landslides in the Chimney Rock and Bat Cave areas of Western North Carolina. Following the storm, our Remote Sensing crews were rapidly deployed to begin the survey process, which was operating on an expedited timeline to lay the groundwork for emergency roadway design. Survey control networks were quickly established in collaboration with other consultants to ensure alignment in NCDOT deliverables. We also provided additional conventional control and property surveys for the NC-9 corridor for the design engineer to complete that project.
Our Unmanned Aircraft System (UAS, or drone) teams were able to quickly map planimetrics and topography, providing more than 4 miles of data within the affected areas using drone-based orthomosaic imagery and LiDAR. Wingtra technology was used for imagery, while LIDAR data was obtained with a Riegl sensor.
Specific corridors that our pilots mapped were NC-9 from Bat Cave proceeding north to the Buncombe County line, and US-64 (also known as US-74 ALT) from Bat Cave east to Chimney Rock. Challenges were numerous, including more than one mile of roadway that was nonexistent due to the extensive flooding. Survey control and flight takeoff locations were also difficult to access in that portion of the project area.
The crucial data allowed for road design and rebuilding to begin in earnest in some of the most devastated areas in the region. Additional LiDAR surveys were completed in the same areas focused on the new alignments of three streams: Grassy Creek, Hickory Creek, and Reedy Patch Creek, and also the Broad River. These additional topographic datasets will assist NCDOT in studying the erosion and hydrology impacts from Hurricane Helene.
