IMPLEMENTATION OF UNMANNED AERIAL SYSTEMS FOR DESIGN, RISK ANALYSIS, AND HAZARD MITIGATION OF ROCK SLOPES IN VIRGINIA

This study examined whether the deployment of unmanned aerial vehicles, using photogrammetry and 3D modeling software, could provide rock slope design and remediation recommendations comparable to traditional geologic structure mapping methods using handheld transit compasses and measuring tapes. The authors found that the unmanned aerial systems methods as tested are highly and immediately implementable while offering benefits in both cost and safety. Seven hazardous rock slope sites were selected across Virginia. They varied in terms of highway type, traffic volume, rock type, geologic structure, challenges to flight operations, and more. Unmanned aerial systems captured video, overlapping photographs, and some LiDAR data, from which 3D digital models, orthophoto mosaics, and more were generated. Geologic structure data were extracted virtually from the 3D models and compared with rock structure data collected using ground-based geologic field methods. Data from unmanned systems proved as statistically reliable as those from traditional rock structure data collection methods. The study recommends that VDOT take the necessary steps to accommodate unmanned aerial systems to support geologic structure mapping for rock slope design and remediation activities.