Unmanned Aerial Systems (UAS) have gained significant use in supplying digital site information to highway agencies since FHWA began supporting deployment through EDC. Since 2016, Federal Lands Highway (FLH) has successfully used UAS to collect site information for 3D design modeling and other digital project delivery applications.
UAS can often collect data faster, more cost effectively, and in a safer manner, than if traditional survey crews were used. For example, UAS assist staff in gathering site information in difficult and nearly inaccessible places, such as narrow roads and steep terrains. This site information is essential for accurate 3D design modeling. FLH estimates UAS will save $45,000 in survey costs on just one project, the Dent Bridge Road Safety Improvement project in Idaho. UAS data also provides a complete map of existing conditions—also known as a ‘digital terrain model’—for 3D design and other digital applications versus traditional surveying, which is less accurate.
UAS and other digital data gathering practices, such as mobile Light Detection and Ranging (LiDAR), provide orders of magnitude of more information to feed better 3D designs and visualization. These digital tools support design optimization and better communication across the various project delivery disciplines and to other stakeholders. 3D modeling allows the public to ‘see’ beyond what plan sheets can show, helping them understand alignment options and associated environmental impacts during public outreach, whether in-person or through Virtual Public Involvement.
Data supplied by UAS for 3D design models also provide the ability to calculate more accurate quantities automatically and to do project cut-fill balancing. The digital terrain model can provide full site coverage versus traditional survey, which generally provides ground elevation points at 50+ foot intervals and is more demanding on survey staff.