An Assessment of As-Built Accuracy Using Ground-Based Photogrammetry Compared to Traditional GPS Survey

Public infrastructure, like electric and telecommunication utilities, is increasingly moving underground to avoid above ground congestion in urban areas and for protection of their facilities. Locating underground utilities remains a challenge in the United States, and accurate as-built records are crucial for urban development and utility management. Emerging geospatial, three-dimensional (3D), and as-built utility survey technologies are essential for producing reliable and accurate geospatially referenced subsurface utility data. However, the practice for collecting utility as-built data using 3D modelling technologies is one of the least-used approaches among the United States DOTs. Therefore, this study aimed to compare the positional accuracy of digital as-built data of underground utility captured through ground-based photogrammetry with traditional real-time kinetic (RTK) corrected GPS survey points with elevations calculated by survey level. The results demonstrated geospatially accurate 3D scan, and the notable accuracy achieved by device orientation demonstrates ground-based photogrammetry's value for utility as-built data collection.