Evaluating completeness and positional accuracy of traditional utility records compared to subsurface utility engineering: A comparative case study analysis

Abstract

Accurate and complete mapping of subsurface utilities such as gas lines, water pipes, and power cables is essential for efficient and safe infrastructure projects. This study investigates the completeness, positional accuracy, and reliability of traditional utility records compared to Subsurface Utility Engineering (SUE) investigation data by examining documented utilities for a highway reconstruction project in South Dakota. SUE investigations followed the Quality Level standards defined in the American Society of Civil Engineers (ASCE) 38–22 “Standard Guideline for investigating and documenting existing utilities.” A composite map was developed by overlaying the traditional and SUE investigation datasets. An analysis of the linear footage mapped revealed significant under-documentation in the traditional records, known as One Call records, with SUE investigations designating and mapping 160% more utility infrastructure across all asset types. Positional accuracy metrics further exposed deficiencies in traditional mapping. Only 32% of utility footage analyzed aligned within 2 feet (ft) when comparing One Call records to SUE investigation data. Moreover, about 21% of utilities in One Call records deviated by over 20 ft compared to the SUE data. These findings demonstrate the necessity of rigorous SUE practices to mitigate risks from inaccurate and incomplete utility data. SUE provides comprehensive, precise subsurface infrastructure mapping, which is essential for informed engineering design, conflict prevention, and efficient, low-risk construction. This study affirms SUE’s value in reducing utility-related risks and supporting efficient project delivery through accurate subsurface mapping.