Abstract Manager

Utility conflicts remain one of the primary contributors to redesign effort, schedule delays, and cost escalation in transportation infrastructure projects. While Subsurface Utility Engineering (SUE) practices have advanced, test pit programs on many projects are still based on fixed intervals or historical norms that do not reflect the actual variability of utility conditions along a corridor. As a result, resources may be directed to low-risk areas, while segments with higher uncertainty or greater construction impact remain insufficiently investigated. This paper presents a risk-based framework for planning and prioritizing test pits to support more accurate utility identification and improved constructability outcomes.

The methodology builds on the intent of ASCE 38 and CSA S250, which define how utilities should be investigated and documented. However, these standards do not provide guidance on determining where higher-confidence data (such as QL-A test pits) is most needed. The proposed framework incorporates multiple factors—utility density, record reliability, asset age and material, historical disturbance, ground conditions, and anticipated construction activities—to generate a risk profile along the project alignment. These risk profiles are then used to identify priority locations for test pits and to rationalize where conventional spacing can be reduced without compromising design confidence.

Case studies from a recent urban corridor project and a road project demonstrate the application of the framework. The results show that the risk-based approach reduced test pit quantities while improving certainty at critical utility locations and minimizing construction-phase conflicts. The structured scoring process also provided a transparent rationale for investigation decisions, supporting more effective coordination among designers, contractors, and utility owners.

As underground utility environments become more complex and requirements for accurate design data increase, implementing a risk-informed strategy for test pits can enhance corridor planning, reduce design uncertainty, and improve cost and schedule reliability. The proposed framework offers a practical, adaptable tool that can be integrated into SUE programs across a range of transportation projects.