Subsurface utility engineering for highway projects: A study of utility impact rating and benefit-cost analysis

Accurate locations of buried utility infrastructures are very important for utility owners, utility managers and engineers, designers, and contractors that perform new installations, repairs, and maintenances in highway projects. A lack of reliable information on underground utilities not only can result in property damages, construction delays, design changes, claims, injuries, and even deaths, but also cause traffic delays, local business disruptions, environmental problems, and utility service breakdowns. Subsurface Utility Engineering (SUE) is an engineering process to reduce the potential of underground utility conflicts in the project planning phase. SUE utilizes new and existing technologies to accurately identify, characterize, and map underground utilities with three major activities including designating utilities, locating utilities, and data management. SUE can be the most suitable method for mitigating risks associated with uncertain underground information. Although many damage prevention practices have existed, the damage prevention practice using the SUE concept has not been developed for contractors, designers, engineers, and other stakeholders associated with or impacted by underground utilities. This study focuses on an in-depth analysis of SUE projects executed by Penn DOT districts. Based on this analysis and the utility impact score which refers to utility complexity at the construction site, a decision-support tool called utility impact rating form has been developed to determine which projects should include SUE and identify the appropriate levels of SUE investigation to be used. The computerized utility impact rating form is developed using Visual Basic software to provide a graphical interface for the purpose of enhancing the efficiency of the calculation and selection processes. A detailed benefit-cost analysis is also performed on twenty-two SUE projects and eight non-SUE projects. All of the projects show a strong relationship between SUE benefit-cost ratio and complexity level of buried utilities. The analysis clearly indicates that there is no relationship between SUE benefit-cost ratio and project cost and also no relationship between complexity level of buried utilities and project cost. The conclusion of this study is that SUE quality levels A and B should be based on the complexity of the buried utilities at the construction site to minimize associated risks and obtain maximum benefits.