A definitive study of twenty-two projects utilizing subsurface utility engineering (SUE) and eight non-SUE projects from Pennsylvania Department of Transportation (PennDOT) districts has revealed that $11.39 can be saved for every $1 spent on SUE.  The cost of conducting a SUE survey was estimated at 1.65% of total project cost.

Eleven main benefit factors were considered in the analysis.

1. Utility relocation cost
2. Utility damage cost
3. Emergency restoration cost
4. Traffic delay cost
5. Business impact cost
6. User service cost
7. Environmental impact cost
8. Information gathering and verification cost
9. Legal and litigation cost
10. Efficient utility design and construction
11. Other utility related costs and benefits

On the cost side two kinds of costs are involved in conducting a SUE survey. One is the use of geophysical techniques such as EMI and GPR to identify the location of underground utilities and other objects.  The other is potholing (using safe excavation techniques) to confirm the location of the utilities and objects identified.  In this study for the projects utilizing SUE, costs are obtained from directly from project accounting. For the projects that did not use SUE, costs are estimated from interviews, historical data, and individual project studies.

For the twenty-two projects where SUE was applied, all underground utilities and other objects were located to ASCE 38-02 quality level A (potholing) or B (EMI and GPR).  For the eight projects utilized traditional methods, the location of underground networks was estimated to ASCE quality levels C (site visit) and D (as-builts).

Previous ROI studies of SUE only used projects where SUE surveys were performed to quantify the cost savings of SUE.  In this study, non-SUE projects were used to determine the cost savings of SUE because direct costs incurred by problems that would have been avoided by SUE can be considered as SUE benefits. The results of the study revealed that $11.39 can be saved for every $1 spent on SUE on road projects. A ratio of 1.65% was determined as the ratio of SUE cost to total project cost. It was concluded that SUE can provide accurate utility information with important project benefits at reasonable cost. Project relocation cost is the most important item to the cost savings, representing 40.33% of total savings. The study also showed that the greater the complexity level of buried utilities, the higher the SUE benefits.

Source

Yeun J. Jung, Evaluation of subsurface utility engineering for highway projects: Benefit–cost analysis, pages 111-122 in Tunnelling and Underground Space Technology Volume 27, Issue 1 Pages 1-168 (January 2012)