A recent Purdue University study sponsored by the Federal Highway Administration (FHWA) found that every $1.00 spent on subsurface utility engineering (SUE) results in a documented savings of $4.62 in utility relocation costs.

Subsurface utility engineering (SUE) locates existing utilities early in the design process. This early identification allows designers to modify the alignment of roadway features, thus minimizing expensive utility impacts and relocation costs. SUE also reduces accidental utility damage and associated service disruptions, minimizes construction injuries resulting from utility hits, and decreases the risk of construction delays and change-orders due to unforeseen utility conflicts.

To maximize the benefits, a five-phased approach is recommended.

Initial Investigation.In this phase, the utility owners in the project area are contacted and utility record plans obtained. Field edits are conducted to locate manholes and valve boxes. This initial phase is of limited scope and historically is the only utility investigation performed.

Utility Designation. The horizontal alignment of utilities is identified using equipment such as sonic, magnetic, and radar devices. Using this information, slight horizontal adjustments in design can produce substantial cost savings by moving construction away from the utilities, thus minimizing relocation.

Utility Locating. Horizontal and vertical locations are provided by excavating 8 inch to 12 inch diameter holes along the length of the utility lines. Non-destructive excavation methods are used to locate the utilities so that elevation data, not acquired in phase 2 above, can be obtained.

Survey. The x, y, and z utility locations are obtained using conventional survey techniques and the data is transferred to a CADD/GIS system.

Design. Once the three-dimensional location of the utilities is transferred into the design files, the designer makes horizontal and vertical adjustments and may, in many cases, avoid utility relocation altogether.

In order to continue and expand the use of this cost-saving tool, FHWA funds are being made available to help pay for SUE by allowing it as a reimbursable expense. Many first-time users of SUE accelerate their use of it once they realize the benefits and savings incurred.

For more information on SUE, contact Steve Boddecker, L.S. at (716) 858-1234, ext. 303 or sboddecker@fisherassoc.com.