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  • Writer's pictureRachel Timokhina, CP&Y Blog Writer

What lurks beneath? How SUE takes the fear out of what lies below.

Updated: Sep 14, 2020

Unknowns terrify project owners. Hidden utilities often result in costly conflicts, damage, project delays, service disruptions, redesigns, claims, and even injury or death to workers and/or the public. There is, however, a cost-effective, time-saving solution.

"Subsurface Utility Engineering (SUE) is the process of mapping and managing information about existing utilities in order to expose project unknowns early in the life of a project when such issues least impact budget and schedule. SUE allows project owners to anticipate possible challenges and manage risk before construction begins."

Don’t get spooked! Manage risk with tailored SUE Quality Levels.

Although SUE offers a variety of benefits and Quality Levels (QL) to match each project’s specific needs, many project owners do not take full advantage of this service. CP&Y offers full, in-house SUE and is eager to help project owners decide when SUE services are necessary and, if so, what QL is most economical for their situation.

"Quality Level (QL) refers to the level of certainty attained from SUE services regarding the location of the utilities in question. Basically, the more (literal) digging you do, the more precisely you know a utility’s location."

Some project owners believe that SUE is only necessary for “high-profile projects in dense urban sections with high-volume traffic” as opposed to “smaller, off-system” projects.[1] The truth is that SUE can be an appropriate, complimentary service for all civil infrastructure projects. While each QL may vary in cost, all levels of SUE service can be justifiable investments when used appropriately. The four QLs of SUE allow project owners to develop cost-effective solutions for each unique project.

Starting with Quality Level D (QLD), existing utilities records are compiled into a composite drawing. These records are usually copied straight from as-built drawings, utility company records, field notes, distribution maps, and perhaps even oral recollections from former project engineers. Keep in mind that these sources may be out of date or just wrong, propagating misinformation or entirely lacking the vital information necessary for a project’s success.

Graphic illustrating the "Degree of Precision" getting progressively more precise as the step graphics move from Quality Level D to A.

The same is true of Quality Level C (QLC), which only looks at visible, above-ground structures, like manholes or valves, to confirm existing utilities records already compiled in QLD. These structures are then added to the composite drawing, but do not necessarily confirm the exact location of underground utilities. QLD and QLC are usually the least expensive SUE options as these levels require less time and use fewer technologies.

Quality Level B (QLB), however, is a more detailed look at what could be lurking below and conflicting with a project’s design. At this level, geophysical technologies are used to locate the horizontal positions of utilities, a process known as designating.

Likewise, Quality Level A (QLA) is progressively more detailed and uses test holes to physically view utilities and confirm vertical positions (i.e., the utility’s depth). The SUE process known as locating provides “precise plan and profile mapping of underground utilities through the nondestructive exposure of underground utilities, and also provides the type, size, condition, material, and other characteristics of underground features.”[2]

Three boxes, each with a different version of mapped utility locations.

Image A. shows existing record drawings for electrical utilities. Image B. illustrates the project owner’s interpretation of the electrical line location. Image C. shows the actual location of the line, demonstrating the need for SUE services even when existing records are available.

As the figure above demonstrates, all SUE quality levels are not created equal. A study prepared by the Purdue University Department of Building Construction Management found that QLB and QLA identified 80-90% of existing utility facilities, which is 10-50% more than found with QLD and QLC alone.[3] With that knowledge, imagine how often utility data is incorrect from the beginning of a project without the use of any SUE services.

Take a risk and get tricked, or treat yourself to certainty? The benefits of SUE.

Contrary to what some project owners may believe, engaging SUE services or using a higher SUE Quality Level does not necessarily negatively impact the project schedule and overall project cost.

Even for QLA, SUE crews “can typically expose a utility, obtain and record the utility information, and close the hole in a two- to four-hour window.”[4] The same Purdue University study noted that QLB and QLA produced an estimated “project delivery time savings of 12-15%.”[5] This extra time is produced by avoiding the project delays associated with redesign, utility relocation, extensive change orders, business closures, and alterations to traffic control plans among other issues.

Project cost is similarly misunderstood when it comes to SUE services. According to a study performed by the Texas A&M Transportation Institute for the Texas Department of Transportation (TxDOT), the use of SUE technologies is on the decline “due to significant reductions in funding for utility investigations.”[6] A lack of funding for upfront project costs can lead to even greater overall project costs once construction begins.

With cost being the biggest roadblock for project owners, it is interesting to note that even the most detailed data collection services (QLB and QLA) may only require 0.2-3% of the total project cost when used strategically.[7] For example, gathering QLB information for the entire project and using QLA only in critical locations will minimize cost and maximize the effectiveness of SUE services for a project. This is how higher QLs of SUE data collection can still be affordable options for even the most frugal of project owners.

If minimized project delays and negligible service costs are not enough, perhaps project owners will be persuaded by a potential return on investment (ROI) of $4.62 in savings for every $1.00 spent on SUE. This means there is a “potential minimum stretching of project dollars by 4.62% if comprehensive QLB and QLA mapping is performed correctly.”[8]

Furthermore, “SUE services obtained during the design stage would also allow for notification of the utility companies of pending transportation projects early enough to gain their participation in mitigating conflicts, obtain cheaper prices from the construction contractor by identifying utility systems prior to bidding projects and create a safer environment for construction activities.”[9]

Other, less-visible ways that SUE services can minimize project expenses may include lower insurance and financing costs, as well as fewer fees from associated construction claims.

Let CP&Y help.

With millions of dollars at stake, you need a partner with the experience and integrity to make every dollar and every minute count. CP&Y provides services for all aspects of field-related practices, including SUE, for a wide spectrum of civil infrastructure projects.

No matter the type, location, or size of your civil infrastructure project, the four Quality Levels of SUE offer customizable solutions for each project’s schedule and budget. By appropriately combining Quality Levels, project owners can more effectively and economically locate utilities to save project delivery time (by as much as 12-15%) and overall project cost (with a ROI of nearly $5 for every $1 spent).

Furthermore, our SUE crew follows standards as set by the American Society of Civil Engineers (ASCE), specifically ASCE 38-02. This set of standards is integrated with additional, more detailed procedures, which help further manage risks associated with inaccurate or incomplete utility mapping.

We provide complete and accurate data while meeting tight deadlines and producing site data that can be relied upon with complete confidence. Whether rural or urban, a single building or an entire subdivision, we are ready to apply our experience and technology to produce outstanding service and accurate results.

For more information about how CP&Y’s knowledgeable team of SUE experts can help you take the fear out of what lurks beneath your project, visit our SUE services page and get in touch.


Connect with Glenn Fox, SUE Manager for more information about how we can help you mitigate what lurks below!

CP&Y's SUE Manager, Glenn Fox, brings over 30 years of experience managing numerous teams of SUE professionals to provide services for a variety of design and construction projects including drainage improvements, road widening, pipeline corridors, and more. His knowledgeable expertise has been published in magazines such as Underground Focus, Pipeline and Gas Journal, and Trenchless Technology among others. • (972) 265-4600 • Connect with him on LinkedIn


[1] Kraus, Edgar, Yingfeng Li, John Overman, and Cesar Quiroga. “Utility Investigation Best Practices and Effects on TxDOT Highway Improvement Projects.” Best Practices for Utility Investigations in the TxDOT Project Development Process, April 2013, page 36.

[2] U.S. Department of Transportation: Federal Highway Administration. “Subsurface Utility Engineering: An Introduction.” Utility Program: Subsurface Utility Engineering, April 2018.

[3] Lew, J. (2000). Cost Savings on Highway Projects Utilizing Subsurface Utility Engineering, Report No. FHWA-IF-00-014, Purdue University, Federal Highway Administration, Washington, DC.

[4] Fox, Glenn. “Subsurface Utility Engineering (SUE).” PowerPoint Presentation, Kimley Horn, City, DD Month YYYY.

[5] (Lew, J.) Note: these figures are specific to research performed in the State of Virginia.

[6] Kraus, Edgar, Yingfeng Li, John Overman, and Cesar Quiroga. “Utility Investigation Best Practices and Effects on TxDOT Highway Improvement Projects.” Best Practices for Utility Investigations in the TxDOT Project Development Process, April 2013, page 65.

[7] Quiroga, Cesar, James Anspach, Paul Scott, Edgar Kraus. “Feasibility of Mapping and Marking Underground Utilities By State Transportation Departments.” Publication No. FHWA-HRT-16-019, July 2018, page 121.

[8] Anspach, James, J.J. Lew, Paul Scott, Kevin Slack. “Cost Savings on Highway Projects Utilizing Subsurface Utility Engineering.” PowerPoint Presentation, Purdue University, 2000.

[9] Via, Patrick. “Knowing what’s below saves time and money.” Texas811: Volume 2, Issue 3, pages 16-18.

#SUE #Utilities #QualityLevels #SubsurfaceUtilityEngineering #CostEffectiveSolutions #GlennFox #ASCE #ROI

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