Understanding Positional Accuracy of Subsurface Utilities

When transportation projects move from planning to design to construction, few challenges create more disruption, and more risk, than unknown or inaccurately located subsurface utilities. Conflicts between proposed work and buried infrastructure can lead to delays, redesigns, cost increases, or even safety incidents on site. As projects across Michigan’s Metro Region continue to grow in complexity, understanding how accurate utility location data really is has never been more important.

At this year’s ACEC–MDOT Partnership Workshop, Tyler Dawson  will present Understanding Positional Accuracy of Subsurface Utilities, a session focused on bringing clarity to one of the highest‑risk components of transportation design.

Why Positional Accuracy Matters

Utility information comes from multiple sources: historic owner records, site features, geophysical exploration, and physical exposures. Each provides a different level of certainty, and each carries its own risk. As shown in the submitted abstract, the session examines how these inputs vary in accuracy and how that impacts engineering decisions throughout a project’s lifecycle.

In reality, positional accuracy is not a single data point—it is the product of method, interpretation, and field conditions. The MDOT Metro Region case studies included in this presentation demonstrate just how wide the range can be, even when following standardized Subsurface Utility Engineering (SUE) processes.

A Look Inside the Session

During the workshop, Tyler will discuss:

• Where utility data comes from, and how reliability changes across Quality Levels (D through A).
• How geophysical designations compare to actual exposed utility locations, based on real project data.
• The frequency and types of utility conflicts encountered on Metro Region projects.
• How improved processes, standards, and technologies can reduce uncertainty in the future.

These insights are backed by both field experience and quantitative comparison between predicted and observed utility locations—highlighting patterns that designers and construction professionals can use to better anticipate risk.

Who Benefits From This Knowledge

This information is especially valuable for designers and construction staff, offering a practical understanding of how utility uncertainty translates to project‑level risk and how proper SUE methods can reduce that exposure. The takeaway is clear: when teams understand the limits of utility accuracy, and implement strategies to improve it, they make more informed decisions, reduce change orders, and improve overall project outcomes.

NTH’s Commitment to Advancing Best Practices

At NTH, our subject matter experts are deeply committed to improving the tools, standards, and processes that support safe, efficient infrastructure in Michigan and beyond. Tyler’s participation in this workshop reflects our ongoing work in subsurface utility engineering, geophysical investigations, and risk‑informed design practices, as also demonstrated in other SUE and geophysical work across the organization.