Provider guide and directory
Subsurface Utility Engineering Services
Subsurface utility engineering, or SUE, is an engineering practice for managing risks associated with existing utilities during project planning and design. It combines records research, visible-feature survey, surface geophysics, utility mapping, coordination, and selective physical exposure at defined utility quality levels. SUE is not a synonym for an ordinary private utility locate, a single GPR scan, or a map without the required engineering and survey framework.
What subsurface utility engineering is
SUE organizes utility information according to the level and source of evidence needed for a design decision. The project owner and qualified professionals define the limits, required quality, standards, coordinate control, deliverables, conflict questions, and responsibilities. Locating technologies are tools within that process—not the entire service.
A SUE scope may support route selection, design development, conflict analysis, utility coordination, test-hole decisions, plan production, and communication of utility risk. The applicable standard, contract language, professional licensure, and jurisdiction should be confirmed for each project.
Utility quality levels D, C, B, and A
FHWA guidance commonly describes four quality levels. They indicate the source and comprehensiveness of utility information rather than a universal numerical accuracy. Current project requirements should be tied to the applicable contract and standards rather than inferred from a label alone.
Quality Level D
Information derived from existing records or verbal recollections, useful for broad planning but limited by source quality.
Quality Level C
Surveyed visible utility features correlated with available record information and discrepancies.
Quality Level B
Appropriate surface geophysical methods used to designate horizontal utility positions, with results surveyed to project control.
Quality Level A
Selected utilities physically exposed and measured to obtain precise horizontal and vertical information plus observed characteristics.
Records, designating, survey, test holes, and deliverables
A formal workflow compiles and evaluates records, surveys visible appurtenances, applies suitable geophysical methods, surveys designated positions, resolves discrepancies, selects test-hole locations, measures exposed utilities, and communicates the resulting quality level on project deliverables. Not every utility needs the same level at every location.
Surface designation may use GPR and electromagnetic locating. Selected critical points may then require utility potholing or another controlled exposure method. The results may be delivered through plan sheets, CAD, GIS, reports, conflict matrices, test-hole logs, or client systems.
SUE vs. private locating and utility mapping
A private locate can support excavation planning by marking interpreted utilities. Utility mapping can capture and organize located evidence. SUE goes further by defining utility information quality within an engineering risk-management process, with survey, standards, professional responsibility, and project deliverables appropriate to design.
| Scope | Primary purpose | What should not be assumed |
|---|---|---|
| Private utility locate | Identify and mark site utilities for a defined field need | Formal quality levels, survey control, engineering certification, or design deliverables |
| Utility mapping | Capture utility evidence spatially and deliver usable data | That every feature has SUE quality-level evidence or engineering oversight |
| Subsurface utility engineering | Manage utility risk for planning and design using defined quality levels | That one technology, one scan, or one test hole constitutes the complete process |
Provider qualifications and scope limitations
Confirm which entity is responsible for engineering, surveying, geophysics, vacuum excavation, utility coordination, safety, and final certification. Licensure and practice requirements vary by jurisdiction. The proposal should identify the governing standard, requested quality levels, project control, deliverables, exclusions, and professional-of-record responsibilities.
Even formal SUE manages rather than eliminates utility risk. Records can be incomplete, surface methods can miss features, access can be restricted, test holes sample selected points, and utility conditions can change after collection. Deliverables need dates, sources, quality designations, and limitations.
Common questions
Frequently asked questions
Is SUE the same as private utility locating?
No. Private locating is a field service that may contribute evidence. SUE is an engineering practice that manages utility information and project risk through defined quality levels, survey, coordination, standards, and deliverables.
What is Quality Level B utility information?
FHWA describes QL-B as information developed using appropriate surface geophysical methods to designate horizontal utility positions, with the results surveyed to project control. The contract and applicable current standard define the project requirement.
Does Quality Level A mean every utility is exposed?
No. QL-A information is normally obtained at selected locations where precise horizontal, vertical, and characteristic information is needed. The project owner and responsible professionals define where that level is required.
Who should provide SUE services?
A team must have the engineering, surveying, geophysical, excavation, coordination, and safety qualifications required by the project and jurisdiction. Confirm the responsible professional and subcontracted roles rather than relying on a service label alone.
Technical references
Technical definitions and limitations on this page were checked against these primary government resources.
Provider discovery
Find subsurface utility engineering providers
Compare SUE providers by engineering, survey, geophysical, test-hole, coordination, and deliverable qualifications—not by locating equipment alone.
Capabilities to confirm
- Responsible engineering and surveying professionals required by the project
- Current standards and quality-level scoping experience
- Records, surface geophysics, survey, and discrepancy-resolution workflow
- Test-hole coordination and physical exposure capability
- CAD, GIS, plan, conflict, and certified deliverables as required
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Related locating services
Utility mapping
Compare general mapped deliverables with formal SUE quality levels.
Utility potholing and daylighting
Review physical exposure used for selected verification points.
GPR utility locating
Review one surface-geophysical method used in some scopes.
Electromagnetic utility locating
Review conductive designation methods used in some scopes.
Helpful next steps
Private utility locating
Review what a private locate covers, the methods behind it, and what to confirm before hiring.
Find private utility locators
Search the directory by location and confirmed capability.
Private utility locating cost factors
Understand how scope, access, methods, and deliverables shape a provider quote.
What is a utility locator?
Review the role, the equipment, and the split between one-call and private locating.
How to locate underground utilities
Compare records, electromagnetic locating, tracer wire, sondes, radar, and physical verification.
Compare provider capabilities
Find a subsurface utility engineering company
Define the project phase, design footprint, required standard and quality levels, coordinate control, test-hole needs, professional responsibilities, and deliverables.