Accurate buried asset locating is essential for preventing utility strikes, project delays and safety incidents. In Australia, more than 15,000 underground utility strikes occur each year, with total direct and indirect costs reaching about $4.6 billion annually.
Traditional locating methods such as electromagnetic tracing, tracer wire and Ground Penetrating Radar (GPR) remain important. Still, each has limits in real field conditions, especially in clay soils and when dealing with non-conductive materials like poly pipe. A more reliable approach combines multiple locating methods with high-accuracy positioning, rigorous standards and GIS-ready mapping.
Why Buried Asset Locating Is Failing in the Field
Buried asset locating is intended to pinpoint utilities before excavation, maintenance or development. However, on many sites, the outcome remains uncertain because traditional locating tools depend on electrical conductivity or ideal ground conditions.
Electromagnetic (EM) locators work well on metallic pipes and cables, but they struggle when faced with non-conductive materials such as poly pipe or PVC. Without a conductive path, these tools cannot reliably trace the asset line.
Service records and historical plans provide a useful starting point, yet they rarely deliver the centimetre-level accuracy required for complex sites or dense utility corridors. Where urban development overlays older networks, gaps in documentation or ambiguous records can lead to incorrect assumptions, and ultimately:
- unexpected relocations or redesigns
- delays to approvals and delivery
- higher costs from rework and traffic control
- increased safety controls and risk exposure
Source: insite.ipwea
The Reality of Trace Wire and GPR Limitations
Many non-metallic pipelines and conduits rely on tracer wire to support locating. In practice, tracer wire is only effective when it is installed correctly and remains intact.
Over time, tracer wires can:
- corrode
- snap during earlier works
- disconnect at joints
- be missing entirely due to legacy installation practices
When that happens, the locating workflow breaks down.
Where GPR helps
Ground Penetrating Radar (GPR) extends the ability to detect both metallic and non-metallic utilities by emitting radar waves and analysing return signals. Unlike EM locators, GPR can often reveal:
- PVC and poly pipe
- concrete and terracotta pipes
- voids and trenches
- disturbed ground zones
Where GPR struggles
GPR is not foolproof. Its effectiveness depends heavily on ground conditions. In clay-rich, water-logged, or highly conductive soils, radar waves attenuate quickly, limiting depth penetration and clarity. Moisture, roots, reinforced concrete, and mixed fill can also distort return signals.
Even when GPR identifies an object, it does not reliably confirm:
- material type
- condition
- diameter
- exact depth (without skilled interpretation and validation)
What to Do When Traditional Locating Fails
When standard locating methods do not produce reliable results, better outcomes come from combining tools and workflows, rather than forcing one method to do everything.
Common options include:
- Sonde with EM locators: A transmitter (sonde) inserted inside a non-conductive pipe emits an active signal, allowing an EM receiver to trace it.
- 3D GPR mapping: Grid-based scanning produces a volumetric view of subsurface features, improving confidence in alignment and continuity.
- Vacuum excavation or potholing: For critical crossings or high-risk zones, non-destructive exposure provides direct verification and supports higher accuracy classification.
- Complementary geophysical methods: Acoustic and tracer gas approaches can assist where radar and EM cannot provide confidence, particularly in saturated or deeply buried environments.
Why Accurate Positioning Changes Everything
Precision matters. Knowing the approximate route of a pipe is helpful, but modern infrastructure planning increasingly requires positional accuracy that supports:
- GIS integration
- spatial digital twins
- asset management systems
- future maintenance and renewals
Traditional locating often results in temporary ground marks. Without high-accuracy coordinates, those marks are difficult to reconcile with corporate systems and future planning.
High-accuracy GNSS surveys combined with utility locating enable assets and verification points to be positioned with centimetre-level precision, or sub-metre to decimetre, in real time. That makes it possible to deliver subsurface datasets that remain usable long after the construction or field services team has left the site.
Accurate positioning reduces risk and supports consistency across design datasets, operational maintenance, risk management, and as-built records.
Why Datum Matters When Mapping Underground Assets
Mapping underground assets is not only about detection. It is about placing assets correctly within a spatial reference framework so they align with the rest of the environment.
Datum and coordinate systems ensure buried utilities align with:
- above-ground features
- survey control networks
- council basemaps and corporate GIS
- design files and construction set-out
- As a foundation for digital twins and 3D models
Without a consistent datum, two surveys of the same network can differ enough to create misalignment and uncertainty. This becomes especially problematic when data is shared between contractors, councils, utilities, and consultants.
A common datum ensures that excavation markings, CAD deliverables, and GIS datasets use the same location language.
AS 5488: Subsurface Utility Mapping and Accuracy Levels Explained
In Australia, AS 5488 Subsurface Utility Mapping (SUM) defines how subsurface utility information should be classified and communicated. Standards are important, especially when data is to be represented as an asset for the long term.
AS 5488 defines Quality Levels from A to D:
- Quality Level A – Precise horizontal and vertical position obtained via direct exposure (e.g., potholing)
- Quality Level B – Utility features inferred from surface geophysical methods (e.g., GPR, EM)
- Quality Level C – Mapping based on existing records with limited verification
- Quality Level D – Approximate location derived solely from historical information
The higher the Quality Level, the greater the confidence for designers, contractors and asset owners. Aligning buried asset locating efforts to AS 5488 supports safer planning and reduces the likelihood of costly surprises during construction.
From Reactive Locating to a Mapped Source of Truth
Too often, buried asset locating is treated as a reactive step: mark the ground, then dig carefully.
Leading practice shifts this into a mapped, reusable source of truth. This means:
- locate points are GNSS-referenced and datum aligned
- outputs integrate with GIS, CAD and digital twin environments
- documentation aligns to AS 5488 Quality Levels
- results become operational assets, not temporary markings
The deliverable is no longer a one-off location. It becomes structured spatial intelligence that supports planning, maintenance, compliance and lifecycle decisions.
Conclusion
Traditional underground locating tools remain essential, but they are no longer sufficient on their own in modern infrastructure environments. Tracer wire systems and EM locators struggle with non-conductive pipes and complex ground conditions. GPR extends detection capability, but performance varies depending on soil type and moisture.
To achieve reliable, high-accuracy underground asset data, organisations must adopt integrated locating workflows, high-precision positioning, consistent datum control and standards-aligned deliverables under AS 5488.
RapidMap: Turning Buried Asset Data Into Planning Confidence
Accurate underground asset data transforms uncertainty into actionable spatial intelligence. When locating buried utilities for infrastructure works, council programs or development planning, prioritising precision, interoperability and compliance reduces risk and improves long-term asset visibility.
RapidMap helps councils and utilities produce reliable subsurface maps and spatial datasets that align with GIS, digital twins and asset management systems.
We provided an exceptional mobile GIS application solution for Design and Construction Partners for the NBN rollout to correct much of the optical fibre network data in the field, with an audit trail for each corrected Pit and Duct infrastructure record. This ensured project success across design, construction, and commissioning, enabling the handover of new infrastructure datasets to NBN to meet highly complex data models with full connectivity.
Contact RapidMap to improve buried asset locating accuracy and turn subsurface data into a GIS-ready source of truth for safer planning, accurate visualisation, reporting, and to ensure maintenance teams are fully informed on what they will find when they arrive on site to maintain or repair the infrastructure.
