PAS 128 Utility Surveys
PAS 128
Underground utility surveys carried out to the PAS 128 specification, with every service classified by survey quality level so you know exactly how reliable each result is.
What it is
PAS 128 is the industry specification for detecting, verifying and locating underground utilities. A PAS 128 survey doesn’t just show where services appear to be. It grades the reliability of every detection against defined quality levels (QL-D through QL-A), so designers and engineers can make decisions with a clear understanding of confidence.
Our surveyors combine electromagnetic location, ground penetrating radar and existing records to build a complete, quality-assured picture of the buried infrastructure across your site.
What’s involved
Desktop records search (QL-D)
We gather and review statutory undertakers’ records and existing drawings to establish the expected utility picture.
Site detection (QL-C / QL-B)
Electromagnetic location and GPR sweeps detect and trace services on the ground, correlated against the records.
Verification (QL-A)
Where required, trial holes or vacuum excavation confirm the precise position and depth of critical services.
Survey & deliverables
Detected services are surveyed to control and issued as a quality-attributed CAD model and report.
What you receive
- PAS 128 classified utility drawing (2D CAD / DWG)
- Quality level attribution on every detected service
- Topographic base survey to OS or site grid
- Survey report detailing methodology and confidence
- GIS-ready data on request
- Optional 3D utility model
Where it’s used
Design and feasibility stages, highway and infrastructure schemes, development sites, and any project where accurate knowledge of buried services reduces risk and prevents costly strikes.
Standards & compliance
Surveys are delivered to PAS 128:2022 survey categories and quality levels. Detection equipment is regularly calibrated and our surveyors work to documented procedures aligned with safe digging practice (HSG47).
Common questions
They describe how a utility’s position was established, from QL-D (records only) to QL-A (physically verified). Higher quality levels carry greater positional confidence.
No survey can guarantee 100% detection, but a PAS 128 survey maximises detection using multiple complementary methods and clearly states the confidence of each result.
Related services
Underground Detection & Tracing
Electromagnetic location and signal tracing of buried services, pinpointing the route and depth of live cables and pipes before you dig.
Setting Out Engineering
Accurate setting out for construction, transferring the design onto the ground so structures, foundations and services are built in exactly the right…
As-Built Surveys
Verification surveys of completed works, confirming what was actually built, where, and to what level, for handover, records and compliance.
