Our Services

Utility survey.
PAS 128 detection and mapping.

PAS 128-compliant buried services surveys across the UK — GPR, EML and sonde tracing combined with statutory undertaker records reconciliation. Classified by Quality Level, delivered as RICS-standard CAD with full audit trail.

PAS 128
British Standard compliant
QL-A–D
All Quality Levels covered
OSGB36
National datum referenced
Request a Quote PAS 128 Quality Levels
What it is

In-depth guide: PAS 128 Quality Levels Explained →

What is a utility survey?

A utility survey is the measured detection, classification and mapping of buried services across a site — water, gas, electric, telecoms, fibre, drainage, district heating — combined with the reconciliation of statutory undertaker records. The deliverable is an AutoCAD DWG with utilities on dedicated layers (one per service type and PAS 128 Quality Level), referenced to OSGB36 horizontally and ODN vertically.

It is the single most important risk-management deliverable in the early-design and CDM dutyholder workflow. Designers, civil engineers, principal contractors and asset owners use it to design around live infrastructure, evidence their Regulation 11 risk assessment, and avoid the legal and safety consequences of damaging buried apparatus. Every Angell Surveys utility deliverable is produced under the RICS Surveys of Land, Buildings and Utilities professional statement and the PAS 128 quality framework.

PAS 128 Quality Levels

Four Quality Levels — classified per service, per location.

PAS 128 classifies utility survey accuracy into four levels. Every detected service is recorded on the drawing with its Quality Level explicit alongside it, so the designer knows the confidence interval on every line.

Quality Level Method Plan Accuracy Depth Accuracy Use Case
QL-D Statutory records desktop study only Variable / unverified None Initial feasibility, route option appraisal
QL-C Site reconnaissance, records reconciliation, visible feature survey ±500 mm None / inferred Outline design, early-stage cost planning
QL-B Geophysical detection (GPR + EML + sonde) with cover-lift verification ±150 mm ±15–40 % Standard design base; Network Rail / Highways minimum specification
QL-A Intrusive verification by trial pit or vacuum excavation ±50 mm ±25 mm Critical setting-out, working adjacent to live apparatus

Every detected utility on the deliverable DWG is annotated with its PAS 128 Quality Level. Quality Levels are mixed within a single survey — a site may have a QL-B trunk main reconciled with a QL-C records-only branch and a QL-A trial-pit-verified manhole connection. The drawing legend records the survey type per service type.

Methodology

How we detect.

Multi-sensor detection combined with records reconciliation and cover-lift verification — the only reliable way to classify a buried service.

Ground Penetrating Radar (GPR)

Multi-frequency GPR for non-conductive services (drainage, fibre, plastic gas) and depth measurement of all detected lines. 250–800 MHz antennas matched to ground conditions and target depth.

Electromagnetic Locator (EML)

Active and passive EML for conductive metallic services and live electricity. Power, RF and signal-clamp modes used to disambiguate parallel and crossing services.

Sonde & Signal Clamp

Inserted sonde tracing through chambers, rodding eyes and accessible pipework for non-conductive lines that GPR cannot resolve. Signal clamps for traceable conductive services.

Records Reconciliation

Statutory undertaker records (Cadent, NGN, SGN, water and sewerage operator, DNO, Openreach, district heating) requested up-front, reconciled with detection on the deliverable drawing.

Cover-lift Verification

Chambers, valves, hydrants and inspection covers opened where accessible to verify service type, material, diameter and invert level. Recorded with photographs in the report.

QL-A Intrusive Verification

Coordinated vacuum excavation or trial pits where critical setting-out requires QL-A accuracy. Issued with photographic record and section drawings of verified positions.

Who It's For

When you need a PAS 128 utility survey.

A

Civil & Highways Engineers

Pre-construction utility clearance for site setting-out, drainage design and earthworks. Reduces CDM risk and avoids the cost of striking live apparatus.

B

Principal Contractors

Site possession evidence for statutory undertakers and works coordinators. PAS 128 QL-B is the minimum specification for Network Rail and Highways England.

C

Design Consultants

Foundation, drainage and SUDS design coordinated against detected utility positions. 3D BIM utility model on request for clash detection.

D

Asset Owners

Operational record verification for water, energy and rail operators. Reconciliation of as-laid drawings with current ground truth.

Our Process

How we work.

A documented, PAS 128-aligned workflow from records request through to QA-signed deliverable.

01

Records & Scoping

Statutory undertaker records requested up-front. Site boundary, target Quality Level and works window agreed. RAMS prepared for site safety and access.

02

Site Detection

Multi-sensor sweep with GPR + EML + sonde where applicable. Cover-lift verification at every accessible chamber. Survey control referenced to OSGB36 / ODN.

03

Reconciliation & Drawing

Detected services reconciled against statutory undertaker records. AutoCAD DWG produced with utilities on layers by service type and PAS 128 Quality Level.

04

QA & Issue

PAS 128 report issued with methodology, equipment, observation log, photographs and accuracy statement. Drawings revision-controlled and signed off before issue.

Sector Applications
Water & Wastewater Rail Infrastructure Highways & Bridges Nuclear Renewables & Energy Built Environment Telecoms & Fibre
FAQ

Utility survey questions.

The questions clients ask us most often before instructing a utility survey.

What is a utility survey?
A utility survey is a measured investigation of buried services — water, gas, electricity, telecoms, drainage, fibre, district heating — across a site. The survey records the horizontal position, depth, diameter and material of each detected line, classified by the four Quality Levels of the PAS 128 specification. The output is an AutoCAD DWG with utilities on dedicated layers (one layer per service type and Quality Level), referenced to OSGB36 / ODN, used by civil engineers, architects, contractors and asset owners to design around live infrastructure and avoid the legal and safety consequences of damaging buried services.
What is PAS 128 and which Quality Level do you survey to?
PAS 128 is the British Standards Institution publicly available specification for underground utility detection, verification and location. It defines four Quality Levels — QL-D (records-only desktop study), QL-C (site reconnaissance with records reconciliation), QL-B (geophysical detection by Ground Penetrating Radar and Electromagnetic Locator) and QL-A (intrusive verification by trial pit or vacuum excavation). Every Angell Surveys utility deliverable is classified to the appropriate PAS 128 level per service type per location, with the survey type recorded on the drawing alongside each utility.
What survey methods do you use to detect buried services?
We use Ground Penetrating Radar (GPR) for non-conductive services and depth measurement, Electromagnetic Locator (EML) for conductive metallic services and live electricity, and signal-clamp/sonde-based tracing for pipework with rodding access. Cover-lift verification is performed where chambers, valves and inspection covers are accessible. For QL-A intrusive verification we coordinate vacuum excavation or trial pits through the principal contractor. Statutory undertaker records (water, gas, electric, BT, district heating) are requested up-front and reconciled with the survey on the deliverable drawing.
Is a utility survey required before planning or construction?
Yes — increasingly so. CDM 2015 Regulation 11 requires designers to eliminate or reduce risks to those who will construct, maintain, demolish or otherwise interact with their work. Buried services are a primary CDM risk and a PAS 128-compliant utility survey is the standard route to evidence the risk assessment. Local planning authorities and statutory undertakers (Network Rail, Highways England, Crossrail, HS2) typically specify a PAS 128 QL-B survey as a minimum for any works requiring possession or land entry. Most utility companies will not authorise works adjacent to their apparatus without one.
What deliverables will I receive?
Standard outputs are an AutoCAD DWG (utilities on layers by service type and PAS 128 Quality Level), a PAS 128 report (methodology, equipment, observation log, statutory undertaker correspondence, photographs, drawing list), and a PDF preview at 1:200 or 1:500. Optional outputs include a 3D BIM utility model (IFC), a GIS-ready ESRI shapefile or GeoJSON export, and a clash-detection layer for design coordination. Outputs are referenced to OSGB36 / ODN unless a contractor-defined site grid is specified.
Are you RICS regulated?
Yes. Angell Surveys is regulated by the Royal Institution of Chartered Surveyors (RICS) — verify via our public profile at ricsfirms.com/office/681790/Angell-Surveys-Ltd. All utility survey work follows the RICS Surveys of Land, Buildings and Utilities professional statement and the PAS 128 quality framework, with independent verification and full QA records issued alongside the drawings.
How long does a utility survey take?
A standard 0.5–1 ha development site takes one to two days on site with deliverables issued within 5–10 working days. Linear infrastructure (highway corridor, rail possession, utility crossing) is scoped against the worked length and access window. Records-only (QL-D) studies can be turned around in 48 hours where the statutory undertakers respond promptly.
Do you cover the whole of the UK?
Yes — utility surveys delivered across England, Wales, Scotland and Northern Ireland. We hold the safety, training and insurance to work on Network Rail possessions, Highways England restricted zones, water and energy operator sites, and nuclear-licensed facilities.
Related Services
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Topographic Survey
External site levels, contours and surface features captured to OSGB36 / ODN — commonly delivered as a paired output with PAS 128 utility surveys.
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Service
Aerial Survey
UAV photogrammetry for site context and corridor mapping — integrated with utility surveys for full-site existing-ground documentation.
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Service
Confined Space & Remote Inspection
Collision-tolerant UAV inspection of deep chambers, manholes and inaccessible service voids — without manned entry.
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Request a Quote

Need a PAS 128 utility survey? Scoped and quoted within 24 hours.

Most scoping responses sent within one business day.

RICS-regulated work, led by Philip M. Angell MRICS.

Discuss your PAS 128 Utility Survey Call 020 4652 4948