Type B Detection Survey
Two detection methods over the whole area, every service positioned and labelled with how confident we are.
The drawing you can dig to.
What it is
Type B is the survey most people mean when they say PAS 128. Two detection methods over the whole area, every service positioned and labelled with how confident we are, delivered as a drawing your designer can overlay and your groundworker can read.
What is included
- Type D records search
- Passive sweep of the whole area with the RD8200, active signal applied to every connectable service
- GPR over the whole area with the GS8000 at M3P or as specified
- Surface marking in colour code
- Positions fixed by GNSS RTK
- Office post-processing
- DWG/DXF and PDF with a quality level on every line
- Report with methodology, kit, operator qualification and limitations
- Within 5 working days of the site visit
What the quality levels on your drawing mean
- QL-B1 and QL-B2: dig with care.
- QL-B3: trial hole before machine excavation.
- QL-B4: assume present until proven otherwise.
Typical scope and time
A single street frontage or a small site is one day on site. A development plot is two to three days. The office work is included in the five days. Book at least a week ahead so the statutory records are in before we arrive.
Who does it
Our utility surveyors hold the ProQual Level 3 Certificate in Utility Mapping and Surveying and deliver surveys to PAS 128:2022.
Limits
A Type B survey records what was detected. It does not guarantee every service has been found. Where the drawing says QL-B3 or B4, a trial hole is the next step, and HSG47 still applies. If you need a service exposed and measured, that is Type A.
Where it helps
- Before excavation, piling, trenching or ground anchors
- Before a basement dig or a pavement opening in a London street
- Where the statutory records are old, incomplete or contradict each other
- On a site with a history of services being added and abandoned
- When the client or principal designer has specified PAS 128
- Before EV charger, district heating or substation works
What you receive
- Marked-up ground in survey paint, colour-coded by service
- Utility drawing in DWG/DXF and PDF, each line labelled with type and PAS 128 quality level
- Report stating survey type, methodology, kit, operator qualification and limitations
- Records pack from the Type D search
- Within 5 working days of the site visit
A note on interpretation. A PAS 128 survey records what was detected to the stated quality level. It does not guarantee that every service has been found. Safe digging practice, trial holes where the drawing says QL-B3 or B4, and HSG47 still apply.
Often surveyed together.
GPR Concrete Scanning
Ground penetrating radar finds rebar, post-tension cables, conduits, and voids hidden inside concrete, before they become a problem.
Learn moreFerro Scanning
Electromagnetic scanning to map reinforcement, measure cover depth, and estimate bar diameter without touching the concrete.
Learn moreMore from PAS 128 Utility Surveys.
- PAS 128 Utility SurveysPAS 128 Explained
The British specification for finding and recording buried utilities, in plain English.
- PAS 128 Utility SurveysCAT and Genny Survey
A quick electromagnetic sweep for energised cables and metallic pipes, honestly described.
- PAS 128 Utility SurveysGPR Utility Survey
Why GPR is the second detection method, what it finds that a locator cannot, and where it struggles.
Got a dig coming up?
Send drawings, photos or proposed fixing locations and we'll advise the right survey approach.