What an As-Built Survey Actually Tells You
On construction sites, no matter how carefully the plans are drawn, the final build will always differ in some way. That’s where an as-built survey comes in. It’s the record of what’s actually been constructed, not just what was designed on paper. For highways, infrastructure, and building projects, this is a vital document that helps everyone from project managers to future maintenance teams understand exactly what’s in the ground and above it.
An AKN engineer using a GNSS rover on site to record accurate as-built survey data for project handover.
What Is an As-Built Survey?
An as-built survey is a measured record of the completed works on site. Using total stations, GNSS, and sometimes utility detection methods, surveyors capture the precise positions, levels, and dimensions of finished structures. These might include:
Kerb lines, manholes, and drainage runs
Road alignments and pavement build-ups
Piling locations and foundations
Utilities and service routes
Boundary markers and property tie-ins
Unlike design drawings, which represent what should be built, as-built surveys confirm what has been built.
Why They Matter for Contractors and Clients
An accurate as-built survey provides:
✅ Verification – Proof that works match the design tolerances and specifications.
✅ Handover records – Essential for local authorities and asset owners to sign off projects.
✅ Future planning – Clear information for future upgrades, maintenance, or utility connections.
✅ Risk reduction – Prevents disputes over what was installed, where, and to what standard.
On highways projects in particular, as-built surveys can be the deciding factor in whether a new road, junction, or drainage system is signed off on time.
For guidance on survey specifications, see the RICS Land Survey Specifications.
What You’ll Actually Learn from the Data
So, what does an as-built survey really tell you?
Location of assets – Every feature is tied to national grid coordinates, so you know precisely where it sits.
Levels and elevations – Finished ground levels, slab heights, and drainage falls are recorded.
Compliance – Confirms whether works meet design intent, tolerances, and health & safety standards (HSE construction guidance).
Unexpected changes – Any deviations made on site due to ground conditions or unforeseen obstacles.
A permanent record – Unlike memory or notes, the survey data becomes an accurate archive for future use.
The Limits of an As-Built Survey
It’s important to be realistic. An as-built survey records what was accessible and measurable at the time. It won’t:
Reveal why changes were made on site
Detect features that were hidden or buried after construction
Replace utility mapping carried out before construction (see our post on Utility Surveys)
In short, an as-built survey isn’t just another drawing. It’s your insurance policy for compliance, your handover record for asset management, and your map for future works.
If you’re planning highways or infrastructure works across Hertfordshire, Essex, Cambridgeshire, Suffolk, or the wider East of England, our team at AKN Engineering can provide reliable as-built surveys alongside setting out, topographic surveys, and utility surveys.
👉 Learn more about our services here, or ☎️call us on 01279 927 033 to discuss your upcoming projects.