As-Built Surveys for Highways Projects: What We Capture and Why It Matters
In highways construction, progress is measured in layers: from sub-base to blacktop, drainage to ducting, kerbs to cat’s eyes. And when the job’s done, the drawings need to show what’s actually been built — not just what was meant to be.
That’s where highways as-built surveys come in.
These surveys are more than just a box-ticking exercise. They're the foundation of quality assurance, compliance, and future maintenance planning — and they matter even if the contractor thinks they don’t need them.
Highways as-built surveys confirm every detail is constructed to spec — from kerb face to road crown.
What Is an As-Built Survey?
An as-built survey documents the final position of installed infrastructure — from kerb lines and drainage covers to road centrelines, lighting columns, and edge restraints. On highways projects, it forms part of the QA process to confirm that construction meets design specifications and tolerances.
These are also referred to as record drawing surveys or roadworks QA surveys in the UK.
The output usually takes the form of a CAD drawing or BIM model, complete with annotations and survey metadata. These drawings provide a permanent, geo-referenced record of:
Horizontal and vertical position of road features
Location of utilities and ducting routes
Levels of manholes, gullies, and kerb lines
Footway, verge, and carriageway widths
Tie-ins to existing roads
Why Do They Matter?
For Handover Most clients, including local authorities and National Highways, require as-builts before sign-off. They're used to check build compliance and issue completion certificates.
For Maintenance Having a reliable record of what’s underground — and where — is critical when it comes to future works, repairs, or expansions.
For Legal Protection If there’s ever a dispute over damage, flooding, or non-compliance, as-built data is your evidence. It shows exactly what was constructed, where, and when.
For Internal QA Contractors use as-built checks to confirm accuracy before signing off work — especially on items like drainage falls, road camber, and kerb alignment.
As noted in Highways England’s Specification for Highway Works, record drawings are a key part of documentation required for adoption and asset management.
What We Capture at AKN
At AKN Engineering, we tailor each as-built to the client’s brief — but our standard capture includes:
✅ Kerb lines, including backs and faces
✅ Road centreline and finished levels
✅ Gullies, manholes, chambers, and drainage routes
✅ Street lighting columns and ducting
✅ Footways, islands, and tactile paving
✅ Verge edges and landscape tie-ins
✅ Retaining structures or significant features
✅ All levels relative to the site control grid
We use total stations and GNSS where appropriate, and process data into clean, layered CAD drawings (or LandXML files for BIM workflows). QA is embedded into our workflow with rigorous ITP/ITR documentation to support each survey.
When Should You Do It?
As-built surveys aren’t just a one-off at the end. On phased or fast-track jobs, we recommend:
Initial capture after sub-base or kerb install
Interim surveys for drainage or structural elements
Final survey post-tarmac or surfacing
Capturing as you go reduces the risk of missing buried assets — and keeps your documentation aligned with what’s actually built.
As-built drawings might not pour concrete or lay asphalt — but they prove you did it right. And on highways projects, that proof matters.
Learn more about how we handle inspection test records (ITRs) to support QA and compliance across highways builds.