What Project Managers Should Understand About Survey Scope (Before the Project Starts)

If there's one stage of a construction project that gets rushed more than it should, it's the survey scope. Most problems later on site — clashes with buried services, unexpected level changes, drainage redesign, programme delays, and cost uplift — can be traced back to one thing: the wrong survey being ordered, or the right survey being ordered too late.

As a site engineer who's had to pick up the pieces more times than I'd like to admit, here's what every project manager should understand about defining survey scope properly at pre-construction stage.

Accurate survey data gathered at pre-construction stage helps project managers avoid redesigns, delays, and service strikes later in the programme.

1. "A topo is not just a topo" — choose the right survey for the right question

A topographical survey can be anything from a basic boundary and level survey to a full-specification deliverable including surface features, elevations, vegetation, kerb types, road markings, drainage details, and height datums tied to the Ordnance Survey grid.

If you don't specify what level of detail you need, the default is almost always the cheapest option — and that's when redesigns start appearing later.

Does your topo need to include:

• All drainage features (gullies, channels, outfalls)?

• Overhead services (telegraph poles, power lines, building connections)?

• Tree surveys with species and girth measurements?

• Road markings and surface material changes?

• Boundary markers, fence types, and wall details?

• Service covers with levels and annotations?

If you don't specify, you won't get them.

A full spec topo should follow the RICS Specification for Topographical Surveys and include:

• Accuracy band – e.g., Band D (±10mm) for engineering setting out vs Band G (±100mm) for general site mapping

• Feature list – what's included and what's explicitly excluded

• Grid system and datum – Ordnance Survey National Grid, local site grid, or project-specific coordinate system

• Format requirements – DWG layers, point cloud, 3D model, CSV data, etc.

If the survey is being used for volume calculations, earthworks design, setting out, or clash avoidance, this must be stated in the scope to avoid missing data and costly re-visits.

2. Utility surveys require a different scope — and PAS 128 Quality Levels matter

"Can you include utilities while you're there?" is a common request — but underground utilities are not covered in a standard topographical survey (though surface features like service covers and valve boxes are).

A proper pre-construction utilities survey should be ordered to PAS 128 standard, with a defined Quality Level:

• QL-D: Desktop utility records search

• QL-C: Site reconnaissance correlating records with surface features

• QL-B: Detection survey using electromagnetic location (EML) and ground-penetrating radar (GPR)

• QL-A: Verification through trial holes or intrusive inspection

The Quality Level determines how confident you can be in the results, what methods were used, and how the data should be used for design and CDM risk management.

Without PAS 128, everything falls under "unknown risk" — and that's when services get hit, delays mount, and risk assessments start looking like guesswork.

3. A good survey scope defines deliverables, not just instructions

A scope that says "topo survey of site" is not a scope. A proper one defines:

• Survey purpose – design, planning, volumetrics, clash detection, BIM, setting out?

• Required standards – RICS topographical survey / PAS 128 utilities / ISO 19650 for BIM

• Accuracy band – Band D (±10mm) for engineering vs Band G (±100mm) for general mapping

• Features included – drainage, trees, overhead services, boundaries, road markings, kerb types?

• Data format – DWG with layering structure, RVT, CSV, LAS point cloud, 3D mesh, IFC?

• Control & coordinates – local grid / Ordnance Survey National Grid / site benchmark requirements

• Access & phasing – survey before demolition? night shift? lane closure needed? utilities live or isolated?

The more specific the scope, the fewer assumptions get made — and the fewer problems appear later.

4. Redrawing someone else's survey is not the same as re-surveying the site

A design team overlaying an old topo with a new layout is not a validated survey. If the survey is older than 12–18 months — or if there has been any construction activity, vegetation clearance, site works, or changes to levels or boundaries — a re-survey should be scoped.

Ground conditions change. Services get installed. Levels settle. Boundaries move. Using outdated survey data is a false economy.

5. The cheapest survey is almost always the most expensive later

A £1,500 topo that needs re-surveying becomes a £3,000 topo. A missing utilities survey turns into a £12,000 service strike, two-week delay, plus redesign costs. A missing benchmark means every setting-out tolerance starts with guesswork.

Surveys are not a commodity — they're part of your risk management strategy.

Get the scope right at pre-construction, and you avoid the chaos later.

Need help scoping a survey properly?

AKN Engineering provides RICS-spec topographical surveys, PAS 128 utility surveys, and pre-construction site engineering support across Hertfordshire, Essex, Cambridgeshire & the South East.

📞 Call 01279 927 033 🌐 Visit www.aknengineering.co.uk

Related reading: Find out more about our combined Topo & Utility Surveys