In this blog, we’ll compare three common pieces of survey equipment: laser levels, total stations and GPS rovers. We’ll look at what each one does best, where it falls short and when it’s worth using them together.
Laser Levels: Fast, Simple Height Control
A rotating laser projects a level (or graded) beam all the way around the site. A detector, usually on a staff or mounted on a machine, picks up the beam so one person can check heights quickly. For tasks that need even greater precision, a digital level reads a barcoded invar staff and stores each reading automatically, which cuts out manual booking errors.
Best suited for:
- Setting out slab, formwork and foundation levels
- Checking excavation depths and drainage falls
- Day-to-day level checks by groundworkers and site engineers
Where it falls short: a laser level gives you height, not plan position. It can tell you how high a point is relative to a reference plane, but it doesn’t tell you the point’s horizontal position or coordinates on the site.
Total Stations: Precision Where It Matters Most
A total station measures angles and distances to work out the exact position and height of a point, often to millimetre accuracy. Robotic total stations go a step further. Motors and sensors let the instrument track the prism automatically, so one engineer can do work that would otherwise take two.
Best suited for:
- Setting out structured grids, anchor bolts and building lines
- Built-up urban sites, indoors, or anywhere satellite signal is unreliable
- Jobs where tight tolerances can’t be compromised
Where it falls short: a total station needs a clear line of sight to the target, plus known control points to set up from. On large, open sites, moving the instrument around to keep line of sight can slow you down.
GPS Rovers: Covering Ground Quickly
A GPS rover (or GNSS rover) uses satellite signals, with real-time corrections, to fix your position anywhere on site. It doesn’t need line of sight between instruments, so one person can walk a large area quickly, taking measurements and setting out as they go.
Best suited for:
- Topographic surveys and large, open sites
- Earthworks, highways and infrastructure projects
- Establishing site control before more detailed work begins
Where it falls short: a rover needs a clear view of the sky. Tall buildings, tree cover and indoor areas can all affect signal and accuracy. Height accuracy is generally lower than horizontal accuracy, so it isn’t the tool for tight level tolerances.
Side-by-Side: Key Differences
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|
|||
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What it measures |
Height |
Position and height |
Position and height |
|
Line of sight needed |
To detector |
To prism |
To sky |
|
Operators |
One |
One (robotic) |
One |
|
Ideal site |
Any |
Built-up, indoor, tight tolerances |
Large, open |
|
Watch out for |
No positional data |
Setup time on large sites |
Signal near building or trees |
When To Use Them Together
On most larger projects, the real answer isn’t choosing one tool. It’s using the right combination. A common approach is to use a GPS rover to establish control and survey the wide site quickly. Then a total station handles precise setting out around structures, and laser levels take care of day-to-day level checks by the teams on the ground.
Why Choose GAP Survey & Safety?
With an extensive range from market-leading brands, GAP’s Survey & Safety division can help you specify the right equipment for your site, not just supply whatever’s on the shelf. Partnering with Leica, Trimble and leading suppliers, we stock the very latest survey equipment. Our specialist depots also offer repair and calibration services, so every instrument arrived ready to work.
Explore our Survey & Safety range or get in touch with your local GAP depot.
