What Is a Total Station? How It Works Explained (2026)
A total station is a surveying instrument that measures horizontal and vertical angles and distances from a fixed position to calculate the 3D coordinates of any observed point. It combines an electronic theodolite (for angles) with an electronic distance meter (EDM) in a single instrument. Total stations are used for construction layout, topographic survey, control network establishment, underground survey, and any application where GNSS signal is unavailable — indoors, underground, under dense canopy, or in tunnels. The APEKS AM02 is a 2″ angular accuracy total station with 1000 m reflectorless and 5000 m prism distance measurement, designed for construction and infrastructure survey.
You are on site to set out the column grid for a new building, but the perimeter is surrounded by scaffolding. The sky is blocked, the RTK receiver cannot get a Fixed solution, and you are losing time. Or perhaps you are deep in a mine drive, hundreds of metres below the surface, where satellite signals simply do not exist. In both cases, the correct instrument is a total station. The total station has been the primary precision survey instrument for engineering and construction for decades, and despite the rise of RTK GNSS it remains essential wherever satellite signals are unavailable, unreliable, or insufficient. This guide explains what a total station is, how it works, and when to choose it over RTK for your survey or construction project.
What Is a Total Station?
A total station is an electronic surveying instrument that integrates three measurement capabilities in one unit:
- Electronic theodolite — measures horizontal and vertical angles from the instrument’s position to any observed point. Angle accuracy is expressed in arc-seconds; a 2″ instrument measures angles to within 2 arc-seconds (0.001°).
- Electronic distance meter (EDM) — measures the slope distance from the instrument to a target using an infrared or laser beam. Two modes are available: reflectorless, where the EDM measures to any surface — walls, buildings, inaccessible points — without a prism (range typically 500–1000+ metres), and prism mode, where a retroreflective prism attached to a target pole reflects the signal back precisely, extending range to 3000–5000+ metres with higher accuracy.
- On-board computer — combines the angle and distance measurements to calculate the 3D coordinate of the observed point automatically, applying corrections for EDM constants, atmospheric refraction and earth curvature. Results are stored internally and transferred to a data collector or directly to survey software via Bluetooth or USB.
How a Total Station Works
The total station must be centred precisely over a point of known coordinates using a tribrach and optical or laser plummet. Once centred and levelled, the instrument height (from ground mark to trunnion axis) is measured and entered.
To establish a coordinate system, the instrument is aimed at a second known point — the backsight — and the known azimuth or coordinates of that point are entered. This orients the instrument’s horizontal circle to the project coordinate system.
The surveyor uses the telescope to aim at the target — either a reflective prism on a staff pole or a reflectorless surface. The crosshair is aligned precisely with the target centre.
The instrument electronically reads the horizontal angle, vertical angle, and slope distance simultaneously. Most modern total stations measure in under 3 seconds.
The on-board processor applies the trigonometric calculation using the instrument position, orientation, measured angles, and distance to output the target’s 3D coordinate (easting, northing, elevation). The result is stored and optionally transferred to a field controller running survey software.
Key Components of a Total Station
Telescope and optics — The telescope magnifies the target for precise aiming. Modern total stations have 30× magnification as standard. The crosshair reticle is illuminated for low-light work.
Electronic distance meter (EDM) — The EDM emits an infrared or visible laser beam and measures the time-of-flight or phase shift of the returned signal to calculate distance. Accuracy is typically expressed as ±(a mm + b ppm × distance); for the APEKS AM02: ±(3 mm + 2 ppm) reflectorless, ±(2 mm + 2 ppm) with prism.
Dual-axis compensator — Automatically corrects for any residual tilt of the instrument after levelling. The APEKS AM02 uses a dual-axis compensator with ±3° compensation range, eliminating angular errors from imperfect levelling.
Display and keyboard — The AM02 has a 2.8-inch colour display with a backlit alphanumeric keyboard for direct data entry. The AM02i uses a 6-inch Android 13 touchscreen with ApekSurv survey software pre-installed.
Data storage and connectivity — Internal memory (AM02: ~20,000 points), Bluetooth for wireless data transfer to controllers and laptops, USB for direct file transfer, and RS-232 for legacy equipment compatibility.
Total Station vs RTK GNSS: When to Use Which
Both total stations and RTK GNSS receivers are core survey tools, but they excel in different environments. The table below summarises where each instrument is the better choice for your project.
| Scenario | Total Station | RTK GNSS |
|---|---|---|
| Indoor layout (warehouses, factories) | ✓ Best choice | ✗ No signal |
| Underground and tunnel survey | ✓ Best choice | ✗ No signal |
| Dense urban canopy / scaffolding | ✓ Works reliably | Limited — multipath |
| Open-site topographic survey (large area) | ✗ Multiple setups needed | ✓ Best choice |
| Construction stakeout (open site) | Capable | ✓ Faster |
| High-precision alignment (±2–5 mm) | ✓ Best choice | Limited at ±8–15 mm |
| One-person operation | Robotic only | ✓ Standard |
| Setup time | 5–15 min per station | Under 3 min |
| Coverage per day | Limited by instrument moves | Unlimited area |
| Battery life | 16 h (AM02 dual battery) | 7–18 h depending on model |
Most professional survey teams use both: RTK for bulk area coverage and open-site work, total station for confined spaces, underground, indoor layout, and precision structural alignment. APEKS manufactures both — the AM02 total station and the full AP-series RTK GNSS range.
Total Station Applications in Construction and Survey
- Building and structural layout — Setting out column grid lines, anchor bolt positions, wall faces, and structural elements indoors or under scaffolding where GNSS is blocked. The total station measures from a known control point inside the building with line-of-sight to a prism on the layout pole.
- Road and infrastructure survey — Cross-section pickup, kerb alignment, drainage invert levels, and bridge structure survey where precise angles are needed and the site is complex enough that total station accuracy justifies the setup time.
- Underground mine survey — Extending a coordinate system from the surface down a shaft and along mine drives using total station traversing. GNSS cannot function underground — total station traverse is the standard method.
- Tunnel and shaft survey — Profile measurement, breakthrough alignment checking, and as-built documentation in tunnels and shafts where satellite signal is absent.
- Precision verification — Independent check measurement of RTK stakeout — verifying that critical structural positions are within tolerance before concrete is poured. The total station provides an independent measurement method for quality assurance.
How to Set Up a Total Station
- Choose the instrument station — Select a stable, accessible point with line-of-sight to the work area and to a known backsight point. Set up the tripod firmly over the station mark.
- Centre over the mark — Use the optical or laser plummet to centre the tribrach over the ground mark to within 1 mm. Adjust tripod leg lengths while watching the plummet.
- Level the instrument — Level the circular bubble by adjusting tripod legs, then fine-level using the plate bubble and foot screws. Re-check centring after levelling.
- Measure and enter instrument height — Measure the vertical distance from the ground mark to the instrument’s trunnion axis (the horizontal rotation axis). Enter this value precisely in the field software.
- Perform backsight orientation — Aim at the backsight point and enter its known coordinates or azimuth. This establishes the instrument’s orientation in the project coordinate system.
- Begin measurement — Aim at each target point in turn. For prism work, ensure the prism is correctly centred over or on the target. For reflectorless work, aim the laser spot directly at the surface point to be measured.
APEKS AM02 and AM02i Total Stations
APEKS manufactures two total station models — the AM02 (standard) and AM02i (Android) — designed for construction and infrastructure survey at competitive pricing without compromising on accuracy or build quality.
| Specification | AM02 | AM02i |
|---|---|---|
| Angle accuracy | 2″ | 2″ |
| Reflectorless range | 1000 m | 1000 m |
| Prism range | 5000 m | 4000 m |
| Display | 2.8″ colour screen | 6″ Android 13 touchscreen |
| Operating system | Real-time OS | Android 13 |
| Survey software | ApekSurv (Bluetooth) | ApekSurv (built-in) |
| Internal memory | ~20,000 points | 4 GB RAM + 64 GB ROM |
| Battery | Dual 7.4V 3000mAh — 16 h | 7000 mAh — 10 h |
| Connectivity | Bluetooth, USB, RS-232 | Bluetooth, WiFi, USB, 4G |
| Compensator | Dual-axis ±3° | Dual-axis ±4° |
| Weight | 5.6 kg | 5.6 kg |
| IP rating | IP55 | IP55 |
Both models connect to ApekSurv field software for CAD-based stakeout, measurement, and data management. The AM02i’s built-in Android system eliminates the need for a separate data collector — the full survey workflow runs directly on the instrument’s 6-inch touchscreen.
Frequently Asked Questions
What is the difference between a total station and a theodolite?
A theodolite measures angles only — horizontal and vertical. A total station adds an electronic distance meter (EDM) to measure distances as well as angles. This means a total station can calculate 3D coordinates directly, whereas a theodolite requires a separate tape or distance measurement to determine coordinates. Modern survey work uses total stations almost exclusively; the pure theodolite is largely obsolete for professional survey.
Can a total station replace RTK GNSS?
For open-site topographic survey, volume calculation, and large-area construction stakeout, RTK is significantly faster and more efficient than a total station. For indoor layout, underground survey, tunnel work, and high-precision structural alignment, total station is the correct tool — RTK cannot function in these environments. Most professional survey teams own both and deploy each for its strengths.
What does “2 arc-second accuracy” mean in practice?
2 arc-seconds is approximately 0.001°. At a distance of 100 metres, a 2″ angular error produces a lateral displacement of approximately 1 mm. At 500 metres, the same 2″ error produces approximately 5 mm displacement. For construction stakeout at typical distances of 20–100 m, a 2″ instrument provides ±0.2–1 mm angular precision — more than sufficient for structural layout tolerances of ±5–10 mm.
What is reflectorless measurement and when is it useful?
Reflectorless measurement allows the total station’s EDM to measure distance to any surface — a wall, a building corner, a road edge — without placing a prism on the target. This is useful for measuring inaccessible points: building façades across a busy road, bridge deck edges, high features on structures, or points inside excavations where it is unsafe to place a prism pole. The APEKS AM02 measures reflectorlessly to 1000 metres with ±(3mm + 2ppm) accuracy.
Does the APEKS AM02 work with third-party survey software?
The AM02 connects via Bluetooth to any Android or Windows field controller running standard survey software. It is compatible with ApekSurv, as well as third-party applications that support standard total station communication protocols (RS-232 and Bluetooth serial). The AM02i’s built-in Android 13 system allows direct installation of compatible survey applications from the Play Store alongside ApekSurv.
TOTAL STATION AND RTK. ONE BRAND. FULL COVERAGE.
APEKS AM02 and AM02i total stations deliver 2″ angular accuracy and 1000 m reflectorless measurement for indoor, underground, and confined-site survey. Pair with APEKS AP-series RTK receivers for open-site coverage. Complete survey capability from one manufacturer.
View APEKS Total Stations →References
- ISO 17123-3:2001 — Optics and Optical Instruments — Field Procedures for Testing Total Stations
- APEKS AM02 Total Station Technical Datasheet, 2026
- APEKS AM02i Android Total Station Datasheet, 2026
- ApekSurv Field Software User Guide, 2026