RTK GNSS Construction Layout & Stakeout: Complete Guide 2026

Construction layout — also called stakeout or setting out — is the process of transferring design coordinates from a drawing or model into physical positions on the ground. The surveyor inputs the target coordinate into survey software; the software then displays the direction and distance to move the pole tip until it reaches the design point. RTK provides the real-time position of the pole tip to centimetre accuracy, replacing the need for a total station on most open-site applications.

The key difference from a pickup survey is fundamental: in a pickup survey, you record where things are. In stakeout, you navigate to where things should be. This distinction drives the entire workflow — from software navigation to the way you move across the site.

Applications in construction:

• Column and pile positions (structural layout)
• Road centreline and edge of carriageway
• Drainage invert levels and pipe alignments
• Retaining wall face and toe
• Building setout from boundary offsets
• Cut and fill slope stakes for earthworks

GNSS Receiver

Any APEKS RTK receiver supports stakeout. For construction sites with confined spaces, scaffolding, and below-grade work, the AP40 Laser+ or AP60 Vision with 120° calibration-free IMU is recommended — tilt compensation allows staking to points that cannot be reached with a vertical pole. For open-site earthworks and road layout, the AP30 Laser or AP10 is sufficient.

Controller / Data Collector

ApekSurv runs on the APEKS CS or TS controller series, or on any Android device via Bluetooth connection to the receiver. For construction sites, a rugged controller is recommended — IP67 and drop-resistant, since the controller is handled continuously during active stakeout and will inevitably meet dust, water, and the occasional fall.

Correction Source

Option 1 — CORS/NTRIP via built-in 4G modem (AP20 and above). Requires active SIM card and CORS account. Setup time: under 3 minutes. Recommended for urban construction where cellular coverage is reliable.

Option 2 — Local APEKS base station. Required for remote sites without cellular coverage. Any APEKS RTK receiver can serve as a base; for sites larger than 15 km, deploy the MAX5 with 5W LoRa and 25 km range.

Mark-Out Materials

Wooden pegs, steel pins, chalk spray, or nails set in concrete — depending on surface type. RTK accuracy is only useful if the physical mark is placed as precisely as the instrument measures. A ±8 mm receiver reading means nothing if the peg is driven 50 mm off the indicated position.

For CORS/NTRIP

Open ApekSurv → Data Link → NTRIP Client. Enter server address and port. For Indonesia: cors.big.go.id port 2101. For Saudi Arabia: NGOSA server. For other markets, use the national CORS credentials provided by the relevant mapping authority. Type credentials manually — do not paste from email, as hidden formatting characters can cause authentication failures.

Select the nearest mountpoint. Confirm differential age below 3 seconds after connecting. Wait for Fixed status before starting stakeout. Fixed is typically achieved within 10–30 seconds on open sites with good satellite visibility.

For Local Base Station

Set the base receiver over a known control point or allow 5 minutes of autonomous averaging for relative accuracy. Configure UHF channel to match the rover. Confirm the rover displays "Fixed" and differential age below 3 seconds before proceeding. For remote sites: deploy APEKS MAX5 on the highest accessible point in the project area to maximise UHF radio range across the site.

Critical: Never begin staking out points in Float solution. Float carries 30–100 cm of error — enough to misplace every structural element on your site. Always confirm Fixed before marking the first peg, and monitor solution status continuously throughout the session.

The Stakeout Sequence

1. Confirm Fixed solution and check RMS is below 20 mm in the ApekSurv status bar. If RMS exceeds 20 mm, wait for improved satellite geometry.
2. In ApekSurv → Stakeout, select the first design point from the imported list. The point ID, design coordinates, and target elevation display on screen.
3. The screen displays an arrow indicating direction to move, and the distance remaining to the target point. A large arrow and bold distance reading make navigation intuitive even in bright sunlight.
4. Walk toward the target. The arrow updates in real time as you move. There is no need to look up from the screen — the direction updates continuously.
5. As you approach within 1–2 metres, slow your movement. The display switches from directional arrow to a cross-hair centring display showing offset in millimetres — both northing and easting components.
6. Position the pole tip at the point indicated. If the ground is flat, level the pole. If in a confined space or trench, use IMU tilt compensation — hold the pole at whatever angle is practical and let tilt compensation calculate the tip position accurately.
7. When the displayed offset is within your tolerance, press Record. ApekSurv records the as-staked coordinate, the offset from design, and the solution status — all stored in the project file for QA reporting.
8. Mark the physical point — drive a peg, spray chalk, or set a nail depending on surface type. Make the mark clear and durable enough to survive site traffic until the construction crew uses it.
9. Move to the next point. Repeat from step 2. A single operator can stake 100–200 points per day on an organised site.
10. At regular intervals, re-check a previously staked peg with the receiver to confirm Fixed solution has not drifted and the coordinate system remains valid throughout the session.

Under Scaffolding and Overhead Obstacles

Standard pole cannot reach vertical. Use IMU tilt compensation on AP40 Laser+ or AP60 Vision. Place the pole tip on the design point at whatever angle clears the obstruction; the 120° calibration-free IMU compensates for pole lean up to 60° from vertical. Confirm Fixed before recording. Accuracy at 45° tilt: approximately ±2 cm horizontal — sufficient for structural layout in most construction scenarios.

Inside Excavations and Trenches

For deep excavations where the receiver cannot reach above the trench edge with a standard pole, use the AP40 Laser+ green laser: position the receiver at ground level, aim the green laser at the design point location on the trench floor, and record the laser offset measurement. This eliminates the need to descend into the excavation with the receiver — a significant safety and efficiency benefit on active earthworks sites.

Near Reflective Structures

Metal formwork, temporary steel structures, and glass facades cause multipath interference — GNSS signals bounce off these surfaces before reaching the receiver antenna, corrupting the position solution. If Fixed is achieved but stakeout positions seem inconsistent (±50–100 mm scatter), move the pole 3–5 metres away from the reflective surface and allow the receiver to reinitialise. Do not record points while standing directly adjacent to steel piling or metal shuttering.

High-Traffic Construction Sites

On active sites with plant movement, the receiver may temporarily lose Fixed solution when the operator passes near a running engine or metal vehicle — the combination of physical obstruction and electromagnetic interference disrupts the GNSS signal. Enable auto-reconnect in ApekSurv so the receiver re-establishes the correction link automatically. If Float persists for more than 30 seconds after the obstruction clears, move to an open area and allow reinitialisation before continuing stakeout.