GPS/GNSS rover layout from a coordinate file requires: (1) loading the point file (.csv or instrument format) into the data collector; (2) initializing RTK with a Fixed solution; (3) running a check shot on a known control point before staking; (4) navigating to each design point using the layout/stakeout function; (5) driving the stake when the horizontal offset is within tolerance. Always verify the check shot before trusting any layout.
Point File Format
Design points are typically exported from the engineer’s CAD file as a CSV with at minimum: point number (or ID), northing (Y), easting (X), and elevation (Z). Most data collectors accept several formats; PNEZD (point, northing, easting, elevation, description) is the most universal. Import the file before leaving the office and verify a sample of points match the plan coordinates.
RTK Initialization Check
Before staking any design points, run a check shot on a control monument of known coordinates:
N: 5,042.18 | E: 3,171.42 | Elev: 284.37
Measured with GPS rover:
N: 5,042.21 | E: 3,171.40 | Elev: 284.39
Horizontal error: 0.03 ft ✓ (within ±0.05 ft)
Vertical error: 0.02 ft ✓ (within ±0.05 ft)
If the check shot fails, do not stake any points until the error is found and corrected.
Navigating to Design Points
In the data collector’s layout/stakeout function, select the target design point. The display shows the distance and direction from your current position to the design point. Navigate toward the design point following the display arrows. When the measured offset falls within your tolerance (typically ±0.05 ft horizontal for construction layout), stop and drive the stake.
Slope Staking from GPS
GPS rovers are particularly effective for slope staking: navigate to the approximate catch point offset from the alignment, measure the ground elevation at your current position, compare to the design elevation at that offset, and adjust until they match. This is faster than total station slope staking on open terrain but requires a Fixed RTK solution for reliable elevation accuracy.
When GPS Layout Fails
- Float solution only: Move to more open sky. Do not stake from a Float solution.
- Check shot fails horizontal: Re-initialize; re-check base station setup; verify base coordinates.
- Check shot fails vertical: Re-verify base antenna height; check geoid model setting.
- Obstructed sky (under trees, near buildings): Switch to total station for layout in these areas.
See also: GPS/GNSS Base and Rover Setup.