Machine control grading is faster and more accurate than conventional staking — but it creates a documentation challenge that conventional staking does not. When a grade is set by stakes, the physical stakes are the record of what was built. When a grade is set by a 3D model loaded into a control box, the documentation of that model — its version, calibration, and independent verification — is the only record that proves the grade was built to the right design.
What documentation is required when grading with 3D machine control?
3D machine control grading documentation must include: the design model file name and version confirming the current IFC model was loaded; base station or RTK network calibration records with coordinates and accuracy check results; independent QC check shots from a survey rover at defined grid intervals confirming the machine is tracking the model; and a final as-built survey confirming the completed grade meets the tolerance specification. Machine control data logs alone are not accepted as QC verification by most owners and engineers of record.
On projects with multiple design revisions, loading the wrong model version is one of the most costly machine control errors. Required model version documentation:
| Record | Content |
|---|---|
| Design model log entry | File name, file modification date, version number per the model file header, and the IFC drawing revision number it was generated from |
| Load date record | Date the model was loaded into each machine control unit; operator who confirmed the load; machine ID number |
| Model receipt confirmation | Email or field ticket from the project engineer or surveyor confirming the model file is current and authorized for construction |
| Superseded model log | When a new model revision is issued, document the date the old model was removed from service and the new model was loaded for each machine |
The accuracy of a machine control system depends entirely on the quality of the GPS correction source. A base station set on an unchecked benchmark, or an RTK network subscription that has experienced a coordinate shift, will produce systematic grade errors across an entire site. Required calibration documentation:
Machine control systems are subject to systematic errors that the machine operator cannot detect — a bad localization, a shifted base station, or a wrong-version model all produce grades that look correct on the cab display but are off by a consistent amount across the entire work area. Independent QC check shots catch these errors before the grade is accepted.
QC check shots must be taken with a separate GPS rover or total station — not the machine control system itself. Required check shot documentation:
| Field | Content |
|---|---|
| Point identifier | Grid ID (e.g., B-7 at 25-ft grid) or station and offset reference |
| Measured elevation | Elevation shot with the QC rover at the graded surface |
| Design elevation | Elevation from the 3D design model at the same plan coordinate |
| Deviation | Measured minus design; positive = high, negative = low |
| Pass/fail | Comparison to the project tolerance — typically ±0.05 ft to ±0.10 ft depending on phase of grading |
| Date, time, and operator | Date, time of shot, rover operator name, and rover equipment ID |
The final as-built survey is performed after grading is complete. Unlike the QC check shots taken during work, the final as-built survey covers the entire graded area at the required grid density and produces the formal record the owner or engineer uses to accept the grade.
For machine control grading projects, the as-built survey is often performed with a drone photogrammetry flight or a GPS rover grid survey. Both methods are acceptable if the accuracy meets the project requirement. The as-built deliverable must include:
Sitemark's documentation tools let machine control crews log model version records, calibration check results, and QC grid shots in the same project as their as-built survey data — producing a complete machine control documentation package organized by date and grading area.
Sitemark captures model version records, calibration logs, QC check shot results, and as-built data in a single project record — giving your owner and engineer the documentation chain they need to accept the grade.
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