Surveying · January 2026 · 7 min
When drone photogrammetry belongs in a highway DPR — and when it does not
UAV mapping is not a replacement for control. Used properly, it shortens corridor capture; used as a shortcut, it poisons quantities.
A drone does not know where it is until you tell it. Ground control, check points and a traverse that would satisfy a total-station survey are what make an orthomosaic a survey, not a film.
For highway and irrigation corridors, photogrammetry earns its keep on terrain, stockpiles, borrow areas and as-built surfaces. It does not replace a prism on a boundary stone, a bridge soffit or a dense urban facade. AGS crews establish GNSS control first, fly second, and deliver a DTM in the coordinate system named in the DPR brief.
If a consultant offers ‘drone survey’ as a line item with no control specification, treat it as photography. Ask for the control schematic, GSD, RMS on check points, and the CAD/GIS formats the designer will actually open.