Construction professionals rely heavily on survey accuracy, but different project phases have different mathematical tolerances. If a coordinate transformation error exceeds these tolerances, the resulting structure will be flawed and liable for damage.
Benchmark Tolerances
- 1st Order Control: ~5 mm (0.015 ft)
- 2nd Order Control: ~10 mm (0.03 ft)
- Construction Layout Stakes: ±30 mm (~0.10 ft)
- Topographic 1-ft Contours: ±0.15—.20 ft
Given that construction tolerances are measured in millimeters and tenths of a foot, a 1-2 meter (3-6 foot) datum shift caused by a GIS error is catastrophic and easily grounds for a professional negligence lawsuit.