Article II

Sec. 20-300b-11. Classes of accuracy

1. (a) Conversion to and from the metric system shall use the U.S. Survey Foot, which is defined as one meter is equal to 39.37 inches. When converting meters to feet the conversion is exactly 3937 divided by 1200, which when expressed to twelve places is 3.280833333333.
2. (b) Horizontal AccuracyEach survey depicting horizontal locations shall conform to a Horizontal Accuracy Class the tolerance of which is defined as follows: ClassPositionalLinearAngularFeetMeters(Use the ratio for D>...)AA1:15,000±0.01'±.003m(1:22,500 @D>225'
3. (69m))±8"A-11:10,000±0.01'±.003m(1:15,000 @D>150'
4. (46m))±10"A-21:5,000±0.02'±.006m(1:7,500 @D>150'
5. (46m))±20"B1:1,000±0.5'±.15m(1:1,500 @D>750'
6. (229m))±2'C±2'±2'±.6m±30'Dcompilation of existing data-NOT A FIELD SURVEYLinear accuracies expressed as "±"apply to distances less than (<) those prescribed as a ratio. Additional accuracy standards for measurements made using Global Navigation Satellite Systems (GNSS) have relative positional accuracy of a ninety five percent level, and are defined as: Confidence LevelClassAccuracyMinimumSpacingFeetMetersG-A0.033' + 1 PPM1.0 cm + 1 PPM500'G-10.049' + 2 PPM1.5 cm + 2 PPM500'G-20.067' + 3 PPM2.0 cm + 3 PPM335'G-B0.33' + 10 PPM0.10 m + 10PPMN/A
7. (c) Vertical AccuracyEach survey depicting vertical location shall conform to a Vertical Accuracy Class the tolerance of which is defined as follows: Level Loop Closure GreaterThan One MileLevel Loop Closure LessThan One MileClassFeetMetersFeetMetersV-1±.02√M±.005√K±.006√N±.002√NV-2±.035√M±.008√K±.010√N±.003√NV-3±.05√M±.012√K±.020√N±.006√NClass V-4* has a GNSS Vertical Accuracy (95% confidence level in feet) of 0.066 feet.Class V-5* has a GNSS Vertical Accuracy (95% confidence level in feet) of 0.164 feet.M or K = The length of the level loop in miles/kilometersN = The number of instrument setups in the level loop* GNSS only. The surveyor expresses his or her opinion that the differences between heights resulting from repeat observations would not exceed the stated accuracy levels.
8. (d) Topographic Survey AccuracyEach Topographic Survey shall conform to a Topographic Accuracy Class, the tolerance of which is defined as follows: ClassHorizontal PositionContour Interval TestFeetMetersT-1¹/₄₀of map scale ¹/₁₅₀₀of map scale 90% within ½ contour intervalT-2¹/₄₀ of map scale ¹/₁₅₀₀ of map scale 80% within ½ contour intervalT-3 This class of topographic map applies to photogrammetric maps for which the surveyor provides the horizontal and vertical control. Refer to the “National Map Standards for Photogrammetric Mapping” for requirements. T-D This class of map standard applies to topographic maps compiled from various sources of information not necessarily verified by the surveyor. In using Topographic Accuracy Class T-1 or T-2, the surveyor is expressing confidence that should a test profile be run in the field, a plotted comparison with a profile scaled from the map shall be in agreement within the above criteria and the remainder shall be within the contour interval.

(Adopted effective June 21, 1996; Amended October 26, 2018)