Classes of accuracy

(a) All surveys prepared in metric format shall use: 1 meter = 3.28083333 U.S. Survey feet. (b) Horizontal Accuracy Each survey depicting horizontal locations shall conform to a Horizontal Accuracy Class the tolerance of which is defined as follows: Class Positional Linear Angular Feet Meters (Use the ratio for D>...) AA 1:15,000 ±0.01' ±.003m (1:22,500 @D>225'(69m)) ±8" A-1 1:10,000 ±0.01' ±.003m (1:15,000 @D>150'(46m)) ±10" A-2 1:5,000 ±0.02' ±.006m (1:7,500 @D>150'(46m)) ±20" B 1:1,000 ±0.5' ±.15m (1:1,500 @D>750'(229m)) ±2' C ±2' ±2' ±.6m ±30' D compilation of existing data-NOT A FIELD SURVEY Linear accuracies expressed as "±"apply to distances less than (<) those prescribed as a ratio. (c) Vertical Accuracy Each survey depicting vertical location shall conform to a Vertical Accuracy Class the tolerance of which is defined as follows: Level Loop Closure Greater Than One Mile Level Loop Closure Less Than One Mile Class Feet Meters Feet Meters V-1 ±.02√M ±.005√K ±.006√N ±.002√N V-2 ±.035√M ±.008√K ±.010√N ±.003√N V-3 ±.05√M ±.012√K ±.020√N ±.006√N M or K = The lengthof the level loop in miles/kilometers N = The number ofinstrument setups in the level loop (d) Topographic Survey Accuracy Each Topographic Survey shall conform to a Topographic Accuracy Class the tolerance of which is defined as follows: Class Horizontal Position Contour Interval Test Feet Meters T-1 1/40of map scale 1/1500of map scale 90% within ½ contour interval T-2 1/40 of map scale 1/1500 of map scale 80% within ½ contour interval T-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 a topographic map 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.