Table 13-2.-Triangulation Order of Precisionthe closing traverse line, BC, shown in figure13-27, is likely to be some distance from thestarting point, C. If this should happen, and, say,the total accumulated linear distance measuredalong the traverse lines is 900.09 ft, the ratio oferror of closure then is .09/900 or 1/10,000. Thisresulting ratio is equivalent to the precisionprescribed for second order work.Attaining Precision with a MaximumAngular Error of ClosureYou know that the sum of the interior anglesof a closed traverse should theoretically equal theproduct of 180° (n – 2), n being the number ofsides in the polygon described by the traverse. Aprescribed MAXIMUM ANGULAR ERROR OFCLOSURE is stated in terms of the product ofa given angular value times the square root of thenumber of interior angles in the traverse.Again, if we use the traverse shown in figure13-27 as an example, the prescribed maximumangular error of closure in minutes is 01 fibecause the figure has three interior angles. Thesum of the interior angles should be 180°. If theFigure 13-27.-An example of a closed traverse with a perfectsum of the angles as actually measured and(zero-error) closure.recorded is 179°57´, the angular error of closureis 03´. The maximum permissible error of closure13-23
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