surveying iii (topographic and geodetic surveys) - Modern Prepper

additional runs are made due to excessive divergence in a second-order section of a level line, therejection limit of individual values from the indiscriminate mean of all measurements is ±9 millimeters√K.(2) Class II is used for the development of nets in more accessible areas. The criteria for ClassII are the same as those for Class I except that Class II lines are single run (in one direction only). TheAE formula is still ±8.4 millimeters √K, where K is the length of the line in kilometers, the line being thedistance between ties to existing benchmarks.PART B: PRECISE DIFFERENTIAL LEVELING4-4. General. In principle there is no difference between precise and ordinary differential leveling(Figure 4-1). In ordinary differential leveling, the distances run between checks are relatively short andwith the usual precautions, and the results are sufficiently accurate for general-purpose surveys. Sincevery small errors cannot be detected, the relative coarseness of the determinations may, throughcompensation of errors, give some degree of accuracy. In precise leveling, the circuits may be ofconsiderable length; therefore, operations must be conducted so that the uncertainty of each individualdetermination, as well as the actual closing error, is reduced to a minimum. This necessitates the useand proper handling of precision instruments and precise rods.Figure 4-1. Direct Differential LevelingEN0593 4-4