The technique of the III and IV classes levelling performed with trigonometric method

Abstract

The III and IV classes leveling are applied in the Russian Federation for extension of height networks, at creating elevation control for building and large-scale surveying. The actual state levelling specification foresees applying the only geometric levelling technique. The geometric leveling performed in hilly and uneven terrain is difficult. Total stations of high precision increase the accuracy of height differences between two points by leap-frog trigonometric leveling. Using high precision total station and fulfillment of methodological requirements made it possible to perform trigonometric levelling of the III and IV classes. The developed methodology includes leveling with length of the sighting beam up to 250 m, as well as for the purpose of additional control, to use the vertical basis of a known length as a target sight. The implementation of trigonometric levelling makes the surveying of hilly and uneven area easier, and makes the beam of sight longer, increasing the productivity of work.