STUDY OF PROCEDURES OF ADJUSTMENTS OF TRILATERATION NETWORKS

Abstract

With the invention of very precise electronic distance measuring equipments, trilateration is becoming increasingly significant as a method of establishing horizontal control. To remove the accidental errors, inherent w4h the measurements, an adjustment of the measured lengths is essential. For the adjust-ment of triiateration networks, a nuber of methods have already been developed. But as no one method of adjustment has been universally accepted as yet$ an attempt has been made in this thesis to investigate some of the available methods in order to find the efficient ones. An introductory reference of a few electronic distance measuring equipments with their ranges and accuracy has been provided. To lay emphasis on the use of trilateration* a new tool of establishing planimetric control, its merits and demerits over traditional triangulation have been discussed in the intro-duction, Basic considerations in trilateratirin a4 juitment pro-cedures have been explained before entering into the actual pro-cedures. A review of most of the methods developed so far has been made in .Chapter 3. An attempt has been. made to develop a new adjustment procedure based on the Abbiock System, which is also included in this Chapter. To investigate into the efficiencies of a few selected adjustment procedures, a network$ consisting of .three braced quadrilateral has been used. This network has been adjusted 2 with the selected methods and the details provided in Chapter tour* 1. In Chapter Pi . a critical analysis has been made o t the ,elected methods on the basis of the results obtained as well ass the computational difficulties involved therein. On the basis of this analysis, a method which is simple$ efficient and. accurate has been recommended*