An approach for improving the precision on short-range electronic distance measurement trigonometry

Abstract

Consider the trigonometric leveling method is simple, flexible and less limited by terrain conditions, it commonly used to inconveniently implemented area. Through the total station rapid development, the horizontal distance measuring between station and target for the traditional triangulation has been substituted by a slope from the Electronic Distance Measurement(EDM) measured. When combined with the appropriate methods of observation and error correction, short-range EDM trigonometric levelingshould be able to improve the accuracy levels of precision leveling. It can be enhanced the efficiency of leveling jobs. The main error of short-range EDM trigonometric leveling is from atmospheric refraction, earth curvature and measurement error of height of instrument and prismatic. The first two errors can be reduced by reciprocal observation and intermediate point. Moreover, intermediate point just only measure the prismatic height between start and end point of the measuring leveling line, The results accuracy and observation efficiency is increased. In this study, about 2km selected sections of Highway 84 at Tainan Yujing District is chosen be an experimental zone. Three kinds of closed leveling line, 200m, 400m and 600m is consisted in this measured planning. Then, non-reciprocal observation, reciprocal observation and intermediate point are introduced to implement the measurement. Experimental results show that the EDM triangle elevation for 600m range or less, the fourth-level observation precision can be achieved in non-reciprocal observation. However, the loop closure error will be caused no any grade leveling accuracy. For the reciprocal observation or intermediate method, third-level precision of measurement accuracy and loop closure error can be accomplished. The results show that the short-range EDM triangle elevation has a higher level of feasibility to instead of the traditional measure.