一、前言近年来由于光电测距仪的广泛使用,在铁路工程测量中,已经较普遍的采用了光电三角高程。但根据大量的观测成果看:在地形起伏较大的山岭地区,一般可以满足五等水准测量(限差为±30~(1/2)L毫米)的精度要求,在有利的地形条件下,精度还要高些;但在平原及水网地区,则精度有所降低,且在按照通用的公 I. Introduction In recent years, due to the widespread use of photoelectric range finder, in railway engineering surveying, the photoelectric triangular elevation has been adopted more generally. However, based on a large number of observations, it is generally considered that the accuracy of the fifth-level leveling (± 30-1 / 2mm L) can be met in mountainous areas where the topography fluctuates greatly. Under the favorable terrain conditions, The accuracy is even higher; but in plain and water network area, the precision is reduced, and in accordance with the general public