The intermediate station trigonometric leveling method for replacing second-order leveling in complex terrain

Elevation measurement is fundamental to engineering construction and the acquisition of geospatial information, with its accuracy directly impacting project quality and safety. However, traditional high-precision leveling often suffers from low efficiency and operational difficulties in complex terrain. To address this, this study proposes a trigonometric leveling method using a high-precision total station based on the intermediate setup approach. By conducting multiple observation sets of distance and vertical angle, and combining them with trigonometric geometric relationships, elevation differences between control points were calculated. Measurements were carried out across seven control points located in topographically challenging areas. The results demonstrate that when the vertical angle does not exceed 30°, the difference in sight distances is less than 0.5 m, and the sight distance is within 600 m, the accuracy of this method meets the requirements for second-order leveling. This study technically verifies the feasibility of replacing second-order leveling with trigonometric leveling in complex terrain areas. On a practical level, it offers an efficient technical approach for surveying operations, contributing to significantly improved operational efficiency and reduced costs, thereby holding broad potential for application.