# Optimization and accuracy analysis of track straightness measurement based on total station free station method

## TL;DR

This paper introduces a free station method using a total station to improve track straightness measurement accuracy in complex environments.

## Contribution

A nonlinear deviation model and optimization strategy for total station positioning to enhance measurement accuracy.

## Key findings

- High-precision angular measurement is critical for minimizing deviation errors.
- Optimizing the total station's position can eliminate distance measurement errors.
- The method achieves ±0.3 mm mean square error in a 160-meter track test.

## Abstract

Aiming at the problems that the traditional method of total station in high-precision track straightness measurement is greatly restricted by the on-site environment, and the error control is difficult, this study proposes the free station method of the total station to establish a nonlinear measurement point deviation calculation model. Based on the Monte Carlo simulation, the influences of different angular measurement errors, distance measurement errors, and total station erection positions on the accuracy of the free station method are systematically analyzed. To ensure the accuracy of the deviation of measurement points, high-precision angular measurement is the key. Optimizing the total station erection position can eliminate distance measurement errors. The total station is set up at 50 m and 100 m along the 160-meter track, respectively, with a vertical distance of 4 m from the track. The mean square error of deviation of most measurement points along the entire line is successfully controlled within ± 0.3 mm. This method can be widely applied in engineering fields such as high-speed railways, precision guide rails, and large-scale structural installations, where sub-millimeter-level position tolerance detection is required in complex environments.