Technology Digests / Evaluation of an IMU-Based Track Geometry Measurement System

TD25-027

February 9, 2026
Authors
  • Yin Gao
  • Alexander Keylin
  • Yuqing Zeng
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Key Findings

  • The IMU-based TG system demonstrated track curvature repeatability of ±0.0002 degree (standard deviation). Based on a comparison of five-lap averages, the repeatability of profile measurements was ±0.024 inch and cross level measurements was ±0.2 inch.
  • Overall, the IMU-based system's data quality, including repeatability and accuracy, falls short compared to comprehensive track geometry system at FAST. This may be due, at least partially, to the placement of the sensors.
  • Curvature data revealed a strong positive correlation between the IMU-based system and the FAST TG car. The area with low correlation can be attributed to calculation variations at zero curvature.
  • Profile data showed a moderate positive relationship between runs from both systems, with correlations below 0.4 at reverse curves and diamond crossings.
  • A year-long analysis indicated that the IMU-based TG system effectively monitors long-term track condition changes and can detect sudden shifts.

Evaluation of an IMU-Based Track Geometry Measurement System

For years, MxV Rail has been actively engaged in the research and evaluation of various track inspection technologies with the goal of improving inspection efficiency, accuracy, and cost-effectiveness for the railroad industry. As part of this ongoing effort, a recent study focused on assessing a relatively low-cost, vehicle-mounted track geometry measurement system (TGMS) that is largely based on inertial measurement units (IMU). The system was installed on a freight car at the Facility for Accelerated Service Testing (FAST®),* and the corresponding testing program examined multiple aspects of the technology, including the system installation and setup and the repeatability and accuracy of the measurements when compared to a comprehensive TG system at FAST. In addition, the effort includes a case study of the system, considering its performance characteristics and limitations. This evaluation provides valuable insights into how low-cost, on-vehicle TGMSs could complement or enhance existing TG inspection methods. Introduction Generally speaking,…