Study of loaded versus unloaded measurements in railway track inspection

• Published in: Measurement : journal of the International Measurement Confederation 2021-02, Vol.169, p.108556, Article 108556
• Main Authors: Wang, Haoyu, Berkers, Jos, van den Hurk, Nick, Layegh, Nasir Farsad
• Format: Article
• Language: English
• Subjects: Freight trains; Inspection; Load; Measurement; Measurement methods; Mobile communication systems; Mobile track inspection system; Numerical methods; Railcars; Railroad cars; Railway networks; Railway tracks; Shafts (machine elements); Track geometry; Track geometry car; Track longitudinal level; Transportation corridors; Unloaded measurement
• ISSN: 0263-2241; 1873-412X
• DOI: 10.1016/j.measurement.2020.108556

•Presents an innovative method for track inspection using a mobile system.•Compares the mobile inspection system with conventional track inspection trains.•Simulates the track longitudinal level using the Finite element method.•Presents a case study wherein the track geometry has been measured every month.•Shows the advantages of frequent measurements in track inspections. To ensure railway operations safe, track geometry parameters, e.g., track gauge, are usually inspected using track geometry cars. The measurement frequency of track geometry cars is low (twice per year) due to high operational costs and track possession. An innovative way to perform track inspection at high frequency and affordable cost is using mobile track inspection systems, which can be easily mounted on passenger or freight trains. Besides track geometry, it also creates a digital copy of railway corridors providing asset managers with the ability to make fully informed decisions on track assets. Differently, the collectors of mobile systems are further away from the axle than track geometry cars, which are regarded as unloaded and loaded measurement respectively. This difference may lead to a discrepancy in measurement results. This paper studies the difference between loaded and unloaded measurements, using experimental and numerical methods. In the experimental research, a section of track was measured using both systems. The track longitudinal level measured using unloaded and loaded methods were compared, and the discrepancy reported. It was found that although the measuring distance can cause discrepancies, the unloaded measurement method still meets the measurement requirement. The largest discrepancies are in track transition zones, which is explained using the numerical method. After that, a case study using the unloaded measurement method is presented, wherein a section of track has been measured every month. The results show the advantages of frequent measurements in track inspections and the potential applications of unloaded track inspections.