Evaluating Track Stiffness and Rail Bending Moments using Vertical Track Deflection Measurements Considering the Effects of Track Geometry

  • Author / Creator
    Do, Ngoan T
  • Vertical track stiffness (or track modulus) is generally accepted as one of the key structural properties of track which impacts the bearing capacity, dynamic response of passing trains, quality of track geometry, and track components’ life. Although it is known that track stiffness parameters can potentially provide useful information for track condition assessment, there is a lack of understanding of factors affecting the track stiffness measurements such as the effects of track geometry variations. For this reason, attempts to establish an automatic framework for track condition assessment using a track stiffness measurement system are limited. In this context, this thesis develops methods for assessing the track stiffness using vertical track deflection (VTD) measurements.
    First, the effectiveness of using measured data from a continuous track stiffness measurement system for estimating track modulus and rail bending moments is investigated. Developed finite element models are employed to study the impacts of applied loads and track modulus on the resulting VTDs and rail bending moments. The relationship between the VTDs and track modulus and bending moments are established using artificial neural networks and wavelet-based techniques. Specifically, local variations of track modulus for different track section lengths are estimated from VTD measurements while the local extremum values of bending moments are also quantified.
    Second, the effects of track geometry and other factors on the VTD measurements are investigated in detail. To understand the relationship between track modulus and track geometry in the measured VTD data, dynamic simulations are conducted to simulate the stochastic variations of track modulus and track geometry. A novel blind source separation technique is developed to reveal the track geometry and track modulus information separately using the numerical VTD measurements. Subsequently, the methodology is further improved and validated with field data collected from a study site. The track geometry variations and VTD collected at the study site support the proposal of using a continuous track stiffness measurement system for both track stiffness and track geometry quality evaluations. The investigation of the field VTD data also reveals the impact of motions of the vehicle carrying the track stiffness measurement system on the reading of VTD values. Finally, conclusions and recommendations for future research are included in the thesis.

  • Subjects / Keywords
  • Graduation date
    Fall 2020
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
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