The Evaluation of Track Impact Factor on the Various Track Type in Urban Transit

Lee²,

Chung

et al. 2020

Self Cite

This study experimentally investigated the effects of rail pad corrosion on the performance of the direct fixation track on a long-span railway bridge in marine conditions. In this study, the dynamic behavior of a direct fixation track on a railway bridge in the presence of corroded rail pads, was determined. Field measurements in this study show that the replacement of corroded rail pads does not affect the track support stiffness. The hard rail pads used in direct fixation tracks are intended to provide electrical insulation rather than flexural track behavior, and so their influence on track support stiffness was found to be insignificant given their high spring stiffness. Additionally, samples of new and corroded rail pads were collected and the spring stiffness of rail pads were analyzed using static, dynamic, and aging tests. The spring stiffnesses of new and corroded rail pads were found to be similar. This means that spring stiffness is not significantly affected by corrosion, a finding that could be explained by the fact that the deformation due to passing train loads was extremely small. Therefore, even though the rail pads on the study bridge exhibited some surface corrosion, their function was not impaired, and they did not need replacement.

Section: Track Support Stiffnessmentioning

confidence: 99%

Rail Pad Corrosion Effects on the Dynamic Behavior of Direct Fixation Track Systems in Marine Environments

Lee²,

Chung

et al. 2020

Self Cite

“…The superscript * in k p represents the complex stiffness), which accounts for the damping properties of the rail pad; k * p = k p + iωc p , where c p represents the viscous damping factor. The stiffness and mass matrices of the rail were then assembled to the dynamic system functions [1,2,41,44,45].…”

Section: Railmentioning

confidence: 99%

“…The qualitative analysis was defined by the display method of the analytical matrices over a discrete surface area (space solution) [46][47][48]. As analyzing the dynamic response of the ballasted track requires the relationship between the track component and force parameters and the track behavior, a numerical model based on conventional track dynamics theory was compared with the FE analysis and the field measurements.…”

Section: Railmentioning

confidence: 99%

Qualitative Prediction Model for Dynamic Behavior of Ballasted Tracks

Kim

2020

Self Cite

Theoretical, experimental, analytical, and statistical evaluations were performed to predict and assess the dynamic behavior of a ballasted track, such as the track support stiffness, track impact factor, or dynamic wheel–rail forces. Field measurements were then performed to evaluate the dynamic behavior of the ballasted track and its components. A qualitative prediction model was then developed to predict and assess track performance as a function of dynamic wheel-rail force and variation in track support stiffness. The developed two-degree-of-freedom dynamic track model can define the rail pad and ballast stiffness ranges based on designed and measured values. Using the proposed model, qualitative analysis results are presented as a discrete space of various track responses and parameters, rather than as single values. The proposed model was then validated using field measurements, which demonstrated that the proposed model predicted the vertical rail displacement and rail bending stress within approximately 2–5% of the obtained field measurements. Overall, the developed qualitative prediction model allows the dynamic response of in-service ballasted tracks to be estimated as a function of the rail pad and ballast stiffness using only a simple field measurement.

“…The problem is that despite this difference in the properties, the evaluation parameters and criteria is the same for both ballasted and ballast-less tracks between different structure types (railway bridges, tunnel structures, earthwork tracks, etc.) of the same track types [20][21][22]. Furthermore, as far as the trackside measurement method is concerned there are also numerous studies and experimental results that take into account the environmental effects on the dynamic stability and the field instrumentation conditions [4,23].…”

Section: Effect Of Different Track Conditions and Types On The Paramementioning

confidence: 99%

Study on the Applicability of Dynamic Stability Evaluation Criteria by Comparison of Trackside Measurement Results of Different Track Structures

Lee

et al. 2020

Countries such as Korea adopt design codes, evaluation criteria and specifications from standards originating abroad; this leads to a lack of distinction of the separate applications of dynamic stability evaluation parameters between various track structures of different track moduli. This paper discusses the applicability of the dynamic stability evaluation method of railway track structures by assessing 10 different types of railway track sections of a newly constructed railway operation line (5 ballasted and 5 concrete type track structures) by field instrumentation testing. Parameters of track support stiffness (TSS), wheel load fluctuation, derailment coefficient, and rail displacement are measured. The respective results are first compared to the standard criteria (design specification) and comparisons between the different track types are presented as ratios. Findings show that while all of the tracks satisfy the design specification requirements, each track type measurement result varies by a noticeable degree, particularly when comparing between concrete and ballast type track structures. Results of the study demonstrate that using the same dynamic stability evaluation criteria can lead to an incorrect assessment of the track performance evaluation of track structure, and a separate evaluation parameter for ballasted and concrete track structures is required.