Effect of Rail Irregularities on Ride Comfort of Train Moving Over Ballast-Less Tracks

Abstract

Rail irregularities are the main factors influencing the ride comfort of trains moving over tracks. Despite various investigations made in this regard for the ballasted tracks, there is a lack of studies for the ballast-less tracks. This limitation is addressed in this study. To this end, a vehicle/slab-track interaction numerical model was developed, which was validated by comparison of the results obtained herein with those of the field tests carried out in this study. The effects of rail irregularities with various amplitudes and wavelengths on the ride comfort were studied by a comprehensive parametric analysis. Particularly, the effects of the wavelengths and amplitudes of rail irregularity on the ride comfort were investigated. Contrary to the current understanding, it was shown that rail irregularities with short wavelength have considerable effects on the ride comfort for the slab-tracks. In addition, the ride comfort decreases significantly when the wavelengths of rail irregularity become less than 0.75[Formula: see text]m in the metro lines. The critical speed of the train (at which the lowest ride comfort is obtained) was derived as a function of rail irregularity. The results obtained indicate that the amplitude of rail irregularity has negligible influence on the critical speed of the train.

Development of train ride comfort prediction model for railway slab track system

“…In order to investigate the effects of track and rolling stock parameters on the TRC, a 2D numerical model of vehicleslab track dynamic interaction was developed in this study. This model is an upgraded/improved version of the one developed by these authors in (Sadeghi et al 2016a(Sadeghi et al , 2019. In the new model, the concrete slab is simulated as a continuous layer, which has less computational cost compared to the original one.…”

“…where is the contact force between the wheel and the rail, ℎ stands for the wheel vertical displacement, is the rail vertical displacement of the wheel-rail contact point, stands for the rail irregularity and is the Hertz spring constant. The stiffness, mass and damping matrices of the whole model were derived by assembling the stiffness, mass and damping matrices of the sub-models (Askarinejad and Dhanasekar 2016, Khajehdezfuly 2019, Sadeghi et al 2016a, 2016b, Sadeghi et al 2019. The vehicle-slab track dynamic interaction equation was solved using Advanced Solution Algorithm (ASA) developed by Sadeghi et al (2016a).…”

“…It means that there is no lateral interaction between the vehicle and the track. Therefore, only the vertical vibration of the vehicle was considered (Sadeghi et al 2019).…”

“…Moreover, the Sperling index requires the least instrumentations for the field measurements (i.e., it needs only biaxial accelerometers). These reasons indicate the suitability of the Sperling index for the prediction of the TRC (Sadeghi et al 2019). The vertical acceleration of carbody (̈( )) obtained from the vehicle/track interaction model was transferred into the frequency domain using the Fast Fourier Transformation (FFT).…”

“…The main limitation of their research is a lack of consideration of rail irregularity, which is mostly observed in the tracks. The importance of the effects of rail irregularities on the TRC has been shown by Sadeghi et al (2019) Evaluation of the results obtained in the literature indicates that the main track and rolling stock parameters, which have noticeable influences on the TRC, are vehicle suspension system properties, rail irregularities, vehicle speed and track stiffness. In this research, the previous researches were further developed (extended) by including rail irregularity effects on the TRC.…”