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Economic analysis of rail facility preservation
Published in Zongzhi Li, Transportation Asset Management, 2018
Construction cost: Rail facility construction cost mainly covers cost components of early stage studies, civil works, rail track facilities, intermodal facilities, and miscellaneous. Earth works forms a key portion of civil engineering works that are related to subgrade construction. The construction of rail track facilities includes elements of rails, sleepers, ballast, and sub-ballast. Depending upon the terrain and railway geometric design, rail facility construction may involve additional civil works associated with structures such as bridges, viaducts, and tunnels, as well as drainages. It also contains electrification and safety systems. Table 12.1 summarizes typical life spans of primary railway components (AREMA, 2003; Voelker and Clark, 2008; Popović et al., 2014).
Effect of uneven subgrade settlement in high-speed railway on double-block ballastless track regularity
Published in Andreas Loizos, Imad L. Al-Qadi, A. (Tom) Scarpas, Bearing Capacity of Roads, Railways and Airfields, 2017
Figure 3 illustrates the characteristics of track deflections due to the uneven subgrade settlement with the wavelength and amplitude are 10 m and 10 mm respectively. It can be seen that due to the track weight, the upper track structure subsides with the uneven subgrade settlement. The track irregularity is formed consequently. The pattern of track deflections is similar to the deformed subgrade. However, due to its high rigidity and integrity, the concrete track is easily to lose contact with subgrade in some particular areas as blue-filled in Figure 3. A wide range of unsupported area appears inside the settlement section with a length of 7.31 m. It is because the amplitude of track deflections is only 4.64 mm which is much less than the settlement amplitude, 10 mm. Besides, there are two arched areas on the track out of the settlement section, as partially enlarged in Figure 3, where tiny voids between the ballastless track and the subgrade occur. The length of track deflection is therefore diffused relative to the settlement wavelength. With increasing train speed and axle load, the settlement-induced track irregularities and the unsupported areas may induce abnormal dynamic responses which pose a safety threat to the train-track system.
Leveraging machine learning to predict rail corrugation level from axle-box acceleration measurements on commercial vehicles
Published in International Journal of Rail Transportation, 2023
Wael Hassanieh, Abdallah Chehade, Alan Facchinetti, Mark Carman, Marco Bocciolone, Claudio Somaschini
Rail corrugation is a problem that is substantially understood in the railway literature. An important source is by Grassie and Kalousek [1] who classified different corrugation types according to the wavelength of the irregularity, the corrugation locations, its appearance on the rail running surface and the main cause of its formation. Corrugation forms as a result of a ‘wavelength-fixing’ mechanism, that occurs when the original longitudinal rail profile, which exhibits vibrational components at all wavelengths, excites the dynamics of the vehicle-track system. This mechanism produces certain dynamic loads that eventually ‘fix’ at certain wavelengths and certain positions of the formed corrugations along the rail lines. These dynamic forces will instigate changes and damages on the rail profile; this process is called ‘damage mechanism’. With the recurring train-track interactions, a positive feedback effect occurs on the degradation process of the rail profile. This phenomenon is further aggravated at certain wavelengths especially if the rail vehicles passing over a specific track section share similar architecture, speed, and dynamics.
Effects of geometric track irregularities on vehicle dynamic behaviour when running through a turnout
Published in Vehicle System Dynamics, 2023
N. Bosso, A. Bracciali, G. Megna, N. Zampieri
The investigation of the effects of turnout track irregularities on the vehicle dynamics and on the generation of dynamic loads is fundamental to reduce surface damages and rolling contact noise and vibrations. In 2000, Andersson and Dahlberg [15] implemented a computer programme modelling a turnout and a half-bogie, and they also simulated the case of an irregular transition at the crossing from the wing rail to the nose. Alfi and Bruni [16] developed a model of train-turnout interaction considering the variation of the rail profile and of the track stiffness in the running direction and simulated the effects of wheel and rail worn profiles and of the low track misalignment irregularity on the train-track coupled dynamics. Li et al. [17] developed a method based on a combination of multibody simulations, run in GENSYS, and FEM analysis in NASTRAN to simulate the track settlement in railway turnout. Xu et al. [18] used a similar solution, based on Simpack and ANSYS, to evaluate the impact of switch and stock rail profile wear on the generation of dynamic loads in vertical and lateral directions and on the contact stresses at the wheel-rail interface. Boiko et al. [19] ran several simulations of a vehicle running on an underground railway considering vertical irregularities on the switch frog and found an expression for the calculation of the dynamic load as a function of the irregularity main parameters and of the vehicle operating conditions.
Study on the influence of lateral and local rail deformation on the train–track interaction dynamics
Published in Vehicle System Dynamics, 2022
Yan Xu, Caijin Yang, Weihua Zhang, Weidong Zhu, Wei Fan, Guiming Mei, Jian Mou
In this paper, a new train–track interaction model is formulated to study the influence of rail lateral and local deformation on train–track interaction dynamics. In the present model, unlike the tradition method to treat the laterally and locally deformed rail as additional rail misalignment, the real shape of the laterally and locally deformed rail is considered as and modelled through the RBM and curved Timoshenko beam theory as a straight-curved-straight beam, thus the present model is more realistic. A passenger car is considered and modelled as a multibody system with 27 DOFs, and the non-ballasted track is considered for the study of high-speed train–track interaction. After the validation of the present model, the dynamic responses of the train–track interaction with lateral and local rail deformation are calculated first, and the results are compared with those from the traditional method. Then the influence of lateral and local rail deformation amplitude, stiffness of the primary and secondary suspension, and vehicle velocity on derailment safety and rail conditions are analysed. The derailment boundary of the high-speed train is finally obtained.