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Track Design, Dynamics and Modelling
Published in Simon Iwnicki, Maksym Spiryagin, Colin Cole, Tim McSweeney, Handbook of Railway Vehicle Dynamics, 2019
The railway track is a basic technical structure that is essential for the operation of trains. A traditional railway track structure usually consists of rails, rail pads, rail-to-sleeper fasteners, sleepers, ballast and subgrade, as shown in Figure 9.1. The purpose of a railway track is to guide the trains to run smoothly, to carry the dynamic loads from wheel-rail interaction and to transmit the dynamic loads to the subgrade, bridge deck or tunnel floor. The railway track should be constructed with precise geometry and must be strong and stable enough to ensure train’s running safety. In addition, the ballastless track (shown in Figure 9.2) is also now widely applied in high-speed railways and urban rail transit. It employs concrete slabs with good integrity to substitute for the sleepers and discrete ballast bed, with the aim of continuously maintaining the track geometry and, at the same time, substantially decreasing the level of repair and maintenance works required.
Transportation - haulage and hoisting
Published in Ratan Raj Tatiya, Surface and Underground Excavations, 2013
While adapting a track mine system, properly laid track and suitable types of mine cars are mandatory to achieve smooth and trouble free transportation of ore, rocks and material in the mine. Selection of a track depends upon the weight of locomotive or the weight on a wheel in case of rope haulage system. In figure/table 7.14(c) suggested rail weights given by Bethlehem catalog 2314 can be used as guide. Grosvenor9 gave a thumb rule to choose rail weight in pounds/yard to be 10lb./yard for each ton. of weight on wheels. Track lying is a skilled job. A track laying operation involves laying of ballast, sleepers, track with fish-plates and bolts, switches and crossings. Ballast provides an elastic bed for the track, distributes the applied load over a large area and holds the sleepers in place. The ballast should be crushed rock, which is not affected by water and produces minimum dust when subjected to heavy weights as it has got adverse effect on locomotive parts and the rolling stock. Its size should be in between 12-50 mm (0.5" -2"). The sleepers could be of wood, concrete or steel. Spacing (L) between them should not exceed 850 mm (2'9"), or the following relation1 can determine it:
Study of the validity of a rectangular strip track/soil coupling in railway semi-analytical prediction models
Published in António S. Cardoso, José L. Borges, Pedro A. Costa, António T. Gomes, José C. Marques, Castorina S. Vieira, Numerical Methods in Geotechnical Engineering IX, 2018
D. Ghangale, J. Romeu, R. Arcos, B. Noori, A. Clot, J. Cayero
The model of geometry of the 2.5D FEM-BEM of the studied system is shown in the Fig. 2. The geometry consists of a ballasted railway track resting on a homogeneous ground. The railway track is composed of the rails, the sleepers, the fasteners and the ballast. The fasteners consist of a top elastomer which is in contact with the rails, below which is a top plate, a base plate and another elastomer sandwiched between the top plate and the base plate. The materials associated to the rails, the fasteners, the sleepers and the ballast in FEM-BEM simulations are described with the Young’s modulus E, Poisson’s ratio v, density ρ and damping ratios Dp and Ds.
Identify severe track geometry defect combinations for maintenance planning
Published in International Journal of Rail Transportation, 2022
Qing Wu, Abul Kalam Azad, Colin Cole, Maksym Spiryagin
Track geometries, in reality, have deviations from their designed parameters or designed geometries. These deviations are called track (geometry) irregularities and track (geometry) defects [1]. The differences between track irregularities and track defects have not been clearly defined in the open literature. This paper regards track irregularities as the numerous deviations that are of relatively small amplitudes whilst track defects are regarded as singular or repeating deviations of larger amplitudes. For example, the largest amplitude of the vertical track irregularity in Federal Railroad Administration (FRA) Class 5 track irregularity [2] is similar to the smallest amplitude band of the vertical track defect in the Australian Rail Industry Safety and Standards Board (RISSB) standards [3]; both of them are around 20 mm. It is also noted that track defects are categorized by amplitudes in RISSB AS7635 standard [3]; the shapes and wavelengths of various defects were not defined. Track irregularities exist in tracks of all standards and are stochastic in nature; they mainly originate from the manufacture of track components, construction tolerances, and general degradation of the track, which all have relatively small tolerances that cannot be avoided. On the other hand, track defects mainly occur due to loading from train operations. Track defects can be caused by various factors such as track settlement, formation subsidence, vehicle dynamic loads, wheel-rail impact forces, etc. Track defects are of major concern [4,5] in maintaining a safe interface between vehicle and track.
Reliability assessment of a curved heavy-haul railway track-bridge system
Published in Structure and Infrastructure Engineering, 2020
The track structure includes steel rail, fastener, sleeper, and ballasts. The prototype of the rail is a 75 kg/m steel rail, which can be considered as a long beam and simulated by beam elements. The fastener and rail gasket are simplified as spring-damper devices arranged with spacing of 0.6 m. The prototype of the sleeper is the type-III sleeper with some details neglected, which is simulated by solid elements. The model of ballast bed is constituted by solid elements and has the same cross-sectional dimensions as the actual size, i.e. the width of the top surface of the ballast bed is 3.4 m, the height of the shoulder is 0.15 m, and the slope is 1:1.75. The ballast behaviour predicted in UIC774-3, due to frictional effects, follows a bi-linear relationship. When the sleeper horizontal displacement is smaller than 2 mm, the ballast resistance has a linear elastic range.
Development of a tram track degradation prediction model based on the acceleration data
Published in Structure and Infrastructure Engineering, 2019
Amir Falamarzi, Sara Moridpour, Majidreza Nazem
Gauge is the deviation from the pre-defined distance between the inner surface of the rails in a rail track. Profile is the vertical deviation in a specific chord length. Alignment is the horizontal deviation from the designated alignment. Twist is the difference between two cross-levels measured in a specific chord length. Cross-level is the deviation between the top of head surfaces of the rails at a specific location. In addition, train traffic in MGT and rail track structural parameters such as rail profile, track surface, rail support and rail type are included in the data set. Rail profile is the cross-sectional shape of a tram rail, which is presented by kilogram per metre. Track surface is the material of pavement laid down between the tracks and categorised into asphalt and concrete surfaces. Rail support is rail ties laid perpendicular to rail and categorised into steel sleepers, timber sleepers and concrete sleepers. Rail type is the shape of tram railhead and categorised Grooved and T-shapes (Public Transport Victoria, 2017).