Recent findings indicate one of major causes of damages, which is attributed to the resonant behaviours, in a railway track and its components. Basically, when a railway track is excited to generalised dynamic loading, the railway track deforms and then vibrates for certain duration. Dynamic responses of the railway track and its components are the key to evaluate the structural capacity of railway track and its components. If a dynamic loading resonates the railway track’s dynamic responses, its components tend to have the significant damage from excessive dynamic stresses. For example, a rail vibration could lead to defects in rails or wheels. The track vibrations can cause the crack damage in railway sleepers or fasteners, or even the breakage of ballast support. Therefore, the identification of dynamic properties of railway track and its components is imperative, in order to avoid any train operation that might trigger such resonances. This chapter deals with the vibration measurement techniques and the dynamic behaviours of ballasted railway tracks, and in particular their major components. It describes the concept of vibration measurements and the understanding into the dynamic behaviour of ballasted railtrack sleepers. It discusses briefly on the track structures and track components in order to provide the foundation of understanding ballasted railway tracks. The highlight in this paper is the state-of-the-art review of dynamic properties of railway track and its components. It summarises the non-destructive acoustic methods, the identification processes, and the properties of each rail track element.
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