Wheel–rail impact loads and noise generated at railway crossings – Influence of vehicle speed and crossing dip angle

Wheel–rail impact loads and noise at railway crossings are calculated by applying a hybrid prediction model. It combines the simulation of non-linear vertical dynamic vehicle‒track interaction in the time domain and the prediction of sound pressure level using a linear frequency-domain model. The two models are coupled based on the concept of an equivalent roughness spectrum. The time-domain model uses moving Green's functions for the linear vehicle and track models, accounting for wheel structural flexibility and a discretely supported rail with spatially-varying beam properties, and a non-Hertzian wheel–rail contact model. Three-dimensional surface geometry of the wheel and crossing is accounted for in the solution of the wheel–rail contact. The hybrid model is compared against field measurements and is demonstrated by investigating the influence of vehicle speed and crossing geometry on the radiated impact noise. Based on simulation results, it is concluded that the impact loads and noise can be mitigated by reducing the effective dip angle at the crossing, which is determined by the vertical trajectory of the wheel when making the transition between wing rail and crossing nose

Identification of effective properties of the railway substructure in the low-frequency range using a heavy oscillating unit on the track

As the demand for predictions of train-induced vibrations is increasing, it is essential that adequate parameters of the railway structure are given as input in the predictions. Gathering this information can be quite time-consuming and costly, especially when predictions are required for the low-frequency emission. This article presents a procedure for deriving the effective properties of the foundation under the sleepers of a railway track from measurements taken with a heavy oscillating unit on the track. The unit consists of two masses inside a modified freight car that exert a dynamic force in the range 3–30 Hz on one of the two axles. The ratio of force applied on the axle over the resulting response measured with an accelerometer is studied. The foundation of the sleepers is modelled using a frequency-dependent complex-valued dynamic stiffness.Design and ConstructionCivil Engineering and Geoscience