Determination of longitudinal profile of railway track using vehicle-based inertial readings

Abstract

ABSTRACT:The longitudinal profile of a railway track excites a dynamic response in a train which can potentially be used to determine that profile. A method is proposed in this paper for the determination of the longitudinal profile through an analysis of vehicle accelerations resulting from the train/track dynamic interaction.The Cross Entropy optimisation technique is applied to determine the railway track profile elevations that best fit the measured accelerations of a railway carriage bogie. Numerical validation of the concept is achieved by using a 2-dimensional quarter-car dynamic model, representing a railway carriage and bogie, traversing an infinitely stiff profile. The concept is further tested by the introduction of a 2-dimensional car dynamic vehicle model and a 3 layer track model to infer the track profiles in the longitudinal direction. Both interaction models are implemented in Matlab. Various grades of rail irregularity are generated which excite the vehicle inducing a dynamic response. Ten vertical elevations are found at a time which give a least squares fit of theoretical to measured accelerations. In each time step, half of these elevations are retained and a new optimisation is used to determine the next ten elevations along the length of the track. The optimised elevations are collated to determine the overall rail longitudinal profile over a finite length of railway track.

Determination of railway track longitudinal profile using measured inertial response of an in-service railway vehicle

“…This article reports on the field testing of a numerical method presented in OBrien et al 28 and on the additional measures that are required to increase the robustness of the method to noisy field measurement. An Irish Rail intercity train was instrumented for a period of 1 month to test a novel method for inferring railway track longitudinal profile through optimisation.…”

“…The method for inferring track longitudinal profiles presented in OBrien et al 28 is a numerical approach that assumes a constant vehicle forward velocity. In reality, train forward velocity changes along the track and will differ between datasets.…”

“…This overlapping allows a refinement of the second half of the elevations inferred in the previous phase and ‘builds’ the profile as the phases progress through the measured data. This stepping technique and the vector transfer methodology required to enable it are described in detail in OBrien et al 28…”

“…This article describes the field testing of a numerical method presented in OBrien et al 28 using a calibrated vehicle model detailed in Quirke et al 29 This is an inverse technique whereby inertial measurement of an Irish Rail train is used to find the longitudinal track profile that generated the measurement. By installing the sensors on the train bogie, a loaded track profile is inferred by the method, considering both the track longitudinal profile and the variation in longitudinal track stiffness.…”

Drive-by Damage Monitoring of Transport Infrastructure Using Direct Calculation of the Profile

“…However, they are expensive to operate and may disrupt regular services during operation. Using in-service vehicles to determine at least some of these parameters represents a possible alternative that can provide much more frequent measurements at much less cost [3].…”