Analyzing track responses to train braking

Abstract

The objective of this study was to suggest a response analysis framework for railway tracks that are subjected to braking. An analytical formulation was developed, in which the rail–track system was modeled as an infinite beam supported by an orthogonal Winkler foundation consisting of linear springs in perpendicular directions. The spring constants were varied over a wide range in order to represent different track types. Braking loads were simulated as representative sets of vertical and longitudinal forces, either concentrated or distributed. Considering a realistic set of model parameters, the approach was demonstrated by evaluating the track responses for a single axle and for a full train. The computations included determination of axial rail stresses, forces at the base of a sleeper, and the associated friction demand required to resist longitudinal slippage. Based on these analyses, it is concluded that longitudinal track responses have a much longer influence zone compared to vertical track responses. This implies that calculations involving a full train must be done on a case-by-case basis, i.e. they cannot be deduced from a single axle analysis. It is also found that high values of friction demand may develop at the sleeper bases indicating possible slippage. Overall, the proposed formulation provides a highly adaptable and easily implementable first-order mechanistic tool for the analysis of track responses to decelerating vehicular loads.