Theoretical Determination of Braking Loads for Railway Tracks

This paper presents a model to determine the theoretical braking loads for railway tracks. Two braking load studies are reviewed: one by the Office of Research and Experiment Committees and one related to the European specifications for braking load. The maximum braking load of a rail is determined by multiplying wheel load with an appropriate coefficient of adhesion. The maximum braking load is not an input in the current track–structure interaction model. Currently, braking load per meter of track, e.g., $30\mathrm{kN}/\mathrm{m}$ of track, is an input in a track–structure interaction model. Thus, a formula is suggested to convert the maximum braking load into an equivalent braking load per meter of track ($\mathrm{kN}/\mathrm{m}$ of track). The formula is applied to compute the braking loads that are validated against the observations from Office of Research and Experiment studies and Eurocode values. It is crucial to choose a proper value of coefficient of adhesion to compute the braking load; therefore the coefficient of adhesion is reviewed. A formula is also suggested to determine the extent of the track affected by the braking load. The formulas are applied to both ballasted and direct-fixation track; they demonstrate how the value for braking load per meter of track and the value for affected track length due to braking change with the track form and quality of track maintenance. The extent of the affected track due to braking may be the length of track on the bridge approaches to be included in a track–structure interaction model. The model for determining the theoretical braking loads for railway tracks would be helpful for attaining a better understanding of the braking action of rolling stock.