Keywords: wheels, rails, damage, wear, fatigue, rolling contact fatigue, track access charging..

Damage to wheels and rails is a significant cost to all railway vehicle operators and infrastructure owners. In addition to the actual effort involved in turning, tamping, grinding and replacing wheels and rails, the impact of the downtime on the operation of the railway system is a major factor in reducing reliability, availability, and efficiency. This paper summarises the key mechanisms that cause damage to railway wheels and rails, and reviews the latest techniques available to predict this damage and explore how it can be used to optimise maintenance methods. Recent tools that have been developed in the UK are presented, and the potential for significant benefits of using these and similar techniques is outlined.

Detailed contact models together with vehicle dynamics simulation tools now allow reliable prediction of wear in the contact patch, and this has been used to succesfully predict the changes in wheel and rail profiles, and the evolution of corrugation. Rolling contact fatigue (RCF) is not a new phenomenon but has become a more significant problem in recent years: partly arising from increases in performance with higher axle loads, speeds, and traffic; and partly as a consequence of improvements in the wear resistance of steels used in wheels and rails. Again, the use of modelling methods and improved understanding of material behaviour means that RCF and localised damage, such as squats and damage to switches and crossings, can be predicted and minimised.

The availablity of these new methods means that the design of track layouts or vehicle suspensions can potentially be improved and damage levels reduced. Examples include the use of non-linear suspension bushes to allow different effective characteristics for high and low frequency motions, and variation of track geometry on the approach to a switch to ensure that changes in contact forces are smooth and impact less on more vulnerable components. Several case studies are presented in the paper.

The methods currently used to allocate charging are also reviewed and conclusions drawn. In particular, the relatively sophisticated techniques being developed in the UK and Sweden, which use knowledge gained from the improved modelling methods, are presented and suggestions are made for the future direction of this important area.

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