Extensive research has been carried out to investigate the interface between train wheels and the rail head, however much of this has been undertaken from a mechanical engineer’s point of view, with the focus being on wheel wear, vehicle dynamics and the effects of increased vehicle weight or speed on maintenance costs.

British research into the direct safety implications of worn rail exists but such work is disparate and difficult to attain, thanks to the process by which the railways have passed from organisation to organisation through years of rationalisation, nationalisation, sectorisation and privatisation.

Most recently the Rail Safety and Standards Board (RSSB) has led the way in current British research into the vehicle/track interface on behalf of the Department for Transport, but the majority of rail research was conducted by the British Rail Research Division in the period between its creation in 1964 and privatisation in 1996. Much of this research remains outside the public domain.

Some of the most relevant research has in fact been undertaken further afield, with the American Society of Mechanical Engineers (ASME) producing several papers on wheel/rail interfaces, with a key example being authored by Gordon et al. (2009) detailing the use of fracture mechanics as an approach to estimating rail wear limits.

This all means that an extensive literature survey needs to be undertaken to establish what relevant research exists, alongside speaking to people who have and are working within the rail industry to gain an idea as to where (and when) the data used in constructing the current guidelines was sourced.

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The process of locating relevant research work is still on-going, but there are several key locations where searching has been focussed; namely the Institution of Civil Engineers (ICE), Institution of Mechanical Engineers (IMechE), American Society of Mechanical Engineers (ASME) and Transportation Research Board.

As a result of the breadth of wheel/rail interface research, the papers this project’s literature review intends to cover will be limited to those specifically looking at the limit states of steel rail under conditions of wear and those which have influenced rail guidelines and legislation.

The relevance of such research with regards to the lower speeds and traffic densities of heritage railway lines will be taken into account.

At the moment only recently published papers have been directly sourced. The list will be updated as the literature survey continues and more historic works are uncovered.

Gordon, J.E., Jeong, D. Y., and Lyons, M. L. (2009). Fracture Mechanics Approach to Estimate Rail Wear Limits. ASME Conf. Proc. 2009, DOI:10.1115/RTDF2009-18035, 137-146.

Based on research carried out in the USA, this paper studies a methodical approach to estimating serviceability and ultimate limit states for rail wear, considering vertical head-height loss, gauge-face side wear and a combination of the two. The process described is based on engineering fracture mechanics; a principle already applied in the aircraft industry. The system applies various assumptions regarding track system arrangement, environmental factors and traffic details (such as speed, axle-loading and frequency) and estimates likely limits of rail wear. The paper also presents some of the results from the application of the methodology.

Jeong, D.Y., Orringer, O. and Tang, Y.H., (1998). Estimation of Rail Wear Limits Based on Rail Strength Investigations. Office of Research and Development; Washington, D.C. [USA].

Based on research undertaken in the USA, Jeong et al. consider the structural strength limitations of heavily worn rails, developing existing methods for determining rail section properties and using them to analyse rail stress. These methods assume the presence of internal transverse defects which provide more restrictive limits when compared to similar plastic bending analysis. The paper then recommends maximum head-height loss for rails inspected at certain frequencies.

Nilsson, R. and Olofsson, U. (2002). Surface cracks and wear of rail. IMechE Proc., Part F: Journal of Rail and Rapid Transit (216), DOI: 10.1243/095440902321029208, 249-264.

This paper looks at both rail wear and surface cracking; however the most interesting feature of this report was a two-year long rail wear measurement experiment on lines with full commuter traffic. The effects of lubrication are also observed. The most useful feature of this report is in its investigations of the interaction of rail degradation mechanics.

Shu, X., Wilson, N. and Wu H., (2005). Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Transportation Research Board; Washington, D.C. [USA].

Whilst covering a lot of ground, this paper contains key derailment criteria and wheel/rail profile management and maintenance guidelines applicable to the rail industry. Simulations were run using data from several transit systems, and this validation allowed geometric definitions of acceptable wear in the wheel/rail interface. Several recommendations and guidelines are then described, with some being more conceptual than quantitative, indicating the nature of the complexity of the engineering and simplicity of industry requirements.

Wilson, N. and Wu H., ‘Railway Vehicle Derailment and Prevention’ in Iwnicki, S. (ed.) et al., (2006). Handbook of Railway Vehicle Dynamics. Taylor & Francis; [UK].

This paper considers the reasons for vehicle derailment and looks into methods of prevention. The paper looks at some of the history and statistics of train derailments, considers the mechanisms of and safety implications surrounding derailment, and concludes by discussing the prediction and prevention of such occurrences.

The survey has considered a large quantity of additional material outside the conditions for review stated above. These papers are included as useful additional reading, and will be referenced by the project. Some of these papers are detailed below:

British Railways Board, (1993). Permissible Track Forces for Railway Vehicles (GM/TT0088). Group Standards, Railway Technical Centre; Derby [UK].

King, A.G.B., (1985). Report on the Derailment that occurred on 3rd February 1983 at Elgin. Department of Transport; London [UK].

Rail Accident Investigation Branch, (2012). Derailment at Princes Street Gardens, Edinburgh. Department for Transport; Derby [UK].

Rail Safety and Standards Board, (2011). Track System Requirements (GC/RT5021). RSSB Ltd; London [UK].