This document provides background information regarding the changes from EN 15302:2008+A1:2010 to the revised version dated 2021, including the reasons for decisions and additional explanation and guidance that is not appropriate in the standard. The range of equivalent conicity results obtained with different software tools is described. The additional wheel-rail contact parameters, rolling radii coefficient and nonlinearity parameter, are explained. More information is also provided on the different calculation methods and the updated reference profiles for the assessment. The influence of simplifications used in determination of equivalent conicity is discussed. To provide more information on the importance of considering the complete measurement and calculation process, methods for plausibility checks, eliminating outliers and assessing the uncertainty and repeatability of measurements are included as well as assessments of the smoothing process. Guidance is given on fields of application of the wheel-rail contact parameters, on the selection of appropriate reference profiles (choice of reference rail profile and rail inclination for assessing wheel profiles and vice versa) and on handling special cases. As some references in EN 14363 to wheel-rail contact test conditions have caused difficulties in understanding, clarifications issued by ERA are mentioned. Interpretation of equivalent conicity results, using tools such as conicity maps, is discussed and various approximations such as ‘quick conicity’ assessments are also described. Information is included on possible additional wheel-rail contact parameters, not yet ready for standardization, but where further experience is needed. NOTE In this document the commonly used term “wheel-rail contact geometry” is used as a synonym for the more precise term “wheelset-track contact geometry”.

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PDF Pages	PDF Title
2	undefined
7	1 Scope 2 Normative references 3 Terms and definitions
8	4 Overview of the most important changes made to EN 15302 4.1 List of main changes 4.2 Additional wheel-rail contact geometry parameters 4.2.1 Rolling radii coefficient 4.2.2 Nonlinearity parameter
9	4.3 Methods for evaluation of equivalent conicity 4.4 Assessment of the smoothing process
10	4.5 New assessment of the complete process 5 Technical background to and justification of changes in the revised EN 15302 5.1 Equivalent conicity 5.1.1 Review of equivalent conicity results obtained with different software tools
13	5.1.2 Comparison with multibody system simulation results
16	5.1.3 Influence of discretisation step size of the rolling radius difference function
17	5.2 Rolling radii coefficient 5.2.1 Background
19	5.2.2 Current method
22	5.3 Nonlinearity parameter
24	5.4 Calculation of equivalent conicity by two-step integration
25	5.5 Calculation of equivalent conicity by direct integration of the kinematic equation of motion 5.6 Calculation of equivalent conicity by harmonic linearization
27	5.7 Updated reference profiles and results based on analytical solutions
29	5.8 Revised assessment of the smoothing process 5.9 Example for uncertainty assessment of the complete process
33	5.10 Influence of simplifications 5.10.1 General 5.10.2 Wheelset roll movement (rotation around the longitudinal axis)
38	5.10.3 Contact elasticity of wheel and rail
41	6 Guidance for the application of the wheel-rail contact parameters given in EN 15302 6.1 Fields of application – Overview 6.2 General guidelines
42	6.3 Selection of appropriate reference profiles for assessment of rail head profiles and/or wheel profiles 6.3.1 General 6.3.2 British Rail Research Survey 6.3.3 Reference profiles in the DynoTRAIN project
44	6.3.4 Assessment of design wheel profiles and design rail profiles
45	6.4 Development of equivalent conicity of wheelsets over mileage
47	6.5 Assessment of the contact geometry of a line 6.5.1 Methods for determining averaged contact geometry parameters
48	6.5.2 Assessment of a line for different wheel profiles
50	6.6 Rolling radii coefficient and radial steering index
53	6.7 Nonlinearity parameter
55	6.8 Equivalent conicity in wheel-rail maintenance and interface with TSIs 6.8.1 General 6.8.2 Equivalent conicity that a vehicle was designed and tested for 6.8.3 Equivalent conicity as parameter in wheel profile maintenance regimes
56	6.9 Clarification of wheel-rail contact test conditions according to EN 14363
57	6.10 Application of Contact angle parameter and Roll angle parameter 7 Alternative contact parameters not handled in the standard 7.1 Difference of contact angles and gravitational stiffness
58	7.2 Contact Concentration Index
62	8 Approximation of equivalent conicity by simple alternative methods 8.1 Background 8.2 British Rail Research investigations 8.2.1 Initial BRR work in 1980s
65	8.2.2 BRR further work in 1990s
68	8.3 Investigations on Quick conicity using DynoTRAIN data 8.3.1 DynoTRAIN project data collection
69	8.3.2 Investigations on rail data
75	8.3.3 Investigations on wheel data
77	8.3.4 Combined assessment – track and wheelset 8.3.5 Next Steps
78	8.4 Ongoing development of Gradient Index Profile (GIP) 8.4.1 Definition of GIP
79	8.4.2 Comparison between equivalent conicity and GIP combined 9 Development and usage of the so called conicity maps
81	10 Plausibility check of measured profiles and elimination of outliers 10.1 Introduction 10.2 Profile area to be covered 10.3 Spacing of points on the profile
82	10.4 Elimination of outliers
83	11 Examples for validation of profile measuring systems 11.1 General 11.2 Evaluations of rail profile measuring systems
85	11.3 Evaluations of ground-based wheel profile measuring systems
86	12 Effect of wheel diameter differences on the running behaviour

Published By	Publication Date	Number of Pages
BSI	2022	90


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Status	Definitive
Pages	90
Publication Date	2022-03-08
ISBN	978 0 539 15052 0
Standard Number	PD CEN/TR 17792:2022
Title	Railway Applications. Wheel-rail contact geometry parameters. Technical report and background information about EN 15302
Identical National Standard Of	CEN/TR 00256878
Publisher	BSI
Committee	RAE/1/-/8
ICS Codes	17.040.20 - Properties of surfaces

BSI PD CEN/TR 17792:2022

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