ISO/TS 14837-34:2024

Technical
Specification
ISO/TS 14837-34
First edition
Mechanical vibration — Ground-
2024-11
borne noise and vibration arising
from rail systems —
Part 34:
Characterizing irregularity of the
running surfaces with respect to
vibration excitation
Vibrations mécaniques — Vibrations et bruits initiés au sol dus à
des lignes ferroviaires —
Partie 34: Caractérisation des irrégularités de surface de
roulement associées à l'exitation vibratoire
Reference number
© ISO 2024
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Characterizing roughness related to vibration excitation . 3
4.1 Roughness and noise or vibration phenomena .3
4.2 Roughness spectrum .3
4.3 Roughness level .3
4.4 Roughness wavelength range .4
4.5 Characterization of roughness .5
5 Principles of measurement and analysis . 5
Annex A (informative) Characterization of localized geometrical features . 8
Annex B (informative) Measuring equipment . 9
Annex C (informative) Processing of roughness profiles in site-specific cases .12
Bibliography .13

iii
Foreword
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This document was prepared by Technical Committee ISO/TC 108, Mechanical vibration, shock and condition
monitoring, Subcommittee SC 2, Measurement and evaluation of mechanical vibration and shock as applied to
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iv
Introduction
The mechanisms of excitation of ground-borne noise and vibration from railway systems are listed in
ISO 14837-1:2005, 4.2.2, which identifies five excitation mechanisms acting at the wheel-rail interface. These
mechanisms include
a) moving loads (quasistatic) excitation,
b) excitation caused by wheel or rail roughness,
c) parametric excitation,
d) wheel or rail defects, and
e) discontinuities of the track.
This document is concerned with excitation by roughness. The aim of this document is to
f) define the term roughness used in connection with the source of ground vibration from railways,
g) provide guidance regarding the procedures that can be used for roughness excitation measurement and
analysis, and
h) provide guidance regarding the equipment that can be used to measure roughness excitation.
The term acoustic roughness is already defined by common use and in EN 15610. The mechanism by which
acoustic roughness generates vibration, leading to noise in the range f = 50 Hz to f = 6 kHz, is essentially
the same as that which is a source of ground vibration in the frequency ranges of approximately f = 1 Hz to
f = 80 Hz and approximately f = 20 Hz to f = 250 Hz, that leads to ground-borne or structure-borne noise.
This document therefore draws upon the established definitions, methods of measurement and methods
of analysis for acoustic roughness to provide guidance for the measurement and analysis of the roughness
pertaining to ground-borne vibration and ground-borne noise.

v
Technical Specification ISO/TS 14837-34:2024(en)
Mechanical vibration — Ground-borne noise and vibration
arising from rail systems —
Part 34:
Characterizing irregularity of the running surfaces with
respect to vibration excitation
1 Scope
This document specifies methods for measuring and analysing irregularities of running surfaces for use
in the prediction and assessment of ground-borne noise and vibration arising from railway systems. This
document
a) defines the data that can be described as rail or wheel roughness and that can be used to quantify a
source term for the generation of the dynamic forces that can lead to ground-borne vibration from
railway vehicles,
b) gives guidance regarding the types of equipment that can be used to measure roughness as a variation
of height along the running direction of the rail surface or wheel parameter,
c) gives guidance regarding the methods that can be used to obtain an estimate of the roughness wavelength
spectrum from measurement records taken over a length of rail head or wheel perimeter, and
d) gives guidance regarding the presentation of a roughness spectrum representing the condition of a
length of rail or of a wheel related to its ability to generate vibration.
This document does not
e) give guidance regarding the characterization of localized geometrical features (e.g. switches, crossings,
rail squats, occasional rail joints and localized geometrical defects of the running surface). These features
are likely to produce dynamic forces that are not linear with their amplitude because of the change of
geometry at the wheel-rail contact. Hence these features are not characterized by methods of analysis
defined within this document. Annex A provides further information regarding the characterization of
localized geometrical features,
f) give guidance regarding the specification or testing of roughness measurement equipment that can be
used. Annex B provides an overview of measuring equipment,
g) give guidance regarding the measurement or analysis of track quality for any other purpose than the
assessment of ground-borne vibration,
h) present any example of roughness spectra intended to represent typical roughness. Roughness levels
vary greatly between track sites and any examples used in this document have not been selected on any
other basis than their usefulness for the purpose of demonstrating the principles of analysis,
i) promote any particular make, model or manufacturer of measurement equipment, and
j) recommend or promote software for the implementation of the analysis procedure.
2 Normative references
There are no normative references in this document.

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply. For an explanation of
roughness-related terms, see Clause 4.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
running surface
part of the wheel tread or the rail head, along which the wheel-rail contact passes during rolling
Note 1 to entry: In the case of the rail this is the bright band of the surface of the rail head that contains all the running
positions of the wheel-rail contact.
[SOURCE: EN 15610:2019, 3.9]
3.2
roughness
variation in height of the rail or wheel running surface associated with a particular noise or vibration
phenomenon
3.3
roughness spectrum
amplitude of the roughness expressed as a function of the roughness wavelength λ
[SOURCE: EN 15610:2019, 3.2, modified — “acoustic” has been deleted in the term and the definition.]
3.4
roughness level
L
r
level expressed in decibels, given by the following formula:
r
RMS
L =⋅10 log
r 10
r
where
L is the roughness level in dB;
r
r is the root mean square roughness in μm; and
RMS
r is the reference roughness with r = 1 μm
0 0
Note 1 to entry: This definition applies to values measured either in the form of a roughness wavelength spectrum or
for a specific roughness wavelength band.
[SOURCE: EN 15610:2019, 3.3, modified — “acoustic” has been deleted in the term and the definition and
Note 1 to entry has been replaced.]
3.5
roughness wavelength
λ
ratio expressed in m given by the following formula:
λ=vf/
where
f is the frequency in Hz
v is the train speed in m/s
4 Characterizing roughness related to vibration excitation
4.1 Roughness and noise or vibration phenomena
Roughness is the variation in the height of the rail or wheel running surface. Therefore,
a) acoustic roughness is the roughness associated with the excitation of rolling noise,
b) ground-borne noise roughness is roughness associated with the excitation of ground-borne or structure-
borne noise, and
c) ground-borne vibration roughness is roughness associated with the excitation of low-frequency ground
vibration.
The vehicle-track interaction equation for the excitation of force by vertical profile irregularities in the height
of the rail and/or wheel running surfaces is the same for 4.1 a), b) and c). Only the roughness wavelength
range changes.
4.2 Roughness spectrum
The roughness spectrum is an estimation of the statistical properties of the roughness record over the length
of measurement. A roughness spectrum represents the general geometrical condition of the running surface
and does not represent the geometry of localized features (e.g. a crossing nose, rail joint, dipped joint or
certain kinds of track or rail or wheel defect) that do not occur with sufficient frequency in a measurement
record
...