ISO/TS 13473-4:2008

TECHNICAL ISO/TS
SPECIFICATION 13473-4
First edition
2008-05-01
Characterization of pavement texture by
use of surface profiles —
Part 4:
Spectral analysis of surface profiles
Caractérisation de la texture d'un revêtement de chaussée à partir de
relevés de profils de la surface —
Partie 4: Analyse spectrale des profils de la surface

Reference number
©
ISO 2008
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ii © ISO 2008 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Basic outline of methodologies of spatial frequency analysis. 6
5 Sampling of surface profiles . 8
5.1 Sampling of road sections. 8
5.2 Measurement of laboratory samples . 9
6 General principles and requirements . 9
6.1 Requirements concerning profilometers .9
6.2 Conversion of spatial frequencies to temporal frequencies. 9
6.3 Drop-outs. 11
6.4 Anti-aliasing filtering . 12
6.5 Digital sampling . 12
7 Spectral analysis in constant-percentage bandwidth bands (octave- or one-third-octave
bands) by analogue filtering (Method 1). 13
8 Spectral analysis in constant-percentage bandwidth bands (octave- or one-third-octave
bands) by digital filtering (Method 2). 15
9 Spectral analysis in narrow constant bandwidth bands by means of Discrete (Fast)
Fourier Transform methods (Method 3) . 15
9.1 Overview of methodology. 15
9.2 Slope and offset suppression . 16
9.3 Windowing. 16
9.4 Discrete Fourier Transform and Power Spectral Density. 18
9.5 Wavelength resolution . 19
10 Transformation of constant bandwidth spectral data to constant-percentage bandwidth
spectral data. 19
11 Uncertainty of analysis results. 21
12 Reporting of analysis results . 22
Annex A (normative) Uncertainty of spectral analysis results. 23
Annex B (informative) Aliasing .28
Annex C (informative) Estimation of the deviation in energy within a frequency band caused by
variations in speed . 30
Annex D (informative) Compensation for speed variations during processing of the measured
data. 31
Annex E (informative) Explanation of the relation between the wavelength resolution and the
spatial frequency resolution. 32
Annex F (informative) Spectral analysis and profile asymmetry. 33
Bibliography . 35

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
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The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
In other circumstances, particularly when there is an urgent market requirement for such documents, a
technical committee may decide to publish other types of document:
— an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in
an ISO working group and is accepted for publication if it is approved by more than 50 % of the members
of the parent committee casting a vote;
— an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical
committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting
a vote.
An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for a
further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is
confirmed, it is reviewed again after a further three years, at which time it must either be transformed into an
International Standard or be withdrawn.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO/TS 13473-4 was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.
ISO 13473 consists of the following parts, under the general title Characterization of pavement texture by use
of surface profiles:
⎯ Part 1: Determination of Mean Profile Depth
⎯ Part 2: Terminology and basic requirements related to pavement texture profile analysis
⎯ Part 3: Specification and classification of profilometers
⎯ Part 4: Spectral analysis of surface profiles [Technical Specification]
⎯ Part 5: Determination of megatexture
iv © ISO 2008 – All rights reserved

Introduction
Pavement texture is one of the basic road surface characteristics and as such is related to many functional
characteristics, such as noise emission from tyre-road interaction, friction between tyre and road, rolling
resistance and tyre wear.
Spectral analysis of measured surface profiles is frequently used as a method of pavement characterization.
However, recent practice has shown that the methodology of spectral analysis is not sufficiently well known in
the field of pavement measurements to assure reproducible results. Improvement of the reproducibility by
offering guidance in the form of a standardization document seems therefore advisable.
Although the principles of frequency analysis are used in various fields of signal processing, it seems that a
tailored elaboration of these principles for the application in the field of pavement texture measurements is
appropriate and will enhance the use of these methods and the quality of the results achieved.
This elaboration, in the form of an ISO Technical Specification, is intended to stimulate the international
exchange of knowledge and data concerning pavement characteristics.

TECHNICAL SPECIFICATION ISO/TS 13473-4:2008(E)

Characterization of pavement texture by use of surface
profiles —
Part 4:
Spectral analysis of surface profiles
1 Scope
This Technical Specification describes the methods that are available to perform a spectral analysis of
pavement surface profile signals. It specifies three possible methods for spatial frequency analysis (or texture
wavelength analysis) of two-dimensional surface profiles that describe the pavement roughness amplitude as
a function of the distance along a straight or curved trajectory over the pavement.
The result of the frequency analysis will be a spatial frequency (or texture wavelength) spectrum in constant-
percentage bandwidth bands of octave or one-third-octave bandwidth.
This Technical Specification offers three alternative methods to obtain these spectra:
1) analogue constant-percentage bandwidth filtering;
2) digital constant-percentage bandwidth filtering;
3) constant narrow bandwidth frequency analysis by means of Discrete Fourier Transform, followed by
a transformation of the narrow-band spectrum to an octave- or one-third-octave-band spectrum.
The objective of this Technical Specification is to standardize the spectral characterization of pavement
surface profiles. This objective is pursued by providing a detailed description of the analysis methods and
related requirements for those who are involved in pavement characterization, but are not familiar with general
principles of frequency analysis of random signals. These methods and requirements are generally applicable
to all types of random signals, but are elaborated in this Technical Specification in a specific description aimed
at their use for pavement surface profile signals.
NOTE The user of this Technical Specification should be aware that spectral analysis as specified in this document
cannot express all characteristics of the surface profile under study. In particular, the effects of asymmetry of the profile,
e.g. the difference of certain functional qualities for “positive” and “negative” profiles cannot be expressed by the power
spectral density, as it disregards any asymmetry of the signal. (See Annex F.)
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 13473-2:2002, Characterization of pavement texture by use of surface profiles — Part 2: Terminology and
basic requirements related to pavement texture profile analysis
ISO 13473-3, Characterization of pavement texture by use of surface profiles — Part 3: Specification and
classification of profilometers
IEC 61260, Electroacoustics — Octave-band and fractional-octave-band filters
3 Terms and definitions
For the purpose of this document, the terms and definitions given in ISO 13473-2:2002 and the
...