SIST EN ISO 11819-2:2017
(Main)Acoustics - Measurement of the influence of road surfaces on traffic noise - Part 2: The close-proximity method (ISO 11819-2:2017)
Acoustics - Measurement of the influence of road surfaces on traffic noise - Part 2: The close-proximity method (ISO 11819-2:2017)
ISO 11819-2:2017 specifies a method of evaluating different road surfaces with respect to their influence on traffic noise, under conditions when tyre/road noise dominates. The interpretation of the results applies to free-flowing traffic travelling on essentially level roads at constant speeds of 40 km/h and upwards, in which cases tyre/road noise is assumed to dominate (although in some countries it is possible that tyre/road noise does not dominate at 40 km/h when the proportion of heavy vehicles is high). For other driving conditions where traffic is not free-flowing, such as at junctions or under heavy acceleration, and where the traffic is congested, the influence of the road surface on noise emission is more complex. This is also the case for roads with high longitudinal gradients and a high proportion of heavy vehicles.
A standard method for comparing noise characteristics of road surfaces gives road and environment authorities a tool for establishing common practices or limits as to the use of surfacings meeting certain noise criteria. However, it is not within the scope of this document to suggest such criteria.
ISO 11819-1 defines another method: the statistical pass-by (SPB) method. The close-proximity (CPX) method specified in the present document has the same main objectives as the SPB method, but is intended to be used specifically in applications that are complementary to it, such as:
- noise characterization of road surfaces at almost any arbitrary site, with the main purpose of checking compliance with a surface specification (an example for conformity of production is suggested in Reference [1]);
- checking the acoustic effect of maintenance and condition, e.g. wear of and damage to surfaces, as well as clogging and the effect of cleaning of porous surfaces;
- checking the longitudinal and lateral homogeneity of a road section;
- the development of quieter road surfaces and research on tyre/road interaction.
NOTE This document does not describe the conditions of application for formal purposes of the measurement with the CPX method. Such conditions may be defined in other standards or legal texts. However, suggestions for the applicability of ISO 11819-1 and this document are provided in Annex D.
Measurements with the CPX method are faster and more practical than with the SPB method, but are more limited in the sense that it is relevant only in cases where tyre/road noise dominates and power unit noise can be neglected. Furthermore, it cannot take heavy vehicle tyre/road noise into account as fully as the SPB method can, since it uses a light truck tyre as a proxy for heavy vehicle tyres and does not take power unit noise into account.
The CPX method specified in this document is intended to measure the properties of road surfaces, not the properties of tyres. If the method is used for research purposes, to provide an indication of differences between tyres, the loads and inflations would normally be adjusted to other values than specified in this document.
Akustik - Messung des Einflusses von Straßenoberflächen auf Verkehrsgeräusche - Teil 1: Nahfeldmessmethode (ISO 11819-2:2017)
Dieses Dokument legt eine Methode zur Bewertung verschiedener Straßenoberflächen hinsichtlich ihres Einflusses auf Straßenverkehrsgeräusche unter Bedingungen fest, bei denen Reifen/Fahrbahn-Geräusche dominieren. Die Interpretation der Ergebnisse bezieht sich auf frei fließenden Verkehr auf im Wesentlichen ebenen Straßen mit konstanten Geschwindigkeiten von mindestens 40 km/h. Für diese Fälle wird angenommen, dass Reifen/Fahrbahn-Geräusche dominieren (allerdings besteht in einigen Ländern die Möglichkeit, dass bei 40 km/h und hohem Aufkommen schwerer Fahrzeuge Reifen/Fahrbahngeräusche nicht dominieren). Bei anderen Fahrbedingungen, wenn der Verkehr nicht frei fließt, wie an Kreuzungen, bei hoher Beschleunigung oder verstopften Straßen, ist die Zusammensetzung des Verkehrsgeräusches komplexer. Dies gilt auch für Straßen mit großer Längsneigung und hohem Aufkommen schwerer Fahrzeuge.
Ein genormtes Verfahren zum Vergleich der akustischen Eigenschaften von Straßenoberflächen gibt Straßen und Umweltbehörden ein Hilfsmittel an die Hand, Straßenoberflächen im Hinblick auf die Einhaltung bestimmter Lärmgrenzwerte auszuwählen. Dieses Dokument hat jedoch nicht zum Ziel, solche Grenzwerte vorzuschlagen.
ISO 11819 1 legt ein anderes Verfahren fest: Das statistische Vorbeifahrtverfahren. Die in diesem Dokument beschriebene Nahfeldmessmethode (en: Close-Proximity Method, CPX) hat dieselben Ziele wie das SPB Verfahren; allerdings soll sie in Situationen zu Anwendungen kommen, in denen sie letztere ergänzt, zum Beispiel:
— Lärmcharakterisierung von Straßenoberflächen an jedem beliebigen Ort, wobei der Hauptzweck in der Prüfung der Einhaltung einer Oberflächenspezifikation besteht (ein Beispiel für die Übereinstimmung der Herstellung wird in Literaturhinweis [1] vorgestellt);
— Prüfung der akustischen Wirkung von Wartung und Zustand, z. B. Abnutzung und Beschädigung von Oberflächen oder Verstopfung und Reinigung poröser Oberflächen;
— Prüfung der Homogenität eines Straßenabschnitts in Längs- und Seitenrichtung;
— die Entwicklung geräuschärmerer Straßenoberflächen und Erforschung der Reifen/Fahrbahn-Interaktion.
ANMERKUNG Dieses Dokument enthält keine Vorgaben hinsichtlich der Bedingungen zur formellen Anwendung von Messungen mit der CPX-Methode. Derartige Bedingungen können in anderen Normen oder Rechtstexten definiert werden. Allerdings enthält Anhang D Vorschläge zur Anwendung von ISO 11819 1 und diesem Dokument.
Messungen mit der CPX-Methode sind schneller und praktikabler als Messungen mit dem SPB-Verfahren; allerdings sind sie in der Hinsicht eingeschränkt, dass sie nur in Fällen relevant sind, in denen Reifen/Fahrbahn-Geräusche dominieren und Antriebsgeräusche vernachlässigt werden können. Des Weiteren können bei ihnen die Reifen/Fahrbahn-Geräusche schwerer Fahrzeuge nicht in dem Umfang wie beim SPB-Verfahren berücksichtigt werden, da bei ihnen Kleinlaster-Reifen stellvertretend für LKW Reifen zur Anwendung kommen und die Antriebsgeräusche nicht berücksichtigt werden.
Die in diesem Dokument dargestellte CPX-Methode dient der Messung der Eigenschaften von Straßenoberflächen und nicht der Eigenschaften von Reifen. Falls die Methode zu Forschungszwecken zur Erbringung von Hinweisen für Unterschiede von Reifen verwendet wird, würden die Belastungen und der Fülldruck üblicherweise auf andere Werte als jene in diesem Dokument eingestellt werden.
Acoustique - Méthode de mesurage de l'influence des revêtements de chaussées sur le bruit émis par la circulation - Partie 2: Méthode de proximité immédiate (ISO 11819-2:2017)
ISO 11819-2:2017 décrit une méthode d'évaluation de différents revêtements de chaussée en ce qui concerne leur influence sur le bruit émis par la circulation, dans des conditions où prédomine le bruit de contact pneumatique/chaussée. L'interprétation des résultats s'applique à des véhicules se déplaçant dans des conditions de circulation fluide sur des routes sensiblement planes à des vitesses constantes de 40 km/h et plus, auquel cas le bruit de contact pneumatique/chaussée est supposé prédominer (bien que dans certains pays, le bruit de contact pneumatique/chaussée peut ne pas prédominer à 40 km/h lorsque la proportion de véhicules lourds est élevée). Dans les autres conditions de conduite, où la circulation n'est pas fluide, par exemple au niveau des carrefours ou en cas de forte accélération, et aux endroits où l'on rencontre souvent des encombrements, l'influence du revêtement de la chaussée sur l'émission sonore est plus complexe. C'est également le cas pour les routes à fortes pentes longitudinales et supportant des trafics à forte proportion de véhicules lourds.
Une méthode normalisée de comparaison des caractéristiques acoustiques des revêtements de chaussée fournit aux autorités responsables du réseau routier et de l'environnement un outil leur permettant d'établir des pratiques courantes ou des limites pour l'utilisation de revêtements conformes à certains critères acoustiques. La définition de ces critères ne fait toutefois pas l'objet du présent document.
L'ISO 11819‑1 définit une autre méthode: la méthode statistique au passage (SPB). La méthode de proximité (CPX) décrite dans le présent document a les mêmes objectifs que la méthode SPB, mais elle est conçue spécifiquement pour des applications complémentaires telles que:
- la caractérisation acoustique des revêtements de chaussée au niveau de pratiquement n'importe quel site arbitraire, principalement dans le but de vérifier la conformité à des spécifications de revêtement (un exemple de la conformité de la production est suggéré dans la Référence [1]);
- la vérification de l'impact acoustique de l'entretien et de l'état des revêtements, par exemple l'usure et la dégradation de l'état de surface, ainsi que le colmatage et l'effet du nettoyage des revêtements poreux;
- la vérification de l'homogénéité longitudinale et latérale sur une zone d'essai;
- le développement de revêtements de chaussée moins bruyants et l'étude de l'interaction pneumatique/chaussée.
NOTE Le présent document ne décrit pas les conditions d'application pour les besoins formels du mesurage selon la méthode CPX. Ces conditions peuvent être définies dans d'autres normes ou dans des textes de loi. Toutefois, certains conseils vis-à-vis de l'applicabilité de l'ISO 11819‑1 et du présent document sont donnés à l'Annexe D.
Les mesures réalisées avec la méthode CPX sont plus rapides et plus pratiques que celles réalisées avec la méthode SPB, mais elles sont plus limitées dans le sens où elles ne sont applicables que dans les cas où le bruit de contact pneumatique/chaussée prédomine et où le bruit du groupe motopropulseur peut être négligé. Par ailleurs, elle ne peut pas prendre en compte le bruit de contact pneumatique/chaussée des véhicules lourds de façon aussi complète que la méthode SPB car elle repose sur l'évaluation du bruit émis par un pneumatique de camion léger pour caractériser les pneumatiques de véhicules lourds et ne prend pas en compte le bruit du groupe motopropulseur.
Akustika - Merjenje vpliva cestnih površin na prometni hrup - 2. del: Metoda merjenja v neposredni bližini (ISO 11819-2:2017)
Ta standard določa metodo za merjenje učinka cestnih površin na hrup cestnega prometa v primerih, ko prevladuje hrup pnevmatik/prometa.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2017
Akustika - Merjenje vpliva cestnih površin na prometni hrup - 2. del: Metoda
merjenja v neposredni bližini (ISO 11819-2:2017)
Acoustics - Measurement of the influence of road surfaces on traffic noise - Part 2: The
close-proximity method (ISO 11819-2:2017)
Akustik - Messung des Einflusses von Straßenoberflächen auf Verkehrsgeräusche - Teil
1: Nahfeldmessmethode (ISO 11819-2:2017)
Acoustique - Méthode de mesurage de l'influence des revêtements de chaussées sur le
bruit émis par la circulation - Partie 2: Méthode de proximité immédiate (ISO 11819-
2:2017)
Ta slovenski standard je istoveten z: EN ISO 11819-2:2017
ICS:
17.140.30 Emisija hrupa transportnih Noise emitted by means of
sredstev transport
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 11819-2
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2017
EUROPÄISCHE NORM
ICS 17.140.30
English Version
Acoustics - Measurement of the influence of road surfaces
on traffic noise - Part 2: The close-proximity method (ISO
11819-2:2017)
Acoustique - Méthode de mesurage de l'influence des Akustik - Messung des Einflusses von
revêtements de chaussées sur le bruit émis par la Straßenoberflächen auf Verkehrsgeräusche - Teil 2:
circulation - Partie 2: Méthode de proximité immédiate Nahfeldmessverfahren (ISO 11819-2:2017)
(ISO 11819-2:2017)
This European Standard was approved by CEN on 19 January 2017.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 11819-2:2017 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 11819-2:2017) has been prepared by Technical Committee ISO/TC 43
“Acoustics” in collaboration with Technical Committee CEN/TC 227 “Road materials” the secretariat of
which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by October 2017, and conflicting national standards shall
be withdrawn at the latest by October 2017.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 11819-2:2017 has been approved by CEN as EN ISO 11819-2:2017 without any
modification.
INTERNATIONAL ISO
STANDARD 11819-2
First edition
2017-03
Acoustics — Measurement of the
influence of road surfaces on traffic
noise —
Part 2:
The close-proximity method
Acoustique — Méthode de mesurage de l’influence des revêtements de
chaussées sur le bruit émis par la circulation —
Partie 2: Méthode de proximité immédiate
Reference number
ISO 11819-2:2017(E)
©
ISO 2017
ISO 11819-2:2017(E)
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
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ii © ISO 2017 – All rights reserved
ISO 11819-2:2017(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
3.1 Road and pavement related definitions . 2
3.2 Measurement methods and equipment . 2
3.3 Acoustic quantities and symbols . 3
3.4 Symbols used for correction terms . 4
4 Symbols and abbreviated terms . 4
5 Measurement principle . 6
6 Measuring instruments . 6
6.1 Sound level instrumentation. 6
6.2 Frequency analysis instrumentation . 7
6.3 Sound calibration instrumentation . 7
6.4 Vehicle speed measuring instrumentation . 7
6.5 Position monitoring instrumentation . 7
6.6 Temperature measuring instrumentation . 7
6.7 Tyre load measuring equipment . 7
6.8 Inflation pressure measuring equipment . 7
6.9 Verification of measuring system and measuring instrumentation . 7
7 Test sites . 8
8 Meteorological conditions . 8
8.1 Wind . 8
8.2 Temperature and other weather-related issues. 8
9 Test vehicle . 9
9.1 General design . 9
9.2 Microphone positions and mounting . 9
9.3 Performance requirements and conformity of the test vehicle .11
9.4 Reference tyres .11
9.5 Tyre rubber hardness.11
9.6 Tyre mounting .11
9.7 Tyre run-in .12
10 Measurement procedure .12
10.1 Preparations for measurements .12
10.2 Measurement of sound .12
10.3 Procedure for study of typical road section .12
10.4 Minimum number of runs for very short road sections .13
10.5 Lateral position on the road .13
10.6 Longitudinal position on the road .13
10.7 Consideration of disturbing noise .13
10.8 Test vehicle speed .13
10.8.1 Reference speeds .13
10.8.2 Test speed and acceptable deviations .13
10.9 Tyre loads .14
10.10 Tyre inflation .14
10.11 Temperature measurement .14
10.11.1 General.14
10.11.2 Air temperature .15
10.11.3 Road surface temperature (optional) .15
ISO 11819-2:2017(E)
10.12 Overview and summary .15
11 Analysis procedure .15
11.1 Definition of steps in the calculation process .15
11.2 Results expressed as overall levels .16
11.2.1 General.16
11.2.2 Case A .17
11.2.3 Case B.17
11.2.4 Expression of CPX levels .17
11.3 Results expressed as one-third-octave-band levels .18
11.3.1 General.18
11.3.2 Case A .18
11.3.3 Case B.18
11.4 Correction for analysis of spectral levels .18
11.5 Acoustic variability .18
12 Measurement uncertainty assessment according to ISO/IEC Guide 98-3 .19
13 Repeatability and reproducibility: System comparison according to ISO 5725-2 .21
14 Test report .21
Annex A (normative) Certification of the test vehicle.24
Annex B (normative) Averaging within each road segment .30
Annex C (informative) Detailed explanation of the calculation procedure .32
Annex D (informative) Applicability of ISO 11819 methods.37
Annex E (informative) Guidelines for design and use of the test vehicle .39
Annex F (informative) Guidelines for measurements .43
Annex G (informative) Application of the CPX method for surveying large road networks .45
Annex H (informative) Application of the CPX method for other objectives .48
Annex I (informative) Summary of measurement parameters .49
Annex J (informative) Validity and stability of the method .50
Annex K (informative) Measurement uncertainty .53
Annex L (informative) Reference road surface .56
Annex M (informative) Calculation of close-proximity sound indices .58
Annex N (informative) Summary of measuring and data-processing procedures .59
Annex O (informative) Example of test report .61
Bibliography .64
iv © ISO 2017 – All rights reserved
ISO 11819-2:2017(E)
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 technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.
A list of all parts in the ISO 11819 series can be found on the ISO website.
ISO 11819-2:2017(E)
Introduction
The emission and propagation of road traffic noise greatly depends on road surface characteristics,
notably on texture, flow resistivity and acoustic absorption. All these characteristics influence the
generation of tyre/road noise and, in addition, the acoustic absorption can influence the propagation
of sound, particularly when the propagation takes place close to the surface. Power unit noise, which is
usually generated at a greater height above the road surface than tyre/road noise, may also be affected
during propagation by the porosity characteristics of the road surface. These effects lead to differences in
sound pressure levels, associated with a given traffic flow and composition, from different road surfaces
of up to 15 dB, which can have a substantial impact on the environmental quality alongside a road.
It is therefore important to be able to measure the influence of surface characteristics on tyre/road noise
by a standardized method. Within the constraints of this method, this document offers an objective
rating of the road characteristics to satisfy a need expressed by road planners, road administrators,
contractors, manufacturers of so-called “low-noise surfaces” and other parties concerned with the
control of road traffic noise.
A method satisfying the needs expressed in the foregoing, but having serious practical constraints,
appears in ISO 11819-1. That method, called the statistical pass-by (SPB) method, is intended for
use essentially for two main purposes. It can be used: first, to classify surfaces in typical and good
condition as a type according to their influence on traffic noise (surface classification); and second, to
evaluate the influence on traffic noise of different surfaces at particular sites irrespective of condition
and age. However, due to severe requirements on the acoustical environment at the measurement site,
the method cannot generally be used for approval of new or rebuilt surfaces at any arbitrary location.
In addition, the SPB method has a number of other practical limitations, which are outlined in Annex D.
The method specified in this document, together with ISO/TS 11819-3, complements the SPB method in
applications where the latter has limitations.
vi © ISO 2017 – All rights reserved
INTERNATIONAL STANDARD ISO 11819-2:2017(E)
Acoustics — Measurement of the influence of road surfaces
on traffic noise —
Part 2:
The close-proximity method
1 Scope
This document specifies a method of evaluating different road surfaces with respect to their influence
on traffic noise, under conditions when tyre/road noise dominates. The interpretation of the results
applies to free-flowing traffic travelling on essentially level roads at constant speeds of 40 km/h and
upwards, in which cases tyre/road noise is assumed to dominate (although in some countries it is
possible that tyre/road noise does not dominate at 40 km/h when the proportion of heavy vehicles is
high). For other driving conditions where traffic is not free-flowing, such as at junctions or under heavy
acceleration, and where the traffic is congested, the influence of the road surface on noise emission is
more complex. This is also the case for roads with high longitudinal gradients and a high proportion of
heavy vehicles.
A standard method for comparing noise characteristics of road surfaces gives road and environment
authorities a tool for establishing common practices or limits as to the use of surfacings meeting certain
noise criteria. However, it is not within the scope of this document to suggest such criteria.
ISO 11819-1 defines another method: the statistical pass-by (SPB) method. The close-proximity (CPX)
method specified in the present document has the same main objectives as the SPB method, but is
intended to be used specifically in applications that are complementary to it, such as:
— noise characterization of road surfaces at almost any arbitrary site, with the main purpose of
checking compliance with a surface specification (an example for conformity of production is
suggested in Reference [1]);
— checking the acoustic effect of maintenance and condition, e.g. wear of and damage to surfaces, as
well as clogging and the effect of cleaning of porous surfaces;
— checking the longitudinal and lateral homogeneity of a road section;
— the development of quieter road surfaces and research on tyre/road interaction.
NOTE This document does not describe the conditions of application for formal purposes of the measurement
with the CPX method. Such conditions may be defined in other standards or legal texts. However, suggestions for
the applicability of ISO 11819-1 and this document are provided in Annex D.
Measurements with the CPX method are faster and more practical than with the SPB method, but are
more limited in the sense that it is relevant only in cases where tyre/road noise dominates and power
unit noise can be neglected. Furthermore, it cannot take heavy vehicle tyre/road noise into account as
fully as the SPB method can, since it uses a light truck tyre as a proxy for heavy vehicle tyres and does
not take power unit noise into account.
The CPX method specified in this document is intended to measure the properties of road surfaces,
not the properties of tyres. If the method is used for research purposes, to provide an indication of
differences between tyres, the loads and inflations would normally be adjusted to other values than
specified in this document.
ISO 11819-2:2017(E)
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method
for the determination of repeatability and reproducibility of a standard measurement method
ISO 11819-1, Acoustics — Measurement of the influence of road surfaces on traffic noise — Part 1:
Statistical Pass-By method
ISO/TS 11819-3, Acoustics — Measurement of the influence of road surfaces on traffic noise — Part 3:
Reference tyres
ISO/TS 13471-1, Acoustics — Temperature influence on tyre/road noise measurement — Part 1: Correction
for temperature when testing with the CPX method
IEC 60942, Electroacoustics — Sound calibrators
IEC 61260-1, Electroacoustics — Octave-band and fractional-octave-band filters — Part 1: Specifications
IEC 61672-1, Electroacoustics — Sound level meters — Part 1: Specifications
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM: 1995)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11819-1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1 Road and pavement related definitions
3.1.1
road section
total stretch of the road lane subject to testing
3.1.2
road segment
part of a road section, being 20 m long and intended for normalization of sound pressure levels from the
actual speed on that segment to a certain reference speed
3.2 Measurement methods and equipment
3.2.1
statistical pass-by method
SPB method
measurement procedure designed to evaluate vehicle and traffic noise generated on different sections
of road surface under specific traffic conditions
Note 1 to entry: The measurements are taken from a great number of vehicles operating normally on the road.
Results obtained using this procedure are normalized to standard speeds according to the category or type of
road being considered. The method is specified in ISO 11819-1.
2 © ISO 2017 – All rights reserved
ISO 11819-2:2017(E)
3.2.2
reference tyres
test tyres specified for the purpose of representing certain features in tyre/road sound emission,
designed and constructed for use in this method with specified and reproducible standard properties
Note 1 to entry: The reference tyres are specified in ISO/TS 11819-3.
3.3 Acoustic quantities and symbols
3.3.1
close-proximity level
CPX level
L
CPX
time-averaged A-weighted sound pressure level (SPL) of the tyre/road noise as determined by the CPX
method, either broadband or spectral bands, as required
Note 1 to entry: The CPX level is expressed in decibels. In order to provide more information, additional suffixes
are used; see Table 1.
3.3.2
CPX level for passenger cars and other light vehicles
L
CPX:P
A-weighted sound pressure level characterizing the road surface under test, which is based on the
tyre/road sound pressure levels of one or more tyres representative of passenger car tyres
Note 1 to entry: The L is expressed in decibels. Passenger car tyres are denoted P1, P2 … .
CPX:P
3.3.3
CPX level for heavy vehicles
L
CPX:H
A-weighted sound pressure level characterizing the road surface under test, which is based on the
tyre/road sound pressure levels of one or more tyres representative of heavy vehicle tyres
Note 1 to entry: The L is expressed in decibels. Heavy vehicle tyres are denoted H1, H2 … .
CPX:H
3.3.4
CPX index
L
CPX:I
index composed of the weighted average of the CPX level for passenger cars and other light vehicles (
L ) and CPX level for heavy vehicles ( L )
CPX:P CPX:H
Note 1 to entry: The L is expressed in decibels. The method is intended to describe performance of road
CPX:I
surfaces for a certain traffic composition in a similar way to the SPB method in ISO 11819-1, although the
numerical values for a given speed are higher. More information on the calculation of CPX indices is given in
Annex M.
3.3.5
acoustic variability due to road surface inhomogeneities
s
t
standard deviation of the A-weighted sound pressure levels over all segments, when using reference tyre t
Note 1 to entry: The acoustic variability is expressed in decibels. This variability is normally dominated by
road surface variations, although random uncertainties could add a little. Measurement speed and wheel tracks
normally do not influence this value significantly. This measure is, therefore, considered to be an indication of
road surface homogeneity as far as noise properties are concerned.
ISO 11819-2:2017(E)
3.4 Symbols used for correction terms
3.4.1
measured speed
ν
actual speed during a measurement
Note 1 to entry: The measured speed is expressed in kilometres per hour.
3.4.2
reference speed
v
ref
preferred speed for measurement
Note 1 to entry: The reference speed is expressed in kilometres per hour. Most commonly used reference speeds
are 50 km/h, 80 km/h and 110 km/h, but alternative speeds may be used if required for technical, safety or
legislative reasons.
3.4.3
speed coefficient
B
coefficient determining the speed dependence of the sound pressure levels, normally used for correction
of the sound pressure level to a certain reference speed
Note 1 to entry: The correction for deviations from the reference speed is given by the expression B⋅lg(v/v ),
ref
expressed in decibels, where B is dimensionless. Values of B for specific pavements are given in 11.1 d).
3.4.4
temperature coefficient
γ
t
coefficient used for correcting CPX level for the effect of temperature for tyre t
Note 1 to entry: The temperature coefficient is expressed in decibels per degree Celcius.
3.4.5
rubber hardness coefficient
β
t
coefficient used for correcting CPX level for the effect of tread rubber hardness of tyre t
Note 1 to entry: The rubber hardness coefficient is expressed in decibels per Shore A. Refer to 11.1 f) for
application.
3.4.6
device-dependent correction for sound reflections
C
d, f
correction for individual measuring devices in one-third-octave bands from 315 Hz to 5 000 Hz with
the centre frequency f, to account for deviations from acoustic hemi-free-field conditions
Note 1 to entry: The device correction for sound reflections is expressed in decibels. Information on the
determination of C is given in A.2.
d,f
4 Symbols and abbreviated terms
Table 1 lists the symbols used in this document. All acoustic variables are A-weighted.
4 © ISO 2017 – All rights reserved
ISO 11819-2:2017(E)
Table 1 — Symbols and abbreviated terms used in this document and their value or unit
Symbol Value/unit Explanation
Measure of the acoustic properties of the tested
L
dB
CPX:t,v
ref road section, for tyre t, at the reference speed v
ref
Energy-based average spectrum at the microphone
L'
dB positions m = 1 and m = 2 (for the subscript
CPX:t,,wr,,if
symbols, see below)
Time-averaged tyre/road SPL (“CPX level”) over the
L
dB
CPXt:,wr,,if,,mv,
ref
time it takes to run a road segment (20 m)
Measure of the acoustic properties of the tested road
L
dB section, for tyre(s) “P” representing passenger cars
CPX:P,v
ref
and other light vehicles, at the reference speed, v
ref
Measure of the acoustic properties of the tested
L
dB road section, for tyre(s) “H” representing heavy
CPX:H,v
ref
vehicles, at the reference speed, v
ref
“CPX index” representing the overall acoustic
L =
CPX:I,v
ref
properties of the tested road section, for tyre(s)
dB
representing light and heavy vehicles combined
05,,⋅+LL05⋅
CPX:PC,,vvPX:H
refref
(with equal weighting), at the reference speed, v
ref
Speed coefficient; i.e. increase in CPX level with
B Dimensionless tenfold increase in speed, to be able to correct for
deviations from the reference speed, v
ref
Device correction term (frequency dependent) to
C dB
d, f
account for deviations from free field conditions
Temperature coefficient for correction for tyre t to
dB/°C account for deviations from reference temperature
γ
t
of 20 °C. The value is negative for tyres P1 and H1
Rubber hardness coefficient for correction for
dB/Shore A tyre t to account for deviations from a reference
β
t
hardness
315 Hz, …
f One-third-octave-band centre frequency
5 000 Hz
i 1, 2, 3 … Road segment number
1, 2 Front and rear mandatory microphone positions
m
3, 4, 5, 6 Optional microphone positions
Total number of runs, n , wheel tracks, n , or road
r w
n 1, 2, 3 …
segments, n
i
r 1, 2, 3 … Run number
Rubber hardness in durometer type A of test tyre
H
A
tread
H Reference rubber hardness in durometer type A
ref
Acoustic variability; a measure of road surface
s dB
t
homogeneity
Tyre type defined for testing
P
t Passenger car tyres
H
Heavy vehicle tyres or approximate proxy
Air temperature at road segment i (index not
T °C needed if continuous temperature measurements
i
are not made)
ISO 11819-2:2017(E)
Table 1 (continued)
Symbol Value/unit Explanation
ν km/h Actual measured speed
Preferred nominal speed for measurement; thus a
v km/h
ref
reference speed used when reporting results
The wheel tracks in a lane where test tyres are
rolling. Track number 1 is closest to the road
w 1, 2, 3, …
shoulder, 2 is the opposite wheel track within that
same lane; 3, 4, and so on are additional tracks
5 Measurement principle
In the CPX method, the average A-weighted SPLs emitted by specified tyres are measured over
an arbitrary or a specified road distance, together with the vehicle testing speed, by at least two
microphones located close to the tyres. For this purpose, a special test vehicle, which is either self-
powered or towed behind another vehicle, is used. Reference tyres are mounted on the test vehicle,
either one by one or both at the same time. Two uniquely different reference tyres have been selected in
order to represent the tyre/road characteristics which are to be studied.
Although the microphones are positioned in close proximity to the source of tyre/road noise, a
substantial part of the propagation effect associated with acoustically absorptive surfaces is actually
included in the microphone signal. This is demonstrated by model calculations and the results of the
CPX validation experiment (References [2], [3]). See Annex D for further information.
The tests are performed with the intention of determining a tyre/road sound pressure level, here
referred to as the CPX level, L , at one or more of the nominated reference speeds. This can be
CPX
achieved by testing at a reference speed or by normalizing for speed deviations.
For each reference tyre and each individual test run with that tyre, the average sound pressure
levels over short measuring distances (segments of 20 m each), together with the corresponding
vehicle speeds, are recorded. The sound pressure level of each segment is normalized to a reference
speed by a simple correction procedure. Averaging is then carried out according to the purpose of the
measurement, i.e. measuring a particular segment or a number of consecutive segments (a section).
The CPX level, L , is the resulting average sound pressure level for the two mandatory
CPX:t,v
ref
microphones at the reference speed, v for reference tyre t, where t is P or H.
ref
Where both close-proximity sound levels have been determined, the close-proximity sound index L
CPX:I
is the average of L and L with equal weight given to the two indices. L is intended for
CPX:P CPX:H CPX:I
single value comparison.
There are some issues in the method which deserve special caution when applying this method, especially
under circumstances that are not the most common. Annex J provides a discussion of such issues.
6 Measuring instruments
6.1 Sound level instrumentation
Within the minimum frequency range of 315 Hz to 5 000 Hz, the sound level meter or the equivalent
measuring system shall meet the requirements of IEC 61672-1, class 1. The microphones shall be of the
“free-field” type.
An appropriate windscreen shall be used having a diameter of at least 90 mm. The sound properties
of windscreens will deteriorate as the material is progressively exposed to dirt. It is therefore good
practice to check the performance of the windscreens frequently and to replace them with new, fresh
material when they show patterns of dirt coverage.
6 © ISO 2017 – All rights reserved
ISO 11819-2:2017(E)
6.2 Frequency analysis instrumentation
Frequency analysis of the measured sound using one-third-octave-band resolution is mandatory. The
range 315 Hz to 5 000 Hz (centre frequencies of one-third-octave bands) is the minimum range to be
covered. The one-third-octave-band filters shall conform to IEC 61260-1.
6.3 Sound calibration instrumentation
At the beginning of the measurements, and following any warm-up time specified by the manufacturer,
the overall sensitivity of the sound level meters or the equivalent measuring system (including the
microphone) shall be checked. If necessary, adjust it according to the manufacturer’s instructions. This
may require use of a standard sound source, such as a calibrator or pistonphone. This check shall be
repeated at the end of the measurements, and at least after every 4 h of operation. Any deviations shall
be recorded in the test report. If the calibration readings differ by more than 0,5 dB between the checks,
all intermediate measurements shall be considered invalid.
The sound calibration device shall meet the requirements of IEC 60942, class 1.
6.4 Vehicle speed measuring instrumentation
The average speed of the vehicle over the measured segment shall be measured, with a maximum
permissible error of ±1 % of the indicated value.
For speed measurement, if a tyre is used it shall not be mounted on a drive axle.
6.5 Position monitoring instrumentation
GPS or other means of identifying the start positions of measurements are very useful in order to avoid
problems in identifying a test section and to be able to return to the same place at a later occasion or
for other types of measurements. It is recommended that the GPS system is of a type specified with a
maximum permissible error of ±5 m.
6.6 Temperature measuring instrumentation
The air and (optional) road temperature measuring instrument(s) shall have a maximum permissible
error of ±1 °C, as specified by the manufacturer. Meters utilizing the infrared technique shall not be
used for air temperature measurements.
6.7 Tyre load measuring equipment
The weighing equipment used to determine the load of the test tyres shall have a maximum perm
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