Road and airfield surface characteristics - Test methods - Part 2: Assessment of the skid resistance of a road pavement surface by the use of dynamic measuring systems

This method defines a process for comparing the friction results from a number of devices.
By combining together the friction and texture from individual measuring devices, it allows skid resistance determined by different dynamic methods to be expressed on a common scale, namely the Skid Resistance Index (SRI).
As its precision has not been determined, the method should not be used in specifications for surface materials.
Friction is essential for a safe grip between vehicle and surface. Surfaces can be in different conditions and of different types, which can lead to varying friction. Another important factor is the climate and weather conditions that indeed affect the friction, in most cases for the worse. This standard excludes surfaces when they are in winter road condition. It also excludes road marking surfaces.

Verfahren zur Bestimmung der Griffigkeit von Fahrbahndecken durch Verwendung von dynamischen Messsystemen

Diese Technische Spezifikation beschreibt ein Verfahren zur Bestimmung der Griffigkeit von Fahrbahndecken für Straßen oder Flugplätzen.
Mit dem hierin festgelegten Verfahren wird eine Vorgehensweise für den Vergleich von Ergebnissen der Bestimmung der Griffigkeit mit verschiedenen Geräten festgelegt.
Durch Verbindung der Reibungsbeiwerte und Texturkennwerte einzelner Messgeräte kann die mit verschie-denen dynamischen Verfahren ermittelte Griffigkeit durch einen gemeinsamen Kennwert, nämlich den Griffig-keitskennwert (SRI), angegeben werden.
Das Verfahren sollte nicht in Leistungsbeschreibungen für Baustoffe für Fahrbahndecken angegeben werden, da seine Präzision noch nicht ermittelt wurde.
Diese Norm gilt nicht für Fahrbahndecken unter den im Winter herrschenden Witterungs¬bedingungen. Sie gilt ebenfalls nicht für die Oberfläche von Straßenmarkierungen.

Caractéristiques de surface des routes et aérodromes - Méthodes d'essai - Partie 2: Évaluation de l’adhérence d’un revêtement de chaussée à l'aide de systèmes de mesure dynamique

La présente méthode définit un processus permettant de comparer les valeurs de frottement obtenues à l'aide de nombreux appareils.
En combinant le frottement et la texture déterminés par des appareils de mesure distincts, elle permet à l'adhérence, déterminée par différentes méthodes dynamiques, d'être exprimée sur une échelle commune, à savoir l'Indice d'Adhérence (SRI).
Étant donné que la fidélité de cette méthode n'a pas été déterminée, il convient de ne pas l'utiliser pour la spécification des matériaux de surface.
Le frottement est essentiel pour une adhérence sûre entre le véhicule et la surface. Les surfaces peuvent être dans différents états et de différents types, ce qui peut conduire à un frottement variable. Les conditions climatiques et météorologiques sont un autre facteur important ayant aussi une incidence, le plus souvent négative, sur le frottement. La présente norme exclut les surfaces lorsqu'elles sont dans des conditions hivernales. Elle ne concerne pas non plus les marquages routiers.

Značilnosti cestnih in letaliških površin - Preskusne metode - 2. del: Ocena torne sposobnosti cestne vozne površine z uporabo dinamičnih merilnih sistemov

Ta tehnična specifikacija opisuje metodo za določanje torne sposobnosti vozne površine ceste ali letališke steze. Ta metoda opredeljuje postopek za primerjanje rezultatov trenja, pridobljenih z različnimi pripomočki. Z združevanjem trenja in teksture, izmerjenih s posameznimi merilnimi pripomočki, omogoča, da se torna sposobnost, določena z različnimi dinamičnimi merilnimi metodami, izrazi s skupno lestvico, namreč z indeksom torne sposobnosti (SRI). Ker natančnost metode ni določena, se ne sme uporabljati pri specifikacijah materialov za površine. Ta standard izključuje površine v zimskem stanju ceste. Izključuje tudi površine s talnimi označbami.

General Information

Status
Published
Public Enquiry End Date
19-Apr-2009
Publication Date
02-May-2010
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
13-Apr-2010
Due Date
18-Jun-2010
Completion Date
03-May-2010

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Standards Content (Sample)

SLOVENSKI STANDARD
SIST-TS CEN/TS 13036-2:2010
01-junij-2010
=QDþLOQRVWLFHVWQLKLQOHWDOLãNLKSRYUãLQ3UHVNXVQHPHWRGHGHO2FHQDWRUQH
VSRVREQRVWLFHVWQHYR]QHSRYUãLQH]XSRUDERGLQDPLþQLKPHULOQLKVLVWHPRY
Road and airfield surface characteristics - Test methods - Part 2: Assessment of the skid
resistance of a road pavement surface by the use of dynamic measuring systems
Verfahren zur Bestimmung der Griffigkeit von Fahrbahndecken durch Verwendung von
dynamischen Messsystemen
Caractéristiques de surface des routes et aérodromes - Méthodes d'essai - Partie 2:
Évaluation de l’adhérence d’un revêtement de chaussée à l'aide de systèmes de mesure
dynamique
Ta slovenski standard je istoveten z: CEN/TS 13036-2:2010
ICS:
17.040.20 Lastnosti površin Properties of surfaces
93.080.10 Gradnja cest Road construction
93.120 *UDGQMDOHWDOLãþ Construction of airports
SIST-TS CEN/TS 13036-2:2010 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TS CEN/TS 13036-2:2010

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SIST-TS CEN/TS 13036-2:2010


TECHNICAL SPECIFICATION
CEN/TS 13036-2

SPÉCIFICATION TECHNIQUE

TECHNISCHE SPEZIFIKATION
March 2010
ICS 17.040.20; 93.080.20
English Version
Road and airfield surface characteristics - Test methods - Part 2:
Assessment of the skid resistance of a road pavement surface
by the use of dynamic measuring systems
Caractéristiques de surface des routes et aérodromes - Oberflächeneigenschaften von Straßen und Flugplätzen -
Méthodes d'essai - Partie 2: Évaluation de l'adhérence d'un Prüfverfahren - Teil 2: Verfahren zur Bestimmung der
revêtement de chaussée à l'aide de systèmes de mesure Griffigkeit von Fahrbahndecken durch Verwendung von
dynamique dynamischen Messsystemen
This Technical Specification (CEN/TS) was approved by CEN on 5 June 2009 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their
comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available
promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS)
until the final decision about the possible conversion of the CEN/TS into an EN is reached.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.






EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2010 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 13036-2:2010: E
worldwide for CEN national Members.

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Contents Page
Foreword .3
Introduction .4
1 Scope .5
2 Normative references .5
3 Symbols, terms and definitions .6
3.1 Symbols .6
3.2 Terms and definitions .6
4 Safety .9
5 Measurement procedure .9
5.1 Friction measurement .9
5.2 Macrotexture measurement . 10
5.3 Measurement location . 10
5.4 Time interval between friction and macrotexture measurements . 10
6 Determination of the Skid Resistance Index (SRI) . 10
6.1 General . 10
6.2 Calculations . 11
6.3 Device-specific parameters . 11
6.4 Precision . 11
6.5 Test report . 11
7 Calibration of friction testing devices . 12
7.1 General . 12
7.2 Surfaces for calibration . 12
7.3 Test conditions . 12
7.4 Calculations . 13
7.5 Types of calibration . 14
7.5.1 General . 14
7.5.2 Type 1 calibration . 15
7.5.3 Type 2 calibration . 15
7.5.4 Type 3 calibration . 16
7.6 Calibration report . 16
7.7 Periodicity . 16
Annex A (informative) Example of calibration calculations report . 17
Bibliography . 43

2

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Foreword
This document (CEN/TS 13036-2:2010) has been prepared by Technical Committee CEN/TC 227 “Road
materials”, the secretariat of which is held by DIN.
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.
This document is one of a series of standards as listed below:
 EN 13036-1, Road and airfield surface characteristics — Test methods — Part 1: Measurement of
pavement surface macrotexture depth using a volumetric patch technique
 CEN/TS 13036-2, Road and airfield surface characteristics — Test methods — Part 2: Assessment
of the skid resistance of a road pavement surface by the use of dynamic measuring systems
 EN 13036-3, Road and airfield surface characteristics — Test methods — Part 3: Measurement of
pavement surface horizontal drainability
 EN 13036-4, Road and airfield surface characteristics — Test methods — Part 4: Method for
measurement of slip/skid resistance of a surface — The pendulum test
 prEN 13036-5, Road and airfield surface characteristics ― Test methods ― Part 5: Determination of
longitudinal unevenness indices
 EN 13036-6, Road and airfield surface characteristics ― Test methods ― Part 6: Measurement of
transverse and longitudinal profiles in the evenness and megatexture wavelength ranges
 EN 13036-7, Road and airfield surface characteristics — Test methods — Part 7: Irregularity
measurement of pavement courses: the straightedge test
 EN 13036-8, Road and airfield surface characteristics — Test methods — Part 8: Determination of
transverse unevenness indices
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria, Croatia, Cyprus,
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.

3

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Introduction
The skid resistance of a surface is determined by considering the friction measurement carried out using one
of a number of permitted devices, and a measurement of surface texture also carried out using one of a
number of permitted procedures. The permitted devices for friction measurements are those which have their
measuring principle and procedure described in CEN/TS 15901-1 to CEN/TS 15901-10.
Where required, the procedures set out in this Technical Specification may be used for the measurement of
friction only.
If there is a need to compare the skid resistance of a surface measured by different devices, Annex A
(informative) may be used. That annex, by combining together the friction and texture for individual measuring
devices, produces a skid resistance index (SRI).
NOTE The use of an informative annex is not obligatory.
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1 Scope
This Technical Specification describes a method for determining the skid resistance of the pavement surface
of a road or airfield.
This method defines a process for comparing the friction results from a number of devices. By combining
together the friction and texture from individual measuring devices, it allows skid resistance determined by
different dynamic methods to be expressed on a common scale, namely the Skid Resistance Index (SRI). As
its precision has not been determined, the method should not be used in specifications for surface materials.
This standard excludes surfaces when they are in winter road condition. It also excludes road marking
surfaces.
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.
EN 13036-1, Road and airfield surface characteristics ― Test methods ― Part 1: Measurement of pavement
surface macrotexture depth using a volumetric patch technique
CEN/TS 15901-1, Road and airfield surface characteristics ― Part 1: Procedure for determining the skid
resistance of a pavement surface using a device with longitudinal fixed slip ratio (LFCS): RoadSTAR
CEN/TS 15901-2, Road and airfield surface characteristics ― Part 2: Procedure for determining the skid
resistance of a pavement surface using a device with longitudinal controlled slip (LFCRNL): ROAR (Road
Analyser and Recorder of Norsemeter)
CEN/TS 15901-3, Road and airfield surface characteristics ― Part 3: Procedure for determining the skid
resistance of a pavement surface using a device with longitudinal controlled slip (LFCA): The ADHERA
CEN/TS 15901-4, Road and airfield surface characteristics ― Part 4: Procedure for determining the skid
resistance of pavements using a device with longitudinal controlled slip (LFCT): Tatra Runway Tester (TRT)
CEN/TS 15901-5, Road and airfield surface characteristics ― Part 5: Procedure for determining the skid
resistance of a pavement surface using a device with longitudinal controlled slip (LFCRDK): ROAR (Road
Analyser and Recorder of Norsemeter)
CEN/TS 15901-6, Road and airfield surface characteristics ― Part 6: Procedure for determining the skid
resistance of a pavement surface by measurement of the sideway force coefficient (SFCS): SCRIM®
CEN/TS 15901-7, Road and airfield surface characteristics ― Part 7: Procedure for determining the skid
resistance of a pavement surface using a device with longitudinal fixed slip ratio (LFCG): the GripTester®
CEN/TS 15901-8, Road and airfield surface characteristics ― Part 8: Procedure for determining the skid
resistance of a pavement surface by measurement of the sideway-force coefficient (SFCD): SKM
CEN/TS 15901-9, Road and airfield surface characteristics ― Part 9: Procedure for determining the skid
resistance of a pavement surface by measurement of the longitudinal friction coefficient (LFCD): DWWNL skid
resistance trailer
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CEN/TS 15901-10, Road and airfield surface characteristics ― Part 10: Procedure for determining the skid
resistance of a pavement surface using a device with longitudinal block measurement (LFCSK): the
Skiddometer BV-8
EN ISO 13473-1, Characterization of pavement texture by use of surface profiles ― Part 1: Determination of
Mean Profile Depth (ISO 13473-1:1997)
3 Symbols, terms and definitions
3.1 Symbols
B Device-specific parameter
SRI Skid Resistance Index
MPD Mean Profile Depth
MTD Mean Texture Depth
F Measured friction value at speed S
F Regression line intercept at speed zero

0
m Number of valid results from a measurement series
M Total number of valid results per device
N Total number of friction testing devices meeting in a calibration exercise
N Number of reference devices participating in a calibration exercise
R
n Number of surfaces used for calibrating friction testing devices
r Number of runs of a given device on a given surface
S Slip speed
S Speed parameter
0
V Operating speed
β Regression line slope
σ Residual standard deviation of SRI
SRI
σ Residual standard deviation of S
S 0
0
3.2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.2.1
friction
resistance to relative motion between two bodies in contact
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NOTE 1 The frictional force is the force which acts tangentially in the contact area.
NOTE 2 Friction is essential for a safe grip between vehicle and surface. Surfaces can be in different conditions and of
different types, which can lead to varying friction. Another important factor is the climate and weather conditions that
indeed affect the friction, in most cases for the worse.
3.2.2
friction measuring device
device that measures the frictional force acting tangentially in the contact area
NOTE The results from the friction measuring device are commonly known as a "device coefficient" or "friction value".
3.2.3
skid resistance
characterisation of the friction of a road surface when measured in accordance with a standardised method
NOTE 1 Numerous factors contribute to skid resistance, in particular:
 physical properties of specific friction measuring devices − the contact pressure, contact area, tread pattern
and rubber composition of the tyre, or slider in the case of a some test devices;
 slip speed of the tyre/slider over the surface and the vehicle speed;
 surface conditions, i.e. wet or dry, clean or contaminated surface, as well as air and water temperature;
 surface texture characteristics of the road surface, i.e. the microtexture and macrotexture of the surface.
If these factors are held constant for a particular measuring device, or if the conditions of test are standardized,
the skid resistance of the surface can be determined.
NOTE 2 The skid resistance of a road surface in Europe varies seasonally. Generally, wet skid resistance is higher in
winter as a result of the effects of wet detritus and the effects of frost and wear by tyres on microtexture and macrotexture.
Wet skid resistance is lower in summer as a result of dry polishing by tyres in the presence of fine detritus.
NOTE 3 The change in skid resistance of a surface in service is affected by the volume of traffic and the composition of
the traffic, i.e. cars, buses, commercial vehicles of different sizes, as the tyres of these vehicles polish and/or wear away
the surfacing material in different ways. The geometry of the road will affect the change in skid resistance. Generally, tyres
polish less on straight roads than on bends.
NOTE 4 Where the surface contains aggregate with a coating of binder, e.g. bitumen, resin or Portland cement, the
skid resistance will change as the coating is worn away by tyres.
NOTE 5 Skid resistance is a particular friction characteristic. Devices for measuring this surface characteristic may be
known as skid resistance or friction measuring devices.
3.2.4
Skid Resistance Index
SRI
objective estimate of skid resistance which is independent of the friction measuring device used
NOTE 1 Being a surface-related property, skid resistance is (ideally) independent of speed, measuring device and
measuring method. Currently, there is no method available to measure it. However, a common index (Skid Resistance
Index, SRI), which constitutes an estimate of skid resistance, can be determined as described in Clause 6.
NOTE 2 The SRI is intended to facilitate objective comparison of surfaces, and is based on friction and macrotexture
measurements and subsequent calculations. The friction measured with a particular device is combined with
corresponding macrotexture data as well as pre-determined device-related constants representing most devices used in
Europe, normalized to a certain fixed slip speed, to estimate the Skid Resistance Index.
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3.2.5
microtexture
deviation of a pavement surface from a true planar surface with characteristic dimensions along the surface of
less than 0,5 mm, corresponding to texture wavelengths with one-third-octave bands with up to 0,5 mm of
centre wavelengths
NOTE 1 Peak to peak amplitudes normally vary in the range 0,001 mm to 0,5 mm.
NOTE 2 Those devices that utilize a relatively low slip speed measure primarily the component of friction affected by
microtexture. Microtexture makes the surface feel harsh but is normally too small to be observed with the unaided eye. It is
produced by the surface characteristics of the individual aggregate or other particles that come into direct contact with the
tyre. It is a primary component in skid resistance at slow speeds.
3.2.6
macrotexture
deviation of a pavement surface from a true planar surface with characteristic dimensions along the surface of
0,5 mm to 50 mm, corresponding to texture wavelengths with one-third-octave bands including the range
0,63 mm to 50 mm of centre wavelengths
NOTE 1 Peak to peak amplitudes normally vary in the range 0,1 mm to 20 mm.
NOTE 2 This type of texture has wavelengths of the same order of size as the tyre-tread elements. It is normally
produced by suitable proportioning of the aggregate and mortar of the mix or by surface treatments. It is a major factor
influencing skid resistance at high speeds but it also has an effect at low speeds.
3.2.7
wheel path
parts of the pavement surface where the majority of vehicle wheel passes are concentrated
NOTE 1 The wheel path is not a fixed location on a pavement surface. On a worn pavement, the wheel path is usually
easily identified visually. On a newly laid surface, the position of the wheel path should be estimated by experienced
device operators.
NOTE 2 For special circumstances such as acceptance tests, a particular path may be defined, for example,
(700 ± 150) mm from the edge of the running lane of a road.
3.2.8
Mean Profile Depth
MPD
descriptor of macrotexture, obtained from a texture profile measurement as defined in EN ISO 13473-1
3.2.9
Mean Texture Depth
MTD
result of the volumetric measurement of macrotexture in accordance with EN 13036-1
3.2.10
calibration
periodic adjustment of the offset, the gain and the linearity of the output of a measurement method so that all
the calibrated devices of a particular type deliver the same value within a known and accepted range of
uncertainty, when measuring under identical conditions within given boundaries or range of parameters, e.g.
speed, texture, wetting, temperature
NOTE The method of calibration of devices used to produce a Skid Resistance Index is given in Clause 7.
3.2.11
calibrated device
device that holds a valid calibration certificate following a Type 1, Type 2 or Type 3 calibration
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3.2.12
new device
any device which has not been calibrated
3.2.13
reference device
any friction device calibrated in accordance with a Type 1 or Type 2 calibration procedure
NOTE The reference device is used in conjunction with the procedure to determine the Skid Resistance Index.
3.2.14
operating speed
speed at which the device traverses the surface
3.2.15
slip speed
relative speed between the tyre and the travelled surface in the contact area
3.2.16
slip ratio
slip speed divided by the operating speed
NOTE This may be expressed in tables or reports as a percentage but in any calculation, as part of the procedure of
the Technical Specification, its decimal value should be used.
3.2.17
contact area
overall area of the road surface instantaneously in contact with a tyre
NOTE This term describes the overall area generally covered by the tyre. Due to the effects of surface texture or any
tyre tread pattern, not all of the tyre or road surface in the contact area may be in contact at any instant.
3.2.18
test section
length of road between defined points (e.g. location references, specific features, or measured distances)
comprising a number of subsections over which a continuous sequence of measurements is made
4 Safety
Appropriate safety measures shall be in place to maintain a safe working area in accordance with regulations,
including measures to control traffic as necessary.
All devices should be operated safely and fitted with safety devices in accordance with the relevant
procedures and regulations.
NOTE The wetting of surfaces can have an effect on other users of the site and every effort should be made to
ensure that they do not have to make any sudden changes in speed or direction.
5 Measurement procedure
5.1 Friction measurement
The skid resistance of the surface at the time of test is reported as the friction measurement carried out by
one of the devices included in CEN/TS 15901-1 to -10 and according to the specific procedure described in
the relevant Technical Specification. The information required to be reported by the relevant specification
procedure for the device and this Technical Specification shall be reported.
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NOTE Measurements should not be made when rainfall significantly increases the depth of water applied by the
friction measuring device.
5.2 Macrotexture measurement
The macrotexture measurement shall be carried out either in accordance with EN ISO 13473-1 or
EN 13036-1.
5.3 Measurement location
Under normal circumstances the friction as well as the macrotexture measurement shall be taken along a line
nominally in the nearside wheel path of the most heavily trafficked lane; the actual distance from the edge will
vary. However when required other tracks across the surface may be measured. The transverse location of all
tests shall be defined and reported.
NOTE 1 Other transverse locations may need to be measured for example to demonstrate that a surface is consistent
transversely when first constructed.
NOTE 2 The locations for testing airfield pavements may be given in ICAO International Standards and recommended
practices: Annex 14 to the Convention on International Civil Aviation.
Devices that measure macrotexture or friction as they travel, sample the surface at discrete intervals, the
longitudinal test location is given in the operating procedure of the device. Static devices measure at sampling
intervals defined in the procedure or as defined by the physical constraints of the site, the tests location shall
be recorded. In addition for all devices, the start and finish location, referenced along the test section from a
known point, shall be recorded.
5.4 Time interval between friction and macrotexture measurements
The time interval between the friction measurement, on one hand, and the macrotexture measurement, on the
other hand, shall not exceed seven days.
NOTE If macrotexture measurements cannot be carried out on the same area at the same time as the friction
measurement, they should be taken on the same area at a time as close as practicable.
6 Determination of the Skid Resistance Index (SRI)
6.1 General
Where required, this procedure enables the measurement of friction made with different devices to be brought
to a common index, known as the Skid Resistance Index (SRI) using a complementary macrotexture
measurement.
The measurement of friction shall deliver a friction coefficient value (F, dimensionless) and the actual slip
speed (S, in kilometres per hour).
The slip speed (S) shall be derived from the operating speed (V) using the following formulae depending on
the test principle used by the device:
 Longitudinal force measurement: S = V* Slip ratio;
NOTE 1 For locked-wheel systems, the slip ratio equals 1.
 Sideway force measurement: S = V* sin(Yaw angle).
NOTE 2 The yaw angle is the angle formed by the equatorial plane of a wheel and the direction of travel of the vehicle.
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The macrotexture measurement shall deliver the Mean Profile Depth (MPD) of the tested section as defined in
EN ISO 13473-1. This is the preferred method. If no adequate profilometer is available, the macrotexture can
be measured by means of the volumetric method in accordance with EN 13036-1, which gives the Mean
Texture Depth of the tested section (MTD, in millimetres).
6.2 Calculations
The estimate of the Skid Resistance Index (SRI) shall be computed by means of the following equations:
[]()S−30 / S
0
SRI = BFe (1)
with
b
S = aMPD (2)
0
where
F is the measured friction coefficient at slip speed (S, in kilometres per hour);
a, b and B are parameters specific to the friction measuring device used.
From an MTD value, one can best estimate MPD by the formula:
MPD = (5 MTD − 1)/4 for MTD > 0,2 (3)
MPD = 0 for MTD < 0,2 (4)
which has been obtained by correlating MTD with MPD.
6.3 Device-specific parameters
Parameters a, b and B are determined in the course of a calibration exercise as described in Clause 7.
6.4 Precision
The precision has not been determined. Research is still ongoing.
6.5 Test report
The report shall include the following:
a) date and time of the measurement(s);
b) identification of the operator(s);
c) identification of the test section;
d) identification of the friction testing device;
e) values of constants a, b and B together with the reference to their determination;
f) identification of the texture measuring device;
g) value of MPD or MTD of the section;
h) friction value of the section;
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