kSIST FprEN 17019:2016

SLOVENSKI STANDARD
01-oktober-2016
Tehtanje cestnih vozil v gibanju
Weigh-in-Motion of Road Vehicles
Wägung von Fahrzeugen während dem Fahrt
Pesage en marche des véhicules routiers
Ta slovenski standard je istoveten z: FprEN 17019
ICS:
17.100 Merjenje sile, teže in tlaka Measurement of force,
weight and pressure
43.180 'LDJQRVWLþQDYGUåHYDOQDLQ Diagnostic, maintenance and
SUHVNXVQDRSUHPD test equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

FINAL DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2016
ICS 17.100
English Version
Weigh-in-Motion of road vehicles - Requirements
Pesage en marche des véhicules routiers - Exigences Wägung von Fahrzeugen während der Fahrt -
Anforderungen
This draft European Standard is submitted to CEN members for formal vote. It has been drawn up by the Technical Committee
CEN/SS F05.
If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprEN 17019:2016 E
worldwide for CEN national Members.

Contents Page
European foreword .4
Introduction .5
1 Scope .6
2 Normative references .6
3 Terms, definitions, symbols and abbreviations .7
3.1 Terms and definitions taken from the Vocabulary of International Metrology .7
3.2 Specific statistical and metrological terms and definitions . 10
3.3 Terms and definitions related to vehicles . 11
3.4 Terms and definitions related to WIM systems . 13
3.5 List of symbols and abbreviations . 14
4 Site selection criteria. 15
4.1 Road geometry . 15
4.2 Pavement characteristics . 15
4.3 WIM site classes (not for B-WIM) . 16
4.4 Particular requirements for bridges . 17
5 Operating conditions and environmental requirements . 18
5.1 General conditions . 18
5.2 Sensors requirements . 19
5.3 Electronics requirements . 20
6 Accuracy class tolerances with respect to the weights . 20
6.1 General clauses – Detailed procedure . 20
6.2 General – Simplified procedure . 21
6.3 Accuracy classes . 21
6.4 Other tolerances. 24
6.5 Reference gross weights and axle loads measured statically . 24
7 On-site system checks and calibration . 25
7.1 General clauses . 25
7.2 Definitions of test conditions . 25
7.3 Minimum required test conditions . 26
7.4 Calibration methods . 26
8 Type (model) approval . 29
8.1 General . 29
8.2 Choice of test site . 29
8.3 Installation and pre-calibration of the system . 29
8.4 Test plan . 30
8.5 Reference static loads and weights . 30
8.6 Test analysis and report . 31
9 Initial and in-service verifications . 31
9.1 Initial verification . 31
9.2 In-service verification . 31
10 Procedure to check the accuracy of a WIM system by testing . 32
10.1 General rules – Detailed procedure . 32
10.2 General rules – Simplified procedure . 32
10.3 Test plans – Detailed procedure. 32
10.4 Test plans – Simplified procedure . 33
10.5 Minimum required confidence levels – Detailed procedure . 33
10.6 Minimum required confidence levels – Simplified procedure . 34
10.7 Test results analysis – Detailed procedure . 34
10.8 Test results analysis – Simplified procedure . 38
11 Data storage and transmission . 38
11.1 Data storage . 38
11.2 Data transmission . 40
11.3 Operating ranges and information . 40
Annex A (informative) Comparison of this Standard and the OIML R 134-1
International Recommendation . 41
A.1 General . 41
A.2 Scope and application . 41
A.3 Detailed comparison of the OIML R 134-1 and this EN standard scope and
requirements . 42
Annex B (informative) Standard test plans and simplified acceptance procedures . 44
B.1 Examples of standardized test plans . 44
B.2 Charts for acceptance tests . 47
B.3 Acceptance tests: simplified procedures . 48
Annex C (informative) Calibration methods . 50
Annex D (informative) Standard results’ format and computer tools for accuracy
assessment, and implementation (example). 53
D.1 Standard results’ format and computer tools for accuracy assessment . 53
D.2 Example of implementation of the checking procedures . 54
Annex E (informative) Comments . 61
E.1 Scope . 61
E.2 Terms and definitions . 61
E.3 User and performance requirements . 62
E.4 Criteria for the choice of WIM sites . 64
E.5 Operating conditions and environmental requirements . 68
E.6 Accuracy class tolerances with respect to the weight . 68
E.7 On-site system checks and calibration by testing . 69
E.8 Type (model) approval of a WIM system . 71
E.9 Procedure to check the accuracy of a WIM system . 72
E.10 Data storage and transmission . 72
E.11 COST 323 vehicle classification . 73
Bibliography . 74

European foreword
This document (FprEN 17019:2016) has been prepared by Technical Committee CEN/SS F05
“Measuring Instruments”, the secretariat of which is held by CCMC.
This document is currently submitted to the Formal Vote.
This European Standard has been prepared by the FiWi (FEHRL institutes WIM initiative)
working group and is based on the European Specification on WIM of Road Vehicles (COST323,
1999) published in 1999 by the COST323 Management Committee. The statistical background
may be found in (Jacob, 2002) and the technical references in (Jacob et al., 2002).
This standard was prepared to deal with aspects related to:
— scope, normative references, terminology and symbols (Clauses 1 to 3);
— site selection, operating conditions and environmental requirements (Clauses 4 and 5);
— accuracy classification (Clause 6);
— system calibration and testing (Clauses 7 to 11);
The informative Annexes A, B, C, D and E provide respectively:
— comparison with the OIML R134-1 international recommendation;
— standard test plans and simplified acceptance procedures;
— guidelines for system calibration;
— guidelines for data and test result presentation, and computer tools for accuracy
assessment;
— comments and explanations of the main clauses.
Introduction
This standard comprises comprehensive and detailed requirements based on a scientific and
technical background developed in the COST323 action (Jacob, O’Brien and Jehaes, 2002). The
procedure for assessing the accuracy of a WIM system is flexible and general. It may use almost
any test plan, depending on the context and means available. The whole standard is based on a
statistical approach of the accuracy assessment, with tolerances which are the boundaries of
confidence intervals, and a level of confidence, reflecting the probability that an individual
measure lays in the specified tolerances or in the confidence interval. This level of confidence
can be specified by the users, depending on the application.
However, several users and WIM manufacturers expressed the need to have a simplified
procedure for common tests and applications, easier to implement and to understand. Therefore
a simplified procedure adapted to standard test plans and with a fixed level of confidence of
95 % was developed. Wherever possible, the detailed clauses of this standard were simplified to
allow common users to easily assess a WIM system accuracy.
When a simplified approach is available, the section concerned is duplicated as follows:
— Section title – Detailed procedure,
— Section title – Simplified procedure,
and they are numbered with consecutive numbers at the same level.
The clauses of the simplified procedure may be applied instead of those of the detailed
procedure, if respecting the conditions of application.
The simplified procedure mainly applies for the check of the accuracy of a WIM system
(Clause 10). The condition is to fix the confidence level at 95 %. The acceptance test can be done
using approximate analytical formula (Annex B, B.3.1) or one of the four standard test plans
proposed (Annex B, B.1)and charts (Annex B, B.2).
More in details:
— Clauses 1 to 5, 7 to 9 and 11 are common to the detailed and simplified procedures;
— in Clause 6 (Accuracy classes tolerances) the simplified procedure only deals with fixed
accuracy classes referred by a letter and a number (e.g. B(10)) as stated in 6.2, while the detailed
procedure also includes interpolated classes (6.1 and 6.3.4);
— the detailed procedure to check the accuracy by testing is given in 10.1, 10.3, 10.5 and 10.7,
while the simplified procedure is described in 10.2, 10.4, 10.6 and 10.8, using the standard test
plans given in the Annex B.
1 Scope
1.1 This standard specifies the requirements for installation, calibration, performance and
accuracy assessment, and test methods for Weigh-in-Motion (WIM) systems, that are used to
determine gross weights, axle and group-of-axle loads for road vehicles when they are weighed
in motion.
1.2 This standard applies to:
1.2.1 WIM systems installed on road infrastructure (including bridges), but not to the WIM
systems installed on-board of vehicles;
1.2.2 High speed WIM (HS-WIM) systems, i.e. systems installed in one or more traffic lane(s)
of a road, and operated automatically under normal traffic conditions, and to low speed WIM
(LS-WIM) systems, i.e. systems installed in a controlled weighing area, and operated under
controlled conditions;
1.2.3 WIM systems using either scales which are able to weigh standard masses statically, or
other sensors which may measure the loads indirectly;
1.2.4 on-site full WIM system performance assessment and model (type) approval, but
excludes laboratory (product) tests or tests on parts of systems (e.g. sensors only).
1.6 The scope of this standard covers all WIM applications, except trade.
NOTE For load enforcement of road vehicles, this standard or the OIML (International Organization
for Legal Metrology) international recommendation R 134-1 and 134-2 (OIML, 2004 and 2006) applies,
depending on the national requirements and legislation.
1.7 WIM systems used for trade are dealt with in the OIML recommendations R134-1 and
R134-2 (OIML, 2006 and 2004). These OIML recommendations apply to WIM systems installed
in controlled weighing areas, on a specified apron and where the vehicle speed is controlled.
They mainly apply to WIM systems composed of scales, which are capable of weighing standard
masses statically. The OIML recommendations are limited to the highest accuracy classes (0,2 to
10), with tolerances for 100 % of the measurements.
This standard applies to any WIM system, which may be installed either in a controlled weighing
area, or on a road open to traffic. These systems may use road sensors and bridge WIM.
This standard covers type approval testing, initial and in service testing.
This standard specifies the required performance and ability of WIM systems in general, but
does not aim to standardize products.
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 3534-1:2006, Statistics — Vocabulary and symbols — Part 1: General statistical terms and
terms used in probability
ISO 3534-2:2007, Statistics — Vocabulary and symbols — Part 2: Applied statistics
ISO/IEC Guide 99:2007, International vocabulary of metrology — Basic and general concepts and
associated terms (VIM)
3 Terms, definitions, symbols and abbreviations
For the purposes of this document, the terms and definitions given in the Glossary of WIM terms
of the COST 323 final report (Jacob et al., 2002), in ISO 3534-1 and ISO 3534-2, in ISO/IEC Guide
99:2007 and the following apply.
3.1 Terms and definitions taken from the Vocabulary of International Metrology
3.1.0
quantity
property of a phenomenon, body, or substance, to which a magnitude can be assigned
3.1.1
measurement
process of experimentally obtaining information about the magnitude of a quantity
3.1.2
measurand
quantity intended to be measured
3.1.3
measurement method/procedure
generic description of a logical sequence of operations used in a measurement / detailed
description of a measurement according to one or more measurement principles and to a given
measurement method
3.1.4
measurement result
information about the magnitude of a quantity, obtained experimentally
3.1.5
measurement uncertainty
parameter that characterizes the dispersion of the quantity values that are being attributed to a
measurand, based on the information used
3.1.6
standard (measurement) uncertainty
measurement uncertainty expressed as a standard deviation
3.1.7
calibration
(a) operation establishing the relation between quantity values provided by measurement
standards (French “étalon”) and the corresponding indications of a measuring system, carried
out under specified conditions and including evaluation of measurement uncertainty; or
(b) operation that establishes the relation, obtained by reference to one or more measurement
standards (French “étalon”), that exists under specified conditions, between the indication of a
measuring system and the measurement result that would be obtained using the measuring
system
3.1.8
(metrological) traceability
property of a measurement result relating the result to a stated metrological reference through
an unbroken chain of calibrations of a measuring system or comparisons, each contributing to
the stated measurement uncertainty
3.1.9
verification
confirmation through examination of a given item and provision of objective evidence that it
fulfils specified requirements
3.1.10
influence quantity
quantity which, in a direct measurement, is not the quantity being measured, but whose change
affects the relation between the indication of the measuring system and the measurement result
3.1.11
Correction
modification applied to a quantity value obtained from measurement, to compensate for a
systematic effect
3.1.12
(measurement) precision
closeness of agreement between quantity values obtained by replicate measurements of a
quantity, under specified conditions
3.1.13
measuring instrument
device or combination of devices designed for measurement of quantities
3.1.14
measuring transducer
device that provides at its output a quantity having a determined relation to the quantity at its
input
3.1.15
measuring system
set of measuring instruments and other devices or substances assembled and adapted to the
measurement of quantities of specified kinds within specified intervals of values
3.1.16
sensor
element of a measuring system that is directly affected by the phenomenon, body, or substance
carrying the quantity to be measured
3.1.17
detector
device or substance that indicates the presence of a phenomenon, body, or substance when a
threshold value of an associated quantity is exceeded
3.1.18
adjustment
set of operations carried out on a measuring system in order that it provide prescribed
indications corresponding to given values of the quantity to be measured
3.1.19
measuring interval
set of values of the quantities of the same kind that can be measured by a given measuring
system, with specified measurement uncertainty under defined conditions
3.1.20
steady state condition
operating condition of a measuring system in which the possible variation with time of the
quantity being measured is such that a calibration of the measuring system carried out with a
measurand constant with time remains valid
3.1.21
rated operating condition
condition that shall be fulfilled during measurement in order that a measuring system perform
as designed
3.1.22
limiting condition
extreme condition that a measuring system is required to withstand without damage, and
without degradation of specified metrological characteristics when it is subsequently operated
under its rated operating conditions
3.1.23
reference condition
condition of use prescribed for evaluating the performance of a measuring system or for
comparison of measurement results
3.1.24
resolution
smallest change, in the value of a quantity being measured by a measuring system, that causes a
perceptible change in the corresponding indication
3.1.25
stability
ability of a measuring system to maintain its metrological characteristics constant with time
3.1.26
drift
change in the indication of a measuring system, generally slow and continuous, related neither
to a change in the quantity being measured nor to a change of an influence quantity
3.1.27
instrumental uncertainty
component of measurement uncertainty attributed to a measuring instrument and determined
by its calibration
3.1.28
accuracy class
class of measuring instruments that meet stated metrological requirements which are intended
to keep instrumental uncertainty within specified limits under specified operating conditions; or
class of measuring instruments that meet stated metrological requirements which are intended
to keep errors (3.1.32) within specified limits under specified operating conditions
3.1.29
true value (of a quantity)
quantity value consistent with the definition of a quantity. Also an accepted reference to which a
measurement (result) is compared to assess an error
3.1.30
accuracy of a measurement
closeness of agreement between a quantity value obtained by measurement and the true value
of the measurand
Accuracy of a measuring system:
ability of a measuring system to provide a quantity value close to the true value of a measurand
3.1.31
trueness
closeness of agreement between the average that would ensue from an infinite number of
quantity values obtained under specified measurement conditions and the true value of the
measurand
3.1.32
error
difference of quantity value obtained by measurement and true value of the measurand
3.1.33
random error
difference of quantity value obtained by measurement and average that would ensue from an
infinite number of replicated measurements of the same measurand carried out under
repeatability conditions
3.1.34
systematic error
difference of average that would ensue from an infinite number of replicated measurements of
the same measurand carried out under repeatability conditions and true value of the measurand
3.1.35
maximum permissible error
one of the two extreme values of the error permitted by specifications or regulations for a given
measuring system
3.1.36
intrinsic error (of a measuring system)
error of indication when determined under reference conditions
3.1.37
bias (of a measuring system)
systematic error of indication of a measuring system
3.2 Specific statistical and metrological terms and definitions
3.2.1
confidence interval
interval which contains the true value of a quantity value represented by a random variable,
with a given probability, π, or a minimum required probability π
3.2.2
confidence level
probability, π, that an interval contains the true value of a quantity value represented by a
random variable
3.2.3
tolerance – tolerance interval
width of an interval (δ) in which an error shall lie with a minimum required probability. [-δ;+δ]
is called the tolerance interval
3.2.4
outlier(s)
value(s) in a series of measurement results of a given quantity value which has(ve) a much
lower probability of occurrence than expected according to the sample size and distribution
Note 1 to entry: An outlier is suspected of being an erroneous measurement, and can be eliminated
under certain conditions.
3.2.5
performance or acceptance test
test to determine whether an equipment is capable of performing its specified functions or meet
a given accuracy class under specified operating conditions
3.2.6
correction factor
numerical factor by which a quantity value obtained from measurement is multiplied, to
compensate for a systematic effect
3.2.7
calibration factor
numerical factor by which a quantity value obtained from measurement is multiplied, to fit a
true value
3.3 Terms and definitions related to vehicles
3.3.1
axle
set of two or more wheels with centres lying approximately on a common axis oriented
transversely to the nominal direction of motion of the vehicle
3.3.2
wheelbase
distance between the first and last axle of a vehicle, a portion of vehicle or a bogie or group of
axles (3.3.4)
3.3.3
single axle
axle that is spaced more than 2,2 m from its nearest neighbouring axle of the same vehicle,
unless an alternative definition is agreed

In vehicle engineering, a single axle is an axle not linked to another axle by a common suspension.
3.3.4
Group of axles
set of axles on the same vehicle spaced, each from the next one, less than 2,2 m, centre to centre,
unless an alternative definition is agreed
3.3.5
tandem axle
group of two axles, with a wheelbase less than the value specified in 3.3.4
3.3.6
tridem axle
group of three axles, with wheelbases less than the value specified in 3.3.4
3.3.7
axle of a group
one axle of a vehicle that belongs to a group of axles (see 3.3.4)
3.3.8
Gross vehicle weight (GVW)
force due only to the external force of gravity acting vertically downward on the total mass of a
vehicle, including all connected components
Note 1 to entry: Its magnitude is the total vehicle mass multiplied by the acceleration due to gravity
(g = 9,8 m/s ).
3.3.9
wheel load
portion of the gross weight imposed upon the weighing device by the tyre(s) of a stationary
wheel at the time of weighing, expressed in units of mass, due only to the vertically downward
force of gravity acting on the mass of the static vehicle
3.3.10
axle load
sum of all the wheel loads of an axle of a vehicle
3.3.11
axle group load
sum of all the axle loads of the axles which belong to a group of axles (see 3.3.4)
3.3.12
dynamic (impact) tyre force
component of the time-varying force applied perpendicular to the road surface by the tyre(s) of
a wheel of a moving vehicle
3.3.13
dynamic (impact) wheel/axle/group of axles/vehicle force
force applied to the pavement by the moving tyre(s) of a wheel/axle/group of axles/vehicle
Note 1 to entry: For the purposes of this standard, the WIM system is adjusted or calibrated to indicate
the magnitude of the vertically downward, measured dynamic forces in units of mass. The indicated mass
is converted to units of force by multiplying it by the acceleration due to gravity: g = 9,8 m/s .

In vehicle engineering, a tandem (resp. tridem) axle is a set of two (resp. three) axles linked by a common
suspension.
3.3.14
impact factor
ratio of an impact force to the corresponding wheel/axle/group of axles load or gross vehicle
weight
3.3.15
reference (or test) vehicle
vehicle which has accepted true values of the quantities to be measured, e.g. axle loads, gross
weight, axle spacing, length
Note 1 to entry: Axle loads and gross weight are commonly measured statically on approved scales.
3.4 Terms and definitions related to WIM systems
3.4.1
wheel load scale
device on which the whole wheel imprint is applied and which measures a wheel load
3.4.2
axle load scale
device on which all the wheel imprints of an axle are applied at once and which measures the
combined wheel loads of an axle
Note 1 to entry: If verified to appropriately small maximum permissible errors in relation to the
intended tolerance of a WIM system, an axle load scale is commonly used for generating static axle load
reference values.
3.4.3
weigh-bridge
weighing device on which a complete stationary vehicle may be weighed at once
Note 1 to entry: If verified to appropriately small maximum permissible errors in relation to the
intended tolerance of a WIM system, a weigh-bridge is commonly used for generating gross weight
reference values.
3.4.4
strip sensor
sensor installed perpendicular to the direction of travel of a road, with a longitudinal extent (in
the traffic direction) of a few centimetres, but smaller than a tyre imprint length
3.4.5
Weigh-In-Motion (WIM)
process of estimating the gross weight of a moving vehicle, and the portion of that weight that is
carried by each of its wheels or axles, by measurement and analysis of dynamic vehicle tyre
forces
3.4.6
Weigh-In-Motion system (station)
set of mounted sensor(s) and electronics with software which measures dynamic vehicle tyre
forces and vehicle presence of a moving vehicle with respect to time and provides data for
calculating wheel and/or axle load and gross weight estimates, as well as other parameters such
as speed, axle spacing and silhouettes
3.4.7
Bridge WIM (B-WIM)
WIM using an instrumented bridge as an axle or vehicle scale
Note 1 to entry: The strains measured in some of the bridge elements are used to estimate, through
software, the gross weights and axle loads of a vehicle crossing the bridge.
3.4.8
Low Speed WIM (LS-WIM)
weighing a (generally slowly) moving vehicle, on a specific area usually outside the traffic flow,
on a horizontal, straight, and even pavement surface under controlled conditions, such as
constant and limited speed (e.g. ≤ 10 km/h or 15 km/h) in order to minimise dynamic effects
3.4.9
High Speed WIM (HS-WIM)
weighing a vehicle in motion in the traffic flow, at its actual speed
3.5 List of symbols and abbreviations
3.5.1 Symbols
A(5), B+(7), B(10), C(15), D+(20), D(25), E(30)…: main accuracy classes for WIM systems (see
Clause 6).
δ: tolerance for a given quantity; [-δ;δ] is a tolerance interval. δ concerns relative errors and is
expressed as a %.
δ : tolerance (in %) of a gross vehicle weight, which defines the accuracy classes (see Clause 6).
c
δ : minimum tolerance (in %) which ensures, for a given sample and specified test conditions,
min
that an individual random error lies in the tolerance interval [-δ ;δ ] with a minimum
min min
required probability π0.
m: sample mean of individual relative errors.
n: sample size of a set of individual relative errors.
π: probability that an individual random error lies in a tolerance interval; or probability that a
confidence interval contains a true value of a quantity.
π : minimum required probability π.
E1, E2, E3: environmental repeatability and reproducibility test conditions (see Clause 7).
R1, R2, R3, R4: sample repeatability and reproducibility test conditions (see Clause 7).
s: sample standard deviation of individual relative errors.
V : mean traffic speed.
m
W: Measured load (may be a vehicle gross weight, an axle load or a group-of-axles load).
W : Static or reference load (of a vehicle, an axle load or a group of axles).
s
W : In-motion or dynamic (measured by a WIM system) load (of a vehicle, an axle load or a
d
group of axles).
x, x : individual relative errors in a set of measurements; x = 100 × (W -W )/W (in %).
i d s s
3.5.2 Abbreviations
APL: Analyseur de Profil en Long, the APL index which gives an account of the pavement profile
consists of 3 ratings, in short, medium and long wavelengths.
IRI: International Roughness Index; give an account of the pavement profile unevenness; higher
the index, rougher the pavement.
ISWIM: International Society for Weigh in motion.
WIM: weigh in motion.
B-WIM: bridge weigh-in-motion.
HS-WIM: high speed weigh-in-motion.
LS-WIM: low speed weigh-in-motion.
MS-WIM: multiple sensor weigh-in-motion.
4 Site selection criteria
4.1 Road geometry
4.1.1 The road section between 50 m upstream and 25 m downstream of the system shall
meet the geometrical characteristics given in the Table 1 (4.3), first line “Geometry”. In addition
it shall not contain any bumps or other type of sudden local change in slope.
4.1.2 The WIM system shall be installed away from any area of expected frequent acceleration
or deceleration, (e.g. close to traffic lights, toll station, slip roads), in order to weigh vehicles
travelling at uniform speed.
4.1.3 Areas where the number of lanes changes shall be avoided.
4.2 Pavement characteristics
4.2.1 The criteria for rutting, deflection and evenness are given in Table 1.
4.2.2 The pavements shall also meet the following criteria:
— no hard spots in the underlying courses or under the wearing course (toll slabs, service
tunnels, etc.);
— thickness of bonded layers greater than 10 cm;
— good mechanical bonding between courses, in particular of bituminous concrete on granular
materials stabilized by hydraulic binders. The sensors shall be installed in homogeneous
layers, not in a joint;
— surfacing shall be deterioration-free in the area of sensor installation;
— pavement shall be homogeneous across each traffic lane, ruling out the presence of joints of
coated materials within the length of a sensor.
4.2.3 Road sensors shall not be installed on a bridge or on any structure subject to dynamic
effects, except for Bridge WIM systems (see 4.4).

The performance of any WIM system depends on the site characteristics: road geometry and road evenness. Three
WIM site classes are defined in 4.3.
4.3 WIM site classes (not for B-WIM)
To be qualified in one of the classes of Table 1, the pavement of the WIM site shall meet all the
relevant criteria of column I, II or III of the class, depending on the pavement type and on the
parameter measurement method.
Except for Bridge WIM, it is not recommended to install a WIM system on a site which does not
meet at least class III specification.
The recommended site class/WIM system accuracy pairings, according to the current technology
and knowledge, are given in Table E.1 of Annex E.
Table 1 — Classification and criteria of WIM sites
WIM site classes
I II III
Excellent Good Acceptabl
e
Geometry  Longitudinal slope (%) ≤ 1 ≤ 2 ≤ 2
Transverse slope (%) ≤ 3 ≤ 3 ≤ 3
Radius of curvature (m) ≥ 1 000 ≥ 1 000 ≥ 1 000
−2
Semi-rigid Mean deflection (10 mm) ≤ 15 ≤ 20 ≤ 30
−2
Deflection pavements Left/Right difference (10 mm) ±3 ±5 ±10
−2
(quasi-static) All Mean deflection (10 mm) ≤ 20 ≤ 35 ≤ 50
bitumen
−2
pavements Left/Right difference (10 mm) ±4 ±8 ±12
−2
(13 000 kg - Flexible Mean deflection (10 mm) ≤ 30 ≤ 50 ≤ 75
axle)
−2
pavements Left/Right difference (10 mm) ±7 ±10 ±15
−2
Semi-rigid Deflection (10 mm) ≤ 10 ≤ 15 ≤ 20
−2
Deflection pavements Left/Right difference (10 mm) ±2 ±4 ±7
−2
(dynamic) All Mean deflection (10 mm) ≤ 15 ≤ 25 ≤ 35
bitumen
−2
pavements Left/Right difference (10 mm) ±3 ±6 ±9
−2
(5 000 kg - load) Flexible Mean Deflection (10 mm) ≤ 20 ≤ 35 ≤ 55
−2
pavements Left/Right difference (10 mm) ±5 ±7 ±10
Rutting (3 m  Rut depth max. (mm) ≤ 4 ≤ 7 ≤ 10
beam)
Evenness a Index (m/km) 0 to 1,3 1,3 to 2,6 2,6 to 4
IRI index
b Rating (SW, MW, LW) 9 to 10 7 to 8 5 to 6
APL
NOTE The rutting and deflection values are given for a temperature below or equal to 20 °C and suitable
drainage conditions.
a
International Roughness Index.
b
The APL (Analyseur de Profil en Long) is a device which measures the longitudinal profile; it consists of
two single wheel trailers operating at 72 km/h, towed by a car. The rating quantifies the logarithm of the
energy dissipated in one of the wavelength ranges: SW = Small Wavelengths (0,7 m to 2,8 m), MW = Medium
Wavelengths (2,8 to 11,3 m), LW = Large Wavelengths (11,3 to 45,2 m). The scale is from 10 (lowest energy,
excellent evenness) to 1 (highest energy, poorest pavement surface).
4.4 Particular requirements for bridges
4.4.1 B-WIM systems shall be installed on structures such as bridges, culverts or any other
structure which behaves in a similar way.
4.4.2 Braking or accelerating of vehicles on the structure due to junctions close to the site or
any other reason shall be avoided since non-constant speed over the structure significantly
decreases the accuracy of the calculated weights.
If a B-WIM system is installed in location where acceleration, deceleration, stopping or lane
changing is possible, then the system shall identify results of the vehicles during which
measurement any of these events occurred.
4.4.3 Detection of vehicles, axles and their velocity can be done with any type of axle detectors,
with strain sensors or with any other device if the results provide sufficiently accurate input for
other B-WIM calculations.
4.4.4 A B-WIM system shall provide a means to compare the measured and the calculated
responses of the bridge to the crossing of a specific vehicle in order to verify the results.
5 Operating conditions and environmental requirements
5.1 General conditions
5.1.1 WIM system specification shall contain a description of its rated operating conditions
consisting at least of ranges for:
— traffic intensity;
— vehicle speeds;
— temperature;
— humidity;
— electromagnetic conditions;
— mechanical condition.
5.1.2 Traffic intensity range consists of the minimum (zero by default) and maximum numbers
of heavy vehicles that can be recorded by the WIM system per ho
...