oSIST prEN 13848-6:2024

SLOVENSKI STANDARD
01-november-2024
Železniške naprave - Zgornji ustroj proge - Kakovost tirne geometrije - 6. del:
Karakterizacija kakovosti tirne geometrije
Railway applications - Track - Track geometry quality - Part 6: Characterisation of track
geometry quality
Bahnanwendungen - Oberbau - Gleislagequalität - Teil 6: Charakterisierung der
geometrischen Gleislagequalität
Applications ferroviaires - Voie - Qualité géométrique de la voie - Partie 6 :
Caractérisation de la qualité géométrique de la voie
Ta slovenski standard je istoveten z: prEN 13848-6
ICS:
45.080 Tračnice in železniški deli Rails and railway
components
93.100 Gradnja železnic Construction of railways
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
prEN 13848-6
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2024
ICS 93.100 Will supersede EN 13848-6:2014+A1:2020
English Version
Railway applications - Track - Track geometry quality -
Part 6: Characterisation of track geometry quality
Applications ferroviaires - Voie - Qualité géométrique Bahnanwendungen - Oberbau - Gleislagegüte - Teil 6:
de la voie - Partie 6: Caractérisation de la qualité Charakterisierung der geometrischen Gleislagequalität
géométrique de la voie
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 256.
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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye 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: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 13848-6:2024 E
worldwide for CEN national Members.

prEN 13848-6:2024 (E)
Contents Page
European foreword . 4
1 Scope . 5
2 Normative references . 5
3 Terms, definitions, symbols and abbreviations. 5
3.1 Terms and definitions . 5
3.2 Symbols and abbreviations . 6
4 General principles . 7
4.1 Introduction . 7
4.2 Parameters for track geometry quality assessment . 7
4.3 Transparency . 7
4.4 Complexity . 7
4.5 Track-vehicle interaction . 7
5 Methods of assessment of track geometry quality . 7
5.1 General . 7
5.2 Reference method: TQI - Standard deviation (SD) . 8
ref
5.3 Other methods . 9
5.3.1 General . 9
5.3.2 Number of isolated defects . 9
5.3.2 Combined standard deviation (CoSD) . 9
5.3.3 Standard deviation of the combinations of parameters . 10
5.3.4 Point mass acceleration method (PMA) . 11
5.3.5 Methods based on vehicle response . 12
5.3.6 Power Spectral Density (PSD) . 13
6 Levels of aggregation and calculation methods . 14
7 Classes of track geometry quality . 14
7.1 General . 14
7.2 Description of track quality classes (TQC) . 15
7.3 Values of track quality classes . 16
7.4 Assignment of TQCs . 17
7.5 Possible application of TQCs . 17
Annex A (informative) Point mass acceleration method (PMA) . 19
A.1 Introduction . 19
A.2 Calculation of the PMA-assessment figure . 19
Annex B (informative) Vehicle Response Analysis methods (VRA) . 21
B.1 Introduction . 21
B.2 Determination of the assessment tables . 21
B.3 Application of the assessment tables . 24
Annex C (normative) Method for calculating reference TQIs (TQI ) . 27
ref
C.1 Introduction . 27
C.2 Description of the method . 27
Annex D (informative) Method of classification of alternative TQI using the TQCs . 28
D.1 Introduction . 28
prEN 13848-6:2024 (E)
D.2 Description of the conversion method . 28
Bibliography . 30

prEN 13848-6:2024 (E)
European foreword
This document (prEN 13848-6:2024) has been prepared by Technical Committee CEN/TC 256 “Railway
applications”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 13848-6:2014+A1:2020.
The main changes compared to EN 13848-6:2014+A1:2020 are listed below:
— change of the structure of the document;
— revision of Annex A;
— revision of Annex B.
In this document, the Annex C is normative and the Annexes A, B and D are informative.
This document is one of the series EN 13848 “Railway applications — Track — Track geometry quality” as listed
below:
— Part 1: Characterisation of track geometry;
— Part 2: Measuring systems — Track recording vehicles;
— Part 3: Measuring systems — Track construction and maintenance machines;
— Part 4: Measuring systems — Manual and lightweight devices;
— Part 5: Geometric quality levels — Plain line, switches and crossings;
— Part 6: Characterisation of track geometry quality.

prEN 13848-6:2024 (E)
1 Scope
This document provides the method to characterize and classify the quality of track geometry based on
parameters defined in EN 13848-1.
This document also specifies different track geometry classes.
This document does not:
— apply to lines with a nominal gauge less than 1 435 mm;
— specify requirements for Urban Rail Systems.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
EN 13848-1:2019, Railway applications — Track — Track geometry quality — Part 1: Characterization of track
geometry
EN 17343, Railway applications — General terms and definitions
3 Terms, definitions, symbols and abbreviations
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 17343 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1.1
decolouring
algorithm which modifies the spectral content of a signal aimed to compensate or apply the characteristics of a
specific measuring system
Note 1 to entry: The decolouring is used in EN 13848 series to convert a chord measurement signal into a D1 or D2
measurement signal.
3.1.2
track quality index (TQI)
value that characterises track geometry quality of a track section based on parameters and measuring methods
compliant with EN 13848 series
3.1.3
track quality class (TQC)
characterization of track geometry quality as a function of speed and expressed as a range of TQIs
prEN 13848-6:2024 (E)
3.2 Symbols and abbreviations
For the purposes of this document, the symbols and abbreviations given in Table 1 apply.
Table 1 — Symbols and abbreviations
Symbol Designation Unit
AL Alignment mm
ATQI Alternative Track Quality Index
CL Cross level mm
CoSD Combined standard deviation mm
cr Curvature 1/m
D0 Wavelength range 1 < λ ≤ 5 m
D1 Wavelength range 3 < λ ≤ 25 m
D2 Wavelength range 25 < λ ≤ 70 m
D3 Wavelength range 70 < λ ≤ 150 for longitudinal level m
Wavelength range 70 < λ ≤ 200 for alignment
λ Wavelength m
G Track gauge mm
LL Longitudinal level mm
MBS Multi Body System
PMA Point Mass Acceleration (method)
PSD Power Spectral Density 2
m /(1/m
)
SD Standard deviation mm
SD Standard deviation longitudinal level mm
LL
SD Standard deviation alignment mm
AL
TQI Track Quality Index
TQI Reference Track Quality Index
ref
TQC Track Quality Class
V Speed km/h
VRA Vehicle Response Analysis (method)

NOTE In this document, AL stands for “alignment” and is not to be confused with AL standing for “alert limit” as defined
in EN 13848-5.
prEN 13848-6:2024 (E)
4 General principles
4.1 Introduction
In order to provide a sufficient level of safety, ride quality and cost-effective railway traffic, track geometry
quality is assessed.
This document d deals with track geometry quality classification regarding ride quality through TQIs. The safety
aspect on the other hand is covered in EN 13848-5.
TQIs can be calculated using different methods. The ones described in Clause 5 are applied by at least one
European network. The reference method for calculating comparable TQIs is detailed in Clause 7.
4.2 Parameters for track geometry quality assessment
As track geometry measurement, vehicles present their outputs in accordance with the parameters specified in
EN 13848-1, any standardized assessment method shall be based on these parameters.
4.3 Transparency
Any algorithm for track geometry quality assessment complying with this document shall be fully documented,
reproducible and available in the public domain.
4.4 Complexity
Track geometry quality should be assessed by as few TQIs as possible and the algorithm should be
understandable by the user.
4.5 Track-vehicle interaction
Track quality assessment should reflect the principles of track-vehicle interaction. For example, the track
geometry defects of the same amplitude but different wavelengths lead to different vehicle responses and the
required wavelength range will be different depending on the track-vehicle interaction parameters to be
assessed.
5 Methods of assessment of track geometry quality
5.1 General
Considering their wide use across European Railway Networks and the need to have a single, easily
understandable TQI, standard deviation (SD) of longitudinal level and alignment defined in 5.2 is taken as the
reference method to describe track geometry quality. It will be referred to as TQI in the following and is
ref
specified in Annex C.
Establishing a TQI by other means may be used providing that complete documentation is available about the
method and how it relates to the reference method as described in Annex D.
The methods described in the following sub-clauses can be applied to any track geometry data of interest.
Switches may be included.
prEN 13848-6:2024 (E)
5.2 Reference method: TQI - Standard deviation (SD)
ref
The standard deviation is the most commonly used aggregation method to calculate TQI by European railway
networks. It represents the dispersion of a signal over a given track section, in relation to the mean value of this
signal over the considered section.
N
()xx−
∑ i
i=1
SD=
N−1
where
N is the number of values in the sample;
x is the current value of a signal;
i
is the mean value of a signal;
x
SD is the standard deviation.
NOTE 1 Standard deviation is linked to the energy of the signal in a given wavelength range [λ1, λ2] according to the
λ 2
following relationship: SD = 2 S ()ννd , where S is the PSD described in 5.3.8 below.
xx
xx
∫
λ1
SD is commonly calculated for the following parameters:
— longitudinal level D1;
— alignment D1.
It is also calculated for other parameters such as:
— twist;
— track gauge;
— cross level;
— longitudinal level D2;
— alignment D2.
When calculating SD, attention should be paid to the possible influence of the quasi-static part (e.g. track design)
of the signals especially for twist, track gauge and cross level.
For longitudinal level and alignment it is recommended to calculate SD separately for each rail. It may also be
calculated differently (for example: mean of both rails, worst or best of either rail or outer rail in curves).
Length of track section used for standard deviation has influence on the result. If comparable results are
expected, only one length should be used. Commonly, for maintenance reasons standard deviation is calculated
over a length of 200 m. It may be calculated either at fixed distances without overlap or with overlap, as a sliding
standard deviation. Calculation of standard deviation is also done over longer distances such as 1 km, an entire
line or an entire network.
NOTE 2 Distinction between specific track sections, such as plain lines, stations and switches and crossings, can also be
made.
prEN 13848-6:2024 (E)
5.3 Other methods
5.3.1 General
Other possible methods to calculate TQI used by some European railway networks are described in the
following subclauses.
5.3.2 Number of isolated defects
Isolated defects may present a derailment risk; however counting the number of isolated defects exceeding a
specified threshold such as intervention limit and alert limit on a given fixed length of track can be
representative of the track geometry quality. This method is used by several European Railway Networks.
The number of isolated defects per unit of track length is commonly counted for the following parameters:
— longitudinal level D1;
— alignment D1;
— twist;
— track gauge;
— cross level.
It can be also counted for the following parameters:
— longitudinal level D2;
— alignment D2.
Commonly, the number of isolated defects is counted over 1 km or more. It may also be counted over 100 m or
200 m of track.
The number of isolated defects can be counted over 100 m or more according to the Infrastructure Manager.
If required, distinction between specific track sections can be made, such as plain lines, stations and switches
and crossings.
Alternatively, a calculation can be made to specify what percentage of a line exceeds a certain threshold level.
5.3.3 Combined standard deviation (CoSD)
Assessment of the overall track geometry quality of a track section (200 m, 1 000 m.) can be done by a
combination of weighted standard deviations of individual geometric parameters. An example of such a TQI is
given below.
22 2 2
CoSD w SD+w SD++w SD+w SD
G G CL CL
AL AL LL LL
where
SD is the standard deviation of the individual geometry parameters;
w is the weighting factor of the individual geometry parameters;
with the indices:
alignment, average of left and right rails;
AL
G track gauge;
CL cross level;
=
prEN 13848-6:2024 (E)
longitudinal level, average of left and right rails.
LL
It is up to the Infrastructure Manager to determine the weighting factors according to the purpose of the
assessment.
Another method might be to transform the standard deviations of geometry parameters or their combinations
into a dimensionless number that can be used without distinction of line category, speed range and track
geometry parameter.
5.3.4 Standard deviation of the combinations of parameters
Standard deviation for a combination of track geometry parameters can be evaluated. This is based on the
observation that the level of the combined signals may better reflect the vehicle behaviour than the individual
signals.
For example, a standard deviation, over a sliding 200 m length of track, can be evaluated for the sum of
alignment and cross level filtered in the same wavelength range (e.g. D1) as follows:
— the alignments of left and right rails are combined into one signal, in curves by choosing the outer rail and
on tangent track by either averaging or choosing one of the two rails;
— cross level and alignment signals are combined together by using a sign convention so that an alignment
defect to the right is added with the same sign to a cross level defect where right rail is lower than the left
rail. Figure 1 shows an example of the combination of cross level Δz and alignment y where the signs are
both positive;
— the standard deviation of the combined signals is calculated over a sliding 200 m length of track.
prEN 13848-6:2024 (E)
Key
1 reference position
combination of alignment
= (AL + AL ) / 2
y
right left
Δz = z - z cross level
right left
s sum of cross level and alignment
Figure 1 — Combination of alignment and cross level
5.3.5 Point mass acceleration method (PMA)
The PMA method is based on the following principles:
— the PMA model considers an unsprung virtual vehicle. It is assumed to be a point mass, thus only the motion
of the centre of gravity is investigated. This point mass is guided in a certain distance over the track centre
line;
— the point mass is moved at a constant speed corresponding to the maximum allowed speed over the
measured track section;
— due to the geometrical imperfection of the track, which is described by the longitudinal level and alignment
of both rails, the point mass incurs accelerations a and a in the horizontal and vertical directions;
y z
— summation of the magnitudes of the vectorial differences leads to an assessment value of track quality.
Features of PMA method are as follows:
— as the method is based on Newton’s second law a PMA assessment value represents the accelerations which
are needed to guide a point mass;
— as the PMA model does not contain any vehicle specific features but the height of the centre of gravity, it
cannot show any vehicle specific reactions, and therefore it is considered to be a vehicle independent
assessment method;
prEN 13848-6:2024 (E)
— the PMA model takes into account the maximum line speed of the assessed track. To achieve the same PMA
track quality value a track with a high maximum line speed needs to have lower geometrical imperfection
than a track for a lower maximum line speed. In this way one single limit value may serve for possibly all
or at least a wide range of maximum line speeds;
— the derivatives of longitudinal level and alignment dominate the assessment value. Thus, defects of the
same amplitude but with different wavelengths lead to different assessment values;
— the PMA method combines vertical and lateral deviations as well as the left and right rails of the track.
Theoretical background information of the PMA method is given in Annex A.
5.3.6 Methods based on vehicle response
5.3.6.1 Estimation of vehicle response using a theoretical model
Vehicle response analysis (VRA) can be used to make objective, quantified statements about the relationship
between the track geometry quality and the vehicle’s responses at various speeds. It takes into consideration
factors such as successions of isolated defects that might generate resonance, combinations of defects at the
same location and local track design (e.g. curvature and cant).
The VRA methods are based on the following principles:
— calculation of vehicle response to the track geometry measured according to EN 13848-1. The vehicle
response being represented by the wheel-rail forces and by accelerations of the vehicle running gear and
car body;
— consideration of different representative vehicle types, configurations and speeds;
— the assessment criteria takes into account the limit values given by EN 14363;
— the output can be linked to the input track geometry parameters.
When using such methods, attention should be paid to the consistency between the wavelength domain of the
track geometry and the frequency range of the vehicle response parameters.
Features of VRA methods are the following:
— VRA methods use the relationship between track geometry and vehicle behaviour to assess the track
geometry quality. By means of numerical models the method provides an estimation of vehicle response.
This response is compared to its respective limit values;
— VRA methods take into account the superposition of lateral and vertical track imperfections in combination
with the permissible vehicle speed and the resulting local cant deficiency;
— VRA methods don't require any definition of speed classes because the relevant limit values of the vehicle
responses are independent of the speed;
— in case of an exceedance of a defined limit value of vehicle response parameters, the limiting speed to be
applied can be determined;
— the assessment functions can be selected according to the relevant vehicle types which are authorized to
run on a considered track section.
An example of a VRA method is given in Annex B.
prEN 13848-6:2024 (E)
5.3.6.2 Measurement of vehicle response
Although not generally used for TQIs calculation, measurements of vehicle response can help in assessing
interaction between running vehicle and track, with respect to safety as well as ride quality.
Usually, the accelerations of bogie and car body are measured in both lateral and vertical directions, but
measurement of wheel-rail forces, such as lateral and vertical forces (Y and Q), can also be made.
In addition to the analysis method described in Annex E of EN 13848-1:2019, the assessment of accelerations
may be based on EN 14363 or EN 12299.
Inspection runs are usually made on high-speed lines, but they can also be of interest on conventional lines.
The following principles should be respected when using those measurements:
— the vehicles used for these evaluations are representative of the rolling stock used on the assessed lines;
— the runs are made at the maximum speed of the line, with a tolerance of ± 10 %;
— the measurements are made at the parts of the vehicle where the highest response is expected, e.g. the
leading bogie or wheelset;
— the state of the rail surface (wet or dry) is taken into account;
— the position of the train shall be known to be able to loc
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