SIST-TP CEN/TR 14067-7:2021

SLOVENSKI STANDARD
kSIST-TP FprCEN/TR 14067-7:2021
01-februar-2021
Železniške naprave - Aerodinamika - 7. del: Osnove preskusnih postopkov za
zaščito pred letečim drobirjem, ki ga sproža vlak
Railway applications - Aerodynamics - Part 7: Fundamentals for test procedures for train-
induced ballast projection
Bahnanwendungen - Aerodynamik - Grundlagen für Prüfverfahren für zuginduzierten
Schotterflug
Applications ferroviaires - Aérodynamique - Principes généraux pour des procédures
d'essais vis-à-vis des projection de ballast causés par la circulation des trains
Ta slovenski standard je istoveten z: FprCEN/TR 14067-7
ICS:
45.060.01 Železniška vozila na splošno Railway rolling stock in
general
kSIST-TP FprCEN/TR 14067-7:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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FINAL DRAFT
TECHNICAL REPORT
FprCEN/TR 14067-7
RAPPORT TECHNIQUE

TECHNISCHER BERICHT

December 2020
ICS
English Version

Railway applications - Aerodynamics - Part 7:
Fundamentals for test procedures for train-induced ballast
projection
Applications ferroviaires - Aérodynamique - Principes Bahnanwendungen - Aerodynamik - Grundlagen für
généraux pour des procédures d'essais vis-à-vis des Prüfverfahren für zuginduzierten Schotterflug
projection de ballast causés par la circulation des
trains


This draft Technical Report is submitted to CEN members for Vote. It has been drawn up by the Technical Committee CEN/TC
256.

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, 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 Technical Report. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a Technical Report.


EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TR 14067-7:2020 E
worldwide for CEN national Members.

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Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Symbols and abbreviations . 4
5 General aspects of ballast projection and state of the art . 4
5.1 Introduction . 4
5.2 Summary of studies and incidents (by countries, manufacturers) . 5
5.3 Overview of ballasted track systems in Europe . 9
5.4 Ice accumulation induced ballast projection . 14
6 Economic judgement of damage . 18
6.1 Cost of reported damage . 18
6.2 Cost of homologation, measures to rolling stock and infrastructure . 21
6.3 Cost benefit analysis . 25
7 Homologation concepts . 26
7.1 General. 26
7.2 Existing technical approaches . 26
7.3 Responsibilities, interests and intended interface definitions . 27
7.4 Conceptual approaches. 28
8 Comparison of existing methods . 31
8.1 France . 31
8.2 Spain . 34
8.3 Italy . 45
8.4 Belgium . 46
8.5 Other countries . 46
8.6 Comparison of existing methods . 47
8.7 Conclusion drawn from French and Spanish assessments . 47
9 Available background . 47
10 Conclusion and next steps . 48
Annex A (informative) Summary comparison of existing methods addressing ballast
projection . 50
Annex B (informative)  Review of ballast projection papers . 55
Bibliography .100

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European foreword
This document (FprCEN/TR 14067-7:2020) 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 Vote on TR.
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1 Scope
This document discusses:
— economic aspects of ballast projection;
— comparison of methods in France and Spain for rolling stock;
— infrastructure assessment methods;
— review of available literature;
— next steps and recommendations regarding standardization and research.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 14067-4 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• ISO Online browsing platform: available at https://www.iso.org/obp
• IEC Electropedia: available at http://www.electropedia.org/
4 Symbols and abbreviations
For the purposes of this document, the symbols and abbreviations given in EN 14067-4 apply.
5 General aspects of ballast projection and state of the art
5.1 Introduction
The phenomenon of ballast projection caused by trains has been caused in the past by lumps of ice or
accreted snow falling from the train structure during extreme winter conditions, which then strike the
ballast bed causing ballast to be ejected upwards, impacting the train underside or passing trains and
leading to damage. Typically, this damage includes breakage of train underbody equipment, failures of
train systems or reduced efficiencies, breakages of station or train windows, and impact damage to train
or trackside structures. This type of ballast projection occurs to regional trains as well as to high speed
trains and has been well-known for a long period in railways world-wide.
However, in the early 2000s there were a number of significant incidents of ballast projection involving
high speed trains which were not caused by ice fall, but seemed to arise from aerodynamic causes.
Substantial damage was caused to the underside of an ICE3 train in one particular incident in Belgium in
2003. This phenomenon seems to be solely a high speed train phenomenon. The relevant contributory
factors involve:
— the aerodynamic design of the train, particularly the train underbody;
— the air speeds generated under the train, due to the Couette-type flow created by the high speed
train passing over the static track bed;
— train-induced pressures acting on the ballast;
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— track vibrations caused by the traction engines and wheel passing over the rails.
The types of damage from this sort of incident principally includes: ballast stone impacts to the
underbody structure and damage to the underbody equipment, pipes and cables of high speed trains, and
damage to wheels and rails when ballast stones are trapped between them. Although possible, there
seems to be little evidence of collateral damage to other trains or of injury to trackside workers.
It should be noted that although the aerodynamically-induced ballast projection incidents have resulted
in some spectacular damage to trains, there is evidence of minor impact damage to train underbodies at
lower train speeds that appears to be deemed tolerable by train maintainers. Furthermore, since the first
upsurge in these incidents, there has been a complete cessation with no further incidents since 2004. This
reduction in incidents coincides with measures introduced by many European Infrastructure Managers
to reduce ballast levels relative to the top of sleepers.
Nevertheless, there is a widespread concern that this is still a valid train/infrastructure issue needing
certain controls, which is supported by its inclusion in the LOC&PAS and INF TSIs as an issue, (albeit
currently as an open point). Consequently, various national rules regarding the issue have been
developed, mainly focused on rolling stock, leading to a burden on train manufacturers trying to
introduce trains into different countries, as they are required to apply different methods to confirm their
trains’ performance with regard to ballast projection.
Within the revision published in June 2019, ballast projection is addressed in TSI LOC PAS and TSI INS as
an interface issue relevant for operation with train speeds >250 km/h. The issue is connected to the
essential requirements of safety and technical compatibility.
5.2 Summary of studies and incidents (by countries, manufacturers)
5.2.1 General
Table 1, reproduced from Claus [1], summarizes some of the major incidents up to 2006 of both types of
ballast projection this century (those due to winter weather are not exhaustive).
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Table 1— Reported past ballast projection incidents
Date Train Location Speed Track Weather Remarks
Type Type Conditions
2001 ICE 3 Fulda- 230 km/h Mono-block Winter
Göttingen, sleepers, conditions,
Germany lowered snow
ballast
2003 KTX South Korea 300 km/h Mono-block No snow See [Kw03] for
sleepers details
2003 ICE 3 Lille-Calais, 320 km/h Bi-block Winter
France sleepers conditions,
snow
2003 ICE 3 Belgium 300 km/h Mono-block No snow Speeds up to
sleepers, 275 km/h did
ballast not not cause
lowered problems in
double
traction
2004 ICE 3 France 320 km/h Bi-block No snow During
sleepers homologation
test runs
2004 ICE 3 Mannheim- 250 km/h Mono-block Winter Foreign parts
Stuttgart, sleepers, conditions, in the track
Germany lowered snow have been
ballast found
2004 ETR 500 Rome- 300 km/h Mono-block No snow New tack with
Naples, Italy sleepers, ballast above
ballast not the sleepers,
lowered see Fig 4.2.3
2006 ICE-T Hamburg- 230 km/h Mono-block Winter
Berlin, sleepers, conditions,
Germany lowered snow
ballast
The following sections give additional details of incidents and the current status of ballast projection
measures in different European countries.
5.2.2 Italy
During initial runs of the ETR 500 on the then newly constructed Rome-Naples high speed line in 2004 a
ballast projection incident occurred. The sleepers were of the mono-block type, as shown in the
photograph in Figure 1 taken at the time of the incident. It can be seen that the ballast was not specially
lowered between the sleepers, and significant amounts lay on top of the sleepers themselves.
On the first high speed line, the 25 kV Turin-Milan route, problems arose for 300 km/h running of the
ETR 500. Three levels of ballast height reductions were investigated with ballast impacts being
monitored using microphones. The best ballast level was chosen for the maintenance target. Maintenance
procedures were modified to ensure that ballast stones are properly placed, but the intervals between
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track maintenance have not been increased. Since the initial problems, there have been no further
problems with flying ballast for trains regularly running up to the maximum speed of 300 km/h.
Homologation for the ETR 400 (also known as ETR 1000) running above 300 km/h required special
measures and configurations of track to ensure test running up to 360 km/h without problems.
There are no national notified technical rules for ballast projection in Italy. If ballast projection occurs,
the operator of the train has to establish a settlement with the infrastructure manager.

Figure 1 — Part of the Rome-Naples line at the time of the ballast projection incident in 2004, [1]
5.2.3 Spain
Railway Gazette (2005) stated that Spanish Development Minister Magdalena Álvarez, when presenting
a report in March 2005 to the Spanish Parliament on difficulties encountered with the Madrid - Lleida
section of the Madrid - Barcelona high speed line, that train operations at speeds greater than 300 km/h
caused ‘ballast particles to be sucked up and thrown around’.
The Universidad Politecnica Madrid and Adif have studied ballast projection since 2008. Preliminary
studies were undertaken in 2008-2010, followed by the AeroTRAIN Project (2010-2012), and then the
Aurigidas Project (2012-2014). In all of the projects, detailed measurements of surface loads and
induction phenomena were undertaken with ballast risk projection analysis. These were followed by
Norm definition studies in 2015-2017. A national guideline on the issue is being prepared by Adif.
5.2.4 France
In France, the major incident of ballast projection occurred in 2003 and 2004 during homologation tests
of the ICE3 running at 320 km/h (single unit). Damage to the train and the track was very significant and
of a magnitude never seen to TGVs or other high speed trains running in France, even at higher speeds.
Following this, different types of studies were carried out by German and French personnel to understand
the origin of these incidents and to try to avoid or at least limit them.
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As a result of this work, the underbody of ICE3 running in France was modified and tests were carried
out (air speed measurements in the track bed during train passing, microphones, video control,
underbody inspection) in 2005, to check the behaviour of the modified train regarding ballast projection.
These tests confirmed the decrease of the aerodynamic load on the track and the frequency and intensity
of ballast projection.
A review of ballast incidents was carried out after one year of operation. Several incidents were identified,
but have always been observed during cold weather (temperature close to zero and snow) in Germany.
Due to these incidents, for all new high speed trains running in France or for test running at speeds above
320 km/h, some specific monitoring has been required since 2004 on the trains< (accelerometers or
microphones for stone impact counting and video control), and air speed measurements in track have to
be made for all new high speed trains.
A French regulation, SAM X 012 [4], was published by EPSF in 2015 to describe the methodology to assess
a new high speed train regarding ballast projection. This methodology is based on air speed
measurements in the track and consists of comparing the new train with an existing train or with an
absolute criterion (cf § 7.2).
In France, ballast projection also occurs in winter due to snow/ice conditions. To limit these incidents,
speed reductions are applied on French high speed lines.
5.2.5 Germany
The major incident of ballast projection of concern to Germany actually occurred not in Germany, but in
Belgium, during homologation tests on the ICE 3 on a new high speed line. The ICE 3 had run without
incident on high speed lines in Germany. The Belgian high speed line was fitted with mono-block sleepers,
but no ballast lowering had been instigated. Successful trials had taken place with single traction units of
200 m length running at up to 300 km/h. However, when the double units were running at 270 km/h,
ballast impacts on the train underside were audible. During one run severe damage occurred to the train
underside, which led to Siemens having to investigate improved underbody designs to limit the problem.
Passenger reports on 15 Jan 2016 stated that an ICE travelling from Stuttgart to Frankfurt was hit hard
by ballast stones. The incident was reportedly caused by ice lumps dropping from the train. Damage was
caused to the train under-floor surfaces and side windows were cracked. The train continued at reduced
speed. (SOURCE: https://rail-sim.de/forum/index.php/Thread/20576-Bahn-reduziert-
H%C3%B6chstgeschwindigkeit-im-Fernverkehr/?pageNo=3:).
5.2.6 Great Britain
However, the High Speed 1 line (HS1) in Great Britain, runs from London to the Channel tunnel, and
Eurostar trains using the line reach a top speed of 300 km/h. A form of rail damage, known as ‘ballast
pitting’, has been reported, but no ballast projection problems have. This type of damage appears to be
associated with small particles of ballast becoming trapped between the railhead and the wheels of rail
vehicles. It is thought that the speed and the energy of trains cause an explosive crushing of the ballast
particle, which damages both the railhead and the wheel. Inspection and maintenance records of train
wheels on HS1 show that wheel pitting occurs predominantly on the front and rear bogies of a train with
a steady reduction towards the centre of the vehicle. Quinn et al [2010], suggest that the vibrations and
pressure pulse associated with the approaching train play a part in making ballast particles airborne as
the trains travel in the reverse direction on the return journey.
High Speed 2 is a new line soon to begin construction in 2019, and will have a design speed of 360 km/h
and an operating speed of 330 km/h. Obviously, there are no ballast projection problems on this line.
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5.3 Overview of ballasted track systems in Europe
5.3.1 General
There are several aspects of the design of ballasted track directly under passing trains, which may be
relevant to the issue of aerodynamically induced ballast projection. These are:
— sleeper type and sleeper spacing;
— rail fastening systems, and whether these provide restraint to ballast movement;
— ballast size;
— ballast maintenance procedures.
How these aspects vary in different European countries could have an impact on risk of ballast projection
on different railway infrastructure designs.
5.3.2 Sleepers
There are a number of different types of sleepers, which are used in varying proportions by European
railways. They are used to support the rails in position on the ballast bed and are generally of similar
sizes, and differ mostly in their construction materials. These are summarized in Table 2.
Table 2 — Common sleeper types used on European ballasted track.
Sleeper material Size Notes
Timber Typically, 150 mm Different types of wood can be used.
high, 250 mm wide
Ballast longitudinal movements restricted by the
sleeper, unless ballast above sleeper level
Steel Similar size to wooden
sleeper.
Concrete mono-block Similar size to wooden Ballast longitudinal movements restricted by the
sleeper. sleeper, unless ballast above sleeper level.
Concrete twin- or bi- Consists of two blocks connected by a coupling rod
block or pipe to maintain separation of blocks.
Ballast free to move longitudinally between blocks.
Of particular interest is the bi-block sleeper, where there is no constraint to the movement of the ballast
in the direction of the train from the sleeper between the two end blocks.
Examples of the different sleepers are shown in Figure 2.
The sleeper spacing, which for instance varies between 600 mm and 800 mm in Great Britain, depends
on the axle loading of trains using the line, track curvature and whether there are local track formation
difficulties. This is to ensure the vertical and lateral stability of the track. Due to sleeper functionality,
there is unlikely to be any systematic difference between European countries in sleeper spacing, although
within a country there could be differences between lines depending on the factors above. For high speed
lines, it is expected that differences in sleeper spacing between countries will be relatively small, (as axle
loads will be similar, track formation will be of high quality and track curvatures will be larger than on
conventional lines).
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a) Wooden sleepers b) Steel sleepers

c) Mono-block sleepers d) Bi-block sleepers
Figure 2 — Examples of railway sleeper types
5.3.3 Rail fastenings
Rail fastening are used to secure the rails to the sleepers and there are a number of different designs
currently in use. Baseplates may be also used under rails to hold the rails in place and may be used in
conjunction with clip devices.
The DE (Deenik, Eisses) clip, shown in Figure 2 a), is widely used and can be fitted on concrete or wooden
sleepers. A number of manufacturers have also produced other fastening devices, such as Pandrol,
Vossloh, McKay, and Nabla. These other devices are shown in Figure 3.
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a) Rail baseplate b) Pandrol clip c) Vossloh fastening


d) McKay fastening e) Nabla fastening
Figure 3 — Rail fastening systems
It can be observed that the rail fastening systems, although having differing designs, are unlikely to
influence ballast movement or provide any significant impediment to aerodynamic ballast projection.
5.3.4 Ballast Size
EN 13450:2013 Aggregates for railway ballast is a standard which specifies a standard for railway ballast
sizes. Although currently withdrawn, the standard is still referenced in company standards e.g. by
Network Rail in Great Britain. Essentially, ballast is graded according to the mass of ballast which passes
through sieves with holes of varying sizes. Ballast particles range between a nominal 31,5 mm up to a
maximum of either 50 mm or 63 mm. Within each of these ranges there are three sub-ranges referred to
as grading categories, A to F overall. Figure 4 shows grade category A in the range up to 50 mm, and grade
F in the range up to 63 mm, and represents the full range of ballast sizes and distributions. For each grade
category there is also a further sub-range at each sieve size, indicated by a solid line at the maximum
value and a chained line at the minimum. It can be seen that most ballast particles are between 20 mm
and 63 mm, whichever grade of category they are in.
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Key
X sieve size, mm
Y percentage passings by mass
cat A

cat B

Figure 4 — Distribution of ballast sizes, Categories A and F
Ballast is maintained using a number of machines, such as stone blowers. These use smaller ballast
particles, capable of passing through a 20 mm sieve, which are blown under the sleepers once the
machine has lifted them, to maintain the track level. At worst, 80 % of this type of ballast will be large
enough to pass through a 14 mm sieve. It is possible that these sized particles can find their way to the
surface of the ballast bed.
There is no evidence known to the authors of systematic ballast size and shape distributions being
different in different European countries.
5.3.5 Ballast maintenance regimes
5.3.5.1 General
An important consideration for aerodynamic ballast projection is where ballast is permitted to lie
between the running rails, which will depend on the maintenance regime for high speed lines in each
country.
5.3.5.2 Great Britain
5.3.5.2.1 Network Rail
A variety of railway sleepers are used on the standard railway lines in Great Britain. These include
wooden sleepers, concrete mono-block sleepers and steel sleepers. Figure 5 shows a still image from a
Network Rail ballast maintenance video; ballast stones can be seen on the sleepers, despite the
commentary stating “No ballast must be left on the railhead, piled against the rail webs, over the
fastenings or loose on the sleepers”. It is not clear if the instruction was eventually complied with in the
video.
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Figure 5 — Still from Network Rail video on ballast maintenance
5.3.5.2.2 High Speed 1
High Speed 1 is constructed using twin-block concrete sleepers on plain line and mono-block pre-stressed
concrete sleepers in the- vicinity of turnouts and switches. It uses a mixture of ballasted and slab track.
5.3.5.2.3 High Speed 2
High Speed 2 will be constructed with a mixture of slab track and ballasted track. No information has
been obtained regarding the sleeper types to be used.
5.3.5.3 Germany
German infrastructure managers established a procedure to counteract damage by ice dropping
instigating ballast projection. In late autumn the height of ballast is checked and lowered by a sweeping
machine to 4 cm to 6 cm below the base of the rail. This maintenance work is performed according to
internal rule 820.2010 7 (6) for every railway line above 140 km/h except for curves with small radius.
As sleepers are then elevated compared to the ballast bed level, objects dropping from fast running trains
will most likely hit the sleeper only, due to their flat-angle trajectory. The impact on sleepers is acceptable
and avoids the swirl of further ballast stones from the ballast.
5.3.5.4 CER position paper
In 2015, the Community of European Railway and Infrastructure Companies (CER) and European Rail
Infrastructure Managers (EIM) produced a joint position paper on aerodynamic ballast projection,
CER/EIM (2015). This specifically addressed the open points relating to ballast projection in the
LOC&PAS and INF TSIs and set out some principles that were felt should be respected when regulating
for the issue. The paper acknowledges the full-scale track test procedure for the assessment of rolling
stock set out in Annex A of EN 14067-4:2013+A1:2018 Railway applications - Aerodynamics - Part 4:
...