risk assessment regarding composite brake blocks during

REPORT Ref TSJ 2019-5343

September 2020

Risk assessment regarding composite

brake blocks during Swedish winter

conditions

Report Risk assessment regarding composite brake blocks during Swedish winter conditions Ref TSJ 2019-5343

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© Transportstyrelsen Järnväg

Spårtrafik

This report is available on the Swedish Transport Agency website

www.transportstyrelsen.se

Ref TSJ 2019-5343

ISBN

Author Aho Mikael

Month Year September 2020

May be reproduced with acknowledgement of the source

http://www.transportstyrelsen.se/


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Foreword

Railway noise is a health hazard. The European Commission has acted upon

this and decided to address the issue in their regulation (EU) 1304/2014. In

the near future all freight wagons have to use composite brake blocks or disc

brakes to fulfil the requirements. However, it has been shown that

composite brake blocks do not achieve the expected brake capacity in actual

Nordic winter conditions. The Swedish Transport Agency has initiated tests

in winter conditions, but also this risk analysis. The risk analysis completes

the winter tests, as the analysis is based on the test results, and mitigating

measures are identified for further investigation, aiming to achieve a

tolerable risk level.

Borlänge June 2020

Petra Wermström

Road and Rail Director

The signed and stamped version is available from the Swedish Transport Agency.


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Summary

For several years Swedish railway undertakings have been noticing a

number of incidents during winter conditions where there is a significant

and sudden loss of brake performance on trains with wagons equipped with

composite brake blocks. A significant number of incidents, including a

number of SPAD, have been recorded. There is a danger that the number of

incidents will further increase when more wagons equipped with composite

brake blocks are introduced in Sweden. There would thereby also be an

increase in the probability of accidents.

This report highlights the risks which arise with the use of composite brake

blocks during winter conditions as well as the consequences of these risks

and their severity. The risks are highlighted from both the technical and

operational perspectives. A summary of the results of the tests carried out is

also provided and a range of measures to increase safety is identified for

further investigation.

Risk assessments are based partly on estimated risk and partly on

comparison with reference systems. The relevant reference system consists

of cast-iron brake blocks.

Based on the risk analysis and test results, the following conclusions have

been drawn:

There are composite brake blocks which have demonstrated

substandard properties in winter conditions and the use of these

implies an intolerable level of risk.

Those incidents which form the basis of the risk analysis occurred

despite the implementation of a number of operational measures.

These measures are already producing unacceptable consequences

such as delayed and cancelled trains. Further operational measures

(increased test braking/ exercising of brakes etc.) would have

completely unacceptable consequences and would fail to solve the

problem. Increased numbers of SPAD due to a deliberate choice of

new technical solutions is not acceptable and neither is it acceptable

to transfer responsibility for safety from the technical system to the

driver via further operational instructions.

Currently no incidents or events with trains fitted with only LL-type

composite brake blocks have been reported by Swedish railway

undertakings. It should be noted that there are only very few trains

with solely LL brake blocks in northern Sweden. On the other hand,

tests indicate that these blocks can have significantly lower braking

performance than cast-iron brake blocks.


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Current procedures, according to UIC, for the testing of composite

brake blocks in winter conditions do not correspond to actual Nordic

winter conditions.

Based on these conclusions, incidents which occurred and test results,

possible measures have been identified. These must be investigated

further. The possible measures identified concern freight wagons,

locomotives and operational rules. These measures should not be seen as

in themselves reducing risks to an acceptable level. Rather a

combination of measures will be required, partly over a transition period

and also on a permanent basis. Measures also need to be implemented at

national and international levels. One of these measures, which, during a

transition period, would reduce the risk and enable international

transport to and from Sweden, is an exception from the rules so that a

number of freight wagons with cast-iron brakes are allowed to operate

internationally.


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Terms and abbreviations

Term Explanation

ATC2 Train safety system, ATC version 2 (Automatic Train

Control). The system is used in Sweden and Norway and it

is a class B train safety system.

Bg The type Bg consists of one (1) brake shoe holder and one

(1) brake block. The brake block has the standard

measurement of 320 mm x 80 mm (length x witdh). The

“g” in Bg stands “geteilt” in German, “divided” in English

and it means that brake shoe holder and brake block can be

separated.

Bgu The type Bgu consists of one (1) brake shoe holder and two

(2) brake blocks. The brake blocks have the standard

measurement of 250 mm x 80 mm (length x witdh). The

“gu” in Bgu stands for “geteilt mit unterteilter Sohle” in

German, “divided with subdivided blocks” in English.

1 x Bgu Means that there are only brake blocks on one side of each

wheel (often called push-brakes since it’s just pushing from

one side of the wheel) In this case there are Bgu on one

side of the wheel. Typically used for brake systems based

on K-blocks.

2 x Bgu Means that there are brake blocks on both sides of the

wheel. In this case Bgu. Typically used for brake systems

based on GG- and LL-blocks.

Brake inhibition

valve

Brake inhibition valve is also called secondary brake valve

or brake inhibition function. When the brake inhibition

valve is active, the locomotive only brakes if the pressure

reduction is larger than 1,5 bar in HLL. There are

locomotives that has other HLL pressure limits for the

brake inhibition valve (for example activation at pressure

reduction larger than 1 bar). German term

“Nachbremsventil” or “Nachbremsfunction” is commonly

used also in other languages.

Brake position P

and G

Freight wagons can have their brake system in “P” or “G”

position. In P position is the brake application and release

time faster than in G position. A G-braked train has all

vehicles and the locomotive in brake position G. A P-

braked train has all wagons in P and the locomotive in P or

G. Note that other trains (than normal freight trains) can

have other brake positions for the vehicles.


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Term Explanation

CBB Composite Brake Blocks. A term used for CBB’s with high

friction level (K), medium friction level (L) and with low

friction level (LL). Composite brake blocks can be based

on friction materials that are either organic or sintered.

CSM-RA The common safety method for risk evaluation and

assessment according to COMMISSION

IMPLEMENTING REGULATION (EU) No 402/2013 of

30 April 2013 on the common safety method for risk

evaluation and assessment with amendments from:

COMMISSION IMPLEMENTING REGULATION (EU)

2015/1136 of 13 July 2015 amending Implementing

Regulation (EU) No 402/2013 on the common safety

method for risk evaluation and assessment.

ECM Entity in Charge of Maintenance.

Electro-dynamic

brake

Brake in electric or diesel-electric locomotives (or other

tractive units), in which the traction motors are used for

wear-free braking. Brake power can either be fed back to

the overhead line or just converted into heat in brake

resistors. Often called just “electric brake” or “e-brake”.

Abbreviation is ED. German term for ED is

“Elektrodynamische Bremse”.

ERA European Union Agency for Railways.

Exercising (of

CBB based

brake systems)

A brake application performed at speed with the purpose to

restore and/or check braking performance. General

minimum procedures are described in UIC 541-4, 2.2.1.3.

Fly-off snow Fly-off snow refers to the snow that swirls up from the

wind drag and swirls around the vehicles in the train.

In case of moderate fly-off snow, one can from the

locomotive still see the trailing wagons through the fly-off

snow. At heavy fly-off snow there are no visible wagons

(or only parts of the first wagon are visible).

UIC Leaflet 541-4, appendix G, classifies fly-off snow in

winter classes W1 to W5. Moderate fly-off snow is

classified as W3. Heavy fly-off snow is classified as W5.

GG (brake)

blocks.

Cast iron (brake) blocks. Material class is P10. This is the

type of brake block that has been used for a very long time.

GG= Grau Guss in German.


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Term Explanation

HBL Main air reservoir pipe, popularly called “feeding pipe”.

Locomotives and wagons are marked with HBL (from

German ”Hauptluftbehälterleitung”). HBL has yellow

colour marking. Main air reservoir pipe is present only on

some wagons. The individual wagon with HBL can only

take advantage of the HBL if all wagons before and also

the locomotive have HBL and it is connected.

HLL Brake pipe or popularly called “main brake pipe”

Locomotives and wagons are marked with HLL (from

German “Hauptluftleitung”. HLL has red colour marking.

Brake pipe exists on all freight wagons.

Inflected-curve

valve

Relay valve combination with inflected curve which

reduces brake force at a minor service brake for loaded

wagons. At full service brake there is no reduction. Neither

will there be any reduction in brake force for empty to

medium loaded (≤ 14,5 tons axle load) wagons. German

term is: “Knickventil”.

K (brake) block Composite brake blocks with high friction. The brake

blocks are based on a friction material that is either organic

or sintered.

L (brake) block Composite brake blocks with medium friction. These brake

blocks are unusual in Sweden. From a winter perspective

one can assume that they behave as K and LL block.

LL (brake)

block

Composite brake blocks with low friction. These brake

blocks have a weighted friction that corresponds to GG

brake blocks. The brake blocks are based on a friction

material that is either organic or sintered.

Railway

undertaking

(RU)

Here it refers to a railway operator (that runs trains) and is

accountable for a safety management system to handle

wagons with CBB (during winter conditions).

RAMS Reliability, Availability, Maintainability, Safety

The terms are defined in EN 50126.

s brake or ss

brake

s brake and ss brake corresponds to 14,5 respectively

18 tons brake weight per axle.

SPAD Signal Passed At Danger is an event when a train passes a

red signal (stop signal) or ERTMS-marking board when

not allowed to do so.


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Term Explanation

UIC International union of railways. The acronym comes from

the French name “Union internationale des chemins de

fer”.

VK Vehicle Keeper


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CONTENTS

FOREWORD ............................................................................................................. 3

SUMMARY ................................................................................................................ 4

TERMS AND ABBREVIATIONS .............................................................................. 6

1 INTRODUCTION .............................................................................................. 13

1.1 Background ............................................................................................ 13

1.2 Purpose and issues studied ................................................................... 13

1.3 Methods and participants ....................................................................... 13

1.4 Scope and boundaries ........................................................................... 14

2 SYSTEM DEFINITION ..................................................................................... 16

2.1 System objective (intended purpose) .................................................... 16

2.2 System functions and elements ............................................................. 16

2.3 System boundary ................................................................................... 17

2.4 Physical and functional interfaces ......................................................... 18

2.4.1 Permitted line speeds ............................................................... 18

2.4.2 Permitted track axle loads ........................................................ 19

2.4.3 Train protection systems .......................................................... 19

2.5 The system environment ....................................................................... 19

2.6 Existing safety measures and safety requirements identified ............... 19

2.6.1 Approved brake configurations ................................................. 20

2.6.2 Bedding in of brake blocks in trains .......................................... 20

2.6.3 Operational rules – definition of winter conditions .................... 21

2.6.4 Operational roles for low speed operation of CBB wagons...... 22

2.6.5 Operational rules for low-speed running of CBB wagons which have winter problems. .................................................... 23

2.6.6 Operational rules for trains with CBB wagons .......................... 24

2.6.7 Operational rules for trains with CBB wagons which have poor winter properties. .............................................................. 26

2.6.8 Non-implemented operational rules for trains with CBB wagons ..................................................................................... 27

2.7 Assumptions which determine the limits for the risk assessment ......... 28

2.7.1 Reference system..................................................................... 28

3 OPERATIONAL EXPERIENCES AND TEST RESULTS ............................... 29

3.1 Summary of incidents ............................................................................ 29

3.2 Summary of test results ......................................................................... 29

3.2.1 Swedish Transport Agency winter tests ................................... 29

3.2.2 Hector Rail winter testing ......................................................... 30

4 RISK ASSESSMENT ....................................................................................... 32

4.1 Method ................................................................................................... 32

4.2 Identification of hazards ......................................................................... 33


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4.3 Risk assessment .................................................................................... 33

4.3.1 Assessment of severity ............................................................ 33

4.3.2 Estimation of frequency and risk level ...................................... 37

4.4 Comparison with the reference system. ................................................ 46

4.5 Risk assessment – comparison with criteria .......................................... 49

4.5.1 Risk assessment based on explicit risk estimates ................... 49

4.5.2 Risk assessment based on comparison with the reference system ...................................................................................... 50

5 IDENTIFICATION OF POSSIBLE MEASURES ............................................. 51

6 CONCLUSIONS OF THE RISK ANALYSIS ................................................... 60

Appendices

A. Summary of incidents

B. Risk analysis protocol

C. Situations where reduced braking capacity can lead directly to

collision with another train

D. Braking capacity - seen theoretically and practically from the

perspective of the locomotive driver.

E. Comments to ERA’s list of fully approved UIC composite brake

blocks for international transport

F. In-depth account of advantages and disadvantages of certain

proposed measures


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1 Introduction

1.1 Background

For several years Swedish railway undertakings have been noticing a

number of incidents during winter conditions where there is a significant

and sudden loss of brake performance on trains with wagons equipped with

composite brake blocks. During years 2015 and 2016 a number of incidents

were noted where the speed of the train must be reduced in order to achieve

sufficient braking performance and a couple of Signal Passed at Danger

(SPAD) incidents were recorded. Since this time the problem has continued

and at this point a significant number of events, including a number of

SPAD have been recorded. There is a danger that the number of incidents

will further increase when more wagons equipped with composite brake

blocks are introduced in Sweden. Up until the winter of 2020, wagons with

composite brake blocks have mostly been run in “mixed trains”, i.e. trains

consisting of wagons with both composite brake blocks and cast-iron brake

blocks. The reported incidents mostly occurred on trains with wagons

equipped solely with composite brake blocks1.

It should be noted that up to this point no accidents with serious

consequences in human or property terms have taken place where composite

brake blocks were a contributory factor.

1.2 Purpose and issues studied

This report highlights the risks which arise with the use of composite brake

blocks as well as the consequences of these risks and their severity. In

addition to this, the work should identify possible measures which might

lead to managing these risks.

1.3 Methods and participants

This work is based on principles for risk analysis and risk assessment in

accordance with CSM-RA2.

Identification of hazards and assessment of severity is based on the

experience of the analysis group, see Table 1. Frequency assessments are

1 ERA 2020, Report Task force on the winter performance of composite brake blocks. ERA 1177v0.1 2 CSM RA, COMMISSION IMPLEMENTING REGULATION (EU) No 402/2013 of 30 April 2013 on the

common safety method for risk evaluation and assessment and repealing Regulation (EC) No. 352/2009


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based on reported incidents from two railway undertakings during the

2017/2018 and 2018/2019 winter periods.

Risk assessments are based partly on estimated risk and partly on

comparison with reference systems. Risk assessment based on estimated

risk is based on the risk assessment matrix in accordance with EN 501263.

The reference system deemed appropriate is freight trains having wagons

braked entirely with cast-iron brake blocks.

The work was carried out by a working group including representatives

from the Swedish Transport Agency and the railway undertakings. The

participants in the team are detailed below.

Participants Organisation Function

Mikael Aho Swedish Transport

Agency

Investigator

Tore Vernersson Chalmers Investigator

Pär-Johan Wedell AFRY Investigator

Petter Hydén Hector Rail Engineering support. Rolling Stock

Lars Fehrlund Green Cargo Brake expert, Green Cargo

Göran Davidsson COWI Risk analysis consultant

Table 1. Participants in the working group

1.4 Scope and boundaries

The analysis covers systems according to the system definition and

boundaries in chapter 2.

The quantitative analysis is based on the current scope and conditions (in

accordance with chapter 2) regarding operation of wagons with composite

brake blocks. The impact of a large-scale introduction of wagons with

composite brake blocks has not been quantitatively analysed.

As far as is known, the introduction of composite blocks has not undergone

any risk analysis. The introduction has been based rather on the fact that

composite blocks were approved in accordance with an accepted testing

procedure.

The braking system is a fundamental system for railway safety, with both

technical and operational safety being completely dependent on it. In this

case it may be retrospectively stated that a risk analysis should have been

3 EN 50126-1 Railway applications - the specification and demonstration of reliability, availability, maintainability

and safety (RAMS)


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carried out as to whether the current testing methods for brake block

approval successfully reflect actual conditions.

This report is not a risk analysis prior to a proposed change, but rather a risk

analysis of an already existing situation. The Swedish Transport Agency,

who carried out the analysis, is not the proposer and does not itself have

control over the relevant safety measures currently in operation.

It follows, therefore, that this report does not exhaustively include all parts

of the risk management process in accordance with CSM-RA:

The issue of “significant change” is not investigated. It may

retrospectively be stated that the change was significant since it

resulted in a significant number of incidents.

The work does not result in a definitive list of safety measures which

may be implemented, but rather documents possible measures which

need to be investigated further.

Neither does the work show whether safety requirements have been

met following the implementation of the safety measures identified.

The report has not been subject to a formal independent review.


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2 System definition4

2.1 System objective (intended purpose)5

The objective is for the system to be based on K and LL brake blocks

instead of GG brake blocks6. The system must function in trains and at low

speed (shunting with brake active) under normal weather conditions,

including winter conditions.

The system objective is to have the requisite retardation during actual

conditions with the requisite degree of safety.

2.2 System functions and elements7

The system consists of freight wagons with composite brake blocks (CBB)

of types K and LL, which should be used operationally under all Swedish

weather conditions. The brake blocks are either organic or sintered. The

brake blocks are used on wagons whose weight may vary between empty

and fully loaded.

The composite brake blocks which are used in this risk assessment are listed

in8

- ERA Interoperability Unit. List of fully UIC approved composite

brake blocks for international transport. Reference: ERA/TD/2009-

02/INT. Dated 23/07/2015

and/or

- UIC 541-4, Appendix M. Composite brake blocks certified for

international traffic, 5th edition November 2018. Last update

23/04/2020.

The wagons have a brake configuration which is mainly 1 x Bgu for K

brake blocks and 2 x Bgu for LL brake blocks. 2 x Bgu exists for K blocks

but are less common.

4 Translations between different languages must be performed with the same wording as in different language versions of COMMISSION IMPLEMENTING REGULATION (EU) No 402/2013 of 30 April 2013 on the

common safety method for risk evaluation and assessment with amendments from: COMMISSION

IMPLEMENTING REGULATION (EU) 2015/1136 of 13 July 2015 amending Implementing Regulation (EU) No 402/2013 on the common safety method for risk evaluation and assessment 5 CSM-RA, 2.1.2, a. System objective (intended purpose) 6 L brake blocks are not included, but should have the same impact. L brake blocks are currently not in operation in Sweden. 7 CSM-RA, 2.1.2, b. System functions and elements, where relevant (including e.g. human, technical and

operational elements). 8 There are some differences between the ERA list and the UIC list. The ERA list does not list certain brake

blocks, but in those cases the blocks are fitted on TEN (Trans European Network) approved wagons.


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The brake system functions consist of a command given from driver, drivers

safety device or the train safety system regarding braking via the brake pipe

(HLL) that goes through the train. The autonomous (indirect) braking

system, creates a pressure force against the vehicle’s friction elements

which, with the aid of its friction coefficient, generates a braking force when

it is applied to the rotating wheels of the vehicle. In this case there is no

difference between Sweden and the rest of Europe.

The following UIC approved K brake blocks have been assessed based on

observations and incidents9:

CoFren, Cosid 810 (C810), organic

Federal Mogul, Jurid 816 M (J816M), organic

Federal Mogul, Jurid 822 (J822), organic

The following approved brake blocks were assessed based on observation:

Icer Rail / Becorit, IB 116*, organic

CoFren, C952-1, sintered

Wagons with K and LL brake blocks have s or ss brakes.

All trains operate in brake regime P, though it might be the case that the

leading locomotive is in brake regime G.

The wagon axle loads vary between approximately 4.4 and 22.5 tonnes.

Typically, the lowest axle load is approximately 5 tonnes.

Note that the brake blocks are approved by UIC, though it is unclear which

of the testing methods that actually were used10. The temperatures and

exercising used in the UIC bench tests do not, however, correspond to real

winter conditions. For example, the test temperature is either -7 °C or -

10 °C. Additionally, the minimum axle load for UIC testing does not

correspond to the lowest permitted value either.

2.3 System boundary11

In this safety assessment the following are excluded

a) Wagons

o with an axle load of 25 to 35 tonnes operated at the greatest

permitted speed of 50 km/h loaded and 70 km/h empty.

These wagons are operated in a variant of brake position G

on stretches off the normal network.

9 In addition to this there are incidents with nationally approved CBB, but these are far fewer in number. Some

brake blocks previously had UIC approval, for example K brake block, ABEX 229/M128. These were previously approved by UIC based on quality assurance by SNCF. The brake blocks are listed in UIC 541-4, Appendix N.

conformity assessment in accordance with the 2nd edition of UIC 541-4, 1.10.1990 10 The UIC and ERA lists do not specify which testing methods were used, only that the braking blocks are approved. 11 CSM-RA, 2.1.2, c System boundary including other interacting systems.


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o with 25 tonnes axle load at nationally approved and normal

freight train speeds.

The purpose of excluding these is that the wagons cannot be used for

international operation and because these wagons are specially

adapted for national conditions. Also, for the first item braking

performance is adapted for low-speed and 30 tonnes axle load, which

is a special case, not appropriate for the rest of the rail network.

b) Potential environmental impact from alternative brake block types

(compared with GG brake blocks).

c) Effect on braking capacity of the train from potential deficient

braking capacity from the locomotive. We have no deficiencies in

the braking capacity of the locomotive in winter time. This can,

therefore, be completely and entirely excluded.

2.4 Physical and functional interfaces12

2.4.1 Permitted line speeds

Permitted line speeds for freight trains in Sweden depend on available brake

percentage, track design, train length and train protection systems.

Regarding track design, distant signal distance is the crucial parameter, but

gradients also have an impact. A distant signal distance of 1000 m is typical,

but on different tracks this may be greater or less.

Note that the train’s brake percentage must be 61% or higher for it to be

able to be operational as a train in regular traffic. If the brake percentage is

less than 61% the maximum permitted speed is between 20 and 40 km/h

depending on brake percentage and track gradient.

The normal speed for a freight train is 100 km/h, but this may vary. The

whole planning system for the freight train system is based on the standard

train maintaining a line speed of 100 km/h.

The logic regarding the maximum permitted speed is: the longer and heavier

the train, the greater the brake percentage required to maintain a normal

speed (100 km/h).

The objective of the railway companies is to operate trains which are as long

and as heavy as possible, to achieve optimal efficiency. In order to achieve

this, a relatively high brake percentage is required. For example, a brake

12 CSM-RA, 2.1.2, d. Physical (i.e. interacting systems) and functional (i.e. functional data input and output)

interfaces.


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percentage of 80% is required to operate a train with a length of 501 to

600 m with Vmax 100 km/h13.

2.4.2 Permitted track axle loads

In principle an axle load of 22.5 tonnes is permitted, although this may be

higher14 or lower on certain tracks.

2.4.3 Train protection systems

Generally, the national class B System ATC2 is used, but a limited number

of lines have ETCS 2.3.0d with national deviations. In the beginning of

2021, the first lines will be upgraded to ETCS BL 3.6.

There will still be lines with ATC2 at least until 2035.

2.5 The system environment15

The friction element’s capacity to deliver a braking force must be

completely independent of the environment at the time of braking. The

braking system must function both at low speed (shunting) in terminals and

when the train is running.

Low speed operation is carried out at a maximum permitted speed of

30 km/h, but there are sometimes lower maximum permitted speeds.

Normally freight trains operate under all winter conditions, but in the case

of extremely low temperatures (under ca -40° C) and/or extreme snow fall

(where snow clearance has not been carried out) rail traffic is halted by the

infrastructure operators or the rail company. Note that temperatures

below -25° C are uncommon.

2.6 Existing safety measures and safety requirements identified16

Existing safety measures are set out below. These measures are of the kind

that have been applied during previous winters in operation, maintenance

and testing of elements, rolling stock and operations.

The safety requirements which were identified in the iterative risk

assessment process are documented in a later section. The exception is

measures/safety requirements which were identified before this risk

13 This applies to what are known as B lines which are common. 14 The greatest axle load permitted in Sweden is 25 tonnes to the south of Boden. On Malmbanan (the Iron Ore Line) 30 tonnes is permitted. 15 CSM-RA, 2.1.2, e. System environment (e.g. energy and thermal flow, shocks, vibrations, electromagnetic

interference, operational use). 16 CSM-RA, 2.1.2, f. Existing safety measures and, after necessary relevant iterations, definition of the safety

requirements identified by the risk assessment process.


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assessment, but which have still not been tested in operation and

maintenance (which are included below).

2.6.1 Approved brake configurations

All brake systems which are included in this risk assessment are approved

by UIC and ERA. This means that those brake configurations which are

included in this risk assessment are tested for winter conditions. Despite

this, serious shortcomings have been identified.

Note

- that there are three possible testing programmes for winter

conditions17, but it is not stated which programme that was used as a

basis for approval of a certain brake configurations,

- that two of the test programmes are bench tests (which ought to be

the most common). These were carried out at -7 °C and -10 °C

respectively. In these cases artificial snow was used,

- that one of the test programmes is based on field tests18 and here it is

stated that the meteorological conditions must be such that the

temperature is from 0 to -10°C and

- that the test is not carried out at the lowest approved axle loads, i.e.

those axle loads which cause the lowest pressure between brake

block and wheel are not tested.

Based on incidents and observations as well as interviews with experienced

locomotive drivers, it is apparent that the problem of sudden and major

reduction in braking performance is exacerbated by two factors – low-

temperature and fly-off snow. It should also be noted here that the design of

the wagon very likely influences the amount of fly-off snow19. Empty

wagons with high stanchions should produce more fly-off snow. The

maximum negative impact on the function of the brakes is judged to occur

at -15°C or below in combination with maximum fly-off snow20.

This existing safety measure is not sufficient, since the tested brake blocks

have not been verified in winter conditions.

2.6.2 Bedding in of brake blocks in trains

During testing and operationally the blocks must be bedded in21.

17 See UIC 541-4, A.5.1 18 See UIC 541-4, G 19 ”Snow fly-off” (Snörök in Swedish) may be classified according to UIC 541-4, G3.2 20 Hector Rail assessment. 21 With “bedding in” is meant that the geometry of the brake block at the friction surface is the same as the

geometry of the wheel so that maximum contact area is achieved.


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Operationally the rules apply that a maximum of ¼ of the brake blocks may

be changed at the same time22.

Exceptionally, Swedish operators have reduced the speed following a

change on a large number of wagons until the blocks have been bedded in.

This existing safety measure is important in all conditions. However, it is

possible that it might tend more to counteract the sudden and major loss of

braking capacity that may occur in winter conditions. In these cases, the

opposite may apply, since the pressure23 between the brake block and the

wheel increases with low contact area (i.e. blocks not bedded in). Increased

(surface) pressure might increase the capability of wearing off the ice on the

adhesion surfaces of the block.

This existing safety measure is immensely useful during most of the year,

but it is in all likelihood ineffectual in winter conditions.

2.6.3 Operational rules – definition of winter conditions

During winter conditions special rules apply for wagons with CBB. The

definition of winter conditions varies very slightly between different railway

companies but in principle the following definition is applied;

Winter conditions shall be deemed to exist when

- the temperature is below 0°C and

- there is fly-off snow on the tracks and/or

- the tracks are snow or ice-covered and/or

- there is a significant build-up of snow or ice in the underframes of

the wagons.

This definition is in principle identical to the recommendation in UIC 541-4,

section 2.2.1.3:

1. Definition of winter conditions from a braking perspective:

- the temperature is below 0°C and

- there is windblown snow on the tracks and/or

- the tracks are snow or ice-covered and/or

- there is a significant build-up of snow or ice on the wagons in

service

The definition of winter conditions is used to determine the activation of

operational winter measures. It is the individual locomotive driver who is

responsible for applying winter measures in winter conditions.

22 In accordance with recommendations in UIC 541.4, 2.2.2.1. 23 Force per unit of area


22 (91)

The definition of winter conditions is particularly conservative. At the same

time, it is extremely important to have safe and simple rules.

This existing safety measure means that the driver implements measures.

However, it is very apparent that the scope of the requisite measures at, for

example,

- temperatures of around 0° C and a snow-covered track (but without

fly-off snow) and

- temperatures of around -15° C and below, accompanied by heavy

fly-off snow

requires completely different operational measures particularly if the

wagons have organic blocks with poor properties. Under the last

aforementioned condition there is a greater likelihood of

- very strong need for exercising and surveillance or

- high risk for incidents or accidents

- the train needing to be stopped.

From the perspective of brake technology this definition is not optimal and

from a driver perspective it is important to have simple rules. However, the

rules must be reliable and here we can identify potential for improvement. It

would appear that this can only be done, if it is possible to exclude the most

unsafe and dangerous braking systems. After such a change, the definition

used to activate winter measures can be applied for the worst winter

conditions.

The rules apply to trains with 50% CBB or more.

2.6.4 Operational roles for low speed operation of CBB wagons

Low-speed operation means shunting with wagon brakes active. The highest

speed permitted is 30 km/h. Under these conditions, the opportunities to

condition the brake system are limited for the simple reason that kinetic

energy and thus braking power is low.

Besides standard brake tests which are carried out all year round, such as

- visual inspection,

- checking that air is connected (HLL and when appropriate HBL) are

checked on the last wagon

- checking that brake applies and release, (on both sides only in

wintertime but for all block types)24,

- leak tightness test,

24 This fulfils the recommendations in UIC 541-4 section 2.2.1.3, point 2, second bullet point: ” During the brake test prior to leaving the departure station, the train should be checked to ensure that the blocks on either side are

released.”


23 (91)

- free rolling test25 and

- test braking when rolling has begun.

the measures below during winter conditions for normal CBB wagons also

apply. The rules apply to all types of rolling stock trains with more than

50% CBB wagons26:

a) Brake at standstill with full service brake.

This safety measure complies with UIC recommendations27. It is

adjudged that this measure does not contribute to improving brake

performance. It is not possible to notice visually any impact of an ice

layer on the block compared with testing of brake (with ca 0.6 bars

HLL pressure drop). Even after 10 brake cycles with full service

brake, stationary, the braking capacity is not affected. It is currently

being investigated whether the measure should be discontinued.

b) The locomotive drivers are informed and trained to deal with the fact

that in wintertime braking capacity of wagons with CBB can fall

suddenly and strongly.

2.6.5 Operational rules for low-speed running of CBB wagons which have winter problems.

Certain CBB wagons underperform hugely in winter conditions. For these

wagons additional measures are applied in accordance with the following.

a) Immediately after the vehicles is set in motion there should be a test

braking to standstill.

Normally just one test braking is carried out, not necessarily to

standstill. The aim of this test braking is partly to ensure that the

locomotive driver has a good understanding of the braking capacity

of the wagons and partly, to a certain extent, to carry out exercising

of the brake. Obviously the braking energies are low, but it is

possible that certain improvements will be attained.

b) Repeated test braking shall be carried out at least every 15 minutes.

Test braking at low speed should be carried out with between ⅓ and

full service brake.

The aim of this is the same as for the above measure. Note that to

always require full service brake is simply operationally impossible,

and also the probability of wheel flats would rise greatly following

25 This fulfils the recommendations in UIC 541-4 section 2.2.1.3, point 2, third bullet point: ” During departure it

should be checked that all the wheels on the train are rolling freely.”. Note that this recommendation actually

applies to most operators the year-round. 26 Note that this may be critical since it should not be based on the number of wagons but rather on the proportion

of brake weight which is based on CBB. Nevertheless, in practice it usually complies. Every railway company is

responsible for rules in this area. 27 See UIC 541-4 section 2.2.1.3, point 2, first bullet point: ”Before moving stabled trains or parts of trains, a full

brake application should be carried out (pressure drop in main brake pipe ~ 1.5 bar).”


24 (91)

such a requirement. The driver adapts test braking to friction

conditions, gradients and other factors.

c) Every planned braking must be preceded by a test braking. The

brake may not be relied upon and therefore the test braking must be

carried out before a necessary braking.

d) Speed should be adapted according to braking capacity.

It may unfortunately be necessary to limit speed to walking speed.

Following that, extensive test braking (exercising) may be required

before the train can operate on the line.

Generally, locomotive drivers are well trained and aware about the fact that

at low speed in all weather conditions wagons with CBB have lower braking

capacity than those with GG brake blocks. Note that this is well managed.

The above rules were in principle applied during the winters of 2017/2018,

2018/2019 and 2019/2020, though continual improvements have been

implemented and ongoing training has been given. Note that the winter of

2019/2020 was not relevant for the assessment of these rules, since the

winter conditions were very mild.

Overall this is a very troubling situation since large parts of safety have been

moved from the system to the locomotive driver and since there are

uncertainties around whether the requisite safety can be upheld.

2.6.6 Operational rules for trains with CBB wagons

The following rules apply to trains with composite brake blocks in winter

conditions. By CBB trains is meant trains where more than 50% of the

wagons have CBB brake systems.

a) After departure a service braking (without electrodynamic brake)

should be applied before full speed has been reached. This is to

check the braking performance. If the braking is normal, continue in

accordance with normal procedure with the retardation check. If the

braking power is lower than expected this should be repeated until

the braking function is attained and the retardation check can be

carried out. Alternatively, if the braking function is not attained the

train should be stopped28.

This rule is to ensure that the braking function is present before

maximum permitted speed is attained. It is difficult to assess since a

certain speed is required in order to use technical calculations of the

train’s retardation which is carried out in the next step. At this stage

28 This measure corresponds to the recommendation in UIC 541-4, section 2.2.1.3, point 2, fourth bullet point.


25 (91)

the assessment is completely and entirely in the hands of the

locomotive driver.

b) Retardation check is carried out with technical calculation. For the

retardation check a service brake with 1 bar (without

electrodynamic brake) is performed. If the train’s brake percentage

is not reached, the retardation check must be repeated with full

service brake (1,5 bar). If the brake percentage is not reached, the

brake percentage is reduced to the percentage calculated with the

train's safety system.

This function may be found in ATC2, but not in ETCS29 which is

why this barrier is not always found on ETCS rolling stock.

c) Exercising and test braking must be carried out at least every 15

minutes.

The purpose of this is to condition and check the braking capacity of

the train. With this braking there is no specific requirement for the

reduction of HLL30.

d) All braking, with the exception of a) ovan and parts of b) above,

shall be carried out with full service braking (with a reduction of

HLL by 1.5 bars). When the brakes are applied and a braking

function can be clearly observed, the brakes may be operated in the

normal way31.

The aim with this measure is to maximise exercising in the initial

phase of braking and to obtain margins. Also, the probability of

wheel flats is somewhat lower in the higher speed interval. In the

lowest speed interval, it must be accepted that the braking function is

reduced to avoid wheel flats.

e) After each brake application , i.e. in accordance with c) and d) ovan,

with a pressure drop of more than ~ 1 bar, where possible, the

retardation value should be assessed using the train safety system.

The purpose of this is for the locomotive driver to have support in

the assessment of the train’s current retardation capacity.

One fundamental problem is that there is a long brake application time for

the brake in the wagons further back in a long freight train, therefore those

29 Note that there is an ETCS system with internal STM which has the ability to carry out retardation checks at

ETCS level 2 also. ETCS does not have a requirement for this functionality. When there is no possibility of technical calculation, the driver must carry out a retardation check without technical calculation. 30 This exercising of the brakes corresponds fully and entirely with the recommendations in UIC 541-4, section

2.2.1.3. 31 This measure is not included in UIC and indeed should not appear there. This is something that should be

adapted by each railway company.


26 (91)

brake blocks do not receive sufficient exercising. This problem is

exacerbated if the exercising cannot be carried out from full line speed.

2.6.7 Operational rules for trains with CBB wagons which have poor winter properties.

Certain CBB wagons underperform hugely in winter conditions. For these

wagons additional measures are applied in accordance with the following.

a) Immediately after setting the train in motion at low speed a test

braking to a standstill with full service brake with brakes on the

locomotive released (using the release button32 or with active brake

inhibition valve33) shall be carried out. In the final phase of the

braking, HLL may be raised to avoid wheel flats.

The aim of this measure is to obtain certain exercising and to ensure

that the locomotive brake do not conceal deficient braking capacity

in the wagons. In addition, the braking energy is maximised for the

wagons since the locomotive is not braking.

b) Electro-dynamic brake shall not be used for normal braking or

exercising of the brake.

c) During exercising the locomotive's brake shall be released (using

the release button or active brake inhibition valve).

d) Exercising must always be carried out with full service brake, at

least every 15 minutes.

The purpose of the measures, set out in a) to d) ovan, is that for each

brake application (which does not take place before a target) the

braking energy to the wagons is maximised. Also, braking

applications on the locomotive, which does not suffer from winter

problems, serve only to create maintenance costs.

We can also see some indications that brake applications with low

drops in HLL may worsen the braking performance of the wagons at

the next brake application. Full service brake produce a significantly

better exercising than lower reductions of HLL34.

e) Service brake shall always be initiated with full service brake and

the majority of the brake phase shall be performed with full service

brake.

This is in principle the same for other CBB, but the difference is that

32Note that not all locomotives on the Swedish market have a function to release the locomotive. 33 Note that only a few locomotives on the Swedish market have brake inhibition valves and some of them have

too high limits (around 4 bar) so they cannot be used. 34 Exception might be if exercising can be performed with traction since it can then be performed at high speed,

i.e. when kinetic energy is high.


27 (91)

we actually do carry out the majority of the braking with full service

brake.

f) For the retardation check only procedure R235 shall be carried out,

i.e. service brake with a pressure drop of 1.5 bars.

In this case we deviate from customary procedure which is to carry

out the retardation test with 1 bar drop (procedure R1). The purpose

is to maximise brake power. Brake applications with low pressure

reductions are also avoided as they may worsen the braking capacity

of the wagons.

These measures were introduced gradually during the winter of 2017/2018.

During the winter of 2018/2019 all measures were introduced for critical

trains with CBB. Unfortunately, these CBB trains had GG wagons mixed in,

in the hope of attaining a certain level of safety. This safety measure was in

all probability erroneous and inappropriate since

- the quality of exercising of CBB wagons is lowered significantly in

trains with both GG and CBB wagons, since GG wagon braking

initiates directly and absorbs a large amount of the braking energy.

This consequently reduces the exercising of CBB wagons

dramatically,

- the high braking capacity of the GG brakes hides deficiencies of

these CBB wagons and

- damage to the wheels of the GG wagons36 increased sharply as a

result of the increased and unnecessary exercising of the GG

wagons.

2.6.8 Non-implemented operational rules for trains with CBB wagons

During short duration parking of CBB wagons, it is required that they are

braked with at least full service brake. In the winter of 2019/2020 a wagon

set started to roll while it was temporarily parked and braked (in conjunction

with a locomotive turnaround37) and collided with the locomotive thereby

causing a SPAD.

This rule will be introduced by several railway undertakings in Sweden and

is applicable all year round for wagon sets with more than 50% CBB.

35 R1 stipulates a retardation check where, with the aid of technical regulation, the driver can brake with a HLL

drop of 1 bar. R2 stipulates a retardation check with technical calculation where the driver brakes with full service

braking. R2 is normally only carried out were R1 does not produce the required result. 36 Shelling and pitting experienced the greatest increase but the frequency of wheel flats also rose. 37 Moving the locomotive from one end of the wagon set to the other.


28 (91)

2.7 Assumptions which determine the limits for the risk assessment38

The risk assessment is limited to comparing CBB and GG brake blocks in

Swedish conditions

2.7.1 Reference system

The reference system consists of wagons with cast iron blocks (GG brake

blocks). These have the brake configuration 2 x Bgu and have s or ss brake.

In general, the reference system has the highest permitted axle load of

22.5 tonnes and an 18 tonne brake weight per axle39. Some wagons have a

brake weight of 14,5 ton per axle40. Brake weights lower than 14,5 ton are

not common.

Variant configurations from above are very uncommon and this applies to

wagons with low brake performance. There also exist nationally approved

CBB brake blocks for certain applications. These systems are not used as

reference systems.

38 CSM-RA, 2.1.2, g. Assumptions which determine the limits for the risk assessment. 39 ss brakes 40 s brakes


29 (91)

3 Operational experiences and test results

3.1 Summary of incidents

There is a summary of reported incidents in Appendix A. Reported incidents

comes from Green Cargo and Hector Rail.

In the period February 2015 to August 2019, Green Cargo reported 18

events. In most of the cases reduced braking capacity was detected while the

train was running and this was able to be dealt with by reducing speed from

100 to 80 km/h. However, two cases of Signal Passed At Danger (SPAD)

were reported as well as one case where there was very nearly a collision

and one further case where there was a complete loss of braking capacity.

In the period December 2017 to March 2020, Hector Rails reported 21

events. In most of the cases, reduced braking capacity was discovered

during shunting with brake active or in running trains that consequently

were stopped and/or turned back without danger. However, four cases of

SPAD were reported, one case where it was possible to stop merely 1 m

before the signal, one case where during shunting with braked wagons a

level crossing was crossed without permission, and one case where a parked

wagon set began to roll during a locomotive turnaround.

3.2 Summary of test results

3.2.1 Swedish Transport Agency winter tests

The Swedish Transport Agency organised winter testing of LL type

composite brake blocks during the 2016/201741, 2017/201842 and 2019/2020

seasons43.

The results of the brake force comparative test carried out in 2016/2017

showed that the type of wagon can have a major influence on the braking

performance of a composite brake block in winter conditions. During the

tests it was demonstrated that composite blocks lose up to 50% of their

braking capacity compared with cast-iron blocks during heavy fly-off snow

conditions. The amount of fly-off snow appears to vary depending on the

type of wagon; one wagon’s stanchions produced a considerably increased

amount of fly-off snow around the brake apparatus which in turn led to

41 Damill test report “Block Brake Performance in Winter Conditions rev 1.0” 42 ÅF rapport - Report 6179083 and Chalmers evaluation report Swedish tests of block brake performance in

winter conditions Winter 2018-2019 43 Swedish tests of brake block performance in winter conditions 2019-2020: Detailed analyses of experimental

results"


30 (91)

greatly reduced braking capacity for composite brake blocks when directly

compared with cast iron brake blocks.

The results of the braking distance tests from the 2019/2020 season showed

that the IB116* organic composite brake block showed a substantial

variation in braking distances (600 m – 1000 m). On average, the braking

distance increases with the low temperature and fly-off snow by around

25%, when a reference test with negligible or no fly-off snow is compared

with winter tests with a large amount of fly-off snow. No such increase was

observed during winter tests for the C952-1 sintered composite brake block.

The results from these tests are built, however, on the fact that

1. the wagons have undergone recent maintenance44 and have a very high

efficiency in the brake rigging,

2. the wagons are de-iced regularly, every second or third week,

3. the braking system is exercised every 15 minutes at 1.5 bars from the

highest speed down to standstill,

4. the wagon is used in mild winter conditions with a lowest temperature of

-10 °C.

3.2.2 Hector Rail winter testing

Hector Rail carried out testing in the winter of 2017/2018. These tests

demonstrated that

- the UIC recommendations for exercising was not sufficient for

critical wagons and

- the actual brake configuration of 1 x Bgu with J822, λempty≈100 %

was deficient during winter conditions for empty wagons.

During the winter of 2019/20 the idea was to test at least two modified

brake configurations:

Case 1: Modification with increased actual brake percentage at empty state.

The increase was from the current λempty≈100 % to λempty≈118 %45.

The aim of this increase is to increase the ability to remove the ice

on the brake blocks during the exercising. This case has been

implemented on a small number of wagons, but the mild conditions

this winter have not been appropriate for measurements and

monitoring can only be done when we can run complete trains (at

least 13 eight-axle wagons). No test results have been obtained.

44 "Recent maintenance" entails lubrication of the braking system so that high performance can be reached. 45 The maximum permitted is 125 % for wagons with automatic load braking. The purpose of only having 118%

braking is partly to avoid actually going over the maximum limit and because the risk of wheel flats increases.


31 (91)

Case 2: changing blocks from J822 to C810. The purpose was to see

whether this might give improvements. Note that the only reason

for selecting C810 was that the type of wagon (with exactly the

same brake equipment) was already TSI approved. All that was

required was a remarking of the braked weight and type of block. If

this was not simple this alternative would not, of course, be tested

since the probability of achieving improvements with C810 is very

small.

Winter conditions during the winter of 2019/2020 were extremely

mild.

Operational monitoring did, however, show two issues at low speed

(shunting) and for this reason this block will be discontinued on

this type of wagon. However, wear monitoring is ongoing.

Case 3: change of brake block to CoFren C333 (sintered block).

Case 4: change of brake block to Flertex C302 (sintered block). This brake

block does not appear on the UIC or ERA lists of approved brake

blocks. This brake block is, however, the brake block for which no

deficiencies have been identified in Finland hitherto. According to

Hector Rail, this is probably the best alternative, but further testing

will be discussed with the wagon rental company who is also ECM

and VK.

A decision will be made about further tests for the remaining Cases, 1, 3 and

4. It would be reasonable to prioritise Case 4. Cases 1 and 3 would await the

results from this case.

Note that winter conditions in 2019/20 were particularly mild, but sufficient

to reject Case 2 (C810).


32 (91)

4 Risk assessment

4.1 Method

The work consists of the following activities:

1. Identification of hazards. This was carried out in the working group

and was based on incidents that took place as well as the experience

of the group, documented in chapter 4.2.

2. Risk estimation including assessment of severity and frequency.

Assessment of severity is based on the experience of the group.

Assessment of frequency is based on reported incidents and is

detailed in chapter 4.3.

3. Comparison with the reference system. The relevant reference

system is cast iron brake blocks. The comparison is documented in

chapter 4.4.

4. Risk evaluation based partly on estimated risk (point 2 above) and

partly on comparisons with the reference system (point 3 above). For

the risk assessment based on estimated risk, the starting point is the

risk matrix in accordance with EN 50126 (Figure 1 below),

documented in chapter 4.5.

Frequency of occurrence of

an accident (caused by a

hazard) Risk Acceptance Categories

Frequent Undesirable Intolerable Intolerable Intolerable

Probable Tolerable Undesirable Intolerable Intolerable

Occasional Negligible Undesirable Undesirable Intolerable

Rare Negligible Tolerable Undesirable Undesirable

Improbable46 Negligible Negligible Tolerable Undesirable

Highly improbable47 Negligible Negligible Negligible Tolerable

Insignificant Marginal Critical Catastrophic

Severity of an accident (caused by a hazard)

Figure 1. Risk matrix in accordance with EN 50126-1

46 Improbable: an occurrence of a malfunction with a frequency below or equal to 10-7 per hour of operation CSM-

RA Article 3, (37) 47 Highly improbable: an occurrence of a malfunction with a frequency below or equal to 10-9 per hour of

operation CSM-RA Article 3, (36)


33 (91)

4.2 Identification of hazards

The following hazards and consequences have been identified (see also

analysis protocol Appendix B).

Hazards Possible consequences

1. Reduced braking

capacity leading to

extended braking

distance

1.1 Collision with another train

1.2 Collision at low speed with a stationary vehicle/object

1.3 Derailment due to excess speed through a switch or passing a

track buffer.

1.4 Signal Passed at Danger (SPAD) without collision or

derailment

1.5 Loss of braking capacity without SPAD

2. Driver anxiety due to

variation in the braking

capacity of the train

2.1 Stress

2.2 Repeated testing and exercising of brakes

Table 2. Sources of risk and possible consequences

Consequences 1.1 – 1.5 are explicit (objective) risks from deficient braking

capacity. Events 2.1 – 2.2 are more subjective and will vary between

different drivers in different conditions depending on the composition of the

train, brake configuration, weather and track conditions etc. Appendix D

contains a description of the driver’s working circumstances based on the

properties of the brakes.

4.3 Risk assessment

4.3.1 Assessment of severity

Estimation of severity is based on the examples of severity given in

EN50126 for RAM and RAMS (tables C3 and C4), set out in Table 3

below.


34 (91)

Estimated severity of respective consequences (1.1-1.5 and 2.1-2.2) is set

out in Table 4 below. In these evaluations both the RAM effect and the S

effect have been considered.

Table 3. Categories of severity EN 50126 for RAM and RAMS


35 (91)

Consequences Description Estimated

severity

(EN 50126)

RAM tab. C3

Estimated

severity

(EN 50126)

S tab. C4

1.1 Collision with

another train

Collision between a freight train and another train

may lead to multiple fatalities and/or major

environmental damage.

Not assessed Catastrophic

1.2 Collision at

low speed with a

stationary

vehicle/object

Collision between a freight train and another

stationary vehicle/object may lead to individual

fatalities/serious injury (driver) and/or significant

environmental damage.

Not assessed Critical

1.3 Derailment

due to excess

speed through a

switch or passing

a track buffer.

Derailment of a freight train vehicle/object may lead

to individual fatalities/serious injury (driver) and/or

significant environmental damage.

Not assessed Critical

1.4 Signal passed

at danger (SPAD)

without collision

or derailment

The train must be stopped and the driver taken out of

service. This will lead to major traffic delays. An

enquiry into the incident will be carried out. A

SPAD, even if there are no consequences, comprises

a major infringement of safety barriers. A conscious

increase of this type of event is completely

unacceptable.

Considered comparable to "severe system(s) damage"

Table C4.

Significant

Marginal

1.5 Loss of

braking capacity

without SPAD

The train must be taken out of service or continue

running at greatly reduced speed, which will produce

traffic disruption.

Considered comparable with "minor system(s)

damage" Table C4. This categorisation is on the low

side since many of the events meant that the train had

to return to its departure station.

Significant -

Major

Insignificant


36 (91)

Consequences Description Estimated

severity

(EN 50126)

RAM tab. C3

Estimated

severity

(EN 50126)

S tab. C4

2.1 Stress A braking system with variable braking force during

running will in reality lead to a situation where basic

safety can no longer be guaranteed by the technical

system and where responsibility is transferred to the

driver. This situation has resulted in certain drivers

refusing to drive certain trains. Long-term stress and

anxiety can lead to absence from work.

Stress regarding changes to work tasks. The risk of

getting stuck on long uphill inclines, where it is not

possible to condition the brakes, and stress over

falling behind the timetable.

Considered comparable to "severe or minor injuries"

Table C4.

- Marginal

2.2 Repeated

testing and

exercising of

brake

Severely worsened journey times, increased costs.

Considered comparable with "minor system(s)

damage" Table C4.

Major Insignificant

Table 4. Assessment of severity


37 (91)

4.3.2 Estimation of frequency and risk level

Frequency of hazard 1. Reduced braking capacity leading to extended

braking distance has been estimated below.

Estimation of frequency Hector Rail Sggrrs wagons

Failure description 1: Lost brake capacity in winter conditions for unloaded trains in high and

low speed operation with J822 in 1xBgu on Sggrrs wagons.

Loss of brake capacity is more than 20% loss (compared to braked weight marking).

Frequency of occurrence during winter 2017/2018 and 2018/2019: 15 events.

Estimation of hazard rate:

Estimation of operating hours:

- 160 wagons

- Average km per year: 80 000 km/wagon and year

- Average speed (incl. large number of shunting operations): 40 km/h

- Average number of wagons in a train or in shunting: 18 wagons

- Total operating hours:2∗160∗80000

40∗18= 35 555 𝑜𝑝. ℎ𝑟𝑠.

Frequency of occurrence: 𝝀𝑭𝒂𝒊𝒍 =𝟏𝟓

𝟑𝟓𝟓𝟓𝟓≈ 𝟒 ∗ 𝟏𝟎−𝟒 Faults per op. hrs

Note that average speed is estimated very low due to the fact that a lot of shunting is included at

terminals. However, if speed is estimated as 70 km/h, then the frequency of occurrence would

increase to 7*10-4.

Estimation of frequency Green Cargo – Jet Fuel Shuttle

Failure description 1: Reduction of brake performance

Frequency of occurrence of Failure description 1: 7 events

Estimation of hazard rate:

Estimation of operating hours:

- Total number of departures (6000 to 8000): 7000 departures

- Average operating hours per trip: 3 hrs

- Total operating hours: 7000*3=21000 op.hrs

Frequency of occurrence 𝝀𝑭𝒂𝒊𝒍 =𝟕

𝟐𝟏𝟎𝟎𝟎≈ 𝟑 ∗ 𝟏𝟎−𝟒 Faults per op. hrs


38 (91)

Estimated frequency is thus: 10-4 ≤ λ ≤ 10-3.

Comment regarding reported events:

There are uncertainties in the report basis. On one hand, it is well known

that there is an underreporting because often only events that are judged to

pose a serious danger are reported, the actual number of events is thus

probably significantly higher. On the other hand, the information in the

reported events is not always sufficient to determine the conditions that

prevailed at the time. It may therefore be that some of the events, even if

they occurred during the winter months, are not related to fly-off snow

and/or low temperatures.

Based on the table below this gives a frequency level equivalent to

"Probable". Note that these estimates are based on operating hours for a full

year. Considering winter seasons only would roughly imply a halving of the

operating hours and a doubling of the estimated frequencies. This will

however not change the conclusion of the frequency level.

EN 50126-1

Frequency

level

Description Example of a frequency range

based on a single item

operating 24 h/day.

Expected to happen.

Example of equivalent

occurrence in a 30 year

lifetime of a single item

operating 5000 h/year.

Expected to happen.

Calculated frequency

of occurrence of

hazardous events per

operating hour [h-1]

Frequent Likely to occur

frequently. The event will

be frequently

experienced.

more than once within a period

of approximately 6 weeks

more than about 150 times λ≥10-3

Probable Will occur several times.

The event can be expected

to occur often.

approximately once per 6 weeks

to once per year

about 15 to 150 times 10-4≤λ≤10-3

Occasional Likely to occur several

times. The event can be

expected to occur several

times.

approximately once per 1 year

to once per 10 years

about 2 to 15 times 10-5≤λ≤10-4

Rare Likely to occur sometime

in the system life cycle.

The event can reasonably

be expected to occur.

approximately once per 10

years to once per 1 000 years

perhaps once at most 10-7≤λ≤10-5

Improbable Unlikely to occur but

possible. It can be

assumed that the event

may exceptionally occur.

approximately once per 1 000

years to once per 100 000 years

not expected to happen

within the lifetime

10-9≤λ≤10-7

Highly

improbable

Extremely unlikely to

occur. It can be assumed

that the event will not

occur.

once in a period of

approximately 100 000 years or

more

extremely unlikely to

happen within the lifetime

10-9≤λ

Table 5. Frequency of occurrence of hazardous events (time based) EN50126

Note: The symbol λ in this context signifies frequency of failure and not brake percentage.


39 (91)

The quantitative estimation is obviously uncertain, since it is based on a

limited number of events. However, this level is considered reasonable,

though possibly on the low side, even with a more qualitative basis. In the

table above the following examples are given for an item in operation 24/h

per day:

Frequent: More than once every six weeks

Probable: Between once every six weeks and once per year.

Occasional: Between once per year and once every 10 years.

A qualitative assessment is that "occasional" is definitely too low to

correspond to experiences during the last two winters. Viewed only as

winter traffic "frequent" is considered a more reasonable estimate. However,

as a basis the class "probable" is allocated.

The frequency of consequences (1.1 – 2.2) is difficult to estimate, since this

depends on a large number of factors such as track geometries, traffic

conditions etc., but risk levels for these events are discussed below; 1.1 –

1.5 and 2.2 based on the risk matrix in accordance with EN 50126.


For loss of braking capacity to lead to a collision with another train a

number of conditions must be in place.

There are a number of circumstances and situations where the loss of brake

capacity may lead to collision without other malfunctions occurring. These

are described in Appendix C.

1. Crossover stations48

2. Station with connection to line/track 49

3. Simultaneous entrance to station when trains meet.

4. Conventional station

If any of situations 1 to 4 arises the train brakes to a stop. In addition, it

would require that there is another train which is so close that a collision

cannot be avoided. The circumstances are illustrated in a fault tree below.

48 A crossover station is a station on a double track where there can be four switches which make it possible to change between left and right tracks from both directions. 49 Station where another line is connected

https://sv.wikipedia.org/wiki/Driftplats

https://sv.wikipedia.org/wiki/Dubbelsp%C3%A5r

https://sv.wikipedia.org/wiki/J%C3%A4rnv%C3%A4gsv%C3%A4xel


40 (91)

Figure 2. Fault tree – collision with moving train

Estimated frequencies and probabilities for these events/circumstances are

documented below.


41 (91)

Event/

circumstances

"Best estimate"

frequency level/

probability

Sensitivity assessment

Max Min

0. Loss of

braking

capacity

Frequency level:

"Probable" in

accordance with the

above.

For winter traffic

frequency level

"Frequent" is

considered a

reasonable estimate

since a limitation

to winter

conditions implies

that the frequency

increases by just

over a factor of 2.

Not relevant

1. Situation 1

– 4 occurs

For 10% of total running

time the train is in the

situation of braking to a

stop. Example; three

hour journey with four

approaches /exits and

train meetings each of

five minutes gives

20/180 = 0.11

Probability 0.1

Considered to be

small variations –

adjustment not

relevant

Considered to be

small variations –

adjustment not

relevant

2. Another

train is on the

track ahead

An estimate on the low

side is that another train

is present in at least

10% of cases

Probability 0.1

Another train may

be present in up to

every other case

Probability 0.5

10% is considered

to be a low

estimate –

adjustment not

relevant

3. Another

train too close

to avoid

collision

This is difficult to

assess, as it varies

greatly depending on

traffic conditions, best

estimate considered to

be 10% of cases.

Probability 0.1.

In heavy traffic this

figure may be

higher. Probability

0.3

In light traffic this

figure may be

significantly lower.

Probability 0.01

Table 6. Estimate of frequencies/probabilities

This gives the following frequency levels for event 1.1 Collision with

another train:

Best estimate: Probable*0.1*0.1*0.1 → Rare

Max: Frequent*0.1*0.5*0.3 → Occasional

Min: Probable*0.1*0.1*0.01 → Improbable


42 (91)

This results in the following risk categories:

Best estimate: Undesirable

Max: Intolerable

Min: Undesirable

This is illustrated in the figure below.

Figure 3. Risk category/categories for event 1.1 Collision with other train.

1.2 and 1.3 Collision at low speed with another stationary vehicle/object

and derailment due to excess speed through a switch or hitting a buffer

stop

Events 1.2 and 1.3 are considered to have the same severity and are together

adjudged to have a frequency which is a factor of 10 higher than event 1.1.

In order for event 1.1 to occur there would have to be another train present

within a "dangerous distance". This requirement is not relevant here. In the

situations in question there is often a track barrier or a safety switch leading

into a buffer stop, so if braking is not possible there would be a derailment

or a collision with a buffer stop. The lowest frequency class from 1.1

(Improbable) stems from the probability of another train being within a

dangerous distance in this case was set at 0.01. This is not relevant.

This produces the following frequency levels for events and 1.2 and 1.3

combined:

Best estimate: Rare

Max: Probable

Min: Rare


43 (91)

This results in the following risk categories:

Best estimate: Undesirable

Max: Intolerable

Min: Undesirable


Figure 4. Risk category/categories for events 1.2 and 1.3 combined. Collision at low speed with another stationary vehicle/object and derailment due to excess speed through a switch or hitting a buffer stop.

1.4 Signal passed at danger (SPAD) without collision or derailment

Of the 15 events with reduced braking capacity, three resulted in SPAD.

Frequency is adjudged, therefore, to be at least 1/10 of the frequency of all

events and thus assessed according to:

Probable*0.1 → Occasional.

If, on the other hand, the initial frequency is set as frequent in accordance

with the above, the assessment would be:

Frequent*0.1 → Probable.

Severity has been assessed as "Marginal", giving the risk category

"Undesirable", illustrated in the figure below.


44 (91)

Figure 5. Risk category/categories for event 1.4 SPAD without collision or derailment.


The frequency class for Reduced braking capacity without SPAD is

evaluated above as Probable (best estimate) or Frequent (Max). Together

with severity class Insignificant this produces risk categories Tolerable –

Undesirable.


Figure 6. Risk category/categories for event 1.5 Reduced braking capacity without SPAD


45 (91)

2.2 Repeated testing and exercising of brake

Testing and exercising of brake shall always be carried out when the

weather conditions are such that there is a risk of loss of brake capacity.

Thus the frequency category is "frequent". Negative consequences in the

form of worse journey times and increased costs will always arise too.

This exercising is fundamental to ensuring braking distances for wagons

with composite brake blocks and must be carried out manually by the driver.

Driver action being the first line of safety goes against the desired

development where technical systems should be the first line of action. It

also goes against the safety culture the railway undertakings are trying to

implement; a positive safety culture, including provision of a suitable

working environment, will contribute to safety. Encouragement of positive

safety behaviour.

In an operational railway environment individuals, regardless of their

training, expertise, experience, ability and goodwill, may be confronted with

situations where the limits of human reliability in combination with

undesirable and unpredictable actions by the system may lead to undesirable

results. For this reason, necessary measures should be taken to manage

risks, including those which are related to the limits of human reliability.

Good safety management is proactive and relies on a risk-based strategy.

Transferring more responsibility for safety to the driver works against these

goals.

The severity has been rated "Insignificant", which produces the risk

category "Undesirable", illustrated in the figure below.

Figure 7. Risk category/categories for event 2.2 Repeated testing and exercising of brake.


46 (91)

Other events

Event 2.1 There is "always" stress during these weather conditions.

However, in this study it has not been viewed as possible to estimate the

probability that this would lead to absence from work or other impact on the

driver. Therefore, this event has not been accorded a risk category. The fact

that certain drivers refused to drive trains with composite brake blocks does,

nevertheless, mean that the problem is real and must be taken into account.

4.4 Comparison with the reference system.

The reference system consists of cast-iron brake blocks in accordance with

chapter 2.7.1

Regarding the events defined as "SPAD" and "train does not have braking

capacity", it can simply be stated that neither Green Cargo nor Hector Rail

have received a report of any such events for trains whose wagons are

equipped solely with cast-iron brake blocks. On the other hand, as reported

in chapter 3.1, six such events have been reported for trains whose wagons

are equipped with composite blocks. In addition, it should be noted that

these events occurred in spite of the operational measures taken in

accordance with chapter 2.6. Wagons with composite brake blocks comprise

a very small part of the total traffic in service. The conclusion from this is

that the introduction of composite brake blocks has increased the risk of

SPAD.

Comparison with the total number of reported SPAD incidents is, on the

other hand, much more difficult. A relatively large number of SPAD

incidents are reported each year, as shown in the figure below


47 (91)

Figure 8. The total number of SPAD reported on the Swedish rail network from 2015 to 2018. Source: Nationella OSPA-gruppen (National SPAD group)

Compared with these figures, the number of SPAD incidents due to

deficient brake capacity as a result of composite brake blocks is marginal,

but the following factors must be taken into account when making such a

comparison:

The number of SPAD incidents reported due to composite brake

blocks is probably underestimated since previously there has been no

information regarding the proportion of the total braked weight of

the train coming from composite blocks.

The material as a whole includes both passenger and freight traffic.

Without the operational measures taken in accordance with chapter

2.6, it is reasonable to assume that the number of SPAD incidents

due to composite brake blocks would be considerably higher. Many

of these measures, for example greatly reduced speed and cancelled

trains where test braking showed low brake performance, themselves

produce unacceptable consequences for rail traffic.

The material regarding rail traffic which resulted in the reported

SPAD events with composite brake blocks is very limited compared

with the material on which overall SPAD reporting is based.


48 (91)

Regarding SPAD which occurred for reasons other than loss of

braking capacity there is often a chance for the driver or the

technical system to avoid an escalation of the event. If there is no

braking capacity, both the driver and the technical system are out of

play.

As the proportion of composite brake blocks increases the probability of

negative traffic impact also increases. Ultimately, the likelihood of more

SPAD incidents increases which in turn leads to increased risk of serious

impact on humans, environment and/or property.


49 (91)

4.5 Risk assessment – comparison with criteria

4.5.1 Risk assessment based on explicit risk estimates

Estimated risk categories for the following events are shown in the figure

below.


1.2 and 1.3 Collision at low speed with another stationary

vehicle/object and Derailment due to excess speed through a switch

or hitting a buffer stop.

1.4 Signal passed at danger (SPAD) without collision or derailment.


2.2 Repeated testing and exercising of brake

.

Figure 9. Estimated risk categories.

A majority of the events lie in the Undesirable category. The most serious

event "Collision with another train" may, depending above all on which

conditions are in place regarding other traffic, be placed in the categories

from Intolerable to Undesirable. Events 1.2 and 1.3 Collision with stationary

object/derailment may also, depending on circumstances, be placed in a

category from Intolerable to Undesirable.


50 (91)

4.5.2 Risk assessment based on comparison with the reference system

In the case of risk assessment based on comparison with the reference

system, the judgement is that the introduction of composite brake blocks

instead of cast-iron brake blocks resulted in an increased risk of SPAD, in

spite of the operational measures taken.


51 (91)

5 Identification of possible measures

These measures should not be seen as in themselves reducing risks to an

acceptable level. Rather a combination of measures will be required, partly

over a transition period and also on a permanent basis. Also, national and

international measures must be taken, for example in the form of changes to

the European Commission's regulations 1304/2014 TSI Rolling stock –

noise and 321/2013 TSI Rolling stock – freight wagons.

These measures are also intended as operational rules for freight wagons

and locomotives. The judgement is that measures are required within all

these areas.

The nature of these measures is partly to increase safety and partly to enable

traffic to move at good speed.

For certain measures detailed there is an in-depth account of the advantages

and disadvantages in Appendix F.

At this time the proposals have not undergone consequence analysis or cost-

benefit analysis. This must be done and also there may be other measures

which need to be taken into account.


52 (91)

Number Possible measure Impact

G Investigate and test improvements for

freight wagons:

Sub items (G*) provide suggestions for

measures regarding freight wagons.

G1 Develop new testing methods for brake blocks.

Existing tests are carried out within a limited

temperature range which does not correspond

to real conditions. Realistic test conditions

should correspond to temperature, fly-off snow

and realistic conditions regarding exercising

the brake.

Potentially a general requirement for thermal

conductivity may be developed. This could be

tested/calculated relatively easily.

For example, testing could take place under

Module CV in-service running and supervision

of registered organisations. Module CV means

that testing of brake blocks takes place during

in-service running under the auspices of the rail

companies. The registered organisation then

validates the operational experience, together

with other tests which the manufacturer of the

blocks can carry out in bench tests and which

must have passed with approved results before

in-service running takes place.

The registered body issues a certificate

indicating what conditions the blocks may be

used in.

The brake blocks are the interoperability

constituent in TSI freight wagons.

Brake blocks which have

been approved in accordance

with new methods, tests

under real Nordic conditions

provide good braking

performance in wintertime.

Increased transparency where

all test protocols are made

available to whoever wishes

to see them.

The cost of the verification

test will fall, even though

winter tests themselves cost

in the region of SEK 1

million.

G2 Wagons with operational areas consistent with

the Swedish railway system are not permitted

during maintenance to change to, or under

renovation be equipped with, composite brake

block configurations marked with NOT OK or

NOT TESTED in Appendix E.

This means existing wagons

are prevented from being

equipped with brake blocks

with substandard function.


53 (91)


G3 Implement load restrictions and in this way

obtain margins. For wagons with deficient

braking capacity, loads are permitted in relation

to the braked weight of the wagon. Load

restrictions should be established for each

brake configuration.

Allows preservation of line

speed.

Major financial

consequences for transport

purchasers.

G4 Reduce the braked weight which is included in

the braking calculation for the train. Such a rule

would mean that deficient braking capacity for

both empty wagons and wagons loaded up to

the maximum braked weight would be

compensated for. The order of magnitude of

this reduction may be determined based on

tests and in-service running.

Create margins during

braking.

Lower speed

G5 When converting to LL blocks braked weight

shall be maintained or increased.

The empty braked weight shall, if possible, also

be adjusted upwards so that margins are also

maintained for empty wagons and so that the

lowest pressures between wheel and brake

block are avoided.

The impact of increased

margins.

Refitting costs.

G6 Remove the UIC requirement for kink valves50

on wagons with a braked weight of greater than

14.5 tonnes plus 15 % (16.7 tonnes) per axle.

This requirement and its accompanying costs

have meant that rolling stock owners have

reduced or only maintained braked weight of

the wagons when modified to composite brake

blocks.

Significantly reduced

refitting costs for wagons

with s or ss brakes if braked

weights are to be increased

or kept high. This applies to

wagons with RLV (Load

proportional valve) and in

particular to w agons without

such valves.

For rolling stock rakes with

identical wagons a more

proportional braking function

is obtained

50 Requirement in accordance with UIC 541-4, section 2.1.4.1, 3rd indent applying to LL brake blocks and section

2.1.4.2, 4th indent applying to K brake blocks


54 (91)


G7 Proposal for potential measures for new freight

wagons is to equip the wagons with disc

brakes.

The function of disc brakes is adjudged to be

less sensitive to winter conditions based on

those tests previously carried out by Green

Cargo, the Swedish Transport Agency, and

VTG.

Considered to provide

working braking function in

winter time.

Increased costs of wagons

G8 Proposal for potential measures for new freight

wagons:

- Higher actual brake percentage when

empty (lambda 115–120 % empty)51and 18

tonnes braked weight per axle, and

- if the wagon is equipped with K brake

blocks it should be in the configuration

1xBgu52 and

- use only brake configurations with

acceptable winter properties. Experience

has shown that the current approval system

regarding brake configurations has

shortcomings and thus does not provide

guidance. For this reason it is necessary to

base decisions on experience and tests and

- brake systems must have stable53 (and

high) efficiency levels (e.g. "Compact

Freight Car Brake Unit”)

Proposals for the raising of

brake pressure, brake

configurations and efficiency

levels are intended to ensure

that braking performance is

maintained in the winter

months via an increase of

margins and in such a way as

to mitigate the negative

impacts of the loss of braking

performance with composite

brake blocks.

Increased costs of wagons

51 The purpose here is to avoid the lowest pressure between brake blocks and wheel so that the abrasion is attained

which is very likely to remove ice from the brake blocks and provide a certain margin, since only λ=100 % is

included. 52 K brake blocks in the configuration 1 x Bgu avoid very low pressure between wheel and brake block when

empty in comparison with 2 x Bg and 2 x Bgu, since the total nominal brake block area increases by 28 % for

2 x Bg, and 100 % for 2 x Bgu respectively. K brake blocks in the configuration 1 x Bg mean that the nominal brake block area would be reduced by a further 36 %, but since the braked weight must usually then be reduced

there is normally no alternative. There are clear indications that at low pressure ice is not successfully removed,

especially on high friction blocks where the pressure is already low due to the high friction. 53 A stable level of efficiency compensates for the increased risk of wheel flats if the actual empty braked weight is

raised.


55 (91)


L Investigate and test improvements to

locomotives.

Sub items (L*) provide suggestions for

measures regarding locomotives.

L1 Introduce warm braking function on

locomotives.

This function means that the locomotive can

operate with traction while at the same time

HLL is reduced and thus the wagons are

exercised. In this way it is possible to make

exercising appreciably more efficient, since

average speed would not be lost and since

exercising of freight wagon brakes will take

place at high speed (where brake power is

high). The system requires that the brake of the

locomotive are not active (since there is no

need to condition them as they have an

effective braking system).

May increase the possibility

of operating trains with

composite brake blocks in

winter conditions without

compromising load or speed.

The current assessment is,

nevertheless, that these

measures do not solve the

problem for the blocks with

the worst properties.

Costs for modification of the

locomotive.

L2 Introduce brake inhibition valves on the

locomotives.

Brake inhibition valve (or secondary brake

valve) means that the indirect brake of the

locomotive is inhibited except when full

service brake or emergency/fast/train safety

system brake is demanded. Note that there are

variations of what HLL pressure constitutes the

boundary for when the locomotive brake is

activated. An alternative to having this valve is

that during each exercising of CBB’s the

locomotive brake is released manually.












locomotive.


56 (91)


L3 Electric brake at system emergency braking

In Sweden, when rolling stock is equipped with

electrodynamic brake, these are always

disconnected at emergency, rapid, train safety

system or drivers vigilance device braking. The

reason for this is that it has been difficult to

demonstrate theoretically that the traction block

has the requisite safety levels in these brake

modes when electro-dynamic brake is applied.

Note also that in Sweden braked weight is

never used for R+E or P+E in the calculation of

a train’s braking performance. Thus, in Sweden

we have chosen to protect ourselves against a

possible fault in the traction block (which has

never occurred).












locomotive.

L4 Introduction of automatic exercising

equipment.

Such equipment means that the locomotive will

automatically carry out exercising cycles on the

wagons by automatically reducing HLL. The

exercising cycle can be adapted in terms of size

reduction, duration and interval.












locomotive.


57 (91)


D Investigate and test improved guidelines for

operation.

Sub items (D*) provide suggestions for

operational measures

D1 Exception from TSI Noise to permit cast-iron

blocks until 2028, applies to approximately

17,500 wagons

This would allow traffic to

continue unaffected in

Sweden in the wintertime.

This proposal allows high

noise wagons to operate on

the continent.

D2 Report the total braked weight of the train

provided by composite blocks and cast-iron

blocks respectively. Currently the number of

wagons which have composite blocks and cast-

iron blocks are reported. This gives a

misleading picture since braked weight

depends on actual load, the number of axles,

load capacity and braking capacity for each

individual wagon.

The reporting should be divided up into

composite blocks with and without verified

winter properties.

Information regarding how

large a proportion of the

train's total braked weight is

made up of wagons equipped

with composite brake blocks

gives the driver a clearer

picture of how the braked

weight is arranged and thus

provides the driver with

guidance on how to manage

the brake. The effect of this

would be a more restrictive

way of braking, leading to

larger safety margins.

D3 Reduced speeds for freight trains Improved braking margins.

Major rail traffic and

financial consequences arise

(see Table 8); when too

great speed reductions are

required speed may become

so low that access to the

track is not granted.


58 (91)


D4 Investigate the possibility of applying different

rules for different zones in Sweden during

winter conditions. The intention is to introduce

rules which manage those factors which affect

braking capacity, i.e. combination of low

temperature and fly-off snow.

Limitations are implemented

only when they are useful for

safety considerations. Track

speed or load capacity are

limited only where this

contributes to increased

safety.

D5 Improved exercising technique (operational

rules). Develop the regulatory framework for

drivers. Currently there are a number of driver

measures required which probably have little or

no impact on improving safety. Also introduce

other measures which may have an impact

here.

These measures must be developed to take into

account the functionality of the locomotive.

Regular exercising of the

brake results in reduced

speed.

Drivers might well be able to

carry out the exercising

manually.

Laying responsibility for

safety on the driver rather

than on the automatic system

is a negative factor.

D6 During parking full service brake to prevent

rolling.

This means that the risk of wheel flats due to

freezing will increase as will the risk of delays,

since all frozen blocks must be freed and/or

wagons with wheel flats must be changed out

from the train.

Risk of freezing and wheel

flats.

D7 Extra wagons with cast-iron blocks in parallel

with other wagons. Very large negative effect;

reduced exercising of CBB,

large amounts of shelling on

the wheel, increased

frequency of wheel flats, the

risk of hiding non-tested

CBB wagons

Table 7. Possible safety enhancement measures


59 (91)

Negative effects of reduced speed and reduced load respectively. Principal effects of reducing the maximum permitted speed to 80 km/h

(alternatively exercising/testing brake every 15th minute) have been

investigated in a number of reports,54 and are displayed in the table below.

Many of these effects also arise with a reduced load, but this has not been

investigated.

Impact of reduced speed

Reduced freight train capacity

Reduced line capacity which also impacts on passenger trains

Increased transport costs for rail companies (track charges, tickets, etc.)

Increased production cost for railway companies, more wagons, locomotives, drivers

Increased journey times

Shift from railway to road and sea haulage

Increased transport costs for industry (transport purchasers)

Increased environmental impact (CO₂, NOX, Noise, Accidents) when shifting from rail

transport to road and sea haulage

Negative impact on logistics, production planning and warehousing for industry

Collapse of market for single wagon load trains

Insufficient shunting capacity

Worse wagon logistics if extra wagons with cast-iron brake blocks must be used in parallel

with other wagons

Table 8. Impact of reduced speed

54Macroeconomic effects and changed emissions of air pollution and CO2 as a consequence of new regulation of railway noise, Lena Wieweg, Trafikverket, 2018. The national model for freight transportation in Sweden,

REPORT Representation of the Swedish transport and logistics system in Samgods v. 1.1. (Trafikverket, VTI

2016). Konjunkturinstitutet EMEC analysis of proposals for new regulation of noise from railway freight traffic (Ref 2018-209) dated 21 December 2018


60 (91)

6 Conclusions of the risk analysis

Based on the risk analysis and test results, the following conclusions have

been drawn:

There are composite brake blocks which have demonstrated

substandard properties in winter conditions and the use of these

implies an intolerable level of risk; a combined report on tested and

non-tested blocks and results of tests and in service running is given

in Appendix E.

Those incidents which form the basis of the risk analysis occurred

despite the implementation of a number of operational measures.

These measures are already producing unacceptable consequences

such as delayed and cancelled trains. Further operational measures

(increased test braking/exercising of brake etc.) would have

completely unacceptable consequences and would fail to solve the

problem. Increased numbers of SPAD incidents due to a deliberate

choice of new technical solutions is not acceptable and neither is it

acceptable to transfer responsibility for safety from the technical

system to the driver via further operational instructions.

Currently no incidents or events with trains fitted with only LL-type

composite brake blocks have been reported by Swedish railway

undertakings. It should be noted that there are only very few trains

with solely LL brake blocks in northern Sweden. On the other hand,

tests have shown that these blocks may have significantly lower

braking performance than cast-iron brake blocks.

The current procedures according to UIC (see section 2.6.1) for the

testing of composite brake blocks in winter conditions do not

correspond to actual Nordic winter conditions.

Based on these conclusions, incidents which occurred and test results,

possible measures have been identified. These must be investigated

further. The possible measures identified concern freight wagons,

locomotives and operational rules. These measures should not be seen as

in themselves reducing risks to an acceptable level. Rather a

combination of measures will be required, partly over a transition period

and also on a permanent basis. Measures also need to be implemented at

national and international levels. One of these measures, which, during a

transition period, would reduce the risk and enable international

transport to and from Sweden, is an exception from the rules so that a

number of freight wagons with cast-iron brakes are allowed to operate

internationally.


61 (91)

Appendices

A. Summary of incidents

B. Risk analysis protocol

C. Situations where loss of braking capacity can lead directly to

collision with another train

D. Braking capacity - seen theoretically and practically from the

perspective of the locomotive driver

E. Comments to ERA´s list of fully approved UIC composite brake

blocks for international transport

In-depth account of advantages and disadvantages of certain proposed

measures


62 (91)

Appendix A. Summary of incidents


63 (91)

Green Cargo Incidents

No Date Synergy-

number

Train affected Brake blocks Description Result

1 26-02-

2015

48712 Jet-Fuel Shuttle Cosid 810 100% Braking power very poor on line Had to lower maximum speed from 100 to

80 km/h

2 24-04-

2015


80 km/h

3 07-05-

2015

49475 Jet-Fuel Shuttle Cosid 810 100% Braking power very poor on line After a lot of deceleration tests, 100 km/h

was ok

4 03-01-

2016

51713 Jet-Fuel Shuttle Cosid 810 100% Unpermitted passing of STOP-

signal

At low speed in snowy and icy conditions,

the driver could not stop in time. The train

was stopped 20 m after the position of the

signal.

5 13-04-

2016


80 km/h

6 14-04-

2016

52545 Steel Shuttle

"Hälleforspendeln“

ABEX 229/M128

Composite brake

blocks (Note 25 tonne

axle load) 100%

Braking power very poor on

line, mixed blocks

After a lot of deceleration tests, 100 km/h

was ok

7 25-11-

2016

54368 Moelven Pellet

Train

Jurid 816M 100% Unpermitted passing of STOP-

signal

Driver was unaware that the train only had

CBB brakes and failed to stop in time. The

train was stopped 20 m after the position of

the signal.

8 10-01-

2017

55732 Ore-shuttle

"Aitikpendeln”

mix of 60 %

S154/C810 Composite

brake blocks and 40%

M134/S153 sintered 9

Braking power very poor on line Often, the maximum speed has to be

lowered from 80 to 70 km/h when about

90% CBB


64 (91)

No Date Synergy-

number

Train affected Brake blocks Description Result

brake blocks (Note 25

tonne axle load)

9 25-01-

2017


80 km/h

10 01-02-

2017

55906 Jet-Fuel Shuttle Cosid 810 100% Braking power very poor on line 100 km/h was ok despite the lower brake

effect (shorter train)

11 04-02-

2017

55947 Train 6000

between Boden

and Haparanda -

Wagon load train

Mixed brake blocks Complete of loss braking power deteriorating conditions as train came

closer to destination. Almost no braking

power at the end. Minus 3 degrees and

heavy snowdrift.

12 22-02-

2017


Train

Jurid 816M 100% Braking power very poor on line Had to lower maximum speed from 100 to

70 km/h. Light snowfall, -2 degrees

13 29-11-

2017

59383 Train 9662 -

Ställdalen - Wagon

load train

Mixed brake blocks Braking power very poor on line Had to lower maximum speed from 100 to

70 km/h. Heavy snowfall, -2 degrees.

Speed increase from 66 km/h to 70 km/h

going downhill to Ludvika despite 0.7 bar

brake applied.

14 12-01-

2018


Train


80 km/h

15 12-01-

2018


Train


80 km/h

16 08-04-

2018


Train

Jurid 816M 100% Braking power very low on line Had to lower the speed from 100 to 80

km/h

17 07-02-

2019


Train

Jurid 816M 100% Lost braking force

Possibly SPAD

The train was 70m from colliding with two

parked locos


65 (91)

Hector Rail incidents

Number Date Weather

conditions

Incident description Causes Type of wagon Brake block

manufacturer

/ type

1 11-

12-

2017

16:45

Temp: ≈ -10 ° C.

Fly off snow.

Signal passed at Danger

Driver started to brake at 10 km/h. Braking

capacity was extremely low. Passed

approximately 30 meters.

Poor braking capacity Different tank

wagons

High proportion

with CoFren

C810 and

Becorit IB116*

(small amount

of GG)

2 08-

01-

2018

02:00

Temp: ≈ -10 ° C.

Fly off snow.

No incident. Train 41850 from Piteå-

Murjek was stopped in Arnemark 25 km

from Piteå due to poor retardation. Returned

to Piteå with Vmax 30 km/h.

Poor braking performance

from the wagons

13 x Sggrrs Federal Mogul

Jurid 822

3 22-

03-

2018

23:30

Temp: -10 °C ≤ T

≤ -24 °C

Clear weather.

Some minor fly-

off snow.

No incident. Shunting and train operation

was observed. Including shunting in

Svedjan. Train from Piteå-Murjek. Shunting

in Murjek.

Poor braking capacity 12 x Sggrrs Federal Mogul

Jurid 822

4 26-

03-

2018

04:22

Temp - 10 °C

Fly off snow

Report on low braking performance in train

operation. Driver performed several

retardation tests with λ-values around 45 %.

Finally it was very close to passing the

entry signal Nyf 2/6 at danger. Train came

to stop 1 meter in front of signal. λ-value

from emergency brake was 30 %. Nominal

λ-value was 88 %


from the CBB wagons

Train consists of:

10 x Sggrrs at tara

weight

2 x Sgnss with a

total weight 27

tonnes incl. loading

equipment

Federal Mogul

UIC GG

Jurid 822

GG


66 (91)

Number Date Weather

conditions


manufacturer

/ type

5 23-

12-

2018

20:00

Temp. -21 °C. Fly

off snow.

Passing of level crossing and point in wrong

direction in shunting operation at

approximately 20 km/h. About 200 meters

before level crossing driver brakes with 1

bar, then realising that brake is insufficient

and goes to full service brake and then

emergency brake


from the wagons

Train consists of:

13 x Sggrrs at tara

weight

1 x Sgnss with a

total weight 27

tonnes incl. loading

equipment

Federal Mogul

Jurid 822

UIC GG

6 16-

01-

2019

00:00

Temp. -21 °C. A

lot of snow on

track

approximately 10

cm. Fly off snow.

Signal passed at danger. Poor braking performance

from the wagons in

combination with other

disturbances.

Train consists of:

5 x Sggrrs with a

total weight of 145

tonnes

5 x Sggrrs with a

total weight of 134

tonnes

3 x Sgnss with a

total weight of 72

tonnes

Federal Mogul

Jurid 822

UIC GG

7 22-

01-

2019

04:40

Temp. - 25 °C. Fly

off snow.

No incident but cancelled train. Train was

stopped approximately 30 minutes after

departure due to poor retardation. Measured

retardation value was not sufficient for train

operation. Train returned to departure

station with Vmax=30 km/h.

Train was stopped due to

low brake performance


Jurid 822

8 23-

01-

2019

20:30

Temp. -7 °C.

Snow on track.

Fly off snow.

Passing of (ETCS) End of Authority (EoA)

at marker board.


from the wagons in

combination with other

disturbances.


Jurid 822


67 (91)

Number Date Weather

conditions


manufacturer

/ type

9 24-

01-

2019

04:40

Temp. - 20 °C. Fly

off snow.


stopped approximately 30 minutes after

departure due to poor retardation. Measured

retardation value was not sufficient for train

operation. Train returned to departure

station with Vmax=30 km/h.

Train was stopped due to

low brake performance


Jurid 822

10 31-

01-

2019

04:40

Temp. - 27 °C. Fly

off snow.


stopped before departure due to poor

braking performance which was identified

at low speed (shunting).

Train did not depart due to

low retardation identified

in shunting operation (low

speed operation with

connected HLL).


Jurid 822

11 04-

02-

2019

04:40

Temp. - 14 °C. Fly

off snow.









connected HLL).


Jurid 822

12 05-

02-

2019

04:40

Temp. - 21 °C. Fly

off snow.









connected HLL).


Jurid 822

13 22-

02-

2019

00:11

Temp. - 12 °C. Fly

off snow.









connected HLL).


Jurid 822


68 (91)

Number Date Weather

conditions


manufacturer

/ type

14 27-

02-

2019

11:50

Temp. + 4 °C

(uncertainties

regarding actual

temperature). Fly

off snow.





Unclear. 13 x Sggrrs Federal Mogul

Jurid 822

15 06-

03-

2019

11:50

Temp. - 9 °C. Fly

off snow.









connected HLL).


Jurid 822

16 12-

03-

2019

07:00

Temp. -18 °C. Fly

off snow

Passing of signal at danger Driver started to

brake well ahead and long before

intervention from train safety system.


from the wagons.


Jurid 822

17 02-

11-

2019

12:30

Temp: -10 °. Clear

weather. Some

minor fly-off

snow.

No incident. Report of low braking

performance at shunting


from the wagons

2 x Uacns CoFren

C810

18 03-

11-

2019

10:40

Temp: +0.7 °C.

Light snowfall

Report on low braking performance at

shunting. Not an incident since driver

observed the reduced braking capacity and

adjusted speed.


from the wagons.

9 x Sggrrs CoFren

C810

19 30-

11-

2019

00:00

Temp at incident

"a few degrees

minus" but after "a

cold night"

Poor braking performance at shunting in

Lycksele. 19 Sggrrs + TMZ diesel

locomotive

19 x Sggrrs CoFren

C810

20 01-

03-

2020

00:00

Temp -13 °C light

snowfall

Poor braking performance at shunting in

Storuman. 19 Sggrrs + TMZ diesel

locomotive

19 x Sggrrs CoFren

C810


69 (91)

Number Date Weather

conditions


manufacturer

/ type

21 29-

03-

2020

01:00

Temp ≈ -5 to -10

°C

AND some fly off

snow.

Shunting incident in Storflon. Train 41721.

Parked train with service brake 3.5 < HLL <

4.4 roll away at standstill when loco was

running round.


from the CBB-wagons at

standstill, 1/3 of wagon

brake in 10 ‰ downward

slope.

22 x Sggrrs

Federal Mogul

Jurid 822


70 (91)

Appendix B. Risk analysis protocol


71 (91)

Haz.

ID

Description of

failure event

Input:

No of

operating

hours

Input:

No of

Occurre

nces

Frequency

of

occurrence

(year

round)

Frequen

cy of

occurre

nce

(year

round)

Consequences Severity Frequency

of

occurrence

(best

estimate)

Risk

level before

additional

safety

measures

1 Reduced brake

performance

when braking

leading to

prolonged brake

distance

Hector Rail:

35555

Green

Cargo:

21000

15

7

4*10-4

3*10-4

Probable

Probable

1.1 Collision with a moving

train

Catastrophic Rare Undesirable

1.2 Collision at low speed

with another object at

standstill

Critical Rare Undesirable

1.3 Derailment due to too

high speed through a switch

or running through buffer

stop

Critical Rare Undesirable

1.4 Signal passed at danger

(SPAD) w/o collision or

derailment

Marginal Occasional Undesirable

1.5 Loss of brake

performance w/o SPAD

Insignificant Probable Tolerable

2 Driver anxiety

due to varying

brake capacity of

the train

2.1 Stress leading to stress

related disease

Marginal Not

assessed

Not

assessed

2.2 Repeated test- and

exercising of the brakes

Insignificant Frequent Undesirable


72 (91)

Appendix C. Situations where loss of braking capacity can lead directly

to collision with another train


73 (91)

1. “Crossover stations”

A crossover station is a station on a double track where there are

four switches which permit trains from both directions to change between

the left and the right track. These stations also do not have normal safety

switches.

In the example above the route is set for train A, “ TÅG A” in the figure,

driving through signal 52 and on through the station and driving out to

signal U42. The train route is marked in green. The train will switch over to

the other track.

Train B is coming from the other direction on the same track. The train

stops at the approach signal, Signal 21. After train A has passed the station

train B is permitted to drive through.

If train B does not have braking capacity when it arrives at approach signal

21 there will be a SPAD A at approach signal 21 and the train will move

directly into the path of train A. Train A will be travelling at the maximum

permitted speed at certain crossover stations, as much as 130 km/h when

certain switches permit this.

Risk of collision exists.

https://sv.wikipedia.org/wiki/Driftplats

https://sv.wikipedia.org/wiki/Dubbelsp%C3%A5r

https://sv.wikipedia.org/wiki/J%C3%A4rnv%C3%A4gsv%C3%A4xel


74 (91)

2. Connecting track:

Certain stations are branch stations. This means that two (or more) different

lines are joined together at the station.

Laxå is a good example of this, where the Värmland Line connects with the

Western Main Line.

In the above case the route is set for train A through the station passing

through approach signal 22, proceeds to the intermediate signal 24, and the

exit block signal L2. The speed of the train may be up to 200 km/h. The

route set is marked in green.

Train B arrives at the same time or just before from the connecting line and

stops at intermediate signal 2855 before the switch linking the two lines.

If train B has no braking capacity it risks driving directly into the path set

for train A with a SPAD at signal 28, or alternatively derailing close to the

other line, if there is an safety switch.


55 Signal 28 is partly covered by train B in the picture


75 (91)

3. Conventional station

At a conventional station on a single track line where trains meet one train is

admitted into the station at a time. Then the other train passes through the

station while the incoming train remains stationary in the separate main

track.

In the above picture the route is set for train A to proceed through approach

signal 22 on to intermediate signal 34 which is at stop. The train route is

indicated by the green line

From the other direction comes train A which will stop at approach signal

21 which is at stop.

After train A has moved fully in, the route for train B will be set straight

through the station for train B.

If train A does not have braking capacity train A will pass through signal 34

(SPAD-A) and collide with train B at approach signal 21.

If train B does not have braking capacity train B will pass approach signal

21 at stop (SPAD-A) and there is a risk that it will also pass through signal

31 which is indicating stop (SPAD-A), and collide with train A which is on

its way into the separate main track.



76 (91)

4. Simultaneous entry into station on a single track.

Simultaneous entry into a station means that two trains are coming from

opposite directions on a single track to the station where they will meet.

In the above case train A has its route set to pass through approach signal

22, and proceed to 84 (stop light) set to stop. For extra safety intermediate

signal 34 is also set at stop.

From the other direction train B has its route to pass through approach

signal 21 proceed to signal 81 (stop light) set to stop. For extra safety

intermediate signal 31 is also set at stop.

The stop lights which are marked are usually located well into the track,

500–600 m into the track in order to take in long trains simultaneously.

When one of the trains has come in to its track in its entirety without

problem the route is set for the oncoming train. The reason for having this

kind of station is to speed up train meets so that neither of the trains need to

stop if the trains arrive simultaneously.

The obstacle to being able to take in two trains at the same time is that these

stop lights are also governed by ATC.

If either of the trains does not have braking capacity that train would carry

out several SPAD A and collide with the oncoming train.



77 (91)

Appendix D. Braking capacity - seen theoretically and practically from

the perspective of the locomotive driver.


78 (91)

Braking capacity - seen theoretically and practically from the

perspective of the locomotive driver.

As a locomotive driver you have a number of tasks to perform during a

shift.

A shift in this context means you will go from one station or marshalling

yard, either on a departing train or as a replacement on an arriving train

which you will take further to another station or marshalling yard following

a timetable, known as the “driving plan”.

One of your most important tasks is to be able to stop your train safely.

Every time.

Fundamental to this is that one knows how the train brakes and “behaves”,

in order to always be able to stop safely before a danger point.

There are many factors that influence and play a part in how the train

behaves during braking. Every wagon is unique, every set of wagons is

unique, every driver has his/her way of driving, etc. It is easy to think that

the same train is the same every day and that it behaves in the same way and

that it can be handled in exactly the same way, but things are not so simple.

It helps to divide freight trains into two different categories: block trains and

single wagon load trains.

Block train means the whole train consist of the same type of wagon in the

same type of load. As a rule, these trains run in a closed circuit with all the

wagons loaded, in one direction, after which the train goes back in the

opposite direction, either loaded or empty depending on the job.

Single wagon load trains consist of different types of wagon, some loaded

and some empty. The wagons are part of a network between different hubs

and transports until they reach their final decision. These trains vary greatly

in length and in weight, from day-to-day, and also by type of wagon.

As a driver, before you depart you will receive a description of your train. A

wagon list which explains how long the train is, how much each wagon

weighs, and how much each wagon brakes expressed in tonnes (braked

weight).

Information about the wagons in the wagon list is supplemented with the

same information regarding the locomotive/locomotives in the train.

All this is in "Information for the driver".

Then the brake percentage is calculated (braked weight in relation to train

weight).

This value is the technical/theoretical calculation of how much the train

brakes. This information is a vital part of the establishment of the maximum

permitted speed of the train.


79 (91)

Following that, the driver checks in the Trafikverket line manual which

brake percentage table applies to the stretch of line the train will operate on.

The length and brake percentage of the train determine the maximum

permitted speed for that specific train on that specific stretch. The

fundamental principle is that the longer and the heavier the train, the higher

the brake percentage required for higher speeds.

The driver then inputs the following values into the train protection system;

speed ceiling, train length, brake application time, retardation value. (The

retardation value is the brake percentage recalculated as a retardation value

in order to provide the train protection system with information about how

much the train brakes.)

After departure the theoretical calculation is tested in practice via the

execution of retardation checks. There are two different types of check. R1

and R2. What differentiates R1 from R2 is how great the drop in pressure

during the test is. In practice retardation checks are as follows: When the

train has reached its cruising speed braking is initiated with a one bar drop

in pressure in the main pipe. (Retardation check R1).

Braking should develop throughout the whole train before the driver

releases the brakes.

The train speed is reduced significantly since fully applied brake power

must be reached before the brake is released. The same retardation value

that the driver input into the train protection system will now be shown if

the actual braking capacity is the same or better than the theoretical one. A

higher value than the input value cannot be seen in the train protection

system. If the driver does not get the value input he/she repeats the same

procedure, with the difference that the driver now reduces pressure to 1.5

bars. (Retardation check R2). If the driver does not get the value the

procedure is repeated one last time. If the driver does not get the value

which is theoretically calculated, the new retardation value measured with

the last R2 control must be input into the train protection system. Check

must be made with the line manual to be sure of the train’s speed ceiling

with the lower retardation value.

In addition to this check one further dimension is now added, namely how

the train behaves during braking. In certain trains the driver experiences a

rapid and substantial reaction, while on other trains the development of the

braking feels slow at first and then builds up after a while.

This behaviour varies from train to train, from day-to-day. Especially

regarding single wagon load trains which have a different composition

every day, regarding both loaded and empty wagons, their position in the

train, different ratios of composite to cast-iron brake blocks and different


80 (91)

train lengths.

Add to this different conditions, different weather with different adhesion.

As a driver, after your first brake applications you will have an idea of how

the train’s brakes are behaving during that particular journey. This means

that you need to and must adapt your actions in line with this.

If you experience the train as having "good brakes" this means that you have

a feeling that the margins are good. You can drive a little more offensively

without feeling there is a risk of being hurried if the situation arises where

you need to brake to a stop. For example a pre-signal that shows that there is

a stop signal 1000 m ahead (normal distant signal distance on most lines).

If you experience the train as having "poor brakes", meaning that it takes

time before full braking capacity is attained then you, as a driver, need to

drive with greater margins in order to feel that you are in full control when

encountering a stop signal.

Cast iron has historically been the predominant material in wagon brake

blocks. The advantage of cast-iron is that the braking capacity is the same

under most conditions.

Currently, circumstances are somewhat different since different composite

materials have begun to replace conventional cast-iron blocks. Brake blocks

made of composite material do not behave in an equivalent manner in all

types of temperature and weather conditions, which has resulted in a

question mark hanging over actual braking capacity.

If the retardation capacity constantly changes, such that the actual braking

capacity is unclear, the risk of SPAD increases, impacting on safety.

Uncertainty around what the retardation capacity is in practice creates a

work environment problem related to driver stress. Having to constantly

check actual braking capacity can only be done in one way, namely

repeatedly carrying out retardation checks. The impact of this becomes very

costly as journey times deteriorate further (freight trains already have

trouble finding their place in the railway network with increased ”dwelling

time” each year: if average speeds fall journey times increase significantly),

energy expenditure increases and rail transport becomes less effective

overall.


81 (91)

Appendix E

Comments to ERA’s list of fully approved UIC composite brake blocks

for international transport


82 (91)


83 (91)


84 (91)


85 (91)

Not tested. In this configuration

Not OK

Proven in use during Nordic winter conditions.OK: Can be usedNot OK: Can not be used.Not tested: UnknownPossibly OK: Needs verification


Possibly OK


Not OK




86 (91)

L Investigate and test improvements for locomotives:

L1 Introduce warm braking function on locomotives

This function means that the locomotive can operate with traction while at

the same time HLL is reduced and thus the wagons are conditioned. In this

way it is possible to make exercising appreciably more efficient, since

average speed would not be lost and since exercising of freight wagon

brakes will take place at high speed (where brake power is high). The

system requires that the brakes of the locomotive are not active (since there

is no need to condition them as they have an effective braking system).

The advantages are

- that there is less loss of average speed than with exercising without

traction,

- that it is possible to attain maximum traction even at lower speeds,

since it is not necessary to brake to a stop,

- that weak exercising is avoided. There are indications that weak

exercising may even negatively affect braking capacity, which is to

be avoided,

- that exercising is not done, i.e. no wear on the locomotive brakes,

- that exercising also takes place at low speed56 and

- that the driver chooses when to condition, i.e. exercising can be

avoided in those stretches where maximum traction is required.

The disadvantages are

- that safety is transferred from the system to the driver. The driver

must decide him/herself when the exercising should take place. This

is diametrically opposed to the policy adopted,

- that there are safety issues that must be resolved, especially if there

are wagons with apparently underperforming blocks in combination

with wagons with well-functioning blocks. There is then the risk that

the wagons which have well-functioning brake blocks receive too

high braking energies in the wheels,

- that the function must be managed in such a way that running in

HLL is even and stable after each exercising cycle. Problems may

arise with small and frequent drops in HLL. This may increase the

risk of blocked brake57 and uneven braking capacity between the

wagons, with an increased risk of wheel flats.

- that for mixed trains with organic, sintered and GG blocks, the

wagons with GG blocks in particular will experience a higher degree

56 Currently traction is normally blocked if HLL is reduced at speeds over 10 km/h 57 Unintended drag brake


87 (91)

of wheel damage in the form of circumferential shelling58 due to the

increased braking energy since they will be braked instantaneously

with a exercising cycle (probably to be followed by damage to the

wheels of wagons with sintered blocks). With trains with only

organic and sintered blocks, circumferential shelling will probably

increase on wagons with sintered blocks compared with those with

organic blocks,

- that wear on wheels and blocks will increase on those wagons which

have well-functioning brake configurations, while wagons with

underperforming brake configurations will have normal wear and

- that it is uneconomical, due to the costs of energy and wear to blocks

and wheels on the wagons.

L2 Introduce brake inhibition valves on the locomotives.

Brake inhibition valve (or secondary brake valve) means that the indirect

brake of the locomotive is inhibited except when full service brake or

emergency/fast/train safety system brake is demanded. Note that there are

variations of what HLL pressure constitutes the boundary for when the

locomotive brakes are activated An alternative to having this valve is that

during each exercising of CBB’s the locomotive brake is released manually.

The advantages are

- that the driver does not need to release the locomotive brake

manually during exercising (if such rules are applied). This makes

things simpler,

- that exercising with the locomotive brake active is avoided if the

driver for some reason does not release the locomotive brake. In

such a case the exercising will be significantly worse, since the

locomotive brake are functioning in wintertime and will brake

immediately and absorb the braking energy that was needed to

condition the wagons, and the risk of deficient exercising is avoided,

and

- that during retardation checks after an exercising cycle (without

warm braking) the retardation value can more clearly identify

current brake performance.


- that during retardation checks the locomotive brake is not applied,

- that the indirect brake on the locomotive must be checked and that

the locomotive must be conditioned separately, since in principle the

locomotive brake will never be applied in normal running. Note,

however, that the exercising requirement for the locomotive is

negligible in comparison with the requirement for CBB wagons

58 Circumferential shelling and pitting


88 (91)

- that introducing these functions brings costs.

L3 Electric brake at system emergency braking

In Sweden, when rolling stock is equipped with electrodynamic brake, these

are always disconnected at emergency, rapid ,train safety system or drivers

vigilance device braking. The reason for this is that it has been difficult to

demonstrate theoretically that the traction block has the requisite safety

levels in these brake modes when electro-dynamic brake is applied. Note

also that braked weight is never used for R+E or P+E in the calculation of a

train’s braking performance Thus, in Sweden we have chosen to protect

ourselves against a possible fault in the traction block. Note that faults in

traction block are unknown and that faults in CBB function in wintertime

are commonplace.

Advantages are

- that electrodynamic brake provide an extra barrier because in certain

cases the locomotive can compensate for the deficient function of

CBB in wintertime.


- that we protect ourselves against traction block malfunctions, but

this can be seen as ”proven in use” for most locomotives, based on

experience from other countries. Also, this fault is unknown in

modern times.

- that it is expensive since new versions of software have to be created

for the locomotive. The safety assessment ought to be simple, since

the solution is "proven in use"59.

L4 Introduction of automatic exercising equipment.

Such equipment means that the locomotive will automatically carry out

exercising cycles on the wagons by automatically reducing HLL. The

exercising cycle can be adapted in terms of size reduction, duration and

interval.

Advantages are

- safety is improved since the execution of exercising is transferred

from the driver to the system. The driver only needs to activate the

system once in winter conditions,

- that there is less loss of average speed than with exercising without

traction,

59 It is possible to use both “Using standard practice” (CSM-RA. Appendix 1, 2.3) and “Comparison with similar

systems” (CSM-RA. Appendix 1, 2.4).


89 (91)

- that it is possible to attain maximum traction even at lower speeds,

since it is not necessary to brake to a stop,

- that exercising is not done, i.e. no wear on the locomotive brakes,

- that certain exercising can take place at low speed.


- that the system restricts maximum traction when it goes in

automatically. Thus the driver must activate the system in critical

stretches or alternatively reduce the wagon weight for the relevant

braking level during exercising,

- that the level of exercising is always the same. Alternatively the

driver may choose what level of exercising is required for the

current weather conditions,

- that it may be necessary for the driver to carry out additional

exercising,

- that if this is to be successful, major drops in HLL cannot be used.

Tests suggest that low drops in HLL during an exercising cycle can

be counter productive, i.e. braking capacity may be reduced,

- that modern locomotives carry out an automatic equalisation after

each braking cycle, which is not included in the automatic

exercising equipment,

- that this cannot be carried out on all locomotives,

- that there are safety issues that must be resolved, especially if there

are wagons with apparently underperforming blocks in combination

with wagons with well-functioning blocks. There is then the risk

that the wagons which have well-functioning brake blocks receive

too high braking energies in the wheels,

- that the function must be managed in such a way that running in

HLL is even and stable after each exercising cycle. Problems may

arise with small and frequent drops in HLL. This may increase the

risk of blocked brake60 and uneven braking capacity between the

wagons, with an increased risk of wheel flats.

- that for mixed trains with organic, sintered and GG blocks, the

wagons with GG blocks in particular will experience a higher

degree of wheel damage in the form of circumferential shelling61

due to the increased braking energy since they will be braked

instantaneously with a exercising cycle (probably to be followed by

damage to the wheels of wagons with sintered blocks). With trains

with only organic and sintered blocks, circumferential shelling will

probably increase on wagons with sintered blocks compared with

those with organic blocks,

60 Unintended drag brake 61 Circumferential shelling and pitting


90 (91)

- that wear on wheels and blocks will increase on those wagons

which have well-functioning brake configurations, while wagons

with underperforming brake configurations will have normal wear

and

- that it is uneconomical, due to the costs of energy and wear to

blocks and wheels on the wagons.


91 (91)

D7 Extra wagons with cast-iron blocks in parallel with other

wagons.

The advantages are

- that a certain braking function from GG wagons is ensured.


- that there will be greatly increased wheel damage from

circumferential shelling on GG wagons when they brake

instantaneously,

- that there will be a greater incidence of wheel flats on GG wagons

when they brake instantaneously,

- that exercising of CBB wagons is reduced, since GG wagons brake

instantaneously and absorb exercising energy,

- the a reduced braking function on CBB wagons mixed with GG

wagons is hidden and

- that the proportion of GG wagons must be very high, since mixed

trains enable reduced exercising.

The purpose of the risk analysis is to illustrate the risks in the use of

composite brake blocks on freight trains in Sweden in the wintertime. This

demonstrates that the risk needs to be reduced to an acceptable level. For

this reason, a range of measures has been identified which need to be

investigated further and a programme of decisive measures needs to be

established.

risk assessment regarding composite brake blocks during

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