Railway applications - Braking - Calculations for the estimation of stopping distance for specific Wheel Slide Protection testing

This document gives guidelines for the calculation of vehicle stopping distances when testing a WSP system using the methods specified in EN 15595, the standard for Wheel Slide Protection, under the conditions defined in that standard.
This document is only applicable to the calculation of stopping distances for the evaluation of the results of WSP tests carried out in accordance with EN 15595.
This document does not apply to calculations used to determine the stopping performance of a WSP equipped train under operational conditions as it is only applicable for specific WSP test conditions.

Bahnanwendungen - Bremsn - Bremswegberechnungen für den Schleuderschutz

Applications ferroviaires - Freinage - Calculs pour l’estimation des distances d’arrêt pour les essais spécifiques aux dispositifs d’anti-enrayage

Železniške naprave - Zavore - Računski postopki za ocenjevanje zavorne razdalje pri specifičnem preskušanju zaščite pred zdrsavanjem koles

Ta dokument podaja smernice za računske postopke za ocenjevanje zavorne razdalje pri preskušanju zaščite pred zdrsavanjem koles z uporabo metod, določenih v standardu EN 15595 za preprečevanje zdrsavanja koles, pod pogoji, določenimi v tem standardu.
Ta dokument se uporablja samo za računske postopke za ocenjevanje zavornih razdalj za vrednotenje rezultatov preskusov zaščite pred zdrsavanjem koles, izvedenih v skladu s standardom EN 15595.
Ta dokument se ne uporablja za računske postopke, ki se uporabljajo za določanje zmogljivosti zaviranja vlaka, opremljenega s sistemom za preprečevanje zdrsavanja koles, pri obratovalnih pogojih, saj se uporablja samo za specifične pogoje pri preskušanju zaščite pred zdrsavanjem koles.

General Information

Status
Published
Public Enquiry End Date
28-Nov-2018
Publication Date
20-Mar-2019
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
15-Mar-2019
Due Date
20-May-2019
Completion Date
21-Mar-2019

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SLOVENSKI STANDARD
SIST-TP CEN/TR 17315:2019
01-maj-2019
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Railway applications - Braking - Calculations for the estimation of stopping distance for

specific Wheel Slide Protection testing
Bahnanwendungen - Bremsn - Bremswegberechnungen für den Schleuderschutz

Applications ferroviaires - Freinage - Calculs pour l’estimation des distances d’arrêt pour

les essais spécifiques aux dispositifs d’anti-enrayage
Ta slovenski standard je istoveten z: CEN/TR 17315:2019
ICS:
45.040 Materiali in deli za železniško Materials and components
tehniko for railway engineering
SIST-TP CEN/TR 17315:2019 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TP CEN/TR 17315:2019
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SIST-TP CEN/TR 17315:2019
CEN/TR 17315
TECHNICAL REPORT
RAPPORT TECHNIQUE
March 2019
TECHNISCHER BERICHT
ICS 45.040
English Version
Railway applications - Braking - Calculations for the
estimation of stopping distance for specific Wheel Slide
Protection testing
Applications ferroviaires - Freinage - Calculs pour Bahnanwendungen - Bremsen -

l'estimation des distances d'arrêt pour les essais Bremswegberechnungen für den Schleuderschutz

spécifiques aux dispositifs d'anti-enrayage

This Technical Report was approved by CEN on 30 December 2018. It has been drawn up by the Technical Committee CEN/TC

256.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 17315:2019 E

worldwide for CEN national Members.
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CEN/TR 17315:2019 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

Introduction .................................................................................................................................................................... 4

1 Scope .................................................................................................................................................................... 5

2 Normative references .................................................................................................................................... 5

3 Terms and definitions ................................................................................................................................... 5

4 Symbols and abbreviations ......................................................................................................................... 6

5 Calculations ....................................................................................................................................................... 6

5.1 Wheel/rail adhesion improvement .......................................................................................................... 6

5.1.1 General ................................................................................................................................................................ 6

5.1.2 Stopping distance calculation ..................................................................................................................... 6

5.1.3 Dry rail conditions .......................................................................................................................................... 7

5.1.4 Low adhesion .................................................................................................................................................... 7

5.2 Graphical representation of the Stopping Distance Extensions ..................................................... 9

Annex A (informative) Examples of use of the calculations for the estimation of the

stopping distance, and test procedure — stopping distance estimation examples ............. 10

A.1 Workflow ......................................................................................................................................................... 10

A.2 Example 1: Passenger Coach .................................................................................................................... 10

A.3 Example 2: EMU ............................................................................................................................................ 11

A.4 Example 3: EMU two stage braking ........................................................................................................ 13

A.5 Example 4: Multiple Spraying Devices.................................................................................................. 16

A.5.1 General ............................................................................................................................................................. 16

A.5.2 Spraying configuration 1 ........................................................................................................................... 16

A.5.3 Spraying configuration 2 ........................................................................................................................... 17

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European foreword

This document (CEN/TR 17315:2019) has been prepared by Technical Committee CEN/TC 256 “Railway

applications”, the secretariat of which is held by DIN.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

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Introduction

EN 15595 for Wheel Slide Protection (WSP) provides methods for testing a WSP system (Clause 7) and

criteria for the evaluation of its performance under test (Clause 8). This includes tests and evaluation of

the stopping performance of a vehicle/train with the WSP system fitted, carried out as track tests or on a

WSP simulator.

For the evaluation of stopping performance during slide tests (see 8.3), the standard specifies the

maximum permitted stopping distance extension for a vehicle/train, measured as a percentage of its dry

rail stopping distance (Table 8). The maximum extension values are derived from estimations of the

wheel/rail adhesion improvement produced by the operation of the WSP system and the associated

vehicle stopping distances expected in the slide tests, calculated as detailed in this document.

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1 Scope

This document gives guidelines for the calculation of vehicle stopping distances when testing a WSP

system using the methods specified in EN 15595, the standard for Wheel Slide Protection, under the

conditions defined in that standard.

This document is only applicable to the calculation of stopping distances for the evaluation of the results

of WSP tests carried out in accordance with EN 15595.

This document does not apply to calculations used to determine the stopping performance of a WSP

equipped train under operational conditions as it is only applicable for specific WSP test conditions.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

EN 14478, Railway applications — Braking — Generic vocabulary
EN 15595:2018, Railway applications — Braking — Wheel slide protection
3 Terms and definitions

For the purposes of this document, the terms and definitions given in EN 14478 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
adhesion profile

predefined set of data representing the adhesion characteristics of a section of running line

3.2
dry rail

conditions where 100 % of the brake force of the vehicle can be applied with no wheelset sliding more

than 2 %
3.3
dry rail stopping distance
actual measured stopping distance in dry rail conditions
3.4
low adhesion
conditions where the wheel/rail adhesion is in the range 0,08 to 0,05
3.5
very low adhesion
conditions where the wheel/rail adhesion is in the range 0,05 to 0,03
3.6
extremely low adhesion
conditions where the wheel/rail adhesion is below 0,03
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3.7
slide test
test performed under low, very low and extremely low adhesion conditions
3.8
drag test

test to simulate braking on a falling gradient, performed with an auxiliary tractive unit to achieve a

constant speed with a constant brake application
4 Symbols and abbreviations
For the purpose of this document, the following symbols and abbreviations apply.
Table 1 — Symbols
Symbol Definition Unit
g Acceleration due to gravity
m/s
v WSP vehicle reference speed
km/h
ref
v True train speed
km/h
τ Wheel/rail adhesion coefficient
τ Initial adhesion coefficient —
WSP Wheel slide protection —
5 Calculations
5.1 Wheel/rail adhesion improvement
5.1.1 General

The formulae in this clause are means that give an indication for the stopping distance that can be

achieved by a certain trainset with low adhesion.

The formulae take into account different characteristics of the vehicle that are tested and are a practicable

compromise to evaluate track tests.

The formulae cannot give exact values for the stopping distance in true conditions. Therefore each result

is evaluated according to the flow chart given in EN 15595:2018, Figure 4.
5.1.2 Stopping distance calculation

The theoretical stopping distance for a vehicle with speed dependent retardation rates is shown below

(see Formula (1)):
22 2
vv− v
t ( ) ( ) ( )
01 x
sv= ×t+ + ++ (1)
0 a
22ττ××gg2
ave,,0 ave x
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where
s is the stopping distance, expressed in m;

t is the delay time from the start of braking until the brake starts filling, expressed

in s;
t is the build-up time of the brake cylinder pressure up to 95 % of the maximum
pressure, expressed in s;
v is the initial vehicle speed, expressed in m/s;
v to v are the speeds at the different brake forces, expressed in m/s;
1 x
τ to τ are the average wheel/rail adhesions required for each speed range and
ave,0 ave,x
calculated from Formula (2).

The average wheel/rail adhesion required for each speed range τ is calculated as set out in

ave
Formula (2).
1 n
(2)
ττ×++ ×τ
ave 1 n
total total
where

τ to τ are the wheel/rail adhesions that provide the effective brake force between wheel

1 n
and rail on each of the wheelsets;
m to m are the axle loads of the wheelsets;
1 n
m is the total static mass on all the wheelsets;
total
n number of wheelsets.

For unbraked wheelsets τ is set to zero, for braked wheelsets τ is taken from the brake calculation:

i i
where
τ is the τ of the wheelsets number i, where i is between 1 and n.
Examples of the use of theses formulae are shown in Annex A.
5.1.3 Dry rail conditions

The actual measured stopping distance in dry conditions, with WSP operational, is the stopping distance

corresponding to the nominal performance required for the vehicle within the specified tolerances.

τ is calculated from Formula (2) for dry rail conditions.
ave,dry

The friction coefficients τ should be taken from the brake calculation, updated after the brake

i,dry

distance measurement. If the measured frictional coefficient depends on the initial speed, the mean

frictional coefficient for the different speed classes can be used.
5.1.4 Low adhesion

The aim of the WSP under low adhesion conditions is to improve the levels of wheel/rail adhesion

experienced by the wheelsets by attempting to control at an absolute slide of up to 30 km/h at speeds

greater than 40 km/h.

Wheel/rail adhesion improvement is measured using WSP equipment alone, without any other adhesion

enhancing equipment such as magnetic track brake, sanding, etc.
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WSP can be configured to improve wheel/rail adhesion by controlling the slide. Experience has shown

that for sprayed rails the WSP can achieve an improved wheel/rail adhesion τ . This can be

wet,improved

estimated for each sprayed wheelset using Formula (3). This estimation is valid only if the initial speed

is higher than 80 km/h. Below 80 km/h, τ can be taken as the measured initial wheel/rail

wet,improved
adhesion.
ττ=0,09+ −×0,,12 0 33 (3)
( )
...

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