ISO 24221:2024/Amd 1

• Status: Not Published
• ICS: 45.060.01 - Railway rolling stock in general
• Technical Committee: ISO/TC 269/SC 2 - Rolling stock
• Drafting Committee: ISO/TC 269/SC 2/WG 1 - Railway braking
• Current Stage: 6000 - International Standard under publication
• Start Date: 06-Aug-2026
• Completion Date: 19-Sep-2026

• Amends: ISO 24221:2024 - Railway applications — Brake system — General requirements
• Effective Date: 07-Sep-2024

Overview

ISO 24221:2024/Amd 1, issued by the International Organization for Standardization (ISO), addresses amendments to the general requirements for railway braking systems. This Amendment 1 updates definitions, technical terms, and performance requirements to bring the standard in line with operational needs and recent industry practices. Managed by ISO Technical Committee 269, Subcommittee 2 (Rolling stock), the amendment enhances clarity and safety analysis expectations, particularly regarding brake blending and payload conditions.

Key Topics

ISO 24221:2024/Amd 1 introduces several key updates:

• Terms and Definitions: Adjustments to terminology provide greater accuracy and consistency across the standard.
• Dynamic and Emergency Braking: New requirements stipulate that any dynamic brake subsystem or brake blending involved in emergency braking must be subject to a safety analysis. This improves the reliability and safety of railway braking systems under critical conditions.
• Brake Blending: The update clarifies that brake blending can be implemented at either the local (e.g., bogie) or train level. Multiple brake systems can act simultaneously or sequentially, optimizing performance, energy use, and minimizing environmental impact.
• Payload and Load Conditions: Revised criteria for calculating maximum braking payload ensure that brake system design accounts for the full range of operational loads, based on the type of train service (high-speed, metro, commuter, etc.). The amendment references updated parameters for seats, standing areas, catering spaces, and luggage compartments, ensuring design consistency.
• Performance Testing: The amendment refines the conditions under which braking performance must be demonstrated, including new requirements for emergency brake applications and rigorous duty cycles at maximum payload.
• Reference to Related Standards: Alignment with ISO 10516 and EN railway standards ensures compatibility and harmonization across international regulations.

Applications

This amended standard is essential for a range of stakeholders in the railway industry:

• Rolling Stock Manufacturers: Ensures all new vehicles or major modifications comply with the latest international safety and performance benchmarks for braking systems.
• Railway Operators and Maintainers: Provides a reference for evaluating rolling stock, especially regarding emergency braking, brake blending, and payload calculations.
• Safety Assessors and Certifying Bodies: Facilitates risk assessment and conformity evaluations by requiring documented safety analyses of dynamic brake subsystems and brake management systems.
• System Integrators: Supports the implementation of interoperable and robust train braking solutions across diverse rail environments and jurisdictions.
• National Regulators: Offers a harmonized reference for regulatory compliance and cross-border operational consistency in railway safety.

Related Standards

For holistic development and compliance, the following standards are referenced or relevant to ISO 24221:2024/Amd 1:

• ISO 10516 - Railway applications – Braking – Performance requirements and necessary load conditions for the design.
• ISO 24478 - Railway applications – Braking – Brake blending modes.
• EN 14198:2016+A2:2021 and EN 16185-1:2014+A1:2020 - European requirements for brake payload calculations and performance.
• General UIC and IEC standards - For additional requirements governing railway rolling stock brake systems.

By implementing ISO 24221:2024/Amd 1, organizations can ensure that their railway braking systems meet the latest global standards for safety, efficiency, and interoperability, supporting continued advancement of reliable and high-performing rail networks worldwide.

FINAL DRAFT
Amendment
ISO 24221:2024/
FDAM 1
ISO/TC 269/SC 2
Railway applications — Braking
Secretariat: AFNOR
system — General requirements
Voting begins on:
2026-06-10
AMENDMENT 1
Voting terminates on:
Applications ferroviaires — Système de freinage — Exigences
2026-08-05
générales
AMENDEMENT 1
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO 24221:2024/FDAM 1:2026(en) © ISO 2026

FINAL DRAFT
ISO 24221:2024/FDAM 1:2026(en)
Amendment
ISO 24221:2024/
FDAM 1
ISO/TC 269/SC 2
Railway applications — Braking
Secretariat: AFNOR
system — General requirements
Voting begins on:
AMENDMENT 1
Voting terminates on:
Applications ferroviaires — Système de freinage — Exigences
générales
AMENDEMENT 1
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO 24221:2024/FDAM 1:2026(en) © ISO 2026

ii
ISO 24221:2024/FDAM 1:2026(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 269, Railway applications, Subcommittee SC 2,
Rolling stock.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iii
...

ISO 24221:2024/DAMFDAmd 1:2025(en)
ISO/TC 269/SC 2/WG 1
Secretariat: AFNOR
Date: 2025-08-282026-05-27
Railway applications — Braking system — General requirements
AMENDMENT 1
Applications ferroviaires — Système de freinage — Exigences générales
AMENDEMENT 1
FDIS stage
ISO 24221:2024/FDAmd 1(en)
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
EmailE-mail: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 24221:2024/FDAmd 1(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Field Code Changed
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
Field Code Changed
This document was prepared by Technical Committee ISO/TC 269, Railway applications, Subcommittee SC 2,
Rolling stock.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
Field Code Changed
iii
ISO 24221:2024/FDAmd 1(en)
Railway applications — Braking system — General requirements
AMENDMENT 1
Clause 3
Change title to “Terms and definitions”

3.9
Delete 3.9the entire terminological entry.

4.2
th
In the 5 , fifth paragraph, at
At the end of the first sentence, replace “up to the maximum braking load.” with “up to the design mass under
maximum braking payload.”
4.2, eight paragraph
At the end of 4.2, add the following two new paragraphs as follows:
“If a dynamic brake subsystem is involved in emergency braking it shall be subject to a safety analysis.
If brake management or brake blending is used in emergency braking it shall be subject to a safety analysis.”.

4.4
Change 4.4. as follows:
“Replace the text with the following:
Brake blending can take place at either the local level (e.g. bogie level) or the train level, or both.
Brake blending can be realized with more than one brake system acting simultaneously, or by replacing the
braking force of a brake unit or subsystem b
...

PROJET FINAL
Amendement
ISO 24221:2024/
FDAM 1
ISO/TC 269/SC 2
Applications ferroviaires — Système
Secrétariat: AFNOR
de freinage — Exigences générales
Début de vote:
2026-06-10
AMENDEMENT 1
Vote clos le:
Railway applications — Braking system — General requirements
2026-08-05
AMENDMENT 1
LES DESTINATAIRES DU PRÉSENT PROJET SONT
INVITÉS À PRÉSENTER, AVEC LEURS OBSERVATIONS,
NOTIFICATION DES DROITS DE PROPRIÉTÉ DONT ILS
AURAIENT ÉVENTUELLEMENT CONNAISSANCE ET À
FOURNIR UNE DOCUMENTATION EXPLICATIVE.
OUTRE LE FAIT D’ÊTRE EXAMINÉS POUR
ÉTABLIR S’ILS SONT ACCEPTABLES À DES FINS
INDUSTRIELLES, TECHNOLOGIQUES ET COM-MERCIALES,
AINSI QUE DU POINT DE VUE DES UTILISATEURS, LES
PROJETS DE NORMES
INTERNATIONALES DOIVENT PARFOIS ÊTRE CONSIDÉRÉS
DU POINT DE VUE DE LEUR POSSI BILITÉ DE DEVENIR DES
NORMES POUVANT
SERVIR DE RÉFÉRENCE DANS LA RÉGLEMENTATION
NATIONALE.
Numéro de référence
ISO 24221:2024/FDAM 1:2026(fr) © ISO 2026

PROJET FINAL
ISO 24221:2024/FDAM 1:2026(fr)
Amendement
ISO 24221:2024/
FDAM 1
ISO/TC 269/SC 2
Applications ferroviaires — Système
Secrétariat: AFNOR
de freinage — Exigences générales
Début de vote:
AMENDEMENT 1 2026-06-10
Vote clos le:
Railway applications — Braking system — General requirements
2026-08-05
AMENDMENT 1
LES DESTINATAIRES DU PRÉSENT PROJET SONT
INVITÉS À PRÉSENTER, AVEC LEURS OBSERVATIONS,
NOTIFICATION DES DROITS DE PROPRIÉTÉ DONT ILS
AURAIENT ÉVENTUELLEMENT CONNAISSANCE ET À
FOURNIR UNE DOCUMENTATION EXPLICATIVE.
DOCUMENT PROTÉGÉ PAR COPYRIGHT
OUTRE LE FAIT D’ÊTRE EXAMINÉS POUR
ÉTABLIR S’ILS SONT ACCEPTABLES À DES FINS
© ISO 2026 INDUSTRIELLES, TECHNOLOGIQUES ET COM-MERCIALES,
AINSI QUE DU POINT DE VUE DES UTILISATEURS, LES
Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, aucune partie de cette
PROJETS DE NORMES
INTERNATIONALES DOIVENT PARFOIS ÊTRE CONSIDÉRÉS
publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique,
DU POINT DE VUE DE LEUR POSSI BILITÉ DE DEVENIR DES
y compris la photocopie, ou la diffusion sur l’internet ou sur un intranet, sans autorisation écrite préalable. Une autorisation peut
NORMES POUVANT
être demandée à l’ISO à l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
SERVIR DE RÉFÉRENCE DANS LA RÉGLEMENTATION
NATIONALE.
ISO copyright office
Case postale 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Genève
Tél.: [phone]
E-mail: [e-mail]
Web: www.iso.org
Publié en Suisse Numéro de référence
ISO 24221:2024/FDAM 1:2026(fr) © ISO 2026

ii
ISO 24221:2024/FDAM 1:2026(fr)
Avant-propos
L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes nationaux
de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est en général
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la Commission électrotechnique internationale (IEC) en ce qui concerne la normalisation électrotechnique.
Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont
décrites dans les Directives ISO/IEC, Partie 1. Il convient en particulier de prendre note des différents
critères d’approbation requis pour les différents types de documents ISO. Le présent document
a été rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2
(voir www.iso.org/directives).
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d’un ou de plusieurs brevets. L’ISO ne prend pas position quant à la preuve, à la validité et à l’applicabilité de
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www.iso.org/patents. L’ISO ne saurait être tenue pour responsable de ne pas avoir identifié de tels droits de
brevets et de ne pas avoir signalé leur existence.
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information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un engagement.
Pour une explication de la nature volontaire des normes, de la signification des termes et expressions
spécifiques de l’ISO liés à l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion de
l’ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles techniques au
commerce (OTC), voir le lien suivant: www.iso.org/iso/foreword.html.
Le comité chargé de l’élaboration du présent document est l’ISO/TC 269, Applications ferroviaires, Sous-
comité SC 2, Matériel Roulant.
Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent
document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes se
trouve à l’adresse www.iso.org/members.html.

iii
ISO 24221:2024/FDAM 1:2026(fr)
Applications ferroviaires — Sy
...