ISO 24221:2024/FDAmd 1

Applications ferroviaires — Système de freinage — Exigences générales — Amendement 1

General Information

• 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: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 10-Jun-2026
• Completion Date: 10-Jun-2026

Relations

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

Overview

ISO 24221:2024/FDAmd 1 is an amendment to the international standard for railway applications focused on braking systems and their general requirements. Published by the International Organization for Standardization (ISO), this amendment refines core provisions in the main standard to ensure higher safety, accuracy, and operational efficiency in railway braking systems. Developed under the supervision of ISO/TC 269/SC 2, Rolling Stock, it reflects the latest industry insights and practical innovation for global railway systems.

Key Topics

This amendment introduces several targeted updates to the standard, enhancing both technical clarity and functional requirements:

• Terminology Adjustments: The title of "Clause 3" has been updated to "Terms and definitions," and a specific term (3.9) has been deleted, improving the standard's applicability.
• Load and Payload Conditions: The requirements now distinguish between the design mass in working order (MVD), design mass under normal payload (MND), and define how to calculate the design mass under maximum braking payload (MXB).
• Braking Performance: Updated references ensure braking system design addresses performance across all relevant load scenarios, as detailed in ISO 10516.
• Dynamic and Blended Braking:
  • Safety Analysis: Mandates safety analysis for dynamic brakes and brake blending used in emergency braking.
  • Brake Blending Requirements: Specifies how braking forces from different subsystems can be combined ("blended") and aligns blending modes with ISO 24478.
  • Prioritizes dynamic brake activation for environmental and economic benefits.
  • Requires blending to comply with adhesion limits.
• Maximum Design Speed: Clarifies references to “maximum design speed” in all relevant requirements.
• Operational Duty Cycles: Expands emergency braking scenarios to include duty cycles at maximum payload on level track and under degraded conditions.

Applications

ISO 24221:2024/FDAmd 1 is crucial for various stakeholders in the railway industry:

• Manufacturers: Ensures braking systems meet precise load and safety requirements, helping to design compliant rolling stock for international markets.
• Rail Operators: Aids in selecting, operating, and maintaining braking systems that achieve required performance across different operational scenarios and loading conditions.
• Safety Assessors: Provides a refined framework for verifying that rail vehicles meet international standards for dynamic brake systems and emergency braking capabilities.
• Regulators and Procurement: Offers updated criteria for evaluating conformity and contractual compliance in railway projects.

Key practical benefits include improved safety margins in emergency situations, better adaptation to real-world loading variability, and potential cost reductions through the prioritized use of dynamic brakes for service braking.

Related Standards

ISO 24221:2024/FDAmd 1 is referenced alongside several other important railway and braking system standards, including:

• ISO 10516: Defines mass and payload parameters for railway vehicles, referenced for load condition determinations.
• ISO 24478: Outlines blending modes for railway braking systems, directly influencing blended braking requirements.
• EN 14198 and EN 16185-1: European standards that further specify payload and braking requirements for different types of trains.

Alignment with these standards ensures consistency and interoperability across the global rail sector, supporting international trade and operational safety.

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Keywords: ISO 24221:2024, railway applications standard, braking system requirements, general requirements, amendment, railway safety, dynamic brake, blended braking, maximum design speed, railway load conditions, ISO 10516, ISO 24478, railway compliance, international railway standards.

Standards Content (Sample)

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
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
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
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
...