prEN ISO 3691-4
(Main)Industrial trucks - Safety requirements and verification - Part 4: Driverless industrial trucks and their systems (ISO/DIS 3691-4:2026)
- Abstract
This document specifies safety requirements and the means for their verification for driverless industrial trucks (hereafter referred to as trucks) and their systems.
Examples of driverless industrial trucks (trucks as defined in ISO 5053‑1:2020) include: “automated guided vehicle”, “autonomous mobile robot”, “bots”, “automated guided cart”, “tunnel tugger”, “under cart”, etc.
This document is also applicable to driverless industrial trucks which are provided with:
— automatic modes which either require operators’ action(s) to initiate or enable such automatic operations;
— the capability to transport one or more riders (which are neither considered as drivers nor as operators);
— additional manual modes which allow operators to operate the truck manually; or
— a maintenance mode which allows manual operation of truck functions for maintenance reasons.
This document is not applicable to trucks solely guided by mechanical means (rails, guides, etc.) or to remotely-controlled trucks, which are not considered to be driverless trucks.
For the purposes of this document, a driverless industrial truck is a powered truck, which is designed to operate automatically. A driverless truck system comprises the control system, which can be part of the truck and/or separate from it, guidance means and power system. Requirements for power sources are not covered in this document.
The condition of the operating zone has a significant effect on the safe operation of the driverless industrial truck. The preparations of the operating zone to eliminate the associated hazards are specified in Annex A.
This document is applicable to all significant hazards, hazardous situations or hazardous events during all phases of the life of the truck (ISO 12100:2010, 5.4), as listed in Annex B, relevant to the applicable machines when it is used as intended and under conditions of misuse which are reasonably foreseeable by the manufacturer.
In particular, this document does not apply to significant hazards related to:
— noise;
— vibrations;
— ionising and non-ionising radiation;
— laser radiation;
— sales literature (commercial documents);
— declaration of vibrations transmitted by mobile machinery.
It does not apply to additional hazards that can occur:
— during operation in severe conditions (e.g. extreme climates, freezer applications, strong magnetic fields);
— during operation in nuclear environments;
— from trucks intended to operate in public zones (see in particular ISO 13482:2014);
— during operation on a public road;
— during operation in potentially explosive environments;
— during operation in military applications;
— during operation with specific hygienic requirements;
— during operation in ionizing radiation environments;
— during the transportation of (a) person(s) other than (the) intended rider(s);
— when handling loads the nature of which can lead to dangerous situations (e.g. molten metals, acids/bases, radiating materials);
— for rider positions with elevation function higher than 1 200 mm from the floor/ground to the platform floor.
This document does not contain safety requirements for trailer(s) being towed behind a truck.
This document does not contain safety requirements for elevated operator trucks.
This document does not apply to trucks manufactured before the date of its publication.
- Status
- Not Published
- Publication Date
- 05-Dec-2027
- Technical Committee
- CEN/TC 150 - Industrial trucks - Safety
- Current Stage
- 4060 - Closure of enquiry - Enquiry
- Start Date
- 09-Sep-2026
- Completion Date
- 09-Sep-2026
prEN ISO 3691-4 is the CEN draft standard for industrial trucks - Safety requirements and verification - Part 4: Driverless industrial trucks and their systems. It specifies the safety requirements and the means of verification for powered driverless trucks used in industrial environments, including automated guided vehicles, autonomous mobile robots, bots and similar trucks. The document is written for manufacturers, system integrators, commissioning teams, safety staff and buyers who need to design, verify or use these trucks and their systems.
What does prEN ISO 3691-4 specify?
prEN ISO 3691-4 specifies safety requirements for driverless industrial trucks and their systems, plus the methods used to verify those requirements. It is aimed at trucks that operate automatically, including trucks with automatic modes, riders, manual modes and maintenance mode.
The scope focuses on driverless industrial trucks used where people have specific training, instruction or awareness. It excludes trucks solely guided by mechanical means and trucks solely remotely controlled by an operator. It also leaves out the truck power source as a subject in its own right.
The document is organized into these main parts and annexes:
| Clause / Annex | What it covers |
|---|---|
| Clause 1 | Scope and application limits |
| Clause 2 | Normative references |
| Clause 3 | Terms and definitions |
| Clause 4 | Safety requirements and protective or risk-reduction measures |
| Clause 5 | Verification of the safety requirements |
| Clause 6 | Information for use |
| Annex A | Integration requirements for operating zones and site preparation |
| Annex B | Significant hazards addressed by the document |
| Annex C | Determination of rated capacity for trucks with masts |
| Annex D | Load transfer operations |
| Annex E | Verification of safety requirements and risk-reduction measures |
| Annex F | Warning signal design guidance |
| Annex G | Cross-reference with truck types in ISO 5053-1 |
| Annex H | Muting by a combination of truck signals |
| Annex I | Alternative performance levels for some safety functions |
| Annex J | Alternative method for clearance management based on localization systems |
What are the key requirements of prEN ISO 3691-4?
prEN ISO 3691-4 combines truck design requirements with site integration rules. In practice, it is not only about the truck itself: the operating zone, load transfer points, warnings, controls and verification steps also matter.
Safety scope, operating zones and integration
Clause 1 applies the document to all significant hazards during the truck lifecycle, including reasonably foreseeable misuse. Annex B lists the hazard groups that the document addresses, and Annex A sets the integration requirements for the operating environment.
Annex A matters in practice because the truck is only part of the safety solution. The site may need escape routes, clearances, pedestrian control, floor compatibility, warning signs, fixed structures, load transfer arrangements and zone definitions such as operating zone, restricted zone, restricted VNA zone and confined zone. Where third parties integrate the truck, Clause 6.4 requires commissioning instructions that describe the integration requirements and any safety-related parameters that can be adjusted at integration.
Movement, stopping, holding and charging
Clause 4.2 requires a movement stop function with an external interface, and Clause 4.3 requires a truck holding function that keeps the truck stationary if the power supply is interrupted. For the reader, this means the truck must not drift or roll away when power is lost.
Clause 4.4 addresses overspeed. The truck must either trigger a protective stop or reduce speed before the overspeed limit is reached. Where speed limits can be parameterized, the parameters must be handled in line with ISO 13849-1:2023. This matters when a system integrator adapts the truck to a new site and needs to set safe speed limits.
Clause 4.5 covers automatic battery charging. The charging interface must be protected so that it does not create electric shock or short-circuit hazards, and the truck must not move in a way that strains the connection unless it is designed for that use. Clause 4.6 covers load handling, including keeping the load in the designated position and preventing hazardous movements when it is not. Clause 4.7 requires steering faults to be detected or contained so that unsafe steering does not escape the monitored zone.
Person detection, speed limitation and warning
Clause 4.9 is central to the standard. It requires sensitive protective equipment (SPE) to detect persons in the truck path, support safe selection of active detection zones, and manage blind spots and muting. Temporary reduction of the detection zone is allowed only with strict limits, including low speed and short duration, so the truck cannot use a reduced sensing area as a routine operating mode.
Clause 4.9 also links detection to speed limitation. Side detection and clearance-based speed limitation are used to control the truck where space is tight or where people may enter the path. Clause 5.3 provides the verification method for side detection, so this is not just a design idea - it has to be tested.
Clause 4.9.4 and 4.9.5 add an additional stop function and control over automatic restart after a person has been detected. Clause 4.9.6 covers emergency stop. Clause 4.17 requires warning signals before movement, during movement, when detection zones are reduced or muted, and when the truck changes direction. Clause 4.18 requires that loss of communication must not create a hazardous situation.
Functional safety, performance levels and verification
Clause 4.14 requires safety functions of the control system to meet minimum performance levels in Table 5, according to ISO 13849-1:2023. Annex A.5 extends that approach to integration functions in the site, such as access-point control, muting and confined-zone operation.
Clause 5 sets out how the requirements are verified. It includes design checks, measurement, visual examination, specific tests and functional tests. The document requires verification of person detection, side detection, stability and structural strength, and it ties functional safety validation to ISO 13849-1:2023. Annex E maps each requirement to the verification type, which helps manufacturers and assessors decide what must be checked on the truck, what must be measured and what must be tested.
Annex H gives a structured way to implement muting with multiple truck signals. Annex I provides an alternative way to demonstrate some performance levels for collision-related safety functions. Annex J gives an alternative method to show PL b for truck localization used for clearance management and prevention of automatic restart. These annexes matter when the truck uses more advanced control logic or localization functions.
What terms does prEN ISO 3691-4 define?
- Driverless industrial truck system - a combination of one or more driverless industrial trucks and ancillary components used to control truck operation.
- Automatic mode - a mode of operation where no operator oversight or action is required for the operation.
- Manual mode - a mode where the truck is under the control of an operator.
- Maintenance mode - a mode that allows truck functions to be operated and may override safety functions for maintenance reasons.
- Sensitive protective equipment (SPE) - equipment that detects persons or parts of persons and sends a signal to the control system to reduce risk.
- Contact SPE - a pressure-sensitive protective device or safety-related sensor that generates a signal when physically contacted.
- Non-contact SPE - electro-sensitive protective equipment or a safety-related sensor system with one or more detection zones that signals when actuated.
- Protective stop - a safety-related stop function.
- Automatic restart - resumption of truck operation without intervention.
- Rider designated position - a position on the truck intended for persons to ride safely.
Who uses prEN ISO 3691-4?
prEN ISO 3691-4 is used by truck manufacturers, automation suppliers and system integrators who design driverless trucks and their control systems. It is also used by commissioning teams and site designers who prepare the operating zone, access routes, load transfer areas and warnings.
Safety managers, quality managers and buyers use it to check whether a truck and its intended use fit the required safety approach. Warehouse, manufacturing and logistics operators use it for automated guided vehicles, autonomous mobile robots, automated guided carts and other driverless trucks in industrial handling tasks.
Which standards are used with prEN ISO 3691-4?
- ISO 5053-1:2020, ISO 5053-2:2019 and ISO 5053-3:2024 - truck vocabulary and type definitions used throughout the document.
- ISO 12100:2010 - general risk assessment, risk reduction and information-for-use principles.
- ISO 13849-1:2023 and ISO 13849-2:2012 - design and validation of safety-related parts of control systems.
- ISO 13850:2015, ISO 13851:2019, ISO 13855:2024, ISO 13856-2:2013, ISO 13856-3:2013, ISO 13857:2019, ISO 14119:2024, ISO 14120:2015 and ISO 14122-2:2016 - emergency stop, two-hand control, safety distances, pressure-sensitive devices, guards and access.
- ISO 22915 series parts 2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 20 and 22 - stability verification for the relevant truck types and operating cases.
- IEC 61496-1:2020, IEC 61496-2:2020, IEC 61496-3:2025 and IEC FDIS/62046:2026 - electro-sensitive protective equipment and person-detection applications.
- IEC 60204-1:2016 + AMD1:2021 and IEC 61558-1:2017 - electrical equipment of machines and protected power supplies.
- EN 1175:2025, EN 12895:2015+A1:2019, EN 1570-1:2024 and EN 619:2022 - electrical and electronic truck requirements, EMC, lifting tables and handling equipment.
- ISO/DIS 3691-1:2025, ISO 3691-2:2023, ISO 3691-6:2021 and EN 16307-1:2020 - companion industrial-truck requirements used where the truck type or function calls for them.
- ISO 2867:2011, ISO 4413:2010, ISO 4414:2010, ISO 7010:2019 and ISO 7250-1:2017 - access systems, hydraulics, pneumatics, safety signs and human body measurements.
What does the prEN ISO 3691-4 document contain?
The document brings together design requirements, integration rules, verification methods and user information for driverless industrial trucks. Clause 4 covers the truck safety functions, including stopping, holding, charging, load handling, steering, stability, detection of persons, warning systems, communication loss and the special cases of towing, confined zones and VNA applications.
Clause 5 and Annex E describe how those requirements are checked, including design review, measurement, inspection and functional testing. Annex C gives the basis for rated capacity, Annex D illustrates load transfer operations, Annex F gives guidance on audible and visual warning signals, and Annex G links the document to truck types in ISO 5053-1.
The annexes also add practical integration rules. Annex A defines how the operating environment should be prepared, Annex H shows one muting method, Annex I gives an alternative performance-level route for some safety functions, and Annex J gives a localization-based route for clearance management.
Relations
- Effective Date
- 13-Dec-2023
Frequently Asked Questions
prEN ISO 3691-4 is a draft published by the European Committee for Standardization (CEN). Its full title is "Industrial trucks - Safety requirements and verification - Part 4: Driverless industrial trucks and their systems (ISO/DIS 3691-4:2026)". This standard covers: This document specifies safety requirements and the means for their verification for driverless industrial trucks (hereafter referred to as trucks) and their systems. Examples of driverless industrial trucks (trucks as defined in ISO 5053‑1:2020) include: “automated guided vehicle”, “autonomous mobile robot”, “bots”, “automated guided cart”, “tunnel tugger”, “under cart”, etc. This document is also applicable to driverless industrial trucks which are provided with: — automatic modes which either require operators’ action(s) to initiate or enable such automatic operations; — the capability to transport one or more riders (which are neither considered as drivers nor as operators); — additional manual modes which allow operators to operate the truck manually; or — a maintenance mode which allows manual operation of truck functions for maintenance reasons. This document is not applicable to trucks solely guided by mechanical means (rails, guides, etc.) or to remotely-controlled trucks, which are not considered to be driverless trucks. For the purposes of this document, a driverless industrial truck is a powered truck, which is designed to operate automatically. A driverless truck system comprises the control system, which can be part of the truck and/or separate from it, guidance means and power system. Requirements for power sources are not covered in this document. The condition of the operating zone has a significant effect on the safe operation of the driverless industrial truck. The preparations of the operating zone to eliminate the associated hazards are specified in Annex A. This document is applicable to all significant hazards, hazardous situations or hazardous events during all phases of the life of the truck (ISO 12100:2010, 5.4), as listed in Annex B, relevant to the applicable machines when it is used as intended and under conditions of misuse which are reasonably foreseeable by the manufacturer. In particular, this document does not apply to significant hazards related to: — noise; — vibrations; — ionising and non-ionising radiation; — laser radiation; — sales literature (commercial documents); — declaration of vibrations transmitted by mobile machinery. It does not apply to additional hazards that can occur: — during operation in severe conditions (e.g. extreme climates, freezer applications, strong magnetic fields); — during operation in nuclear environments; — from trucks intended to operate in public zones (see in particular ISO 13482:2014); — during operation on a public road; — during operation in potentially explosive environments; — during operation in military applications; — during operation with specific hygienic requirements; — during operation in ionizing radiation environments; — during the transportation of (a) person(s) other than (the) intended rider(s); — when handling loads the nature of which can lead to dangerous situations (e.g. molten metals, acids/bases, radiating materials); — for rider positions with elevation function higher than 1 200 mm from the floor/ground to the platform floor. This document does not contain safety requirements for trailer(s) being towed behind a truck. This document does not contain safety requirements for elevated operator trucks. This document does not apply to trucks manufactured before the date of its publication.
This document specifies safety requirements and the means for their verification for driverless industrial trucks (hereafter referred to as trucks) and their systems. Examples of driverless industrial trucks (trucks as defined in ISO 5053‑1:2020) include: “automated guided vehicle”, “autonomous mobile robot”, “bots”, “automated guided cart”, “tunnel tugger”, “under cart”, etc. This document is also applicable to driverless industrial trucks which are provided with: — automatic modes which either require operators’ action(s) to initiate or enable such automatic operations; — the capability to transport one or more riders (which are neither considered as drivers nor as operators); — additional manual modes which allow operators to operate the truck manually; or — a maintenance mode which allows manual operation of truck functions for maintenance reasons. This document is not applicable to trucks solely guided by mechanical means (rails, guides, etc.) or to remotely-controlled trucks, which are not considered to be driverless trucks. For the purposes of this document, a driverless industrial truck is a powered truck, which is designed to operate automatically. A driverless truck system comprises the control system, which can be part of the truck and/or separate from it, guidance means and power system. Requirements for power sources are not covered in this document. The condition of the operating zone has a significant effect on the safe operation of the driverless industrial truck. The preparations of the operating zone to eliminate the associated hazards are specified in Annex A. This document is applicable to all significant hazards, hazardous situations or hazardous events during all phases of the life of the truck (ISO 12100:2010, 5.4), as listed in Annex B, relevant to the applicable machines when it is used as intended and under conditions of misuse which are reasonably foreseeable by the manufacturer. In particular, this document does not apply to significant hazards related to: — noise; — vibrations; — ionising and non-ionising radiation; — laser radiation; — sales literature (commercial documents); — declaration of vibrations transmitted by mobile machinery. It does not apply to additional hazards that can occur: — during operation in severe conditions (e.g. extreme climates, freezer applications, strong magnetic fields); — during operation in nuclear environments; — from trucks intended to operate in public zones (see in particular ISO 13482:2014); — during operation on a public road; — during operation in potentially explosive environments; — during operation in military applications; — during operation with specific hygienic requirements; — during operation in ionizing radiation environments; — during the transportation of (a) person(s) other than (the) intended rider(s); — when handling loads the nature of which can lead to dangerous situations (e.g. molten metals, acids/bases, radiating materials); — for rider positions with elevation function higher than 1 200 mm from the floor/ground to the platform floor. This document does not contain safety requirements for trailer(s) being towed behind a truck. This document does not contain safety requirements for elevated operator trucks. This document does not apply to trucks manufactured before the date of its publication.
prEN ISO 3691-4 is classified under the following ICS (International Classification for Standards) categories: 53.060 - Industrial trucks. The ICS classification helps identify the subject area and facilitates finding related standards.
prEN ISO 3691-4 has the following relationships with other standards: It is inter standard links to EN ISO 3691-4:2023. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
prEN ISO 3691-4 is associated with the following European legislation: EU Directives/Regulations: 2023/1230, 2023/1230, 2023/1230, 2023/1230; Standardization Mandates: M/605. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.
prEN ISO 3691-4 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-september-2026
Vozila za talni transport - Varnostne zahteve in preverjanje - 4. del: Vozila brez
voznika in njihovi sistemi (ISO/DIS 3691-4:2026)
Industrial trucks - Safety requirements and verification - Part 4: Driverless industrial
trucks and their systems (ISO/DIS 3691-4:2026)
Flurförderzeuge - Sicherheitstechnische Anforderungen und Verifizierung - Teil 4:
Fahrerlose Flurförderzeuge und ihre Systeme (ISO/DIS 3691-4:2026)
Chariots de manutention - Exigences de sécurité et vérification - Partie 4: Chariots de
manutention sans conducteur et leurs systèmes (ISO/DIS 3691-4:2026)
Ta slovenski standard je istoveten z: prEN ISO 3691-4
ICS:
53.060 Industrijski tovornjaki Industrial trucks
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
DRAFT
International
Standard
ISO/DIS 3691-4
ISO/TC 110/SC 2
Industrial trucks — Safety
Secretariat: SIS
requirements and verification —
Voting begins on:
Part 4: 2026-06-17
Driverless industrial trucks and
Voting terminates on:
2026-09-09
their systems
Chariots de manutention — Exigences de sécurité et
vérification —
Partie 4: Chariots sans conducteur et leurs systèmes
ICS: 53.060
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
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Reference number
ISO/DIS 3691-4:2026(en)
DRAFT
ISO/DIS 3691-4:2026(en)
International
Standard
ISO/DIS 3691-4
ISO/TC 110/SC 2
Industrial trucks — Safety
Secretariat: SIS
requirements and verification —
Voting begins on:
Part 4:
Driverless industrial trucks and
Voting terminates on:
their systems
Chariots de manutention — Exigences de sécurité et
vérification —
Partie 4: Chariots sans conducteur et leurs systèmes
ICS: 53.060
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland Reference number
ISO/DIS 3691-4:2026(en)
ii
ISO/DIS 3691-4:2026(en)
Contents Page
Foreword .vi
Introduction .viii
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 5
4 Safety requirements and/or protective/risk reduction measures .11
4.1 General .11
4.1.1 Overall requirements .11
4.1.2 Normal climatic conditions . 12
4.1.3 Electrical requirements . 12
4.1.4 Electrostatic charges . 13
4.1.5 Stored energy components. 13
4.1.6 Edges or angles . 13
4.1.7 Guards . 13
4.1.8 Interlocking devices for guards . 13
4.1.9 Two-hand control devices .14
4.1.10 Transmission parts .14
4.1.11 Sensitive protective equipment (SPE) .14
4.1.12 Hydraulic systems .14
4.1.13 Pneumatic systems.14
4.1.14 Automatic restart .14
4.1.15 Foot protection . 15
4.1.16 Lifting and transport of the truck, attachments and truck parts .16
4.1.17 Requirements for trucks which can have riders or operators onboard .16
4.1.18 High temperatures .18
4.1.19 Exhaust emissions.18
4.1.20 Errors of fitting .18
4.1.21 Normal stop .18
4.1.22 Operational stop .19
4.2 Movement stop function with external interface .19
4.3 Truck holding function .19
4.4 Overspeed .19
4.5 Automatic battery charging . 20
4.6 Load handling . 20
4.7 Steering .21
4.8 Stability . 22
4.8.1 General . 22
4.8.2 Tilting platform stability test . 22
4.8.3 Stability requirements for trucks not covered by 4.8.2 . 23
4.9 Safeguarding and complementary protective measures. 23
4.9.1 Detection of persons in the path . 23
4.9.2 Critical edge . 28
4.9.3 Speed limitation requirements. 29
4.9.4 Additional stop function .31
4.9.5 Automatic restart after detection of persons .31
4.9.6 Emergency stop .32
4.10 Modes of operation . 33
4.10.1 General . 33
4.10.2 Automatic mode . 34
4.10.3 Manual mode . . 34
4.10.4 Maintenance mode . . . 36
4.11 Trucks intended to tow trailers . 36
4.11.1 General . 36
4.11.2 Mechanical requirements .37
iii
ISO/DIS 3691-4:2026(en)
4.11.3 Automatic towing and coupling devices .37
4.12 Trucks intended for confined zone .37
4.13 Trucks intended for use in VNA . 38
4.13.1 General . 38
4.13.2 Truck requirements for VNA applications fitted with impeding devices . 38
4.13.3 Trucks requirements for VNA applications in a restricted VNA zone . 39
4.14 Safety functions of the control system . 39
4.15 Electromagnetic immunity . 44
4.16 Attachments fitted to a truck . 44
4.16.1 General . 44
4.16.2 Conveyors fitted to a truck .45
4.16.3 Lifting tables . 46
4.17 Warning systems . 46
4.18 Loss of communication .47
5 Verification of the safety requirements and/or protective/risk reduction measures .47
5.1 General .47
5.2 Tests for detection of persons .47
5.2.1 Contact SPE.47
5.2.2 Non-contact SPE . 48
5.2.3 Routine verification . 54
5.3 Test for side detection . 54
5.4 Stability tests . 55
5.4.1 General . 55
5.4.2 Stability tests for trucks not covered by 4.8.2. . 55
5.5 Fitness for purpose . 55
5.5.1 General . 55
5.5.2 Structural tests . 56
5.5.3 Dynamic tests . 56
6 Information for use .57
6.1 General .57
6.2 Instruction handbook.57
6.2.1 General .57
6.2.2 Concerning the trucks and system .57
6.2.3 Operation of the trucks and system . 58
6.2.4 Routine service and maintenance of the trucks and system . 58
6.2.5 Operating information .59
6.2.6 Information for the application .59
6.2.7 Details for floor/ground conditions . 60
6.2.8 Details for power sources . . 60
6.2.9 Truck modification . 60
6.3 Minimum marking . . 60
6.3.1 Marking . . 60
6.3.2 Warning signs for trucks .61
6.3.3 Information plates .62
6.4 Putting into service (commissioning) . 63
Annex A (normative) Requirements for the integration of truck(s) .64
Annex B (informative) List of significant hazards .86
Annex C (normative) Determination of rated capacity for truck with masts .91
Annex D (informative) Load transfer operations .93
Annex E (normative) Verification of the safety requirements and/or protective/risk reduction
measures .96
Annex F (informative) Specification of warning and indicator signals .117
Annex G (informative) Cross reference with industrial truck types of ISO 5053-1 .122
iv
ISO/DIS 3691-4:2026(en)
Annex H (normative) Requirements for the implementation of muting by a combination of truck
signals . . .125
Annex I (normative) Determination of alternative performance levels for safety functions .127
Annex J (normative) Alternative method to demonstrate Performance Level b (PL b) for
clearance management based on Localization Systems. . 128
Annex ZA (informative) Relationship between this European Standard and the essential
requirements of Regulation (EU) 2023/1230 aimed to be covered .131
Bibliography .135
v
ISO/DIS 3691-4:2026(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 110, Industrial trucks, Subcommittee SC 2,
Safety of powered industrial trucks, in collaboration with the European Committee for Standardization (CEN)
Technical Committee CEN/TC 150, Industrial Trucks - Safety, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
This document has been prepared under a standardization request addressed to CEN by the European
Commission. The Standing Committee of the EFTA States subsequently approves these requests for its
Member States.
For the relationship with EU Legislation, see informative Annex ZA, which is an integral part of this
document.
This third edition cancels and replaces the second edition (ISO 3691-4:2023), which has been technically
revised.
The main changes are as follows:
— the Scope has been updated to include:
a) a list of types of trucks not covered;
b) a reference to the operating environment as defined in Annex A;
c) a list of significant hazards not covered;
d) the exclusion of domestic animals;
— the list of normative references has been updated to include the most recent editions of documents;
— the term entries have been updated and additional term entries, added in Clause 3;
— 4.9 integrates changes for detection of persons and safeguarding;
— 5.2 has been updated to include new test pieces dependant on Non-contact SPE;
vi
ISO/DIS 3691-4:2026(en)
— 5.3 includes additional testing for side detection;
— Annex A now includes all the specific content required for the commissioning phase of the installation;
— Annex F has been added for specification of warning and indicator signals;
— Annex G has been added for cross reference with industrial truck types of ISO 5053-1;
— Annex H has been added for implementation of muting by a combination of trucks signals;
— Annex I has been added for determination of alternative performance levels for safety functions;
— Annex J has been added for demonstration with an alternative method of a PL b for clearance management
based on localisation systems.
A list of all parts in the ISO 3691 series can be found on the ISO website.
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.
vii
ISO/DIS 3691-4:2026(en)
Introduction
This document is a type-C standard as stated in ISO 12100:2010.
This document is of relevance, in particular, for the following stakeholder groups representing the market
players with regard to machinery safety:
— machine manufacturers (small, medium and large enterprises);
— health and safety bodies (regulators, accident prevention organizations, market surveillance, etc.).
Others can be affected by the level of machinery safety achieved with the means of the document by the
above-mentioned stakeholder groups:
— machine users/employers (small, medium and large enterprises);
— machine users/employees (e.g. trade unions, organizations for people with special needs);
— service providers, e.g. for maintenance (small, medium and large enterprises);
— consumers (in case of machinery intended for use by consumers).
The above-mentioned stakeholder groups have been given the possibility to participate at the drafting
process of this document.
The machinery concerned and the extent to which hazards, hazardous situations or hazardous events are
covered are indicated in the Scope of this document. This document covers driverless industrial trucks and
their systems.
When requirements of this type-C standard are different from those which are stated in type-A or type-B
standards, the requirements of this type-C standard take precedence over the requirements of the other
standards for machines that have been designed and built according to the requirements of this type-C
standard.
This document takes into consideration the current state of the art and especially:
— non-contact sensitive protective equipment technology;
— hybrid operated trucks (i.e. manual and automatic operation);
— updates to clearances;
— additional safety functions (e.g. side detection, critical edge detection);
— safeguarding for specific zones.
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DRAFT International Standard ISO/DIS 3691-4:2026(en)
Industrial trucks — Safety requirements and verification —
Part 4:
Driverless industrial trucks and their systems
1 Scope
This document specifies safety requirements and the means for their verification for driverless industrial
trucks (hereafter referred as trucks) and their systems.
NOTE 1 Examples of industrial trucks can be found in ISO 5053-1:2020
For the purpose of this document, driverless industrial trucks are:
— powered mobile machines;
— having at least three wheels;
— operating in an industrial environment;
— designed to carry, tow, push, lift, tier in a rack, or stack a load (load handling);
— controlled by automation, independent of their level of autonomy and;
— which remain stable in the absence of power.
NOTE 2 Level of autonomy is to be understood as type of navigation.
This document is also applicable to trucks which are provided with one or more of the following:
— automatic modes which either require operators’ actions to initiate or enable such automatic operations;
— the capability to transport one or more riders (which are not considered as drivers);
— additional modes which allow operators to operate the truck manually;
— maintenance modes which allow manual operation of truck functions for maintenance reasons.
This document is applicable where trucks operate in an area of application where people have specific
training, instruction or awareness.
This document is applicable to all significant hazards, hazardous situations or hazardous events during all
phases of the lifecycle (ISO 12100:2010, 5.4), as listed in Annex B, relevant to the applicable machines when
they are used as intended and under conditions of misuse which are reasonably foreseeable. This document
is not applicable to the following:
— solely mechanically guided trucks;
— trucks that are solely remotely controlled by an operator (see ISO/DIS 3691-1:2025).
This document does not cover significant hazards related to:
— protection against corruption;
— special requirements for guards / adjustable guards restricting access;
— noise;
ISO/DIS 3691-4:2026(en)
— vibrations;
— ionising and non-ionising radiation;
— laser radiation;
— cleaning of internal parts;
— sales literature (commercial documents);
— supervisory function;
— declaration of vibrations transmitted by mobile machinery;
— self-evolving behaviour or logic (e.g, artificial intelligence).
It does not address the hazards that can occur:
— during operation in severe conditions (e.g. extreme climates, freezer applications, strong magnetic
fields);
— during operation in nuclear environments;
— during operation on a public road;
— during operation in potentially explosive environments;
— during operation in military applications;
— during operation with specific hygienic requirements;
— during operation in ionizing radiation environments;
— during the transportation of (a) person(s) other than (the) intended rider(s);
— when handling loads the nature of which can lead to dangerous situations (e.g. molten metals, acids/
bases, radiating materials);
— for rider positions with an elevation function higher than 1 200 mm from the floor/ground to the platform
floor.
This document does not contain safety requirements for trucks intended to operate in public zones or spaces
accessible to any persons without specific training, instruction or awareness.
This document does not contain safety requirements for trailer(s) being towed behind a truck.
This document does not contain specific safety requirements for elevated operator trucks.
This document does not apply to trucks manufactured before the date of its publication.
This document does not take into consideration domestic animals as they are not expected to be present in
industrial environments.
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.
ISO 2867:2011, Earth-moving machinery — Access systems
ISO/DIS 3691-1:2025, Industrial trucks — Safety requirements and verification — Part 1: Self-propelled
industrial trucks, other than driverless trucks, variable-reach trucks and burden-carrier trucks
ISO/DIS 3691-4:2026(en)
ISO 3691-2:2023, Industrial trucks — Safety requirements and verification — Part 2: Self-propelled variable-
reach trucks
ISO 3691-6:2021, Industrial trucks — Safety requirements and verification — Part 6: Burden and personnel
carriers
ISO 4413:2010, Hydraulic fluid power — General rules and safety requirements for systems and their components
ISO 4414:2010, Pneumatic fluid power — General rules and safety requirements for systems and their
components
ISO 5053-1:2020, Industrial trucks — Vocabulary — Part 1: Types of industrial trucks
1)
ISO 7010:2019 , Graphical symbols — Safety colours and safety signs — Registered safety signs
ISO 7250-1:2017, Basic human body measurements for technological design — Part 1: Body measurement
definitions and landmarks
ISO 10896-1:2020, Rough-terrain trucks — Safety requirements and verification — Part 1: Variable-reach
trucks
ISO 10896-2:2016, Rough-terrain trucks — Safety requirements and verification — Part 2: Slewing trucks
ISO 12100:2010, Safety of machinery — General principles for design — Risk assessment and risk reduction
ISO 13849-1:2023, Safety of machinery — Safety-related parts of control systems — Part 1: General principles
for design
ISO 13849-2:2012, Safety of machinery — Safety-related parts of control systems — Part 2: Validation
ISO 13850:2015, Safety of machinery — Emergency stop function — Principles for design
ISO 13851:2019, Safety of machinery — Two-hand control devices — Principles for design and selection
ISO 13855:2024, Safety of machinery — Positioning of safeguards with respect to the approach of the human
body
ISO 13856-2:2013, Safety of machinery — Pressure-sensitive protective devices — Part 2: General principles for
design and testing of pressure-sensitive edges and pressure-sensitive bars
ISO 13856-3:2013, Safety of machinery — Pressure-sensitive protective devices — Part 3: General principles for
design and testing of pressure-sensitive bumpers, plates, wires and similar devices
ISO 13857:2019, Safety of machinery — Safety distances to prevent hazard zones being reached by upper and
lower limbs
ISO 14119:2024, Safety of machinery — Interlocking devices associated with guards — Principles for design and
selection
ISO 14120:2015, Safety of machinery — Guards — General requirements for the design and construction of fixed
and movable guards
ISO 14122-2:2016, Safety of machinery — Permanent means of access to machinery — Part 2: Working platforms
and walkways
ISO 15870:2000, Powered industrial trucks — Safety signs and hazard pictorials — General principles
ISO 22915-2:2018, Industrial trucks — Verification of stability — Part 2: Counterbalanced trucks with mast
ISO 22915-3:2021, Industrial trucks — Verification of stability — Part 3: Reach and straddle trucks
1) As impacted by ISO 7010:2019/Amd 1:2020, ISO 7010:2019/Amd 2:2020, ISO 7010:2019/Amd 3:2021,
ISO 7010:2019/Amd 4:2021, ISO 7010:2019/Amd 5:2022,ISO 7010:2019/Amd 6:2022, ISO 7010:2019/Amd 7:2023,
ISO 7010:2019/Amd 8:2024, ISO 7010:2019/Amd 9:2025 and ISO 7010:2019/Amd 10:2025.
ISO/DIS 3691-4:2026(en)
ISO 22915-4:2018, Industrial trucks — Verification of stability — Part 4: Pallet stackers, double stackers and
order-picking trucks with operator position elevating up to and including 1 200 mm lift height
ISO 22915-5:2020, Industrial trucks — Verification of stability — Part 5: Single-side-loading trucks
ISO 22915-7:2016, Industrial trucks — Verification of stability — Part 7: Bidirectional and multidirectional
trucks
ISO 22915-8:2026, Industrial trucks — Verification of stability — Part 8: Additional stability test for trucks
operating in the special condition of stacking with mast tilted forward and load elevated
ISO 22915-9:2014, Industrial trucks — Verification of stability — Part 9: Counterbalanced trucks with mast
handling freight containers of 6 m (20 ft) length and longer
ISO 22915-10:2023, Industrial trucks — Verification of stability — Part 10: Additional stability test for trucks
operating in the special condition of stacking with load laterally displaced by powered devices
ISO 22915-11:2011, Industrial trucks — Verification of stability — Part 11: Industrial variable-reach trucks
ISO 22915-12:2015, Industrial trucks — Verification of stability — Part 12: Industrial variable-reach trucks
handling freight containers of 6 m (20 ft) length and longer
ISO 22915-13:2026, Industrial trucks — Verification of stability — Part 13: Rough-terrain trucks with mast
ISO 22915-14:2010, Industrial trucks — Verification of stability — Part 14: Rough-terrain variable-reach trucks
ISO 22915-15:2020, Industrial trucks — Verification of stability — Part 15: Counterbalanced trucks with
articulated steering
ISO 22915-17:2020, Industrial trucks — Verification of stability — Part 17: Towing tractors, burden and
personnel carriers
ISO 22915-20:2023, Industrial trucks — Verification of stability — Part 20: Additional stability test for trucks
operating in the special condition of offset load, offset by utilization
ISO 22915-22:2014, Industrial trucks — Verification of stability — Part 22: Lateral- and front-stacking trucks
with and without elevating operator position
IEC 61496-1:2020, Safety of machinery - Electro-sensitive protective equipment - Part 1: General requirements
and tests
IEC 61496-2:2020, Safety of Machinery — Electro-sensitive protective equipment — Part 2: Particular
requirements for equipment using active opto-electronic protective devices (AOPDs)
IEC 61496-3:2025, Safety of machinery —Electro-sensitive protective equipment — Part 3: Particular
requirements for Active Opto-electronic Protective Devices responsive to Diffuse Reflection (AOPDDR)
I EC 6 020 4 -1:2016 +A M D1: 2021, Safety of machinery — Electrical equipment of machines — Part 1: General
requirements
IEC 61558-1:2017, Safety of power transformers, power supply units, reactors and similar — Part 1: General
requirements and tests
IEC FDIS/62046:2026, Safety of machinery - Application of protective equipment to detect the presence of
persons
EN 619:2022, Continuous handling equipment and systems - Safety requirements for equipment for mechanical
handling of unit loads
EN 1175:2025, Safety of industrial trucks — Electrical/electronic requirements
EN 1570-1:2024, Safety requirements for lifting tables - Part 1: Lifting tables serving up to two fixed landing
E N 128 95:2015+A 1: 2019, Industrial trucks — Electromagnetic compatibility
ISO/DIS 3691-4:2026(en)
EN 16307-1:2020, Industrial trucks - Safety requirements and verification - Part 1: Supplementary requirements
for self propelled industrial trucks, other than driverless trucks, variable-reach trucks and burden-carrier trucks
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5053-1:2020, ISO 5053-2:2019,
ISO 5053-3:2024 and ISO 12100:2010 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:
...