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Guide · Rail & Metro · Built in India
CLC/TS 50701 is the CENELEC technical specification for cybersecurity in railway applications. It adapts the IEC 62443 industrial cybersecurity series to rail: the system is divided into security zones joined by conduits, a risk assessment sets a target security level from SL 1 to SL 4 for each, and cybersecurity work is tied into the EN 50126-1 RAMS lifecycle. At product level, specifications usually point to IEC 62443-4-1 for secure development and IEC 62443-4-2 for component security capabilities.
The short answer
CLC/TS 50701 (Railway applications, Cybersecurity) was first published by CENELEC in 2021 and revised as CLC/TS 50701:2023. It gives railway operators, system integrators and product suppliers requirements and guidance for managing cybersecurity within the EN 50126-1 RAMS lifecycle, and it can also be applied to systems and equipment developed outside that process. It covers the communications, signalling and processing domain, rolling stock and fixed installations. Its security models, concepts and risk assessment process are based on or derived from the IEC 62443 series. It does not add functional safety requirements; its aim is that the RAMS characteristics of railway systems cannot be reduced, lost or compromised by cyber attacks. An international successor, IEC 63452, is in development and is intended to replace it in Europe as EN IEC 63452.
Why it matters
Trains and stations now carry networked electronics: passenger announcement and information systems, IP CCTV cameras and recorders, remote diagnostics units and their links to depots and control centres. Each connected device is a possible entry point, and an attack on one could affect passenger information, video evidence or train data. Rolling-stock and station tenders therefore increasingly ask how equipment fits the operator's zones and conduits, which security level it supports and how its software will be updated over the life of the fleet. The operator or system integrator runs the risk assessment and sets the targets; each supplier shows what its equipment can support.
Key requirements
A summary of the concepts most railway cybersecurity specifications use. Always check the exact edition and the requirements named in your tender.
The system under consideration is divided into security zones, groups of assets with similar protection needs, connected by conduits that control communication between them. TS 50701 gives railway guidance on zoning and describes typical conduits: gateways between zones of the same security level, filtering firewalls, and one-way data diodes or network taps.
IEC 62443 defines security levels by the attacker a zone or component must resist, from SL 1 for casual or coincidental misuse to SL 4 for sophisticated attacks by attackers with extended resources and high motivation. A risk assessment sets the target level (SL-T) for each zone and conduit; components have a capability level (SL-C) and the installed system an achieved level (SL-A).
Technical requirements are grouped under seven foundational requirements: identification and authentication control, use control, system integrity, data confidentiality, restricted data flow, timely response to events, and resource availability. IEC 62443-3-3 sets system requirements for each security level and IEC 62443-4-2 sets the matching component requirements.
TS 50701 maps cybersecurity activities and deliverables onto the EN 50126-1 lifecycle, from risk assessment and requirements through design, integration and acceptance to operation and maintenance. For products, IEC 62443-4-1 defines a secure development lifecycle for suppliers: security management, security requirements, secure design and implementation, security testing, handling of security issues, security updates and security guidelines for users.
Related standards
TS 50701 is the railway layer on top of IEC 62443: IEC 62443-2-1 covers the asset owner's security programme, IEC 62443-3-2 security risk assessment and zoning, IEC 62443-3-3 system security requirements, and IEC 62443-4-1 and 4-2 product development and component requirements. It is designed to be consistent with the EN 50126-1 RAMS process while keeping safety approval and cybersecurity acceptance as separate as possible. EN 50159 covers safety-related communication in transmission systems from a safety point of view. For onboard equipment, cybersecurity sits alongside EN 50155, EN 50121 and EN 45545-2 rather than replacing them. The edition and requirements should be agreed between buyer and supplier at tender stage.
Checklist
Use these points when writing a specification or comparing suppliers. Ask for documented evidence for the exact hardware and software version rather than relying on a datasheet statement.
Scope and roles: who is the asset owner, who is the system integrator, who performs the risk assessment, and which domain applies: rolling stock, fixed installations, or communications, signalling and processing?
Edition: does the specification name the edition, for example CLC/TS 50701:2023, and say how a move to IEC 63452 would be handled during the project?
Zones and target levels: which zone and conduits will the equipment sit in, and what target security level (SL-T) has been set for them?
Component capability: which IEC 62443-4-2 capability level (SL-C) does the supplier state for the device, and is there documented evidence for that exact hardware and software version?
Secure development: does the supplier follow a secure development lifecycle such as IEC 62443-4-1, including security testing and handling of reported vulnerabilities?
Interfaces and hardening: are all network ports, services, accounts and remote access paths documented, with unused ones disabled and default passwords changed?
Updates and sourcing: how will security updates be delivered and tested over the life of the fleet, and does your programme favour Built in India / Make in India manufacturing?
Envision TechWorks
Envision TechWorks products are designed, manufactured and tested in an ISO 9001:2015 facility in India: production-ready and Built in India for Make in India programmes. PAPIS onboard passenger announcement and information hardware is built to EN 50155, and production includes in-circuit and functional test, AOI and X-ray inspection, and thermal cycling. Share the cybersecurity requirements named in your tender, such as the TS 50701 edition, zones and target security levels, and the team can discuss your requirements.
Related
The rolling-stock electronics standard for onboard equipment, covering temperature classes, power supply, shock and vibration, EMC and testing.
Read the EN 50155 guide →Passenger announcement and information system for metro trainsets, with hardware built to EN 50155.
See PAPIS product details →Onboard and station IP surveillance with centralised video management and vandal-resistant cameras for rolling stock and stations.
See IP CCTV product details →Railway fire safety for materials and components: hazard levels HL1 to HL3, requirement sets and reaction-to-fire tests.
Read the EN 45545-2 guide →Platform and concourse displays that show route maps, arrivals, service status and emergency messages on sunlight-readable screens, managed centrally from the control room.
See Station PIS product details →IoT remote diagnostics for locomotive and rolling stock fleets — edge data acquisition, cloud analytics and predictive maintenance alerts, Built in India.
See RDPMS product details →FAQ
CLC/TS 50701 is the CENELEC technical specification Railway applications, Cybersecurity. It tells railway operators, system integrators and product suppliers how to manage cybersecurity within the EN 50126-1 RAMS lifecycle, using models and a risk assessment process based on the IEC 62443 series. The current edition is CLC/TS 50701:2023.
IEC 62443 is the general cybersecurity series for industrial automation and control systems. TS 50701 adapts its concepts, such as zones and conduits, security levels and the seven foundational requirements, to railway systems and the railway lifecycle. Product-level requirements usually come from IEC 62443-4-1 for secure development and IEC 62443-4-2 for component security capabilities.
Security levels describe how capable an attacker a zone, conduit or component is meant to resist: SL 1 casual or coincidental misuse, SL 2 intentional attacks with simple means and low resources, SL 3 sophisticated attacks with moderate resources and system-specific skills, and SL 4 sophisticated attacks with extended resources and high motivation. The risk assessment sets the target level.
That is the plan. IEC 63452, an international railway cybersecurity standard developed with TS 50701 as an input, is in its final stages of development and is intended to be adopted in Europe as EN IEC 63452, replacing CLC/TS 50701. Until it is published, TS 50701 remains the published European reference, so check which document your tender names.
Envision TechWorks designs, manufactures and tests products in an ISO 9001:2015 facility in India. Share the cybersecurity requirements named in your tender, such as the TS 50701 edition, zones and target security levels, and the team can discuss your requirements, Built in India.
Share the TS 50701 edition, zones and target security levels named in your tender, and the team will discuss your requirements, Built in India.