RAMS — EN 50126 (Reliability, Availability, Maintainability and Safety)

What Is RAMS?

RAMS is the process in which the reliability (R), availability (A), maintainability (M) and safety (S) requirements of a railway system are defined, analyzed and proven with the life cycle approach defined in the EN 50126 series.

Purpose of RAMS

The goal is to demonstrate through documented analysis that the system meets safety objectives and provides the expected availability throughout the operation.

Which Products Is RAMS Applied To?

Signaling and control systems
Vehicle subsystems (brake, door, traction)
infrastructure equipment
Passenger security systems

In Which Sectors Is RAMS Used?

DemiryoluElectricalElectronicsCyber Security

Standards Related to RAMS

EN 50126-1
EN 50126-2
EN 50129 (safety-related electronic systems)
EN 50128 / EN 50657 (software)
EN 50155electronic equipment in railway vehicles test
EN 50121electromagnetic compatibility in railway applications test
EN 45545fire safety in railway vehicles test
IEC 61373vibration and shock in railway vehicle equipment test

RAMS Conditions

life cycle: Phases defined in EN 50126; Output and verification are defined in each phase
Analizler: Hazard analysis (PHA/SHA), FMEA/FMECA, fault tree (FTA), Markov models
Emniyet hedefi: Tolerable hazard ratio (THR) and SIL assignments
Evidence: The safety case report is prepared in the EN 50129 structure.

Equipment for RAMS

Reliability and safety analysis software
Fault data and field records
Verification and validation registration system
Independent safety assessment (ISA) access

Sample Requirements for RAMS

System boundaries and operating context must be defined
The source of failure rate data must be traceable
Assumptions and constraints should be written clearly
The need for independent evaluation is defined in the project

Duration of RAMS

Months depending on system scope; years on major projects.

RAMS Procedure

1System boundaries and operating context are defined.
2Hazard analysis is performed and a danger log is opened.
3RAMS requirements and SIL assignments are determined.
4FMECA, FTA and availability models are established.
5Verification and validation evidence is collected.
6A safety situation report is prepared and independently evaluated.

RAMS Acceptance Criteria

RAMS is not a pass/fail experiment; The outcome is a set of documented evidence that shows that safety objectives have been met.

Evaluation of Results

The source and validity of the failure rate data determine the outcome; General values taken from catalogs may not represent operating conditions. The hazard log is a living document; it cannot be produced all at once at the end of the project.

RAMS Report

System limits and assumptions
danger log
RAMS requirements and SIL assignments
Analysis results (FMECA, FTA, availability)
Safety situation report and independent evaluation

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

Railway Safety Directive and TSI requirements
Ulusal emniyet otoritesi gereksinimleri

Demiryolu Testleri — What Does This Testing Field Cover?

The section below describes the field that the RAMS test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Railway testing shows that vehicles and components operate safely and reliably in the rail environment. The character of this family comes from the ASSUMPTION OF LONG LIFE: a rail vehicle is designed for a service life exceeding thirty years and its components remain under vibration, temperature cycling and intensive use throughout that period.

Long life also shapes the component supply chain. Spare parts must remain available for thirty years, electronic components going out of production must be replaced, and every substitution must be re-verified. This takes railways out of a "certify once and carry on" logic.

Fire safety is the most tightly regulated part of the field and runs through the EN 45545 series. The logic of the series rests on the LOCATION OF USE and the OPERATION CATEGORY: a metro running in tunnels and an intercity train do not carry the same risk, and seat fabric and cable are not assessed in the same category. Evacuation time is the main factor setting these categories; because evacuation takes longer in an enclosed tunnel, the material requirements become stricter.

For electronic equipment, EN 50155 is the framework standard and carries environmental, electrical and functional requirements together: supply voltage variations, temperature classes, humidity, vibration and shock. On the vibration and shock side the EN 61373 categories are used and these differ by mounting location — a box mounted on the body and a sensor mounted on the bogie do not go through the same profile.

On electromagnetic compatibility the EN 50121 series applies and addresses a problem peculiar to railways: the traction system switches at very high power and can affect both the systems on board and the signalling along the line. The series therefore carries separate parts for the vehicle, lineside installations and signalling.

For safety-related systems a separate body of work applies, and here the evidence is not testing but PROCESS: EN 50126 (RAMS), EN 50128 (software) and EN 50129 (safety-related electronic systems) define the safety life cycle and the safety integrity levels (SIL). Signalling and brake control systems are assessed within this framework.

On the quality side, the sector's own scheme IRIS (ISO/TS 22163) comes into play; major vehicle manufacturers require this certificate from their suppliers.

On the mechanical structure side, the car body and bogie frame have standards of their own: structural verification under static and fatigue loads, weld quality and crashworthiness. These tests are carried out on full-scale rigs and can take months.

Method groups in this field

Fire safety
Classification of materials and components under EN 45545; the requirement set according to operation and design category.
Electronic equipment
EN 50155 environmental and electrical requirements; supply interruptions, temperature classes, humidity and degree of protection.
Vibration and shock
EN 61373 categories; body, bogie and axle-mounted profiles according to mounting location.
Electromagnetic compatibility
The EN 50121 series: separate parts for the vehicle, lineside installations and signalling.
Safety life cycle
EN 50126 RAMS, EN 50128 software and EN 50129 safety-related systems; SIL determination and the safety case.
Structural verification
Static and fatigue loads on the car body and bogie frame, weld quality, crashworthiness.

Commonly confused in this field

EN 45545 requirements vary with the location of use and the operation category; there is no single "railway fire class".
Conformity to EN 50155 does not cover the vibration requirements; EN 61373 is applied in addition.
A civil EMC report is not sufficient for railways; the EN 50121 series defines a different environment and different limits.
For safety-related systems, testing alone is not evidence; safety life cycle records are required.
A component change (even one driven by obsolescence) requires re-verification; in long-life projects this is routine work.
An IRIS certificate is not a product approval; it is a quality system certificate.

Which decisions these results support

Vehicle and component approval, operator acceptance processes
Material selection according to the fire safety category
The safety case and SIL evidence for safety-related systems
Supply chain quality certification
Continuity of component supply and change management

Related Tests

Frequently Asked Questions About RAMS

Can a single test report be issued for RAMS?

No. RAMS is a lifecycle process and evidence set. Test reports are part of this evidence, but do not alone indicate RAMS suitability.