What is the primary purpose of the EN 15663 standard?

The primary purpose of EN 15663 is to establish a harmonized and unambiguous set of definitions for the reference masses of railway vehicles. This ensures consistency in design, testing, and performance calculations across different manufacturers, operators, and countries, which is essential for safety and interoperability in the European railway network.

What is the key difference between 'normal payload' and 'exceptional payload' in EN 15663?

The key difference lies in the passenger or freight density used for calculation. 'Normal Payload' represents a typical, everyday service load (e.g., all seats occupied plus 4 standing passengers per square meter). 'Exceptional Payload' represents the maximum possible 'crush' load (e.g., all seats plus 6-8 standing passengers per square meter) and is used for critical safety calculations like structural strength and braking performance.

Does EN 15663 apply to all types of railway vehicles?

Yes, the standard is designed to be applicable to a wide range of mainline railway vehicles, including locomotives, freight wagons, passenger coaches, and multiple units (both EMUs and DMUs). Its principles provide a framework that can be adapted to virtually any type of rolling stock operating on the European network.

Which mass definition is most important for braking system design?

The 'Design Mass under Exceptional Payload' is the most critical reference mass for designing and verifying braking systems. Engineers must ensure the train can stop safely and within required distances when it is at its absolute maximum weight, which represents the worst-case scenario for the brakes.

Why EN 15663 Is Crucial for European Rail Safety

Unpack EN 15663, the essential standard harmonizing railway vehicle mass definitions. It guarantees safety, interoperability, and precise performance across all aspects of rolling stock.

December 15, 2024 2:02 am

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What is EN 15663: Definition of Vehicle Reference Masses?

EN 15663 is a key European standard for the railway industry that establishes a harmonized and unambiguous framework for defining the reference masses of railway vehicles. Its primary purpose is to provide a common set of definitions for various vehicle loading conditions, ensuring consistency in design, testing, performance calculations, and operational documentation across different manufacturers, operators, and national authorities.

This standard is fundamental for nearly all technical aspects of a rolling stock project. From structural integrity and vehicle dynamics to braking performance and energy consumption, having a precise and universally understood definition of vehicle mass is critical for ensuring safety, interoperability, and reliability.

Key Objectives of the Standard

The implementation of EN 15663 addresses several critical needs within the railway sector:

Harmonization: It creates a single, coherent terminology for vehicle masses, replacing disparate national standards and manufacturer-specific definitions. This simplifies cross-border operations and procurement processes.
Safety: By defining worst-case loading scenarios (e.g., exceptional payload), the standard ensures that critical systems like brakes and structural components are designed and verified to handle the maximum possible loads.
Performance Specification: It allows for clear and comparable performance metrics. Calculations for acceleration, traction, and energy efficiency must be based on a specified reference mass to be meaningful.
Interoperability: It is a cornerstone of the Technical Specifications for Interoperability (TSIs), ensuring that a vehicle approved in one country can be correctly assessed and operated in another based on a common understanding of its mass properties.

Core Mass Definitions in EN 15663

EN 15663 defines several distinct mass states, each corresponding to a specific vehicle condition. These are not just theoretical values but are used in specific calculations throughout the vehicle’s lifecycle.

Design Mass in Working Order

This is a fundamental baseline mass. It represents the vehicle in a state ready for service but without any payload (passengers or freight) or crew. It is the most commonly used reference mass for comparing different vehicle designs.

Includes: The complete structure, bogies, propulsion systems, interior fittings, and all fixed equipment.
Includes Consumables: It also accounts for consumables at a specified level (e.g., 2/3 of sand, full toilet flushing water, full coolant, but no potable water for passengers).
Excludes: Crew, passengers, catering supplies, and any freight.

Operational Mass in Working Order

This state builds upon the design mass by adding the personnel required to operate the vehicle. It represents a train that is “ready to go” before accepting passengers or freight.

Includes: Everything in “Design Mass in Working Order” plus the mass of the standard operating crew (e.g., driver, conductor) and their personal effects. The standard provides nominal values for crew mass.

Design Mass under Normal Payload

This is the reference mass for a vehicle under its typical, everyday operating load. It is crucial for calculating nominal performance, timetabling, and energy consumption under regular service conditions.

Includes: Everything in “Design Mass in Working Order.”
Adds Payload: The “normal payload” is calculated based on standard densities, for example, a specific number of standing passengers per square meter (e.g., 4 persons/m²) in designated areas, plus all seats occupied. For freight wagons, it refers to the typical load, not the absolute maximum.

Design Mass under Exceptional Payload

This represents the maximum possible mass of the vehicle in service, often referred to as “crush load” in passenger vehicles. This value is critical for safety-related calculations.

Includes: Everything in “Design Mass in Working Order.”
Adds Maximum Payload: The “exceptional payload” is calculated using a higher density of standing passengers (e.g., 6 to 8 persons/m², depending on the vehicle type) to simulate peak-hour or special event conditions. For freight, it represents the maximum permissible payload.
Primary Use: This mass is essential for structural strength verification (body, bogies), braking system calculations, and evaluating vehicle dynamics under the most demanding conditions.

Dead Mass

This is the mass of the vehicle as delivered from the manufacturer, completely empty. It is primarily used for transport and logistics before the vehicle is commissioned for service.

Includes: Only the fixed, permanent parts of the vehicle.
Excludes: All consumables (fuel, water, sand), crew, and any payload.

Comparison of EN 15663 Reference Masses

The following table provides a clear comparison of the key mass definitions outlined in the standard.

Mass Definition	Description	Key Inclusions	Typical Application
Dead Mass	The vehicle as built, empty of all consumables and payload.	Vehicle structure and fixed equipment only.	Manufacturing, transport, and initial weighing.
Design Mass in Working Order	Vehicle ready for service, with consumables, but without crew or payload.	Dead Mass + specific levels of consumables (sand, coolant, etc.).	Baseline design comparisons, empty vehicle dynamic tests.
Design Mass under Normal Payload	The vehicle under its typical service load.	Mass in Working Order + standard passenger load (e.g., all seats + 4 persons/m²).	Nominal performance calculations, energy consumption, timetabling.
Design Mass under Exceptional Payload	The vehicle under its maximum possible service load.	Mass in Working Order + maximum passenger load (e.g., all seats + 6-8 persons/m²).	Structural integrity analysis, braking system design, safety-critical calculations.

The Practical Importance of Accurate Mass Definitions

Adherence to EN 15663 is not merely a documentation exercise. The correct application of these definitions has profound technical consequences:

Vehicle Dynamics and Safety

The total mass and its distribution directly influence a vehicle’s dynamic behavior. Simulations and tests for running safety (e.g., derailment risk on twisted track) and ride quality must be performed using the correct reference masses to be valid.

Braking Performance

Braking systems must be designed to safely stop a fully loaded train. Calculations for stopping distances and brake thermal capacity are legally and functionally required to use the “Design Mass under Exceptional Payload” to ensure safety in all conditions.

Structural Integrity

The carbody, bogie frames, axles, and other structural components must withstand the static and dynamic forces generated by the vehicle at its maximum weight. Finite Element Analysis (FEA) and physical load tests are based on the exceptional payload mass to prevent structural failure.

Infrastructure Compatibility

Axle load, which is the total vehicle mass divided by the number of axles, is a critical parameter for infrastructure managers. It determines the wear and tear on tracks and the suitability of a vehicle for operation on specific lines or bridges, which have strict weight limits. All mass states are relevant for these calculations.

Conclusion

EN 15663 serves as a fundamental “common language” for the European railway sector. By providing clear, standardized definitions for vehicle reference masses, it underpins the entire engineering process, from initial concept design to final operational safety. Its role is indispensable in ensuring that railway vehicles are designed, tested, and operated in a consistent, safe, and interoperable manner, forming a bedrock of modern rolling stock engineering.

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