What is the main purpose of EN 45545-4?

The main purpose of EN 45545-4 is to define the fire safety requirements for the design and construction of railway vehicles. It focuses on structural measures like fire barriers and the prevention of ignition sources to minimize fire risk and control the spread of fire, ensuring passenger and crew safety.

How is EN 45545-4 different from EN 45545-2?

EN 45545-4 deals with the overall vehicle design and fire containment structures, specifying *where* fire barriers are needed and their required performance (e.g., EI15 for 15 minutes of integrity and insulation). In contrast, EN 45545-2 specifies the reaction-to-fire performance of the individual *materials* and components used to build those structures and furnish the vehicle.

What are 'fire barriers' according to EN 45545-4?

In the context of EN 45545-4, fire barriers are physical partitions (like walls, floors, ceilings, or doors) designed to prevent the propagation of fire, smoke, and heat from one part of a railway vehicle to another for a specified period. Their performance is measured in terms of Integrity (E) and Insulation (I).

Does EN 45545-4 apply to all railway vehicles?

EN 45545-4 applies to the design of all railway vehicles, including high-speed trains, regional and suburban trains, metro cars, trams, and passenger coaches falling under the scope of the EN 45545 series. The specific requirements may vary based on the vehicle's Operation Category (from OC1 to OC4), which defines the environment in which it operates (e.g., open-air tracks vs. long tunnels).

Europe’s New Standard: EN 45545-4 For Fire-Safe Rail Design

EN 45545-4 defines essential fire safety for rolling stock design. It mandates structural containment, ignition prevention, and protected evacuation routes, ensuring passenger and crew safety.

December 15, 2024 2:02 am

Understanding EN 45545-4: Fire Safety in Rolling Stock Design

EN 45545-4 is a crucial part of the European standard series for fire protection on railway vehicles. While other parts, such as EN 45545-2, focus on the reaction-to-fire performance of materials, Part 4 specifies the core fire safety requirements for the design and construction of the rolling stock itself. Its primary goal is to minimize the probability of a fire starting and to control the spread of fire and its effluents (smoke and toxic gases) should an incident occur, thereby ensuring a safe environment for passenger and crew evacuation.

This standard provides a holistic framework for integrating fire safety into the earliest stages of vehicle design. It addresses the structural measures needed to contain a fire, prevent its propagation between different areas of the train, and protect critical systems and escape routes. Compliance with EN 45545-4 is fundamental for any new rolling stock intended for operation within Europe and is increasingly adopted as a benchmark for best practices globally.

Key Principles and Requirements of EN 45545-4

The standard is built upon several foundational principles aimed at creating a resilient and fire-safe vehicle. These are translated into specific design mandates that engineers and manufacturers must follow.

Fire Containment and Integrity Measures

A central concept in EN 45545-4 is the use of fire barriers to compartmentalize the railway vehicle. These barriers are physical partitions designed to resist the passage of flames and hot gases for a specified duration. The requirements are defined by two key criteria:

Integrity (E): The ability of the barrier to prevent the passage of flames and hot gases. A rating of E15, for example, means the barrier can maintain its integrity for a minimum of 15 minutes.
Insulation (I): The ability of the barrier to restrict the temperature rise on the non-fire-exposed side. An I15 rating means the barrier prevents the unexposed surface from exceeding a specific temperature threshold for 15 minutes, protecting adjacent areas from igniting due to heat transfer.

The standard mandates specific integrity and insulation ratings for different locations, such as floors, ceilings, walls between passenger and technical compartments, and the driver’s cab.

Prevention of Ignition Sources

EN 45545-4 requires a proactive approach to eliminating potential fire-starters. The design must minimize risks from various sources, including:

Electrical Equipment: Measures to prevent short circuits, arcing, and overheating in high-voltage and high-current electrical cabinets.
High-Temperature Components: Ensuring that components like exhaust systems, diesel engines, and braking resistors are adequately shielded and separated from combustible materials.
Friction Sources: Design considerations to prevent fires caused by friction, such as in brake systems or bearings.
Flammable Liquids and Gases: Strict requirements for the installation and protection of systems containing flammable fluids like hydraulic oil, transformer oil, or fuel. This includes measures to contain leaks and prevent them from reaching ignition sources.

Protection of Evacuation Routes

Ensuring that passengers and crew can evacuate safely is paramount. EN 45545-4 dictates requirements for escape routes, including corridors, gangways, and exits. The design must ensure these routes are protected from fire and smoke for a sufficient period. This includes the fire resistance of doors leading to escape paths and the materials used within the escape routes themselves, which must comply with the strict requirements of EN 45545-2.

Fire Barrier Requirement Comparison Table

The application of fire barriers is determined by the location and the associated fire risk. The following table provides illustrative examples of the fire resistance requirements for various barriers within a railway vehicle, as stipulated by EN 45545-4.

Barrier Location	Required Fire Resistance	Rationale / Typical Application
Full-width partition between driver’s cab and adjacent area	E15 / I15	Protects the driver and train controls, allowing the driver to manage the situation and communicate during an emergency.
Floor above high-risk equipment (e.g., diesel engine, transformer)	EI30	Provides robust protection for the passenger area from a fire originating in a high-risk technical zone underneath the vehicle.
Partition separating a passenger area from a technical cabinet with ignition sources	EI15	Contains a potential fire within the technical cabinet, preventing it from spreading to areas occupied by passengers.
External roof of a sleeping car	E15	Protects against external fire sources, such as fires in tunnels or from adjacent vehicles, ensuring the integrity of the roof structure.
Gangway system between carriages	E15	Prevents fire from spreading from one vehicle to the next, maintaining the integrity of the escape route through the train.

How EN 45545-4 Interacts with Other Parts of the Series

EN 45545-4 does not exist in isolation. Its effectiveness depends on its synergy with other parts of the EN 45545 standard, particularly:

EN 45545-2 (Requirements for fire behaviour of materials and components): While EN 45545-4 specifies that a fire barrier with an EI15 rating is needed, EN 45545-2 defines the specific reaction-to-fire properties (e.g., flammability, smoke density, toxicity) of the materials used to construct that barrier. A compliant design must satisfy the requirements of both parts.
EN 45545-5 (Fire safety requirements for electrical equipment): This part provides detailed requirements for preventing fires in electrical installations. EN 45545-4 relies on it to ensure that electrical cabinets and wiring, key potential ignition sources, are inherently fire-safe.
EN 45545-6 (Fire control and management systems): This part covers fire detection systems, alarms, and fire-extinguishing systems. The fire containment strategy of EN 45545-4 is designed to work in tandem with the detection and suppression systems specified in Part 6 to manage a fire event effectively.

The Role of EN 45545-4 in Modern Railway Safety

Ultimately, EN 45545-4 shifts the focus of fire safety from a reactive to a proactive discipline. By embedding fire protection into the fundamental design and construction of the vehicle, it establishes a robust, multi-layered defence against fire risks. It ensures that, in the unlikely event of a fire, the vehicle’s own structure is the first and most critical line of defence, providing the time and a secure environment for a successful evacuation. This structural approach is indispensable for achieving the high levels of safety demanded in modern railway transport.