EN 45545-2 Fire behaviour of materials and components used in railway vehicles

The European standard EN 45545-2 defines the fire behaviour requirements for materials and components used in railway vehicles.
It is the second of seven parts that make up the EN 45545 standard series, which, since its initial publication in 2013 by the European Committee for Standardization (CEN), has progressively replaced various national fire safety standards, creating a unified regulatory framework for fire protection in railway applications.

Part 2, in particular, is essential to ensure that materials contribute as little as possible to fire hazards by limiting flame propagation, smoke production, and the release of toxic gases. For this reason, and to ensure the highest possible level of fire safety, all materials used in railway vehicles must comply with EN 45545-2.

To assess whether a product complies with EN 45545-2, a structured process must be followed. This includes determining the applicable Hazard Level (HL), identifying the product's location within the railway vehicle, and carrying out the appropriate test methods as specified by the relevant requirement set (R).

Our Fire Reaction Laboratory performs testing and certification in accordance with EN 45545, supporting companies and manufacturers in verifying compliance and obtaining the certifications required to operate in the European railway market.

Hazard Levels (HL)

Hazard Levels (HL) define the severity of fire safety requirements that materials used in railway vehicles must meet. They range from HL1 to HL3, with HL1 indicating a low risk, HL2 a medium risk, and HL3 a high risk.

The hazard level is determined based on the type of railway vehicle (e.g., tram, commuter train, metro, high-speed train, sleeper train, freight train, locomotives) and the environment in which it operates. Key factors include the presence and length of tunnels, evacuation time, train capacity, accessibility for rescue services, and whether the train is operated automatically or by staff.

These criteria correspond to the Design Categories and Operation Categories outlined in the previous discussion on EN 45545-1. Once these parameters are identified and correlated, the appropriate Hazard Level (HL) can be determined.



For example, an urban tram operating at street level and easily evacuable will be classified as HL1. In contrast, double-deck trains or sleeper trains are considered high-risk in the event of a fire due to evacuation challenges; as a result, they require higher safety standards for the materials used and must primarily comply with HL3.

Material Position Codes

It is important to emphasize that the fire performance of materials used in the railway sector depends not only on their intrinsic properties but also on their position within the vehicle. For this reason, the standard classifies components based on their location (interior or exterior) and specific function (furnishings, technical/electrical/mechanical equipment) using the following codes:

• IN: Interior vertical/horizontal surfaces (e.g., walls, doors, windows, ceilings, floors)

• EX: Exterior surfaces of the vehicle body (e.g., outer walls, roof, underframe)

• F: Furniture and fittings (e.g., seats, tables, textiles)

• E: Electrotechnical equipment (e.g., cables, electronic devices)

• M: Mechanical equipment (e.g., engines, brakes)

Each main code may include sub-codes that further specify individual applications (e.g., IN1A, IN1B, IN2, IN3…; EX1A, EX1B, EX2, EX3…).

Requirement Sets (R Requirements)

Each position code is associated with specific requirement sets, identified from R1 to R28. Here are some examples:

• IN1A (interior wall panels): Requirement R1

• EX1A (exterior wall panels): Requirement R7

• IN15 (interior floor coverings, e.g., carpets): Requirement R10

• F1A (seat upholstery fabrics): Requirement R21

Each requirement defines the test methods and acceptance criteria that materials must meet to comply with the standard.

Test Methods

Some of the most common test methods and their corresponding measured parameters include:

• ISO 5660-1: Cone calorimeter for heat release evaluation (MAHRE [kW/m²])

• ISO 5659-2 + EN 17084: Smoke density (Ds max; Ds(4); VOF4 [min]) and gas toxicity (CITG) measurements

• ISO 5658-2: Surface flame spread in vertical configuration (CFE [kW/m²]) – for wall panels

• EN ISO 9239-1: Surface flame spread in horizontal configuration (CFE [kW/m²]) – for flooring materials

• ISO 4589-2: Determination of the minimum oxygen concentration required to support combustion (Oxygen Index [%])

Each R requirement may involve one or more of these tests, and the limit values for the measured parameters vary depending on the hazard level required by the vehicle’s classification (HL1, HL2, HL3).




 

Practical Example:
A company manufactures panels for partition walls; the product is intended to be installed on a double-deck train that travels through long tunnels with difficult evacuation conditions. This scenario requires applying the highest hazard level (HL3).

As an interior component, the material falls under the IN classification, specifically IN1A (interior wall panels). The standard associates this code with Requirement R1, which defines the combination of test methods and performance parameters to be assessed, along with the corresponding limit values for the three hazard levels.

If,after performing the required tests, all measured values fall within the limits for HL3, the material is deemed compliant with EN 45545-2 for Requirement R1 at Hazard Level HL3.

In conclusion, the EN 45545-2 standard provides a detailed framework to ensure fire safety in railway vehicles. Identifying the applicable hazard criteria, the specific placement of each material, and the corresponding requirements is essential for designing compliant and safe rolling stock.

Istituto Giordano has been active in the railway sector for years, relying on a team of highly specialized technicians. We offer a wide range of testing and analysis services to meet the technical and regulatory needs of the entire industry.
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