In August 2017, a fire in a suburban rail car in Santiago, Chile, injured 17 passengers and caused €4.2 million in vehicle damage. The fire investigation attributed part of the rapid fire spread to rubber components — specifically, secondary suspension elements and interior rubber profiles — that did not meet the fire performance levels now required under European and international railway fire standards.
This incident is one of dozens in the past decade that have driven the global adoption of EN 45545-2 as the de facto fire safety standard for railway vehicles — not just in Europe, but in export projects worldwide. Understanding what EN 45545-2 requires, and what it means for rubber component procurement, is now essential for rail operators, maintenance contractors, and OEM suppliers.
What Is EN 45545-2?
EN 45545 is a series of European Standards for fire protection on railway vehicles. Part 2 — the most practically important part — specifies the reaction to fire requirements for materials and products used in railway vehicles.
“Reaction to fire” measures how a material behaves when it is exposed to fire: how quickly it ignites, how fast the fire spreads, how much heat it releases, how much smoke it produces, and whether it releases toxic gases.
EN 45545-2 replaced a patchwork of national standards (British BS 6853, French NFF 16-101, German DIN 5510-2, and others) with a single harmonized European standard. From June 2018, it became the mandatory reference for new railway vehicles placed in service in EU member states.
For rubber components specifically — which appear throughout railway vehicles in bogie suspension, interior profiles, door seals, and cable sheathing — EN 45545-2 establishes performance requirements that most standard rubber compounds cannot meet without specific fire-retardant formulation.
Hazard Levels: HL1, HL2, and HL3
EN 45545 categorizes vehicles into three Hazard Levels based on the evacuation difficulty in their operating environment:
HL1 — Low Hazard
Applicable to: Vehicles on open networks where passengers can evacuate quickly — mainline trains without tunnels, open-air tramways.
Requirements at HL1 are the least stringent. Some standard rubber compounds can meet HL1 requirements without special fire-retardant additives. However, with increased tunnel use in urban development, few new projects are designed to HL1 specification.
HL2 — Medium Hazard
Applicable to: Vehicles that may travel through tunnels or enclosed stations but with reasonable evacuation access — regional rail with some tunnels, inter-city trains.
HL2 represents the most common specification for new rolling stock procurement. Standard natural rubber compounds do not meet HL2 requirements. Fire-retardant additives — typically halogenated or halogen-free flame retardants depending on the additional low smoke/toxicity requirements — are required in the rubber formulation.
HL3 — High Hazard
Applicable to: Underground metro, suburban rail with long tunnel sections, vehicles in enclosed stations with high passenger density.
HL3 is the most stringent classification. The combination of fire performance, smoke production, and toxic gas release requirements at HL3 significantly constrains the rubber compound options available. Standard flame retardant systems that work for HL2 may not achieve HL3 compliance. Formulation development is typically required.
What EN 45545-2 Tests for Rubber Components
The standard specifies which test methods apply to different product categories. For rubber and elastomer components:
Heat Release Rate (Cone Calorimeter — ISO 5660)
Measures the rate at which a material releases heat when exposed to a standardized radiant heat source. Key parameters:
– PHRR (Peak Heat Release Rate): Maximum heat release per unit area (kW/m²)
– FIGRA (Fire Growth Rate): Rate of fire spread parameter derived from PHRR and time to peak
Requirements become more stringent from HL1 to HL3. A rubber compound that passes HL1 heat release requirements may fail HL2 by a significant margin.
Smoke Production (ISO 5659-2 — Smoke Density)
Measures the optical density of smoke produced during combustion. Dense smoke is the primary killer in vehicle fires — not the flames themselves — because it prevents evacuation and overwhelms rescue crews.
The smoke production requirements at HL2 and HL3 are often more difficult to meet than the heat release requirements, particularly for halogen-free formulations. Halogenated flame retardants typically produce more smoke than halogen-free alternatives, creating a trade-off in formulation design.
Flame Spread (ISO 4589-2, ISO 11925-2)
Measures whether the material will sustain a flame after ignition is removed. Most rubber compounds need modification to meet the HL2 flame spread requirements.
Toxic Gas Release (NF X70-100)
Measures the concentration of specific toxic gases (CO, HCN, SO₂, HF, HCl, NO₂, and others) released during combustion. This is the test that typically differentiates halogenated from halogen-free approaches to fire retardancy: halogenated compounds may produce lower CO but higher HCl concentrations.
Many metro and urban rail specifications now mandate halogen-free formulations even where EN 45545-2 doesn’t explicitly require it — HCl gas is corrosive to the vehicle structure and electrical systems, independent of its toxicological effects.
EN 45545-2 for Bogie Rubber Components
Bogie components — chevron springs, primary suspension elements, engine mounts, and rubber profiles in the bogie structure — present specific EN 45545-2 compliance challenges.
Why Bogie Rubber Is Different
Bogie components operate in a high-temperature, oil-contaminated environment compared to interior rubber products. The fire retardant system must:
– Maintain effectiveness after exposure to hydraulic oil (common in bogie areas)
– Maintain mechanical performance (stiffness, fatigue life) after fire retardant addition — some FR additives reduce rubber compound mechanical properties
– Maintain low-temperature flexibility for cold-climate operation
Chevron Springs and Primary Suspension
EN 45545-2 applies to chevron springs and primary suspension rubber-metal components when they are part of a vehicle configuration where fire spread from the bogie to the vehicle body is a realistic scenario. For most urban rail applications (metro, tram), this means HL2 or HL3 compliance is required.
Babacan Group’s EN 45545-2 certified chevron springs and primary suspension components are tested at an independent accredited laboratory. Our certificates cover HL1, HL2, and HL3 classifications for specific compound formulations. See our EN 45545-2 certification page for current certificate details.
Rubber Profiles and Seals
Door seals, window gaskets, and bogie area rubber profiles represent a large surface area of rubber in a railway vehicle. EN 45545-2 requirements for profiles and seals focus particularly on smoke production — large surface area means significant smoke generation if the rubber does not meet the low-smoke requirement.
Babacan Group manufactures railway rubber profiles in both halogenated and halogen-free formulations for HL1 through HL3 applications. Our railway systems product range includes profiles tested to EN 45545-2 requirements.
Verifying EN 45545-2 Compliance: What to Demand
Compliance claims without documentation are not compliance. When sourcing rubber components for EN 45545-2 applications:
1. Independent Laboratory Test Certificate
Acceptable: Certificate from an accredited test laboratory (notified body or ILAC-accredited) showing test results against specific EN 45545-2 test methods.
Not acceptable: Supplier declaration of conformity without underlying test data. Self-certification is common in the market but provides no verified assurance.
2. Compound Traceability
The test certificate covers a specific rubber compound, identified by a compound reference number. The certificate is worthless if the compound delivered is different from the compound tested. Demand:
– Compound reference on the delivery documentation
– Confirmation that the delivered compound matches the tested compound
3. Hazard Level Confirmation
Confirm the certificate covers the hazard level of your application. An HL1 certificate does not cover an HL2 application. Some certificates cover multiple hazard levels with different requirement sets — verify specifically.
4. Certificate Validity
EN 45545-2 certificates have validity periods (typically 3–5 years). Request the certificate expiry date and verify it covers the project delivery schedule.
5. Application Category
EN 45545-2 has multiple application categories within each hazard level (based on component location and function). Confirm the certificate covers the application category for your specific component.
Global Adoption Beyond Europe
EN 45545-2 was developed as a European standard but has been adopted or referenced in rail projects globally:
- Middle East: Gulf Cooperation Council rail projects (Riyadh Metro, Doha Metro, Dubai Metro extensions) specify EN 45545-2 compliance in procurement documents
- Asia: Singapore, Taiwan, and South Korea rail authorities reference EN 45545-2 in new rolling stock specifications
- Australia: AS 7510 (Australian railway fire standard) incorporates EN 45545-2 references
- Export markets: European-funded rail infrastructure projects in Africa and Central Asia typically reference EN 45545-2 in technical specifications
Even for projects outside Europe, EN 45545-2 compliance is increasingly the baseline expectation for rubber component supply to rail projects.
Babacan Group EN 45545-2 Capabilities
Babacan Group holds EN 45545-2 certificates covering HL1, HL2, and HL3 hazard levels for our railway rubber component range. Our certified products include:
- Chevron springs (V-springs) for bogie primary suspension
- Primary suspension rubber-metal elements
- Rubber profiles and sealing elements for bogie and body applications
- Elastomeric rail pads for track isolation applications
Our certification documentation is available to project-specified procurement teams. For project-specific compliance verification, contact our railway technical team with your application hazard level and component requirements.
For rail operators tendering replacement parts to existing certified rolling stock, we can match compound specifications to original equipment certificates and provide replacement documentation for inclusion in the maintenance record.
Explore our complete railway systems product range or request a quote with your EN 45545-2 requirements.
Key Takeaways
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EN 45545-2 is now mandatory for new EU railway vehicles and is the reference standard for major rail projects globally. HL1/HL2/HL3 classification determines the performance requirements.
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Standard rubber compounds do not meet HL2 or HL3 requirements — fire-retardant formulation is required. Verify this before accepting delivery.
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Demand independent laboratory test certificates, not declarations of conformity. Self-certification is not verification.
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Compound traceability must link the delivered product to the tested compound. Compound reference number must appear on delivery documentation.
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EN 45545-2 compliance extends beyond Europe — Gulf, Asian, and Australian rail projects reference the standard in specifications.
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