Designing cable management systems for the railway sector requires addressing multiple needs simultaneously: resistance to vibrations, limited space, ease of maintenance, and durability. Above all, however, it involves complying with a key safety standard: EN 45545.
This European standard aims to establish the measures and requirements needed to protect passengers and staff on railway vehicles in the event of a fire on board.
In line with these guidelines, Unex developed the Slotted trunking 88 over three decades ago—a tailor-made solution for electrical and communications enclosures in the railway sector.
Manufactured from Unex’s proprietary U43X compound, the Slotted trunking 88 is halogen-free, which means it does not release corrosive gases in the event of a fire. This feature is crucial in enclosed environments, such as train carriages, where evacuation can be difficult and inhalation of smoke poses a serious risk.
EN 45545: The European standard for fire protection in railway vehicles
The EN 45545 standard provides a very precise regulatory framework outlining the measures and requirements to protect passengers and staff on railway vehicles in the event of a fire on board.
The standard is divided into seven parts, each focused on a specific aspect of fire safety. Among them, part 2 (EN 45545-2) is particularly relevant for component and system manufacturers, as it defines the fire performance requirements for materials and products used in the design and construction of rolling stock.
Depending on its final application in the train, whether inside or outside the vehicle, each component is classified according to a specific set of requirements. These sets are grouped under the designations R1 to R26, each corresponding to a particular type of use or installation. In the case of Slotted trunking 88, the applicable requirements defined by the standard are R22 and R23. The former refers to installation inside the vehicle, while the latter covers external use.
Hazard levels: HL1, HL2 and HL3
The standard defines three hazard levels (HL): HL1, HL2, and HL3, with HL3 being the most stringent.
The hazard levels are determined based on the relationship between the operational categories and the design categories.
Taking into account the variety of types of railway vehicles, their operation, and the characteristics of the infrastructure, railway vehicles are classified as follows:
- according to the type of service operated and the characteristics of the infrastructure, in order to determine an operational category,
- according to the design features and layout of the vehicle, in order to determine a design category.
Technical requirements: R22 and R23
To verify that a product meets the R22 requirements (for interior applications) and R23 requirements (for exterior applications) at hazard levels HL1, HL2, and HL3, the standard sets out a series of standardised tests. These tests measure parameters related to fire behaviour as a requirement:
1. Oxygen Index (OI) according to EN ISO 4589-2:
This test measures the minimum concentration of oxygen required to sustain combustion:
- minimum 28% for HL1 and HL2
- minimum 32% for HL3
2. Smoke Density (Ds max) according to EN ISO 5659-2:
- maximum 600 for HL1
- maximum 300 for HL2
- maximum 150 for HL3
3. Conventional Toxicity Index (CIT) according to NF X70-100-1 and -2:
- maximum 1.2 for HL1
- maximum 0.9 for HL2
- maximum 0.75 for HL3
Unex’s Slotted trunking 88 has been tested in accordance with EN 45545-2:2021, meeting the R22 and R23 requirements for hazard levels HL1 to HL3. This means it is suitable for use both inside and outside the vehicle, even under the most demanding conditions. The tests carried out include assessments of flammability, smoke emission, and toxicity. Thanks to the proprietary formulation of the U43X material, the Slotted trunking 88 successfully exceeds all these requirements, positioning itself as one of the few solutions on the market to offer this level of safety.
Versatility, design, and sustainability
Another widely recognised feature of Unex’s Slotted trunking 88 is its broad range of dimensions, which allows it to adapt to all types of configurations and installation requirements in electrical and communications enclosures and railway systems.
This range covers compact formats such as 40x20 mm or 60x20 mm—ideal for confined spaces—up to high-capacity options like 100x100 mm, which provide over 9,000 mm² of usable cross-sectional area for cable routing.
This versatility results in greater efficiency in installation design, enabling optimal use of available space and reducing the number of trunking runs required. Moreover, the recent expansion of the range has introduced new sizes such as 40x80 mm, 60x100 mm, and 100x30 mm, further enhancing the system’s ability to adapt to complex projects or those with specific requirements for space and cable capacity.
Likewise, the Slotted trunking 88 offers a series of technical advantages derived from its design, making it particularly well-suited for railway applications:
- Burr-free and smooth-edged design: This prevents damage to cabling and enhances installer safety.
- Secure and stable cover: It does not deform or detach, even in vertical installations.
- High robustness: This feature allows for suspended mounting between support profiles without compromising stability.
- Ease of installation: Clean cuts and the 4 mm spacing between retaining fingers facilitate cable exit and optimise the use of available space. See the mounting instructions here.
- Vibration resistance: Successfully tested in accordance with IEC 61373:2010, ensuring resilience in environments subject to continuous movement.
Unex’s commitment to sustainability is also reflected in the Slotted trunking 88. The U43X material contains a thermoplastic component that is both 100% recycled and halogen-free, reducing the product’s environmental impact. It also holds an Environmental Product Declaration (EPD) under the PEP Ecopassport® programme, enabling railway manufacturers to meet the increasingly common sustainability requirements in both public and private tenders.
Safety for the railway sector
The Slotted trunking 88 has been adopted by leading train manufacturers. Its use extends to control, distribution, and signalling enclosures, both in indoor environments and exposed installations.
This proven track record is the result of stable fire performance, a functional structure tailored to the sector’s needs, and strict compliance with EN 45545-2—achieving its highest level (HL3-R22). Decades of experience and its versatile design make it a go-to solution in projects where reliable performance is paramount.
Take a look here at some of the key features of the Slotted trunking 88:
If your railway project requires reliable, versatile, and robust components, you can count on the Slotted trunking 88 and our full range of solutions for rolling stock.
At Unex, we support the selection process with clear information and direct technical assistance.
On the Unex blog, we cover a wide range of topics of interest and share experiences from our clients. We remind you that all legal information and information regarding compliance with applicable regulations can be found on our official website. We invite you to consult it for a more comprehensive and accurate understanding.
