Railway cable testing and certification

The rail network can be grouped into vital areas of operation. Those where specific cable performance is critical to the operations include rolling stock, signalling and power transmission, as well as station and infrastructure. Demand for railway cables is set to increase in the coming years in line with the growth of the urban population globally, and greater electrification requirements for smart rail operations. This in turn requires high levels of safety and proven cable characteristics selected to protect the public, while providing efficient and reliable services.

Operational delays caused by signalling power cable failures can be particularly disruptive to railway traffic flow and often result in significant costs and stoppage time taken to make necessary repairs. Cable quality and compliance is crucial to support the performance of all operations requiring electrical power and works to minimise the risk of failure.

To demonstrate the railway sector’s commitment to safety and quality assurance, all of the separate components used to make up the infrastructure are often subject to comprehensive testing schedules. Individual components and their integrated systems are tested to evidence their performance and safety to exacting standards.

Railway cable applications

1. Rolling stock applications

Cable systems used within rolling stock are integral to supporting the smooth running of the railway network. These applications require cables for use in a broad range of areas, such as power to operate door mechanisms and signage, lighting, CCTV systems and communication systems across both passenger and freight carriage variations.

There are several standards that assess different aspects of rolling stock cabling. A variety of fire performance tests are undertaken across the railway sector, such as BS EN 50305 which ensures the cables tested feature non-toxic and flame-resistant properties if the product were to become exposed to flames.

Standard BS EN 50306 is particularly relevant to cables that require special fire performance characteristics and plays an integral role in delivering a safe passenger experience. Cables designed to meet this standard are required to be halogen free as they are fitted in fixed wiring circuits. Other important rolling stock cable standards include EN 45545, BS 50264 and EN 50382, for which full test details can be found in the BASEC testing guide.

Cables are particularly important in relation to high speed, electrified railway rolling stock vehicles and are key to ensuring an efficient performance and service. Upgrades are continually being implemented to improve speed and modernise the train carriage fleet. Where specific railway cable characteristics are required, rigorous third party testing and certification should be gained to ensure the levels of quality required by the rail operator and electrical applications specifiers can be assured.

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2. Signalling and power transmission applications

Railway infrastructures rely heavily on the efficient use of power cables to support signalling and power transmission. Railway cabling enables the fulfilment of operational functions and ensures passenger safety. This area includes everything from controls, switches and traffic management systems, to connectivity, signal boxes and equipment located on railway tracks themselves. Interaction is required between these applications and the rolling stock to ensure a smoothly operated system.

Signalling failures are the most common cause of disruption to operational reliability, with several thousand delays of more than 100 minutes caused every year. This has a significant impact on the scheduling of railway traffic which often results in journey delays, costing time and money to fix. Considering the increased reliance on electrified systems which is set to continue, correct cable selection is critical. Ensuring products have been independently verified to meet the performance requirements of the relevant standards helps to safeguard the rail networks for years to come.

Standards conformity and requirements for railway signalling and power transmission cabling differs by country and region, often in accordance with the relevant railway authorities and operators. For instance, in the UK, Network Rail manages the railway signalling infrastructures and is responsible for the maintenance and improvements to these applications, requiring electrical power. Albeit, a range of subcontractors are often employed to implement the systems required to meet the high signalling and transmission demands across the network. Infrastructure managers such as Network rail, London Underground and International Operators set their own standards which specify the relevant cable requirements matched to their intended operation. BASEC understands that the need for compliant cabling varies, and working in close partnership with railway organisations BASEC delivers tailored cable testing solutions.

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3.Station and infrastructure applications

An extensive number of sub-areas are grouped under the station and infrastructure umbrella, including ticketing, departure boards, barriers, train and track integration and station lighting. With safety being a major priority in the railway sector as a whole, as a large proportion of the cables used in these applications are located within the train stations themselves enhanced fire performance characteristics are vital to protecting both public safety and asset protection.

Electrical faults are one of the most common causes of railway station and infrastructural cabling failures, which can overheat, short circuit and ultimately lead to a fire. Third party testing and approvals provide an important safety assessment. Fire testing is conducted to assess both circuit integrity and reaction to fire where cables are placed within extreme circumstances, assessed to determine cable performance and characteristics when exposed to flames.

In addition to safety, passenger experience is another important aspect at rail stations. Display boards or ticketing machines that are not functioning correctly also impact on passenger journeys. Growing expectations mean passengers are always ‘switched on’ requiring power to charge personal devices, to access internet applications and expect operations to function smoothly as the bare minimum.

In order to safeguard electrical railway cables, there are many different tests in place to assess quality and performance characteristics based on the needs and requirements of the end application. The criteria for which depend on whether the cabling will be located inside a building, within track side equipment or otherwise.

An example standard, which is specifically relevant to railway cables found in the heavy infrastructure includes the LUL/Tfl S1-085 set by London Underground. This standard was developed to assesses the fire safety performance of cables intended for installation in fixed configurations such as stations and tunnels. The standard is particularly focused on monitoring flammability, smoke emission and toxic fumes produced, so that passenger health and safety impacts can be assessed in advance should a fire scenario.

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Full details for further standards including BS 4589-2/3 which concerns burning behaviour of plastic materials and BS 7846 measuring resistance to fire, amongst others, can be found in the specialist testing, inspection and certification guide for railway cables in the guide linked below.

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