Safe, secure brakes for rail systems - worldwide
Safe, secure brakes for rail systems - worldwide
Public rail transport is an important pillar of mobility in the world's major cities. Underground, tram and rapid transit train systems must be safe and reliable when transporting masses of people. A new braking system from Knorr-Bremse Rail Systems (UK) now aims at providing an even more effective guarantee of reliability in the future. TÜV SÜD Rail GmbH's experts supervised the development of the new system, assessed risk analyses, tested components and certified the safety of the new EP2002 brake design. By commissioning TÜV SÜD Rail to accompany the process, Knorr-Bremse Rail Systems (UK) saved both development costs and time.
Whenever a subway or underground stops running, the conurbations of the world generally experience widespread chaos. From New York to London, Berlin or Peking – public transport is a key element in our increasing demand for mobility. Every day millions of people count on the reliability of trams, underground and rapid transit trains. For this reason, rail systems are required to meet exceptionally high safety standards. If a train brake system is late in operating or even fails to operate at all, passengers' lives may be endangered. However, in normal rail services brake control also plays a critical role, and contributes materially to the passengers' well-being; after all, no-one wants to be catapulted from their seat when the train stops at a station. In Munich, for example, underground trains speed through tunnels at up to 80 km/h, with a 200-metre braking distance and an average distance between stations of around 800 metres. This clearly shows that a sophisticated system is required to ensure that the train brakes in time and comes to a stop at exactly the right point in the station.
Completely reliable under all operating conditions
Brake control is therefore a critical system that plays a key role in safety. The system must be able to stop a train reliably and safely under all operating conditions. In trains, optimum braking is when individual braking forces are triggered at each of the "bogies" – the movable frames in which the axes rest. Knorr-Bremse Rail Systeme (UK) has therefore designed an innovative "decentralized brake control system" for trams, rapid transit and underground trains which enables all brake functions to be controlled locally for individual bogies. TÜV SÜD Rail accompanied the development process from start to finish. "We were involved in the development process from the outset as appraisers ", explains Alfred Beer, Head of Rail Automation at TÜV SÜD Rail. The Munich rail experts were commissioned to perform a number of tasks including preparation of an independent safety report as per standards EN 50126, EN 50128 and EN 50129, and also produced a product safety certificate for the new EP2002 brake control system.
Intelligent mechatronics replace bulky systems
The new development from Knorr-Bremse Rail Systems (UK) has a host of innovative features. The integrated mechatronic system comprising pneumatic, electronic and software elements enables all necessary functions such as load-specific braking forces, service brake and emergency brake to be individually controlled in a decentralized fashion for each bogie. The compact design of the EP2002 saves both space and costs, requiring significantly less compressed air in the braking process than previous centralized systems, and in turn reducing the amount of power required to produce the compressed air. While the highly compact design occupies less space and reduces installation costs, it faced the engineers with considerable challenges during the development phase: "The intelligent electronics in particular demanded comprehensive expertise", recalls Beer, who headed a team of experts to inspect these components and work with the relevant staff at Knorr-Bremse (UK) on-site to repeatedly analyse the safety problems they identified. The specialists from TÜV SÜD Rail accompanied their client through the hardware and software development phases up to the final tests and component certification. "For example, Knorr-Bremse Rail Systems designed and developed the software test concept in close collaboration with us", explains Beer, who, with his colleagues, also undertook inspection of the associated hardware and complemented these tasks by devising additional experiments and tests.
Lifetime testing in all weathers
The development engineers at Knorr-Bremse planned to extend maintenance intervals for the new brake control system, a decision which meant subjecting all components to appropriately tough lifetime testing. The experts at TÜV SÜD Rail designed an application-specific test known as HALT (Highly Accelerated Lifetime Test) which identifies a product's potential weaknesses in the development phase, enabling them to be remedied at lower cost. As part of the HALT procedure, the Munich specialists pinpointed the weaknesses of the new braking system by exposing the individual electronic and mechanical components to conditions including extreme temperature fluctuations and changes in humidity. "The components also had to endure specific vibration and other mechanical stress tests", explains Beer. The ordeal to which the materials are subjected serves as a "time-lapse" laboratory simulation of the stress cycles to which the brake system is exposed in practice over a period of nine years – the targeted maintenance interval. Beer continues: "In parallel to client testing, our colleagues in the UK also ran the tests on their equipment, to give us a broad basis of results on which to draw."
Long-standing cooperation on rail technology
For over five years, the specialists at TÜV SÜD Rail have supported their client Knorr-Bremse Rail Systems (UK) in both design and certification and auditing of new components and systems for the rail industry. The EP2002 has rapidly developed into a standard for a wide range of public transport methods all over the world, and is used by the subway in Peking and by the London Underground in addition to being responsible for train braking in the Philippines and Shanghai, and soon in the Dubai Metro. Over 4,000 systems have been sold to date. "Our global projects and worldwide presence give our safety certificates the appropriate weight on the market, and thus also enhance our customers' opportunities to make sales", confirms Beer.
Alfred Beer, TÜV SÜD Rail GmbH, will be happy to answer any enquiries on "Rail Technology Certification” at Tel.+49 (0)89 / 5190 – 2278.
Editor: Bettina Mayer
