Realisation of a novel functionally redundant actuation system for a railway track-switch

Osama Olaby, Saikat Dutta, Tim Harrison, Christopher P. Ward, Roger Dixon

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This paper focuses on modelling, control, realisation and performance analysis of a full-scale demonstrator for a novel railway track switch. For over a century, railway track switches (or points) have been allowing trains to safely change between routes. As they are safety-critical elements of the rail network, when they fail, the signalling system will prevent trains from using that route. This means poor reliability (or lack of availability) leads to significant delays and costs; hence there is huge interest from researchers and engineers in improving the overall reliability of track switches. This paper presents new results, which represent a meaningful first step toward a revolution in the way track switches are actuated. A “REPOINT-Light” railway track switch demonstrator is introduced which uses a new concept of locking to allow redundant actuation with three actuator bearers operating under closed-loop feedback control. The new concept, its control system and its mechanical viability are tested in experiments at the Great Central Railway in the UK. To support the design of the actuators and the control system, a dynamic simulation model is developed by co-simulation involving Simulink and Simpack. The experimental results presented are used to validate the models and the paper discusses how the models themselves are used as the vehicle for the design of feedback controllers. Virtual testing of the controllers in simulation is a vital step prior to the implementation and deployment of the controllers in the demonstrator switch. The major contribution of this work is demonstrating, for the first time at full scale on a real-world track switch, that it is possible to use one-out-of-three actuator redundancy to provide fault-tolerant operation of railway track switch.
Original languageEnglish
Article number702
Pages (from-to)1-20
Number of pages20
JournalApplied Sciences (Switzerland)
Issue number2
Publication statusPublished - 13 Jan 2021

Bibliographical note

Funding Information:
Funding: The research described has been supported by Railway Safety and Standards Board (RSSB), UK {the in grant number RSSB/2029S(2015)}, for the project titled “REPOINT Phase 3: Repoint Light Prototype Design and Build”.


  • Actuator redundancy
  • Control design
  • Fault tolerance
  • Railway
  • Simulation
  • Track switch

ASJC Scopus subject areas

  • Materials Science(all)
  • Instrumentation
  • Engineering(all)
  • Process Chemistry and Technology
  • Computer Science Applications
  • Fluid Flow and Transfer Processes


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