Extending maintenance intervals of track switches utilising multi-channel redundancy of actuation and sensing

A concept for a novel track switch arrangement has been developed at Loughborough University, which, through a novel locking arrangement, allows parallel, multi-channel actuation and locking functions for the first time. This switch has been developed as part of the REPOINT project, and is referred to as the REPOINT switch. Existing track switches generally use a single-channel actuator and lock, and undergo an intensive maintenance and inspection regime to ensure an acceptable level of reliability/availability. This paper demonstrates, through mathematical modelling with very conservative assumptions, that an increase in switch availability is possible alongside a corresponding decrease in ongoing maintenance intensity using the REPOINT multi-channel approach. The paper firstly introduces the theory behind the design of the REPOINT switch, using a switch with 2-out-of-3 redundant actuation and sensing channels as an example. An existing switch is analysed using real-world data as a benchmark. Availability is determined by the target time in which Maintenance Teams must have replaced any failed components, expressed herein as τ. Availability measures are obtained as functions of τ which show the range of possible switch availability against maintenance response times, for the given set of assumptions. The results show that for a REPOINT installation, gains in system availability are possible even when response times are set many times longer than current standards, indicating a significant reduction in ongoing maintenance cost.