A research team led by the University of Birmingham in Britain is developing a new design for railway points or switches that promises to improve the reliability of actuation mechanisms and reduce delays.
Trials of the new Repoint actuation design at a test track have successfully demonstrated its compatibility and functionality with conventional switch rail arrangements.
Repoint is currently at Technology Readiness Level (TRL) 4-5, the development and demonstration phase. The research team is now seeking partners and funding to design and fully test the full system including the actuators, permanent way, and interfaces with signalling equipment.
While conventional switches have a pair of tapering switch rails or point blades that are moved horizontally by the actuators, Repoint features a lift and move mechanism, which includes a passive lock for when the switch rails are in place. This is combined with a stub switch layout.
Repoint has been developed by a team led by Professor Roger Dixon, professor of control systems engineering at the Birmingham Centre for Railway Research and Education (BRCCE). The team also includes researchers from the universities of Leeds and Loughborough, and from British infrastructure manager Network Rail.
The team has worked with operators, maintainers and designers to understand the limits of existing switch technology and the failures that can occur.
Dixon began work on the project as head of Loughborough’s Control Systems Research Group, in response to a joint call from Britain’s Engineering and Physics Research Council (EPSRC) and the Rail Safety and Standards Board (RSSB) for research into improving capacity on existing lines.
With support from the European Union’s Shift2Rail programme under the In2Track2 project, the team developed a full digital twin or dynamic simulation model which showed that the Repoint design meets and exceeds requirements for speed and performance.
Performance of the switch was investigated using a novel method for simulating track system behaviour, combining rail bending with physics-based models of actuators and control systems.
One simulation scenario was based on power failure disabling four of the six motors that drive the actuators. This showed that with the Repoint design, a single actuator is capable of lifting and moving the switch rails to the desired position.
This redundancy or fault-tolerant design avoids the single point of failure that is a feature of traditional switches and their detection systems, and has been inspired by aircraft control systems.
“Although switches account for less than 5% of railway track-km, they contribute to 18% of delay-minutes and 17.5% of delay costs in Britain,” says Dixon.
“While railway networks continue to carry more passengers and freight, building new track is always difficult and expensive, and increasing the reliability and exploiting the capacity of existing routes is generally the preferred option.”
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