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Inspired by redundancy in aircraft control systems, the new design was developed by researchers at the University of Birmingham. They hope it could improve on a design that has been in use for more than 200 years.
While conventional railway switches guide trains from one track to another by sliding a pair of tapering rails horizontally, the new design, known as Repoint, uses a lift-and-move mechanism, which includes a passive lock for when the points are in place. This is combined with a ‘stub switch’ type layout, which researchers said offers advantages in many situations. The design continues to work even when two of the three actuators – which control the movement of the points – have failed, they said.
The team developed a digital twin to show that the design meets and exceeds requirements for speed and performance. They tested performance of the switch using a novel method for simulating track system behaviour, combining rail bending with physics-based models of actuators and control systems. The simulation scenarios included power failure to four of the six motors that drive the actuators, showing that a single actuator can lift and move the points to the desired position.
Repoint was developed by Professor Roger Dixon, who led a team at Loughborough University until 2018, and is now professor of control systems engineering at the Birmingham Centre for Railway Research and Education.
The journey to a new railway switch started when Professor Dixon, then head of Loughborough’s Control Systems Research Group, responded to a joint call from the Engineering and Physical Sciences Research Council and the UK Rail Safety and Standards Board to look at ways of improving capacity on existing lines. A significant limiting factor to growing capacity was the railway track switch, so a project to re-imagine the switch was proposed and subsequently funded.
“Although switches account for less than 5% of railway track miles, they contribute to 18% of delay minutes, and 17.5% of delay costs in the UK,” said Professor Dixon.
The team engaged with operators, maintainers and designers to understand the limits and issues with existing switch technology. One of the most significant findings was the single point of failure embedded in traditional switches and their detection systems, so the new switch incorporates fault tolerant design.
Professor Dixon said: “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.”
Repoint is at Technology Readiness Level 4-5, the researchers said. It has been successfully tested at a test track, which demonstrated its compatibility and functionality with conventional switch rail arrangements. The researchers are now seeking partners and funding to design and fully test the full Repoint system.
The work was published in Railway Engineering Science.
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