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Less time in the station: Lightweight Tube doors should be able to close faster
London Underground could enjoy the benefits of train doors made from composites that are 30% lighter than existing aluminium versions if a project led by engineering consultancy Atkins comes to fruition.
A consortium including Atkins, rail technology firm Wabtec Corporation, the National Composites Centre and University College London is developing the new doors. Atkins started work on the project in July 2013.
The composite door is just under a third lighter than the existing aluminium door. The doors would be able to close faster owing to their low weight, saving station idling time and allowing London Underground to run an estimated 0.2 extra trains per hour. The door meets all of London Underground’s fire, smoke and toxicity requirements and is also 100% recyclable.
Chris Harrison, a senior engineer in Atkins’ aerospace division, has 16 years’ experience of composite materials. He told PE that a prototype door is currently undergoing fatigue tests and, if it passes these, it will undergo environmental testing. A second composite door would then be made and fitted to a Central line train for testing early next year, said Harrison.
London Underground estimates that the benefits of reduced track wear and energy consumption thanks to the lighter door will amount to a saving of £0.5 million per year. There would be an increase in capacity thanks to the ability to run more trains.
London Underground was unlikely to retrofit the entire fleet with composite doors, but they could be used to replace damaged ones, said Harrison. There would be new rolling stock designs in the next two years that could also make use of the composite door.
Meanwhile, in the aerospace sector, Tim Edwards, head of engineering in Atkins’ aerospace division, said that the use of composites on civil aircraft programmes has been a “steep learning curve for the industry” and that lessons were still being learned in terms of long-term performance and maintenance.
“The main aircraft going into service now have not been flying long enough for the implications of their use of composites to be fully understood,” he said.
“The Boeing 787 has been in service for three years and the A400M is just entering service, and the A350 is due to enter service later this year. There isn’t sufficient in-service experience to know how composites will really perform.”
The 787 Dreamliner is the world’s first airliner to use composites as the primary construction material. Composites have been used in earlier designs, including in horizontal and vertical tailplanes.
The centre wingbox of the A380, the world’s largest passenger aircraft, uses composites. “Those structures have performed well but they are not a primary structure such as a wing or fuselage,” said Edwards.
He said composites had been successful in cutting weight, improving performance, and reducing fuel consumption in aircraft.