Christopher Westcott gets a first look at the future of London Underground’s Rail Adhesion Trains.
THE first of London Underground’s ‘D’ Stock trains were withdrawn from the District Line in mid-January 2015 as replacement ‘S7’ Stock trains arrived from Bombardier in Derby.
While the majority of ‘D’ Stock cars were snapped up by Vivarail for its Class 230 DEMU conversion project, LU drew up plans to retain four units and convert them into two five-car Rail Adhesion Trains (RATs). These would replace the ageing ‘A’ Stock RAT, operating out of Neasden Depot.
Three stage work
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The first of three stages of the conversion work related to the length of the trains. When in passenger service, ‘D’ Stock operates as six-car trains formed of two three-car units. The formation would normally be Driving Motor (DM), Trailer car (T) and uncoupling non-driving motors (UNDM), which would then be coupled to another similar three-car unit.
In the RAT, only one trailer would be required to deliver Sandite to the rails, and so the trailer from the second unit would be redundant. Therefore components located in this spare car that were needed in the finished RAT had to be fitted into the DM and UNDM cars, which required extensive redesign work.
The second stage involved the rewiring of the cars. The 75 ‘D’ Stock trains had been extensively refurbished in 2004-2008, so both wiring and trunking was found to be in good condition. Construction and design standards have changed in recent years, however, and therefore significant changes would be needed to comply with the Electricity at Work Regulations.
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