Looking back


publicity machine decided to have a run for the press. On the day of the run, free drinks were available in the buffet car. Which car had tilt problems? You guessed it. The publicity was not good. A few months later the three trains went into service, with the new tilt packs and no publicity. They were in service for four years with few problems. When other traffic allowed, they cut the London-Glasgow journey to three and a half hours.


There were a few passengers who complained of motion sickness. The original assumptions of the need to eliminate side forces were examined again. It was found that the papers suggesting it were all based on one crude subjective survey done at low speed on a Welsh mountain railway. Motion sickness usually occurs when the body senses a motion which doesn’t match the motion deduced from the visual scene. The problem came from the lack of bodily motion sensations, eliminated by the tilt system, coupled with the sight of the horizon moving up and down. After some testing, it was decided to tune the tilt system to eliminate only half of the side forces. This produced sufficient compensation without significantly reducing passenger comfort. If we had known we only needed to tilt 4½°, the train could have had a larger cross-section and many other challenges would have been easier. Interestingly, now the Class 390 ‘Pendolino’ trains have begun to reach their full speed on the faster sections north of Crewe, there have been some complaints of motion sickness.


The APT started as a research project, but there had been growing resistance to it within the BR establishment once it began to produce real trains with superior performance. Work on the full production ‘service’ trains, APT-S, showed that they could be produced for less cost and would use no more power than current trains. Despite the success of the prototypes in service, the railway regions were discouraged from ordering production trains, so eventually the work ground to a halt and the project was cancelled after some 20 years of development.


The APT programme had developed from an investigation of the interaction between wheel and rail. It had produced a new concept of a train able to travel


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safely much faster than previous trains on existing track. The observations on wheel tread deformation were published in 1970, but, over 40 years later, the UK railways still re-turn their ‘worn’ wheels unnecessarily, costing many millions of pounds every year. There was significant interest from other countries. If the APT had gone into production, we could have had a major export success and still have a strong train building industry.


Today, the experimental train, and a few prototype cars, are in the care of the National Railway Museum at their Shildon site in county Durham. Some other prototype vehicles form a short train at the Crewe Heritage Centre, just north of Crewe station. (These vehicles were bought by Pete Waterman to save them from being scrapped.) Only one small test piece of the production power car structure was ever made to validate a detail design change. I was given a piece of it when I left BR in 1980. The programme was finally cancelled in 1985.


Lessons to be learned The main lesson from the APT experience is that major well established industries can come to believe that they know all there is to know about their underlying technology. Any changes will be small and incremental. They stop questioning the assumptions which underlie their work and refuse to believe that major change is possible. The project failed because it could not convince the BR establishment that there was another way. Since then, the superiority of similar work accepted in other countries came to dominate the UK rail industry and eventually wiped out most of our main line rolling stock industry. The APT programme grew out of the ability to design better suspension systems derived from developments in other industries. It used aluminium extrusions for the trailer cars, later adopted elsewhere but not by BR. It showed what was possible, but its findings were simply ignored.


For more technical details see ‘APT’, Colin Ledsome, Engineering, February 1981.


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