![[APT service run]](graphics/apt.jpeg)
The APT was a revolutionary new design of train. Developed by British Rail it could travel much faster than other trains and counteracted the centrifugal force generated on cornering by tilting the carrages.
The APT is one of the most misrepresented engineering masterpieces of our
time. Ask the average bod in the street about the APT and they will tell
you with much confidence and knowledgability Oh yeah, they scrapped that
because it made everyone sick.
This is a fine example of just how
wrong confident people can be. So here it is for the record.
Initially there was a minor problem with nausia induced by the tiliting motion. This was traced to the fact that the tilting mechanism was a little too perfect at removing the sensation of turning. In the beginning the system was controlled by a detector in each carrage which monitered the forces created by cornering. When these where detected the carrage was tilted to counteract them. To allow the passengers to feel some sensation of cornering the system was rejigged so that the sensors controlled the carrage after them, that is, the carrage started to tilt before the corner was reached, the problem of sickness was solved. Let me repeat that, the APT caused no more travel sickness than any other train.
The reason why people think it did is simply to do with the power of a drink soaked journalist to sway the hearts and minds of the masses. On the inaugural trip of the first production APT from Glasgow to London one of the journalists who had been invited to see this wonder of modern technology was violently sick. He wrote about this in his column telling everyone how dreadfull the ride had been and how completely sick it had made him. What he didn't tell anyone was that he had been tanking up on British Rails complementory plonk all last night and was quite capable of being violently ill sitting on a stationary park bench let alone a train travelling at a good lick.
British Rail had a need for a faster service so they gave a simple brief
to their R&D department: Make it fast
. The obvious way to make a
train faster is to straighten out all the track it runs on so it never has
to turn corners. This is mindnumbingly expensive of course but it works.
However a piece of lateral thinking lead the R&D people to think of the
problem from the different view point. If you can't relay the track, can
you re-invent the train? It turned out that they could.
The APT project was the first to employ the emerging field of computer modeling to discover more of the physics behind railed vehicles. This allowed BR's engineers to design trains which would go much faster than the then accepted 100mph absolute maximum speed. The speed increase was achieved through lighter construction and a lower centre of gravity in the various components. The tilting mechanism was simply for passanger comfort.
The late 60s saw the emergance of the first fruits of this research program. The APT-E or Advanced Passanger Train - Experimental was two carrages long with two roaring gas turbine powered locomotives. The two unpowered carrages where full of instrumentation measuring every neuance of the train and its performance. This train managed speeds of up to 152mph and an average speed of 100mph on the London to Leicester run.
This train provided much valuable data which was collated, examined and used to design and build the APT-P or prototype. Three of these trains where built and used in service. Each train consisted of two cabs, six carrages and two power cars. The cabs went on the ends as you would expect but the locomotive cars where both at one end of the train.
Originally it had been intended to have twelve carrages with the two power cars in the middle. It would have to be done this way since contemporary pantagraph (that's the arm which touches the overhead cables) technology could not cope with having one at each end of the train both operating at an envisaged 150mph. However it did not prove economical to have two service crews and one could not service the whole train since the only access between the two halves was through a cramped, noisy tunnel through the middle of the central power cars.
The APT-P made its maiden trip on the 7th of December 1981. During its trial runs there where some problems with the tilting mechanism (notice in the picture at the top of this page that a couple of the carrages have not tilted) which obviously didn't help but mostly it ran without incident. The thing which really killed the APT was not its tilt but its brakes. It had very powerful hydrokinetic brakes for use at high speeds and these always worked faultlessly. Unfortunately the traditional air brakes it used at slow speeds fell foul of the problems being suffered by all the other trains on the BR network. Namely a very cold winter. This was causing moisture to freeze in the air lines and thus prevent the brakes from working. It was at this time that the APT was withdrawn from service and the media declared it dead.
However the BR engineers where not so quick to dismiss the project. They continued to tune the tilting mechanism and in the summer of 1982 the APT was reintroduced without ceremony. Initially it was used as a releaf train but as it proved itself once more it gained its own departure slot. It then proceded to run with exemplary reliability for two years.
Unfortunately plans to produce the APT-S (Squadron) never came to fruition. BR had lost the will to build a full service fleet of the APT probably under the pressure of Margerate Thatcher, well known dispiser of public transport. Eventually A sledge hammer was put through two of the trains and the other shunted into a siding at Crewe, Grandiously called the Crewe Heritage Centre.
Despite being scrapped some technology from the APT survived. For instance the APT was the first train to make extensive use of extruded aluminium in its construction. Something that the Inter-City 125 and 225 trains would later mimic.
The computer models produced for the APT certainly went on to allow the design of the 125 and 225 trains which we see running today. And BR did not completely give up on the idea. If you've ever wondered why the carrages of the 225 are strangely tapered towards the top this was so they could be retro-fitted with APT tilt-packs.
The APT concept did not die with the project though. Many of the engineers who developed it moved to Scandanavia where their expertease was welcomed. They continued developing the concept there.
Aesthetically the APT was a great train, very sleak, it looked fast. Technically it is by far the most innovative and interesting train for a long time. Appart from that, it set a British record of 160mph which I believe still stands today. Finally the APT did not pussy foot around. When the engineers decided to make it tilt they did it properly. The APT could tilt by 9° using powered tilt-packs. Modern tilting trains manage only 3° induced by simple pendulum forces.
I recently received an e-mail from a gentleman who used to work for the London Underground. He tells me that an Intercity 125 driver once told him that there where safety concerns which added to the APT's demise.
It is undeniable that, given its ground breaking nature, the tilting
mechanism would sometimes fail leaving a carriage stuck in the tilted
position. It is claimed that the worry was that if two APT's passed with
carriages stuck tilting inwards
(towards the other train) they would
collide.
It is not inconceivable that this is true plus the suggestion comes from a
good source. However I have included it under the heading apocrypha
since I am not convinced that it is not another urban myth. It seems like
the sort of statement which would be held as true by drivers of the APT's
more successful offspring without anyone actually checking its veracity.
Unfortunately without technical details of the APT, specifications for British mainline track and BR health & safety regulations from the early 80's I can not verify it either. Make of it what you will.
Although the train itself is undeniably 100% cool on a stick the politics surrounding it are very far from being so. This landmark train was scrapped because of Thatcherite dogma, plain and simple. We lost our chance to lead the world in a technology because it didn't fit into Maggies world view. Now we are having to buy back similar, but possibly inferior, technology from people who knew a good idea when they saw one.
The governments willingness to throw away the APT is a sad reflection on its lack of vision on all engineering matters. It makes me angry to think of it.
An APT-E or at least bits of one live at the York Railway Meusium. To find it simply catch a train to York, get off and you should find directions to the museum from the platform.
The APT-P is still visible at Crewe. If you catch a train going through Crew station and keep your eyes open you should be able to spot it. You could always get off your train at Crewe and visit the railway museum there if you want to see the train first hand.
It is a source of irritation to me that I have never ridden one of these trains even though they existed in my life time. At some point I intend to at least get some pictures of one which I will add to this page.
I highly recomend taking a trip to the APT-P which is being preserved at Crewe. If you can't or if you wish to find out more why not visit the APT-P pages run by Robert Lathams.
The APT-E is also available for public inspection at the York Railway Museum. You may find information on this particular train at Paul Leadley's web pages.
I have to thank Nick Leverton from whose pages I nicked most of the information in the history section.
Alex Lu's pages also provided usefulinformation and the title picture.