By 16 September 2012 39 Comments Read More →

Rail projects : Class 91 – a potential never fulfilled

Mike Humble

The East Coast Main Line (ECML) has been for many years, England ’s rail gateway to the North starting from London Kings Cross to Edinburgh some 392.7 miles in length. Some of the worlds most famous trains and locomotives have plied their trade with evocative names such as the Deltic, flying Scotsman, Mallard and of course, the HST create wonderful images of times when rail travel was exiting, a symbol of national pride and dare I say it, romantic even.

Both the Diesel and Steam traction world speed records have been set on this legendary route and the billiard table flat and arrow straight four track section between York and Northallerton has always been nicknamed by train drivers and rail industry as ‘The racing stretch’ .

InterCity: building on success

It had always been the plan to electrify the ECML, a plan that had first been mooted back in LNER days, but following nationalisation, only the West Coast Main Line via Euston and Glasgow gained the ‘Sparks’ effect and even then opening in sections over a period of nearly 10 years. The ECML became fully wired in 1991 after much delays and Government dithering, and in hindsight following some serious problems with wiring and catenary either failing or at worst collapsing in poor weather conditions proved to be a costly cheap design. The stand alone InterCity division headed up by Dr John Prideux was proving to be a money spinner with the halo effect of the HST bringing valuable business custom to BR and unheard of leisure travel growth on the Eastern Region.

Under the leadership of Dr John Prideux, the InterCity brand was respected and profitable – The 91 had to compliment and improve on the already successful HST.

Across the Pennines, the Advanced Passenger Train (APT) was proving to be a problematic and costly experiment, especially as the tilting train idea had been in the pipeline since the late 1960’s. It was quickly becoming a reality that the APT was not so much too advanced for BR, but more the case that BR was simply not advanced enough for the APT.

With electrification well under way on the ECML, in 1984 the board of BR (BRB) decided that a fleet of high power locomotives and rolling stock would be required for the ECML once total route wiring had taken place to operate alongside the highly successful HST fleet. Invitations by tender were put out and GEC were the final winner to design and construct the locomotives which were to be numbered class 91.

The design was to be called Project Electra and the service would be called Inter City 225 as the operating speed was to be 140mph or 225km/h. GEC designed a new locomotive and had an operational example for proving constructed 1988. Because GEC has no capacity themselves to construct, the task of building this fleet was sub contracted out to British Rail Engineering (BREL) in Crewe. State of the art electronics and design saw the 91 fleet constructed ahead of time but problems with rolling stock production put the service introduction back by some time. Assembly of the new Mk4 designated rolling stock eventually became the responsibility of Metro Cammell (MCW) in Washwood Heath Birmingham.

Withdrawn funds

In true political style, the promised Government funding for upgraded track and signalling that would allow these new trains to achieve their operating speed of 140mph was never acheived. The introduction of a flashing green aspect on the signalling (in effect turning four aspect signalling into five) on certain sections through Cambridgeshire and Lincolnshire, meant 140mph running for only proving tests were possible.

By the time a full 91 service came on line in 1991, journey times to and from London were cut back by nothing more than a few minutes, achieved by better acceleration times than the HST but hampered by having the same top speed in service of 125mph. With over 6300bhp available, the class 91 was still a high performing locomotive in every sense.

Giving little impression of speed, a GNER 91 set hammers down Stoke Bank at 125 mph, almost where A4 Mallard broke the world steam speed record almost 60 years earlier!

Even though these new trains looked utterly superb, in practice they failed to offer the same level of comfort of the proven HST. Whereby the 125 had been designed both in house and with a sensible budget, the class 91 and the Mk4 rolling stock felt lightweight and inferior to older designs. BREL engineers had been working on an updated bogie called the T4 which promised to be just as effective as the T3 on the HST.

Because of budgetary and time constraints, BREL bought in bogies from a Swiss concern called SIG that failed to offer a cosseting ride on our less than perfect track. Engineers could only tweak the design over time in service, but at best the ride quality at speed can only be described as fair. The actual locomotive featured some novel ideas and features to reduce wear on the track and vastly reduced unsprung weight.

The traction motors were mounted in the frame of the loco rather than the bogie with tractive power being fed to the axle gearbox by means of a short yoke jointed prop known as a cardan shaft. Primary braking was operated by rheostatic methods which in layman’s terms, turned the traction motors into generators thus reversing the torque and creating a retarding effect on the transmission.

The heat generated through the braking was dissipated through the resistor packs and this operated from maximum speed down to around 28mph after which, traditional tread brakes would automatically kick in to bring the locomotive to a halt.

The class 91 actually had two drivers’ cabs, it was initially planned to operate the loco as a high speed passenger train during the day and haul freight during the night. Only the leading end was streamlined meaning that locos operating ‘blunt end’ first were restricted to 110mph owing to aerodynamic buffering that could affect the roof mounted pantograph that collects the 25Kv electrical current from the overhead wire. Ideas of using the 91 as a mixed traffic locomotive were soon scrapped and this class of locomotive has only ever operated in passenger service.

Problems in service

Unlike the HST, the 91 class feature conductor operated power doors on the passenger coaches, but passengers who place cases or baggage too close to the doors continue to cause delays on overcrowded trains. Soon after introduction, it became apparent that fine snow could penetrate the air intake system at high speed, once enough powdery snow had got inside the electronics, it would subsequently melt and on a few occasions, short circuit causing the train to fail. The colossal power of the traction motor in both acceleration and braking caused heavy wear on the cardan shafts and bogie mounted gearboxes which required a redesign and even finer levels of assembly tolerances.

The GNER ‘Mallard’ Mk4 interior – The tapered carriage confirms that a retro fit tilt system could be fitted.

Still a record breaker

The complete 91 class went through a massive engineering upgrade known internally as ‘Delta 91’ during the GNER franchise which was completed in 2003, this comprised of various cab and equipment upgrades turning the class from below average to one of the best reliability records on the British railway infrastructure.

During the testing days, the 91 managed to achieve some record breaking runs when being type proved on the ECML. At a similar point in Cambridgeshire where the A4 steam loco Mallard broke the world record for steam in 1938, a shortened 91 set hit 162.4 mph – the fastest ever recorded speed for an electric locomotive in the UK. Another high speed test run saw this class run a time of just under 3 hours 30 minutes from Edinburgh Waverly to London Kings Cross, averaging just over 112mph point to point.

Even though the sun has set on InterCity, the 91 looks like it remains to be the backbone of the ECML for some years to come.

Sadly, GNER had their franchise withdrawn in 2007 following the parent company Sea Containers running into financial difficulty, the franchise was then put out to re-tender. A GNER management alliance with Virgin trains bid was turned down and the line was hand ed to National Express who also ended up suffering mounting losses. Nat Ex hand ed back the franchise to the Government during which time they had cut back dramatically on all operating costs allowing the fleet to become run down and problematic.

These events caused the Government to operate the line under the brand ing ‘East Coast Trains’ who have since put into place various plans to improve reliability and customer confidence. GNER represented a perceived image of style and quality that still seems to be much missed in the private railway sector.

With 6300bhp available, the BR class 91 remains the most powerful passenger locomotive in the UK, but prior to the Mk4 coaches being built, the 91 would operate with a surrogate HST power car recording the highest powered passenger train of its kind, at that time in the world having 8550bhp at the drivers’ disposal.

The refit programme of 2006 – 2007 has seen the class 91 sets turn from being an ugly duckling passenger wise, to a true elegant Swan with impressive new seating, total re-wiring, new spring and damper settings, improved electrics and features such as onboard WiFi and electrical charge points at every seat. These and many more refinements make sure that the class 91 despite its troubled life, remains to ply its trade on the ECML for years to come.

Mike Humble

About the Author:

Upon leaving school, Mike was destined to work on the Railway but cars were his first love. An apprenticeship in a large family Ford dealer was his first forray into the dark and seedy world of the motor trade. Moving on to Rover and then PSV / HGV, he has circumnavigated most departments of dealerships including parts, service and latterly - the showroom. Mike has owned all sorts of rubbish from Lada to Leyland and also holds both Heavy Goods & Public Service Vehicle licences, he buys & sells buses and coaches during the week. Mike runs his own automotive web site and writes for a number of motoring or commercial vehicle themed publications

39 Comments on "Rail projects : Class 91 – a potential never fulfilled"

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  1. David says:

    Brilliant article, thank you. Hope that ‘Best Of British’ becomes a regular feature here.

  2. Paul says:

    Interesting article, but I am wondering why the title – a potential unfulfilled? As far as I was aware the Class 91 has done everything ever asked of it. East Coast Electrification only ever envisaged 125 mph operation. The ability to do 140 mph was a marketing ploy to distinguish the new trains from the 125 diesels and to future proof the fleet if line speeds where raised. Modelling of both the East and West coast line has shown that on most services, raising line speeds to 140 would only achieve marginal savings in travel time. One of the reasons why the West Coast upgrade was scaled back and the Pendolinos now stick to 125. Also, the much publicised problems with East Coast OHLE are mainly down to corrosion issues with specific components – now replaced. Its not the consequence of some imagined cheap design.

    • Steven says:

      The operator of the East Coast now is as you may know Virgin Trains and they hope to raise the line speed to 140mph. But whether they manage to do this in the class 91s operational lifetime or the new class 800 IEPs operational lifetime is something that we will have to wait for. I dont believe that this will be achieved though

  3. Mike Humble mike humble says:

    Paul

    Reasons for unfilled potential are as follows:

    Rolling block signalling: never happened
    Vastly improved journey times with limited stop trains: ditto
    Full 140mph through the Fens & vale of York: ditto
    HST sets to be totally relieved of all stops services: ditto
    Full OHLE to Edinburgh: cancelled

  4. Phil Simpson says:

    Further engineering works could sure turn the 91 into the Pendolino of the East Coast Main Line.

  5. Paul says:

    @ Mike – I dont think rolling block signalling was ever on the agenda when the class 91 was conceived and the ECML Electrified. It was supposed to be a feature of the WCML upgrade, but was technically not achievable at the time. As I said, upgrade to 140mph was never envisaged as part of the ECML Electrification scheme. It was something that might have been an option if a business case existed some time in the future hence the trains where specified with that capability. The new Hitachi IEP trains are specified for 150 mph but are expected to run in revenue service at 125. Full Electrification to Edinburgh did take place as part of the ECML Electrification programme and was energised in 1991. IC225/Class 91s are the mainstay of services between Kings Cross and Edinburgh to this day.

  6. Ken Strachan says:

    Line 4: “rail travel was exiting” – Freudian slip??

  7. Magnus says:

    I’m not a great fan of the 91s, myself; apart from their boring looks, I absolutely hate being in a train that’s being pushed, rather than pulled. Yes, I’m paranoid but it just doesn’t feel right.

    There was a very interesting feature in Rail magazine recently (#700) that Alstom have been testing Pendolinos on the ECML, using different pantographs and the train’s tilt mechanism. East Coast were apparently “impressed”. The eventual aim is to prove that Pendos could, with some modification, run on the ECML at 140mph and with tilt which, Alstom claim, could knock 50mins. off the KX-Edinburgh journey.

    In the meantime, give me an IC125 any day!

  8. The_Saint_ST1 says:

    140mph is just to unsafe without in-cab signalling simply because some drivers may find it physically difficult to see the aspect as they approach.

    An experiment was tried on the Berwick to Edinburgh section (isn’t that the longest, straightest bit?) whereby they would use a flashing green aspect to signify they were safe to run at 140mph. However, for the reasons stated it proved difficult to implement safely and so it was abandoned.

    Likewise on the WCML Trent Valley section (which is now 4-tracked), 135mph running was mooted but this idea also proved difficult to safely implement and too costly, and so that idea was abandoned too.

    Interestingly, the flashing green aspect is still in use today but I think it just signifies that the train is good to go but to expect a line switch ahead.

    Looks like East Coast might be able to get their hands on a few second-hand Pendo’s soon, after the chats I’ve been having 😉 …………..

  9. Jemma says:

    Horrible ugly things. They have them on our line to London and they’re all grotty, worn out and generally undesirable. The best experience I have had on the railways was London to Oxford (Virgin I think) that were nice, clean, comfortable and didnt look like mechanical survivors of Arnhem

    Many of the rail problems such as signalling ironically stem from our winning WW2. We have to live with 200 year old track plans and the like – everywhere in Europe had to rebuild their systems post 1945 (since most of them had been flattened in various ways).

    Interestingly the Deltic was another child-of-the-war, using borrowed (nicked) tech from German diesel aero engines that had in turn been shoehorned into e-boats and hence to BR.

  10. The_Saint_ST1 says:

    Ah but Jemma, look at the tapered profile of the Mk4 carriage interior above. Then look inside a Virgin Pendolino. The layout is different but the interior profiles look the same. The difference is the bogey type used…

    The differences in the Mk4’s to Mk5’s include the Mk5’s use of stir-friction seam welding – the main reason why the Grayrigg train carriages came off the track straight and in one piece – Given the speed and impacts, they didn’t collapse and they saved all but one life. It’s also the reason why the Pendo is so quiet even on the roughest tracks.

    As for the tracks.. oh my, there’d need to be huge investment needed in all HST lines. WCML got some (a lot but still not enough) but sadly it has to share it with slower rolling stock.

  11. Paul says:

    Not sure where any second hand Pendolinos will come from. West Coast is the only franchise using them. First Group are required under the terms of their new franchise to retain all the existing units and intend to increase the fleet by acquiring 6 car units for Birmingham-Scotland services.

  12. Magnus says:

    As I said, Pendos could, with some modification, run at 140; the modification being installing European Rail Traffic Management System – or, in-cab signalling among other things.

    No, I’ve no idea where the second hand Pendos are coming from either, not least as First Group unequivocally state on their website:
    “We know passengers like the Pendolino and Super Voyager trains, and these trains will stay on our routes. We’ll refit all these trains with enhanced WiFi, more comfortable seating areas in both Standard and First Class and improved luggage space. We’ll also refit the toilets on the Pendolino fleet.”

  13. Mike Humble Mike Humble says:

    Have no fear… First will soon back heel the Pendolino`s. If they had their own way, they would be pulling Mk2s behind a pair of 47s

    Virgin West Coast going Worst Group is nothing more than a total and utter tragedy!

  14. Chris Baglin says:

    @7, Magnus,

    I can’t tell the difference between being pushed or pulled- the one time I travelled on this country on an electric loco powered train I was being pushed (can’t remember by what) and I’ve travelled clear across Belgium being pulled then pushed (or vice-versa).I’ve no problem with it- especially as no railway carriage weighs less than about 33 tons- which ought to be enough to keep the thing on the rails…

    I don’t recommend rail travel across Belgium without a very good book- it is flatter than the human mind can possibly conceive, and there is very little of interest outside. Indeed, after about an hour I became convinced that I was part of some bizarre practical joke, and that instead of travelling straight, we were going around in a huge circle, and when we got to the other side, someone would come out and slightly re-arrange the scenery, moving a tree here or there, to create the illusion of distance travelled. Fortunately the Belgians brew good beer, which is very therapeutic. They also brew Stella Artois.

  15. Mike Humble mike humble says:

    And they eat chips with mayonnaise rather than Ketchup… Yuck

    I rest my case m’lud

  16. Andrew-P AndrewP says:

    @ Mike – why is it such a tragedy if First get West Coast? They do a good job on Trans Pennine and Hull Trains and have even turned around Great Western after a bad start – I have not b. Not that Virgin have done a bad job either.

    Anyway, I like these trains as they are fast, comfortable and in my experience very reliable. Since GNER’s refurb which replaced the cheap feeling original interiors. Its just a shame that East Coast’s customer service is not up to GNER’s although it is substantially better than National Express ever managed.

    It looks like the replacement for these things will be the Newton Aycliffe built Hitachi IEP trains – better than Spanish pendolinos

  17. Mike Humble Mike Humble says:

    Turned around Great Western?

    Ahem – I think it was more to do with the serious threat of loosing that franchise owing to shocking (and dare I say it still bloody poor reliability)that they pulled their boots up. Hence the in joke of them being known as Worst Late Western!

    Its a dreadful dreadful line, at least Virgin Trains operated with a certain style and unique flair.

    Call me old fashioned possums, but FTP or Hull trains hardly cater for the serious business commuter or compete with Internal airline travel… do they?

  18. Russell G says:

    Anybody that has to suffer the dreadful bus service in North Sheffield run by First knows the company shouldn’t be running public transport of any kind.

  19. The_Saint_ST1 says:

    Does anyone know whether Project Electra have any influence on the Avocet? I remember hearing about it ages ago and remember seeing a quirky looking locomotive laid up on some siding close to the route I had to take to Palmers Green on the Northern City Line. Apparently the tech used on this was eventually put to use on the class 373’s used on the Eurostar and White Rose GNER services.

  20. Chris Baglin says:

    @18, Russel G,

    The same can be said of Stagecoach. They do ok on our ‘premium’ bus routes- where the Scania double deckers have leather seats (or something that looks a bit like leather), but on lesser routes, or on routes like the council estate I live on, the service leaves a lot to be desired- starting with not putting the bloody heating on during the summer to help cool the engines- that’s what the radiator is for.

  21. Andrew-P AndrewP says:

    @17 Mike, The Great Western franchise is really three franchises lumped together (Thames Trains, Great Western Main Line and Western regional lines) and my understanding was that most of the problems were with the Western bit where they inherited something bad and initially made it worse but it now scores well in terms of both reliabiliy and customer satisfaction.

    Is TransPennine commuter or InterCity – the answer is both so possibly comprable with London – Birmingham but not London – North West – Scotland.

    Hull Trains – agree this is a small operation but the service is excellent and if the same is provided on West Coast there will be few complaints especially as they won’t have the notorious Adelante trains.

    As for Virgin they do a good product but I get the feeling the service has not moved on since the Pendolinos arrived and is not as good as East Coast but this is probably more to do with the fact that I don’t like their trains than anything they do themselves – highly subjective. I do think it’s a shame they lost Cross Country and that the DfT stifled their ideas. It would be interesting to see what they could do with the East Coast – it needs new blood.

  22. Mike Humble mike humble says:

    Some intersting retorts there…

    In my heart of hearts, I think the REAL reason Virgin trains has lost the franchise is mainly down to personality clashes.

    Richard Branson has never conformed to the norm in a business sense, and the City have treated his “new money” style of dealing with nothing but contempt.

    But I truly believe that First are simply not able to operate to the same level of style and flair of Virgin trains and I`ll bet my last Rolo that various asset stripping and other financial cut backs WILL take place before too long.

    I really wanted Virgin to fail at first, but after seeing other TOCs chop and change – some not for the better ie: GNER and ONE Anglia, I grew to respect the company and what they stood for.

    The original Government idea of keeping InterCity as a whole should have been adhered to, instead, it was hurried, not thought through properly and caused some of the great know how and railway men and women to be lost forever.

    Criminal if you think about it!

  23. Magnus says:

    This is all fiddling while Rome burns, anyway; I won’t bore you with my anti-Virgin opinions, suffice to say that they crushed the truly superb Wrexham & Shropshire, so Good Riddance to Beardie.

    The sooner we go back to a defragmented railway, the better.

    Still, it’s not all bad: my favourite pair of DRS Class 37s have just rumbled by my garden with 3 nuclear flasks – I’m just getting a lungful of diesel fumes now – bliss…

  24. cjmillsnun says:

    @19 Project Electra resulted in the cancellation of the class 89, making Avocet a unique locomotive.

    The technology was used on the “Le Shuttle” car and truck trains, the class 373 used TGV technology.

  25. cjmillsnun says:

    OK a separate comment for this.

    I personally think that privatisation should never have happened.

    I’ll explain why.

    BR was modernising its rolling stock and would have completed this before the private companies.

    Intercity had a better reputation than any of the TOCS. I’m no fan of any of them.

    Some of the accidents wouldn’t have happened.

    and most importantly the subsidy provided would’ve been much lower.

    BR was the most cost efficient rail operator in Europe (quite likely in the world). Intercity was profitable. Network SouthEast broke even despite having no subsidy and introducing both the class 442 (a superb train in NSE and SWT trim) and Networker series. Regional Railways was never going to make profit but had a good image. Having an integrated track/train interface helped and the EU ruling could have been complied with by a simple accounting mechanism instead of creating the ridiculous Railtrack and Network Rail. Both organisations are poor relations of BR Infrastructure Services.

    I’m no socialist but Britain’s railways were better under public ownership

  26. Paul says:

    As someone who does a 200 mile round trip commute almost every day by Virgin trains, the day cant come soon enough that they are kicked off the West Coast route. Absolutely idiotic to suggest that First Group will do a worst job. Anyone who suggests otherwise has been taken in by beardy Bransons self promotion and belief that he alone has a divine right to offer a miserable service, but pocket vast amounts of public subsidy.

  27. Tim says:

    I loved travelling by train when I lived in the UK. I used to take the HST to Plymouth just for fun on a day off. Now I live in Denmark, where the trains are crap. They seem to be proud of an ‘intercity’ IC3 that flat out does about 90Mph! Mind you that’s better that the new IC4 multiple units that cannot be coupled to each other without the brakes failing to work. Mind you they were built by an Italian company that has never built a train before. I read about the way a Diesel from the 70’s can be coupled to an electric from the 90’s to produce the railway equivalent of a dragster and weep. What the hell are out Danish railways doing it is embarrassing.

  28. Andrew-P AndrewP says:

    I am writing this fom the ideal place to comment – the 06:00 East Coast train fom York to Kings Cross.

    @Mike – cmpletely agree that Branson’s personality may have something to do with decisions. It will be interesting to see if Virgin or just Stagecoach bid for EastCoast.

    What this whole thread shows is how different the various train companies are and how everyone has their preferences.

    I was surprised that there was never an Intercity plc when privatisarion happened but a different was chosen. Privatisation was inevitable due to a massive investment backlog and the prevailing political climate.

    Has privatisation worked? I don’t think there’s a clear answer – certainly rolling stock leasing has as so much stock has been replaced or upgraded but the current model may be at the end of its life. Passenger numbers are also massively high. However, fragmentation means interfaces and risk (operational and financial as railways in the UK have always been safe).

    I just wish the trains were better on the Harrogate line

  29. Inventor 73 says:

    @AndrewP – totally agree about Harrogate line. Until recently I commuted to Leeds for 3 years when I was without a car and it is pretty appaling, at least now you get the 06:29 HST service to London KX. Glad the horrid class 141’s have gone and 142/144’s are on their way out, as they were the only trains on the line when I came home at a weekend when a student in Manchester.

    I’ve done a lot of commuting to London recently (Olympics and other sporting events I’ve been working on) and the 225’s are better Northbound, but prefer an HST Southbound as there is less buffeting when the power is lifted off, or switching from brakes to power on – mind you my favourite spot is coach E in the “extended leg room” seats right over the bogies that somehow never get reserved…

  30. Andrew-P AndrewP says:

    I do the journey most weeks sometimes more than once and have never noticeed any difference going north or south. Well done on contributing to the success of the Olympics btw.

    For info the buffet car never has any reservations on a 225 and if going north of York sit on the right (if facing forwards) to get the best view.

  31. lord sward says:

    Slightly off topic, but it looks like the WCML service will be state ran shortly. Yea Comrade!

  32. MM says:

    ** COMMENT DELETED **

  33. Chris Mills says:

    Not sure that comment 32 should remain. The last sentence is tasteless.

  34. Ste f says:

    I personally think HST and the class 87 were perfect work horses . Class 87 hit 110mph HST hits 125 . In 2014 nothing goes faster than 125 anyway so why all these fancy trains (pendo) is beyond me .
    Also why this obsession with speed in uk ? It’s a tiny island for god sake so not as important as mainland Europe .
    BR was and still would be the best operator for the railways in this country .
    Trains were bit by British engineers ( best in the world) to run in our climate . So here we are in 2014 with fancy trains built by Italians using British engineering . I give up on British politics as all the y have done is turned good things into bad . Oh we’ll asking as they get rich by it then that is the most important lol

  35. kev says:

    Class 91 and the electra squadrons came out the fire and should have replaced WCML and ECML fleets. at the start of the 1990s Intercity needed another boost..IC125 done their bit for the non wired runs…now we needed a new hero and they were and are it…they have never strayed off the east coast..I have only ever seen one set in Euston and she looked great there.

    As a passenger I love feeling the G when their driver opens up at speed and the locos Toes Dig in and push/pull em faster..

    they are a great squadron..and I hope they continue for many years…they are one of BREL’s best builds…and we must cherish em

  36. Andrew Porter says:

    The Class 91 and mark 4 coaches were intended, when and where required, to incorporate the tilting mechanism developed through the APT-P. What the APT-P had demonstrated was that of using carden shaft drive to the motors, articulated carriages, low mass materials and multiple brake mechanisms, the train could operate at up to 155 mph, stop in the same distance as a conventional train from 100 mph, and not cause any increase in track wear and tear. This was designed to allow the APT-P to use existing track and signalling, to operate safely at 155 mph. The APT-P, with two power cars also had the benefit of distributed power, providing considerable benefit in terms of acceleration.

    The Class 91 and mark 4 coaches failed to use the articulated carriage arrangement of the APT-P, uses less effective regenerative braking that dumps the recovered energy by converting to heat and cannot decelerate the train as fast as the APT-P, has one locomotive without distributed power causing acceleration limits, and uses steel rather than aluminium alloy, therefore, it is heavy. This means, at best, it is marginally better than a Class 90 locomotive with mark 3 coaches and a DVT, as used on the main line covering the Anglia route, trains that were formerly used by Virgin West Coast.

  37. Penske666 says:

    Great article – one of the initial problems were the small grilles insisted on by the design team which caused overheating. not to mention the crap SIG bogies sourced as a cheap alternative to the originals.

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