Class 800 - Updates

[The Stationmaster]

I think it's quite clear that multiple unit technology is not the way forward and the quicker those in charge realise that loco hauled stock is the still the way forward, the better really.

 

It is an interesting, and quite complex, subject to debate.  In my view putting engines underneath passenger accommodation does not deliver the best options for a  passenger environment (witness the Voyagers) and it effectively ties passenger accommodation to the more complex needs of traction maintenance and the downtime it requires.

 

On the other hand sticking the traction into a separate vehicle means 'dead' length in the train in a space which might otherwise be used to cram in carry more passengers but if has the big advantage of separating the complex traction maintenance from the different requirements for servicing coaching stock.  But it does add cost because of a  potential need for shunting staff to attach and detach the traction unit if such needs to take place in other than a depot.

 

So what it boils down to is what you want and how much you are prepared to pay for it?  In my view one of rail's big advantages is the ability to put into the market place a fast and comfortable means of travel which allows relaxation (or work) whilst you're getting from A to B.  therefore from a commercial viewpoint anything which disturbs the passenger environment detracts from the travel product you are trying to sell i and that is critical in the long distance 'inter-city type of market or even for long distance commuting.  I have travelled for several hours, on several occasions on Voyagers and compared with HSTs I find they offer a far less attractive travelling environment because of the noise and, it has to be said, their poor riding over pointwork and less than perfect track at speed.

 

Thus for long distance i would always plump for a separate traction unit, on suburban high density journeys then multiple units are unavoidable BUT no one should ever forget even they are competng with the comfort of a motor car and the facilities it offers.

[D854_Tiger]

That sounds a bit like the idea behind  'Operation Princess', on the Cross Country service in 2002, smaller trains but more of them,

which did not really work out as planned,

 

Exactly what I was thinking ...................

 

 

Operation Princess was far too optimistic, with many services being only four car and five car at the most, and being cross country was also a much more complex operation involving endless conflicting pathing arrangements.

 

The timetable was simply not robust enough and when things went belly up, which was often, could inevitably mean large numbers of passengers trying to cram themselves into just four cars.

 

There will be plenty of nine car IEP sets around on GW and, on the core route, many of the five car sets will be working in pairs (or even maybe more).

 

Expect five car units to be let out alone in Cornwal or through the Cotswolds but on the core route probably only on the slower stopping services or fill in services such as that to Pewsey.

 

A good comparison to make would probably be the Meridians on the EMT network where seven car, five car, four car and peak time five car plus four car operate, plus of course HSTs. Most of the more important busier services are well appointed with the slower stopping trains being shorter formations.

 

I'm not aware of any overcrowding difficulties out of St Pancras but stand to be corrected if this is not so.

[The Stationmaster]

There is also the benefit of increasing train frequency when pathing is difficult. I will take an example from the ECML.  You can have 2x5 car leaving Kings Cross, which split at Doncaster. One goes to Leeds, the other to Newcastle. You get the extra capacity required on the crowded bit south of Doncaster, and increased frequency to Newcastle and Leeds, with the Kings Cross-Edinburgh being 9 car. I expect similar thinking would work well on the GWML, perhaps 2x5 car to Bristol Parkway, one set can then go to Wales and the other to the west country. 

 

There are however  potential major problems with portion working when things go pear-shaped and the longer the distance and the greater diversity of the routes over which the portions work the greater the scope for troubles.  Which is f course one of the reasons portion working has disappeared from much of the railway map in the past 60 years.

 

But it does make sense in some situations such as 2X5 to Plymouth or Cardiff then 1x5 forward to Penzance and Swansea respectively.  Provide your set working and trainplan can accommodate most  of the common perturbation effects the portion working could, for example, still work using stepping-up of the 5 car portions although that is 'real railway work' and needs the right sort of mind to implement it.

[D854_Tiger]

P.S. I believe many of the Oxford services (four trains per hour) will be operated with five car IEP sets, not unusual to see just three cars on some of those trains currently.

[D854_Tiger]

There are however  potential major problems with portion working when things go pear-shaped and the longer the distance and the greater diversity of the routes over which the portions work the greater the scope for troubles.  Which is f course one of the reasons portion working has disappeared from much of the railway map in the past 60 years.

 

But it does make sense in some situations such as 2X5 to Plymouth or Cardiff then 1x5 forward to Penzance and Swansea respectively.  Provide your set working and trainplan can accommodate most  of the common perturbation effects the portion working could, for example, still work using stepping-up of the 5 car portions although that is 'real railway work' and needs the right sort of mind to implement it.

 

 

It's not that clear to me that the new timetable will require that much portion working, Plymouth (portion for Cornwall) and Oxford (portion for Worcester) being the only likely examples mentioned so far and even then only off peak.

 

I suspect the plan is to use five car sets out of Paddington on those services where five cars should be more than enough to cope and double up at peak times.

[Coryton]

There are however  potential major problems with portion working when things go pear-shaped and the longer the distance and the greater diversity of the routes over which the portions work the greater the scope for troubles.  Which is f course one of the reasons portion working has disappeared from much of the railway map in the past 60 years.

 

But it does make sense in some situations such as 2X5 to Plymouth or Cardiff then 1x5 forward to Penzance and Swansea respectively.  Provide your set working and trainplan can accommodate most  of the common perturbation effects the portion working could, for example, still work using stepping-up of the 5 car portions although that is 'real railway work' and needs the right sort of mind to implement it.

 

I don't know how many services will be made up of 2x5 sets but it sounds as if this will be quite common. Running long distance "intercity" quality services with two portions without corridor connections is not something that is common in the UK at present, and brings the problem of the need to duplicate facilities in each portion. (Two kitchens for a 10 coach train...)

 

This was of course one of the less desirable features of the APT-P (to be removed in squadron service by moving the power cars to one end, I believe), and I think passengers without reservations had to obtain a boarding card allocating them to one of the two sections. On the other hand, these days far more people travel with a seat reservation which probably simplifies matters.

 

It will be interesting to see how it all works out. It won't be especially helpful for people arriving at the last minute in Paddington and jumping on the first door if they are going somewhere that only the front bit goes to, or if their reservation is in the wrong bit.

[Coryton]

It is an interesting, and quite complex, subject to debate.  In my view putting engines underneath passenger accommodation does not deliver the best options for a  passenger environment (witness the Voyagers) and it effectively ties passenger accommodation to the more complex needs of traction maintenance and the downtime it requires.

 

On the other hand sticking the traction into a separate vehicle means 'dead' length in the train in a space which might otherwise be used to cram in carry more passengers but if has the big advantage of separating the complex traction maintenance from the different requirements for servicing coaching stock.  But it does add cost because of a  potential need for shunting staff to attach and detach the traction unit if such needs to take place in other than a depot.

 

Thus for long distance i would always plump for a separate traction unit, on suburban high density journeys then multiple units are unavoidable BUT no one should ever forget even they are competng with the comfort of a motor car and the facilities it offers.

 

But of course the separate 'traction unit' doesn't have to be a locomotive - the prime mover could be in one coach, or part of one coach, in an MU, and the traction motors don't have to be under it.

 

It is interesting though that while HST rakes are 'fixed-formation', the fact that power cars can be swapped round and indeed coaches swapped out of rakes is certainly taken advantage of.

 

There seems to be much less flexibility of that kind with an MU design. Maybe modern rolling stock is so much more reliable, or parts more modular, that it doesn't matter.

 

It does mean though that on an 800 passengers aren't likely to have the pleasant surprise I've occasionally had on an HST with a declassified first class coach sitting in the middle of standard class. (Not only is it it lot nicer than standard, it tends to be almost empty because people don't believe it's really standard class). 

 

I sometimes wonder how much 'normal' people are bothered by underfloor engine sound, so it was interesting recently to hear someone living in Southern territory complain about occasionally travelling between Portsmouth and Southampton on the Portsmouth Harbour to Cardiff service because it was a diesel.

[Reorte]

I sometimes wonder how much 'normal' people are bothered by underfloor engine sound, so it was interesting recently to hear someone living in Southern territory complain about occasionally travelling between Portsmouth and Southampton on the Portsmouth Harbour to Cardiff service because it was a diesel.

It's probably one of those things a lot of people simply accept as normal, at least if it's their usual train. It was interesting once to see a young group get on a Mk I on the East Lancs Railway and be amazed that it had started moving before they'd even noticed it (of course that changed a bit once it got above walking pace!) Personally speaking I'm not keen on having a diesel engine under the floor, but on average I find posts flicking past the windows more annoying, a sentiment shared by no-one else as far as I can tell.

[D854_Tiger]

 

I sometimes wonder how much 'normal' people are bothered by underfloor engine sound, so it was interesting recently to hear someone living in Southern territory complain about occasionally travelling between Portsmouth and Southampton on the Portsmouth Harbour to Cardiff service because it was a diesel.

 

For me the game changer was the Turbostar family class 168, class 170 and class 172.

 

Those trains convinced me a DMU could be as nice as loco hauled, OK a bit of noise accelerating but once up to speed you can hardly tell the difference from a mk 3, on the Chiltern main line, where they sit at 100 mph most of the time and the ride is impeccable.

 

Voyagers can grate at low speed but get them up to 125 mph and the engine noise virtually disappears.

 

I know a lot of people don 't like the Voyagers and I don't care for them that much after dark, with all that bright fluorescent lighting, but pound for pound they're just about the most powerful thing on the railway and get one tilting on the WCML it's like proverbial off a shovel.

 

The class 180s have the same engines as Voyagers but they are definitely noisier and seem prone to more vibration, they all round have a bit of a cheaper feel to me, but are not the end of the world wizzing up the ECML with Grand Central.

 

If modern diesel multiple units can attract people back to rail travel then what is not to like about them. 

 

Could never say the same about some of those first generation DMUs, the improbable distances some of them were used over and how laborious they became on stopping services.

 

The view form the front was nice though, enough to forgive them for, the sheer wonder of the Heart Of Wales or the Cambrian from the front seat was pure joy though I never did make it from one end of the HoW to the other without falling asleep.

 

It was always noticeable how despite all the noise and vibration those trains were a great cure for insomnia, on a run half of every coach could be guaranteed to fall asleep.

[phil-b259]

Indeed; it should be conducted with the same ease that South-Eastern couple and uncouple their Hitachi 395s tens of times a day at Ashford, with the leading set ready to continue its journey within a two minute dwell time.

 

 

Yes. SWT reguarly split/join their Desiros at Bournemouth and it takes less than a minute most of the time.

 

Exactly, portion working has long been necessity in the south, yet seems to be regarded with the upmost hostility by those based elsewhere.

 

OK, I get that the lack of end gangways on the units are a complication but I'm sure most users will adapt to the situation.

[Fat Controller]

Exactly, portion working has long been necessity in the south, yet seems to be regarded with the upmost hostility by those based elsewhere.

 

OK, I get that the lack of end gangways on the units are a complication but I'm sure most users will adapt to the situation.

The 395s seem to manage without end gangways. The Train Manager makes an announcement before leaving HS1, north of Ashford, reminding passengers about the imminent split.

[jjb1970]

With respect to vibration and sound proofing it is often a case of you get what you pay for. If you have deep pockets there are multiple techniques for decoupling engine vibration from whatever the engine is mounted to. Especially if it is an e-drive rather than a mech-drive. Many of the techniques are neither new nor especially advanced but they can be quite expensive to implement. Similarly soundproofing is something you can do very effectively if you're willing to pay for it. In both cases you can use either passive or active technology (or a combination of both), active technologies work very well but do tend to be quite expensive and can be quite difficult to implement. I did quite a lot with diesel engines mounted in certain ship types where acoustic signatures are critical and it was quite remarkable just how well isolated the engines were. Similarly I had experience of installing big engines in urban environments and one of the prime requirements was to make sure that neither neighbours, passers by or even people above knew they were adjacent to several MW of diesel engine thumping away, and it can be done extremely successfully.

With regards engines, from a strictly engine perspective there are advantages to using multiple engines, but that need not be distributed power as per underfloor DMU engines. The idea of gen-set switchers is well established in North America and the concept has been used on some of the Class 73 re-builds I believe. Running a small engine at full load is more efficient than a big engine at a high turn down ratio, it also aids reliability and durability of the engine.

[jim.snowdon]

The railway of today is no longer configured for the operation of traditional locomotive hauled passenger trains, only unit trains that can be driven from either end, be they combinations of multiple units, locomotive + driving trailer or topped and tailed by a locomotive (eg HST sets) An additional factor is that of speed, and the dynamics of the wheel:rail interface. The concept of putting all the power in one or two locomotives results in a unit with high axle loadings, and correspondingly high track forces, both vertical and lateral. The benchmark was set by the track forces exerted by a Class 55 at 100mph; anything wanting to travel at higher speeds than that must not exceed those forces, which complicates the engineering of the bogies and final drive, as well as limiting the overall weight of the locomotive. It is where the Pendolinos and Voyager/Meridian sets score by distributing the power throughout the train, keeping the axle loads down, and putting the traction motors under the body, with shaft drive to one axle on each bogie.

 

i appreciate that the French TGV sets run counter to this by employing a locomotive on either end of each set, but equally, they limit their high speed running to track that is designed and built to very high tolerances and reserved only for high speed trains, not the UK main lines that have to cope with more normal standards and all sorts of trains.

 

The other factor benefitting multiple unit trains is the ability to couple and divide trains en route, principally as that provides a mechanism for making best use of the limited number of train paths on the more congested parts of the system, even if it does make crew scheduling more onerous. It is, of course, a system that was widely practiced by the Southern Railway, and still persists on a significant scale on the Brighton Main Line (the Southern's Central Division as was), and to a lesser extent on the Southeastern. That the Western will be running significant numbers of 2x5 car trains is essentially no surprise, given the number of route options served from Paddington. Different on the ECML, where the first branch (in main line terms) is not until Doncaster, and the railway as a whole is very linear. (Its complications at the London end are all within the province of GTR (or whatever they will get called post-Thameslink) and not something that East Coast Trains can resolve.

 

Jim

[jim.snowdon]

Exactly, portion working has long been necessity in the south, yet seems to be regarded with the upmost hostility by those based elsewhere.

 

OK, I get that the lack of end gangways on the units are a complication but I'm sure most users will adapt to the situation.

How many passengers actually use the gangways, other than to get to the catering facilities or a toilet that works, or to get ot the front of the train before arriving at the terminus. Not having inter-unit gangways is a disadvantage only to the latter, who perhaps ought to learn to be more patient.

 

Jim

[Coryton]

. The idea of gen-set switchers is well established in North America and the concept has been used on some of the Class 73 re-builds I believe. Running a small engine at full load is more efficient than a big engine at a high turn down ratio, it also aids reliability and durability of the engine.

 

I.e. you only use as many engines as you need at a given time?

 

Operation Princess was far too optimistic, with many services being only four car and five car at the most, and being cross country was also a much more complex operation involving endless conflicting pathing arrangements.

 

The timetable was simply not robust enough and when things went belly up, which was often, could inevitably mean large numbers of passengers trying to cram themselves into just four cars.

 

There will be plenty of nine car IEP sets around on GW and, on the core route, many of the five car sets will be working in pairs (or even maybe more).

 

Expect five car units to be let out alone in Cornwal or through the Cotswolds but on the core route probably only on the slower stopping services or fill in services such as that to Pewsey.

 

A good comparison to make would probably be the Meridians on the EMT network where seven car, five car, four car and peak time five car plus four car operate, plus of course HSTs. Most of the more important busier services are well appointed with the slower stopping trains being shorter formations.

 

 

I think another problem with Operation Princess was that people didn't conveniently distribute their travel times round the timetable.

 

Replacing an 8 coach train leaving at 5:30 (or 6:30) by a 4 coach train at 5:30 and another 4 coach train at 6:30 isn't helpful if most people want to travel at 5:30, though you can smooth this about quite a bit with advance purchase ticket quotas.

 

But I agree that this is different.

 

When FGW added an extra train per hour between London and Cardiff they bought the (5 car) 180's to do so - so in general they replaced an 8 coach train every hour with one 8 coach and one 5 coach but done sensibly so that in the peaks all the trains were HSTs in the 'busy' direction.

 

This sounds like more of the same. (Of course the 180's didn't turn out so well and they were replaced with extra HSTs giving 2 8 coach trains an hour, though for a while I think some were reduced to 7 coaches).

 

The railway of today is no longer configured for the operation of traditional locomotive hauled passenger trains, only unit trains that can be driven from either end, be they combinations of multiple units, locomotive + driving trailer or topped and tailed by a locomotive (eg HST sets) An additional factor is that of speed, and the dynamics of the wheel:rail interface. The concept of putting all the power in one or two locomotives results in a unit with high axle loadings, and correspondingly high track forces, both vertical and lateral. The benchmark was set by the track forces exerted by a Class 55 at 100mph; anything wanting to travel at higher speeds than that must not exceed those forces, which complicates the engineering of the bogies and final drive, as well as limiting the overall weight of the locomotive. It is where the Pendolinos and Voyager/Meridian sets score by distributing the power throughout the train, keeping the axle loads down, and putting the traction motors under the body, with shaft drive to one axle on each bogie.

 

 

The downside of course is that you end up either running diesel trains long distances under the wires, or with bi-modes lugging all the diesel engines around on parts of the route where they aren't needed.

 

Swapping a diesel for an electric locomotive was more efficient in that sense.

[Coryton]

Hi Rich, thankyou for your detailed reply, which, to be honest, does sound  good. It could almost be something straight from the Great Western publicity department.   Personally, I think it's too good to be true and I remain sceptical. I just dont think there will be both an increase in service frequency and an increase of train length by several coaches on most services.   I could be wrong and I hope I am. I should wait for the new service to begain maybe and then comment.

 

Well if the 800's aren't used to provide extra services there are going to be quite a few expensive trains sitting around doing not very much. And I don't think cascading them would be very practical since they come as a package along with their depots.

 

Having said that, on another thread there was a comment that long distance passenger growth has not been meeting expectations recently, which could make things interesting.

 

Given the apparent high leasing costs of these trains, they are presumably going to need filling with passengers and not all at give-away advance purchase prices to fill seats.

[jjb1970]

I.e. you only use as many engines as you need at a given time?

Yes, that's the principle, it's the same principle used in maritime and electricity generation applications where flexible loading and operation at lower loads is needed (eg. small CHP).

[Reorte]

How many passengers actually use the gangways, other than to get to the catering facilities or a toilet that works, or to get ot the front of the train before arriving at the terminus. Not having inter-unit gangways is a disadvantage only to the latter, who perhaps ought to learn to be more patient.

There's presumably a staffing issue as well. At least I think that was the reason we were given for being turfed out of the rear portion once and into the already crowded first half.

[SouthernMafia]

There's presumably a staffing issue as well. At least I think that was the reason we were given for being turfed out of the rear portion once and into the already crowded first half.

On the occasions I've seen a pair of Voyagers operate south of Reading it has been 1 Train Manager and 2 catering staff (or even up to 4 with First Class hosts).

I imagine IETs will operate in a similar manner.

 

I find posts flicking past the windows more annoying, a sentiment shared by no-one else as far as I can tell.

Commuting along the now very masty GWML I have got used to it but I remember when the first masts were going in West of Reading in significant quantities and feeling almost nauseous because of this new repetitive mast-zipping-past view I had to endure! Edited July 3, 2017 by SouthernMafia

[Ken.W]

 An additional factor is that of speed, and the dynamics of the wheel:rail interface. The concept of putting all the power in one or two locomotives results in a unit with high axle loadings, and correspondingly high track forces, both vertical and lateral. The benchmark was set by the track forces exerted by a Class 55 at 100mph; anything wanting to travel at higher speeds than that must not exceed those forces, which complicates the engineering of the bogies and final drive, as well as limiting the overall weight of the locomotive. It is where the Pendolinos and Voyager/Meridian sets score by distributing the power throughout the train, keeping the axle loads down, and putting the traction motors under the body, with shaft drive to one axle on each bogie.

 

An interesting debate on the merits of loco hauled vs unit trains. Although loco hauled have a number of advantages, including of appeal from an enthusiast's perspective, axle loadings and track forces are a major factor in limiting high speed running. I believe the HST was designed as a unit with two separate power cars in order to comply with these requirements.

Although of coarse an electric loco can be made with sufficient power and still meet axle loadings for high speed running, another factor not previously mentioned is adhesion, which restricts further development in high speed locos.

Modern trains require greater tractive power for the higher performances that are being demanded, but the existing class 91s on the east coast, with 6000hp on an 80 tonne loco already push the limits of adhesion - quite frankly, the b*gg*ers will slip if a cloud comes over! The sanders on them are very much a necessity, whereas in good conditions they'll quite happily, for example, cruise up Stoke Bank at 125, on a wet rail with defective sands you're lucky to manage more than 80

[Coryton]

How many passengers actually use the gangways, other than to get to the catering facilities or a toilet that works, or to get ot the front of the train before arriving at the terminus. Not having inter-unit gangways is a disadvantage only to the latter, who perhaps ought to learn to be more patient.

 

Ooh let's see.

 

Passenger arrives late at Paddington (perhaps because of delays on the tube) and has to get on at the first door they come to, then walk down the train to their reserved seat. But they can't. Even worse, the portion they are in isn't even going where they are.

 

Passenger at intermediate station is standing in the wrong place and gets into the wrong portion...see above.

 

Passenger needs to talk to the guard. But he's in the other part of the train. Or do you run with two guards? 

 

Passenger without a reservation gets onto the train, and wants to walk down to the other end where there are some free seats. But they can't get there.

 

Passenger wants a cup of tea. But the trolley/open buffet is in the other part of the train. Or do you duplicate the catering facilities?

 

Train is running late and the passenger risks missing what should have been an easy connection. They want to walk to the right door to have the shortest dash to get their next train and not have to wait an hour and a half for the next one. But their reserved seat was in the wrong half for that.

 

These are all things I have done or seen done on GWR HSTs.

 

Now I'm not saying that therefore running double sets is wrong, but I don't see that it helps to say that there aren't any disadvantages either when clearly there are.

 

How many passengers actually use the gangways, other than to get to the catering facilities or a toilet that works, or to get ot the front of the train before arriving at the terminus. Not having inter-unit gangways is a disadvantage only to the latter, who perhaps ought to learn to be more patient.

 

[Rob F]

 

 

The view form the front was nice though, enough to forgive them for, the sheer wonder of the Heart Of Wales or the Cambrian from the front seat was pure joy though I never did make it from one end of the HoW to the other without falling asleep.

 

It was always noticeable how despite all the noise and vibration those trains were a great cure for insomnia, on a run half of every coach could be guaranteed to fall asleep.

It was probably carbon monoxide poisoning!

 

Rob

[RJS1977]

Operation Princess was far too optimistic, with many services being only four car and five car at the most, and being cross country was also a much more complex operation involving endless conflicting pathing arrangements.

 

The timetable was simply not robust enough and when things went belly up, which was often, could inevitably mean large numbers of passengers trying to cram themselves into just four cars.

 

There will be plenty of nine car IEP sets around on GW and, on the core route, many of the five car sets will be working in pairs (or even maybe more).

 

Expect five car units to be let out alone in Cornwal or through the Cotswolds but on the core route probably only on the slower stopping services or fill in services such as that to Pewsey.

 

A good comparison to make would probably be the Meridians on the EMT network where seven car, five car, four car and peak time five car plus four car operate, plus of course HSTs. Most of the more important busier services are well appointed with the slower stopping trains being shorter formations.

 

I'm not aware of any overcrowding difficulties out of St Pancras but stand to be corrected if this is not so.

 

In some regards, it wasn't optimistic enough. Passenger numbers increased by 40% after Operation Princess, which would have been a big contributor to the overcrowding problems. Some of the issues were also caused by a desire by Network Rail to reverse Birmingham/Bournemouth trains in the bay platforms at Reading (3 and the old 7), restricting their length.

 

To my mind (as a weekend user) the biggest issue has been on the Leamington - Birmingham via Birmingham International section as the single track between Leamington Spa and Coventry means only an hourly service can serve Coventry and BMI.

 

I haven't noticed the engine noise in a Voyager as being particularly obtrusive, my only issue with the trains themselves is the reduced luggage space caused by the shelves having been designed for tilting trains.

[Reorte]

I haven't noticed the engine noise in a Voyager as being particularly obtrusive, my only issue with the trains themselves is the reduced luggage space caused by the shelves having been designed for tilting trains.

I've found it very much depends upon which coach you're in (is the engine usually off in one, or is one of them unpowered?). It's not too bad in the others but definitely noticable. To be honest I think the Voyagers come in for an unfair amount of criticism (my general dislike of anything vaguely modern notwithstanding), their problem is that they're just too busy for a lot of what they're used on, and the seating too crammed in. But the basic design isn't too terrible and although when they first appeared by initial impression was of commuter trains with ideas above their station when you get one that isn't crowded, and get a decent seat, they're comfortable enough for medium distance journeys.

[Ron Ron Ron]

With regards to loco-hauled versus unit trains and the issue of underfloor engines; I think it's worth pointing out that the Intercity Express Programme started out as the HST2 programme (i.e. a plan to specify and procure a diesel powered replacement for the HST's).

 

Having looked at the various options of format (e.g. loco hauled, push and pull, HST type, DMU etc), the existing format of driving cars containing the power plants was chosen, but with the important difference of having distributed traction along the length of the train. The biggest significant advantage over the trains they would replace.

Loco-hauled was by far the worst option, based on several negative points.

 

As we know, HST2 morphed into the IEP (a broader remit).

Again, loco-hauled and other formats were discounted, based on various criteria.

The IEP specification called for diesel variants to have the diesel generator power plants located in a similar way...in the driving car.

The winning interpretation of the IEP spec., Hitachi's "Super Express Train" (a term that now appears to have been dropped), followed that requirement, going one step further, saving more weight by having no traction motors in those driving power cars.

 

Underfloor engines did not feature in the IEP specification, nor in the selected design.

The change to underfloor engines came later on, after the all-diesel variant was dropped (following the U-turn on electrification of the GWML) and as a response to misgivings regarding the power capability of the Bi-mode version running on diesel (using such a power format, i.e. one diesel plus one electric driving cars).

 

The later 2010 Foster review into the IEP, also independently looked back over the original requirements, including the format.

Again the loco-hauled option came out as the worst choice.

The same conclusion that has been accepted in Germany, Netherlands, France, Italy, Spain, Japan, China and just about anywhere else in the more developed world, barring one or two specific situations.

 

 

.