ScotRail HST Introduction - Updates & Discussion

Paul Kerr · 22 Jul 2018

najaB said:
I suppose it depends on the specific carriage - I agree that there some squeeky Mk.3s but the engine noise is definitely an issue with Voyagers, no matter what carriage.

Agreed, and with a properly executed overhaul the squeaks and rattles on the MK3 will go away.

RailUK Forums

Rail Blues · 22 Jul 2018

Paul Kerr said:
When you say "efficiency" I say cost. If cost were the only factor, then I would agree with you, but cost needs to be balanced against other factors. Every argument I have seen for a multiple unit is based on cost, pure and simple

Not just cost, distributed traction generally allows for faster acceleration all other things being equal and maximises use of platform space.

gsnedders · 22 Jul 2018

Paul Kerr said:
Every argument I have seen for a multiple unit is based on cost, pure and simple.

There's also the argument that if you have a 200m platform, you can either have a 8*23m multiple unit or 1+7 LHCS, and therefore you can fit more people on one train. In plenty of places that's a significant difference. (Yes, ultimately you can extend the platforms, which makes it arguably based on cost, but as we see with the Queen Street platform extensions can be ridiculously expensive.)

Rail Blues · 22 Jul 2018

Paul Kerr said:
Agreed, and with a properly executed overhaul the squeaks and rattles on the MK3 will go away.

Depends on whether this is possible given the state of the mk 3s given comments from those who are/have worked on them they appear to be in a pretty bad state and whether it is possible to get them lucked into shape. It remains to be seen.

I do still think the argument that they're supremely comfortable is shaped in part by a degree of nostalgia and cognitive bias (and I am probably guilty of that in the opposite direction too, expecting them to be noisy and rough riding and actively listening for squeaks)

najaB · 22 Jul 2018

Rail Blues said:
...and maximises use of platform space.

Why? The cab doesn't need to be adjacent to the platform at most stations.

gsnedders · 22 Jul 2018

najaB said:
Why? The cab doesn't need to be adjacent to the platform at most stations.

It's terminus stations where platform length is significant, given typically being beyond the platform makes you foul points and often puts you beyond the starter signal.

The_Engineer · 22 Jul 2018

najaB said:
Why? The cab doesn't need to be adjacent to the platform at most stations.

Can be critical at terminal stations

Paul Kerr · 22 Jul 2018

gsnedders said:
There's also the argument that if you have a 200m platform, you can either have a 8*23m multiple unit or 1+7 LHCS, and therefore you can fit more people on one train. In plenty of places that's a significant difference. (Yes, ultimately you can extend the platforms, which makes it arguably based on cost, but as we see with the Queen Street platform extensions can be ridiculously expensive.)

Fair point, but that's not really a consideration for the lengths of train being run in Scotland. 2+4 and 2+5 with a few 2+6 sets later on. The main platforms in Queen Street were extended to accommodate 7 and 8 car class 385's anyway so the platform length won't be an issue. At Waverley, the western bays are more than adequate, as are the through platforms at Stirling, Perth and Dundee. Platform length might be a consideration if this was being considered for destinations south of the border but it's a bit of a red herring in Scotland.

Paul Kerr · 22 Jul 2018

Rail Blues said:
Not just cost, distributed traction generally allows for faster acceleration all other things being equal and maximises use of platform space.

Not sure I buy the distributed traction argument. We were told that the 158s and later the 170s would be an improvement acceleration wise on the loco hauled Mk3 sets they replaced due to distributed traction and it certainly did not turn out that way. I think to put that one to be we would need to test a 4 car voyager against a 2+4 HST as the power to mass ratio will be pretty much identical. As an engineer I'm very data driven so I would happily admit I'm wrong if the data shows it

jingsmonty · 22 Jul 2018

Journeyman said:
Yes, they've given sterling service for 40 years - and this is precisely why we should be retiring them. They've been belting up and down at full power for years, and the things are falling to pieces. Attempting to patch them up for further use is not a good idea.

170s are not "a joke", I travel on them frequently and find them much more spacious and comfortable than a lot of other trains. The seat/window alignment is good, the seats are comfortable and well spaced, and there's a good mix of airline and table seats. I do appreciate something better is needed for long runs, though - I've already said that.

Short HSTs are fuel-inefficient because the power to weight ratio is unnecessarily high - with a DMU it's more or less constant regardless of the length of the train - and the HST has very basic control systems that don't optimise power output. It's designed for prolonged high power operation at maximum speed, with a longer train, and anything less than that is operating at sub-optimal efficiency. The things are enormous gas guzzlers in the form they're going to operate in.

They're also not cheaper to lease than newer trains, and the Variable Usage Charge, related to axle load, is high because you've got a fairly heavy loco at each end, which makes them more expensive to operate than a multiple unit. It's not a problem with longer sets as it all evens out due to the trailers having lower VUC charges, but for the length and capacity of the train in the shorter setup, VUC charges are steep.

Having driven the HST training train on the HML, I would say that the performance on the steep gradients is nothing short of phenomenal - think 80mph line speed (at intermediate power notch), as opposed to 50-55mph at full throttle in a 158 or 170. Given the high power/weight ratio, you tend to spend a lot of time coasting - it's been calculated that they will be slightly more economical than a 4 car 158. Presumably this would have been considered & been found to be a better option than a 4/5 coach with 1 power car & a dvt? Trust me, the acceleration is game changing!

As for comfort - I have travelled down on the training train & have also travelled North on a 170 - no comparison, Mk3 every time! The 170 had knackered aircon on a hot day & usual HML summer train issues of full toilets, grossly inefficient luggage storage & not enough seats. These trains, I predict, will be a hit with the Scottish public - comfier coaches & quicker trains. The 170s are NOT InterCity trains!

New rolling stock may have been an option (I was half expecting the HSTs to ve cancelled & an add on order for bi-mode Hitachi class 802s instead, but HST is a good option).

The HST clearly isn't the most up to date train out there, but it is as tough as old boots & a proven design.

Even HST power cars with brand new Mk5 coaches (with compatible electrics & a coupler change on the power cars) might have been an option, but a Mk3 with power doors & retention tank toilets will still be far superior to what we have now!

InOban · 22 Jul 2018

Remember that when these trains eventually arrive there will not only be more seats on each train, there will be more trains.

BRX · 22 Jul 2018

Any more news on the bike storage? Is a load of potential storage space still going to be locked out of use in the power cars?

jingsmonty · 23 Jul 2018

BRX said:
Any more news on the bike storage? Is a load of potential storage space still going to be locked out of use in the power cars?

Power car bike storage will be available, but only for end to end journeys, not intermediate stations. Seems to miss a trick, I think....

GrimShady · 23 Jul 2018

Just wondering how a shove duff or 68 Mk 5 set would compare to a similar HST set in terms of acceleration?

Paul Kerr · 23 Jul 2018

GrimShady said:
Just wondering how a shove duff or 68 Mk 5 set would compare to a similar HST set in terms of acceleration?

Looking at the raw numbers, a 47/7 set would be blown out of the water by a short formation HST, and it even looks a class 170 look good

One of the short formations used on the E&G (3 TSOs, 1 CO and 1 DBSO) would weigh about 284 tonnes. The 47s were derated from 2750hp to 2580hp; assuming 90% transmission efficiency through the generator and traction motors reduces the power at rail to 2090hp. That gives you a ratio of ~7.4hp per tonne.

A class 68 with 5 Mk5's would be a lot closer in terms of performance but the HST is still way out in front. The Class 68 weighs 85 tonnes and each Mk5 weighs 43 tonnes, so that gives a total of 300 tonnes. The class 68 engine output is 3800hp, assuming the same power transmission loss ratios as the class 47 reduces your power at rail to 3078hp. That gives a power to mass ratio of ~10.3hp per tonne. So the HST would still considerably outperform a TPE set (~12hp per tonne for a 5 coach HST and 13.4hp per tonne for the HST with 4 coaches).

GrimShady · 23 Jul 2018

Paul Kerr said:
Looking at the raw numbers, a 47/7 set would be blown out of the water by a short formation HST, and it even looks a class 170 look good One of the short formations used on the E&G (3 TSOs, 1 CO and 1 DBSO) would weigh about 284 tonnes. The 47s were derated from 2750hp to 2580hp; assuming 90% transmission efficiency through the generator and traction motors reduces the power at rail to 2090hp. That gives you a ratio of ~7.4hp per tonne.

A class 68 with 5 Mk5's would be a lot closer in terms of performance but the HST is still way out in front. The Class 68 weighs 85 tonnes and each Mk5 weighs 43 tonnes, so that gives a total of 300 tonnes. The class 68 engine output is 3800hp, assuming the same power transmission loss ratios as the class 47 reduces your power at rail to 3078hp. That gives a power to mass ratio of ~10.3hp per tonne. So the HST would still considerably outperform a TPE set (~12hp per tonne for a 5 coach HST and 13.4hp per tonne for the HST with 4 coaches).

Thanks for the info Paul. Wouldn't a 47/7 still be better than a 170 though? They were quicker than the 158s from memory.

Paul Kerr · 23 Jul 2018

jingsmonty said:
Having driven the HST training train on the HML, I would say that the performance on the steep gradients is nothing short of phenomenal - think 80mph line speed (at intermediate power notch), as opposed to 50-55mph at full throttle in a 158 or 170. Given the high power/weight ratio, you tend to spend a lot of time coasting - it's been calculated that they will be slightly more economical than a 4 car 158. Presumably this would have been considered & been found to be a better option than a 4/5 coach with 1 power car & a dvt? Trust me, the acceleration is game changing!

As for comfort - I have travelled down on the training train & have also travelled North on a 170 - no comparison, Mk3 every time! The 170 had knackered aircon on a hot day & usual HML summer train issues of full toilets, grossly inefficient luggage storage & not enough seats. These trains, I predict, will be a hit with the Scottish public - comfier coaches & quicker trains. The 170s are NOT InterCity trains!

New rolling stock may have been an option (I was half expecting the HSTs to ve cancelled & an add on order for bi-mode Hitachi class 802s instead, but HST is a good option).

The HST clearly isn't the most up to date train out there, but it is as tough as old boots & a proven design.

Even HST power cars with brand new Mk5 coaches (with compatible electrics & a coupler change on the power cars) might have been an option, but a Mk3 with power doors & retention tank toilets will still be far superior to what we have now!

Thanks for the great info; this really does blow the argument about performance and supposed poor fuel efficiency out of the water! Looking at the performance numbers of the bimodes from Rail Engineer I for one am glad ScotRail didn't spec a bimode as I think we would have paid more and been sold short. It quotes the 9 car VTEC units at 6.4kW (~8.6hp) per tonne and the 5 car units at 6.9kW (9.2hp) per tonne. The 5-car class 802s for GWR are quoted at 8.6kW (~11.5hp per tonne) so on paper a 5 coach HST will give better performance; all that without having to live with the compromise of an engine under the floor

https://www.railengineer.uk/2017/10/24/bi-mode-trains-unlocking-opportunity/

For all the flak Abellio got for going with the HSTs I think they will be a great success once the overhauls are completed. As you mention they are old but they are a proven platform. For all the fanfare surrounding the bimodes, they have not really been proven as reliable (yet); if the teething problems are anything like the farce we saw with the Voyagers we could be in for a rough ride on that front (I hope that doesn't happen but we'll see)...

Paul Kerr · 23 Jul 2018

GrimShady said:
Thanks for the info Paul. Wouldn't a 47/7 still be better than a 170 though? They were quicker than the 158s from memory.

From the raw numbers it appears not (9.4hp per tonne for a 170 vs 7.4hp per tonne for a 47/7), unless there are big losses from the hydraulic transmissions. The 158s also have higher hp per tonne than a 47/7 with push pull set (9.3hp per tonne) but I believe they would overheat due to cooling system issues if pushed too hard which was the reason why the 47/7s ended up being quicker. The 47/7 also was rated for 100mph maximum vs 90mph for a 158! That's "progress" for you

Journeyman · 23 Jul 2018

Rail Blues said:
Depends on whether this is possible given the state of the mk 3s given comments from those who are/have worked on them they appear to be in a pretty bad state and whether it is possible to get them lucked into shape. It remains to be seen.

I do still think the argument that they're supremely comfortable is shaped in part by a degree of nostalgia and cognitive bias (and I am probably guilty of that in the opposite direction too, expecting them to be noisy and rough riding and actively listening for squeaks)

The Mark 3 was undoubtedly a good design in its day, but just about any modern train is better.

GAVIN YATES · 23 Jul 2018

So, what would we have replacing the HST's in 2030? The question is open ended as it does depend upon government policy and specification for track and train eg how far will electrification go beyond the Central Belt

Journeyman · 23 Jul 2018

Paul Kerr said:
For all the flak Abellio got for going with the HSTs I think they will be a great success once the overhauls are completed.

But how long is that going to take? I thought the HSTs were a good idea when it was first announced, but it's becoming clearer by the day that this is turning out badly. The refurbishments and overhauls are throwing up all sorts of unexpected problems and GWR HST reliability is absolutely dreadful - you're potentially importing that problem to Scotland, and the first time one of these breaks down in service, which won't take long with an MTIN of only about 5000, the negative publicity will be absolutely dreadful.

New trains should have been ordered, and as already said, there's plenty of very good options out there.

jingsmonty · 23 Jul 2018

Journeyman said:
The Mark 3 was undoubtedly a good design in its day, but just about any modern train is better.

I wouldn't agree with that - the refurbishment will cure the main deficiencies of the mk 3 (slam doors & untanked toilets). They compare very well to any modern teain I've been on. They don't have the constricting 'tilt' profile of Voyagers or Mk4s, have far better/bigger windows than a Pendolino & don't have the under engine noise/vibration of 180s/185s (or any other long distance DMU/DEMU).

Only weak points left I would say are the creaky gangways & 1970s couplers (alliance buckeye), but that's not a big deal to me. Mk3 is, arguably, the best coach ever used on the UK railway!

However, I would be interested to see what the Mk5s are like - even given the age difference, it'll have to be something special to beat the impact Mk3 had!

jingsmonty · 23 Jul 2018

Journeyman said:
But how long is that going to take? I thought the HSTs were a good idea when it was first announced, but it's becoming clearer by the day that this is turning out badly. The refurbishments and overhauls are throwing up all sorts of unexpected problems and GWR HST reliability is absolutely dreadful - you're potentially importing that problem to Scotland, and the first time one of these breaks down in service, which won't take long with an MTIN of only about 5000, the negative publicity will be absolutely dreadful.

New trains should have been ordered, and as already said, there's plenty of very good options out there.

You're missing the point that the HST won't be worked anything like as hard as they were on GWR - they were thrashed at full throttle at 125mph day in, day out. On Scotrail, they are restricted to 100mph & will spend a lot of time coasting. It's like a semi-retirement for them!
Granted, I'd agree that they will need more exams/maintenance/tlc than a 170/158, but, given the state of some of the DMUs, that isn't necessarily a bad thing....

Bletchleyite · 23 Jul 2018

jingsmonty said:
However, I would be interested to see what the Mk5s are like - even given the age difference, it'll have to be something special to beat the impact Mk3 had!

They look quite nice from the outside, but seem to have small windows and on the TPE ones window alignment reminiscent of a Class 313. The WCML EMUs are much better, shame they didn't deliver a LHCS vehicle based on those.

43096 · 23 Jul 2018

jingsmonty said:
You're missing the point that the HST won't be worked anything like as hard as they were on GWR - they were thrashed at full throttle at 125mph day in, day out. On Scotrail, they are restricted to 100mph & will spend a lot of time coasting. It's like a semi-retirement for them!
Granted, I'd agree that they will need more exams/maintenance/tlc than a 170/158, but, given the state of some of the DMUs, that isn't necessarily a bad thing....

Full throttle? Not with a Bristol driver....

It will certainly be interesting to see how ScotRail get on with them given their lack of experience with them. In particular, how they deal with the GEC traction motors will be interesting.

47802 · 23 Jul 2018

jingsmonty said:
Having driven the HST training train on the HML, I would say that the performance on the steep gradients is nothing short of phenomenal - think 80mph line speed (at intermediate power notch), as opposed to 50-55mph at full throttle in a 158 or 170. Given the high power/weight ratio, you tend to spend a lot of time coasting - it's been calculated that they will be slightly more economical than a 4 car 158. Presumably this would have been considered & been found to be a better option than a 4/5 coach with 1 power car & a dvt? Trust me, the acceleration is game changing!

As for comfort - I have travelled down on the training train & have also travelled North on a 170 - no comparison, Mk3 every time! The 170 had knackered aircon on a hot day & usual HML summer train issues of full toilets, grossly inefficient luggage storage & not enough seats. These trains, I predict, will be a hit with the Scottish public - comfier coaches & quicker trains. The 170s are NOT InterCity trains!

New rolling stock may have been an option (I was half expecting the HSTs to ve cancelled & an add on order for bi-mode Hitachi class 802s instead, but HST is a good option).

The HST clearly isn't the most up to date train out there, but it is as tough as old boots & a proven design.

Even HST power cars with brand new Mk5 coaches (with compatible electrics & a coupler change on the power cars) might have been an option, but a Mk3 with power doors & retention tank toilets will still be far superior to what we have now!

Well I a bit sceptical about the fuel economy you quote but I will take your word for it, I doubt they will be on a par maintenance cost wise with a 4 car 158 that's for sure.

Anyway while I'm with "Journeyman" on this it is really a pointless debate the decision has been made and Abellio will no doubt get on with it Wabtec permitting which looks like a very long wait from what we have seen so far. I don't doubt many customers will see them as an improvement because they are superior to newer trains in many respects but they wont last forever. My view is new franchises shouldnt be allowed to cascade in stock over 30 years old other than for short term measure or exceptional circumstances.

The idea of Semi-Retirement, hmm not sure about that one they still be working an intensive daily service, and what happens if reliability proves to be substancially lower than the stock they replace?

GrimShady · 23 Jul 2018

I for one will be glad to see them in service, when that finally happens!

I would have thought Mk5 would have made more sense though.

gingertom · 23 Jul 2018

43096 said:
Full throttle? Not with a Bristol driver....

It will certainly be interesting to see how ScotRail get on with them given their lack of experience with them. In particular, how they deal with the GEC traction motors will be interesting.

seeing a lot of talk here about GEC traction motors. Is there some sort of issue with them compared to the Brush equivalents?

gingertom · 23 Jul 2018

Paul Kerr said:
From the raw numbers it appears not (9.4hp per tonne for a 170 vs 7.4hp per tonne for a 47/7), unless there are big losses from the hydraulic transmissions. The 158s also have higher hp per tonne than a 47/7 with push pull set (9.3hp per tonne) but I believe they would overheat due to cooling system issues if pushed too hard which was the reason why the 47/7s ended up being quicker. The 47/7 also was rated for 100mph maximum vs 90mph for a 158! That's "progress" for you

there is a significant difference in traction characteristics between the HST/class 43 and class 68. Gearing for top speed has an effect as does AC traction motors vice DC.
The 68 can put down 317kN of tractive effort whereas the pair of HSTs can only deliver 160 initially and 94 continuous up to 64mph. This makes the 68 go like a rocket away from a standing start with acceleration of 1m/s/s up to 17mph before it tails off. 2+5 HST can only achieve 0.5, tailing off to 0.3 but it can sustain this acceleration rate to 64mph.

jingsmonty · 23 Jul 2018

gingertom said:
seeing a lot of talk here about GEC traction motors. Is there some sort of issue with them compared to the Brush equivalents?

I've read that the GEC traction motors caused endless problems when these power cars were built (1980/81ish, I believe?), but, surely now, over 35 Years on, the issues have been solved! I am a bit suprised that Scotrail didn't go for the Brush motored ones, rather than a mixture, just to maintain a common part?

ScotRail HST Introduction - Updates & Discussion

Member

RailUK Forums

Member

Established Member

Member

Veteran Member

Established Member

Member

Member

Member

Member

Established Member

Established Member

Member

Established Member

Member

Established Member

Member

Member

Established Member

New Member

Established Member

Member

Member

Veteran Member

On Moderation

Established Member

Established Member

Established Member

Established Member

Member