Scotrail HST alternatives?

[Meerkat]

I think there's no sense in going down the line of "but building a locomotive is impossible", because clearly building a locomotive isn't impossible. And if you can build one with cabs you can build one without and shove it in the middle if you want. Though you might also want to put it at one end instead.

If it couldn't share the bogies, you could have it on its own. Stadler offers both options. Basically if you want to do it and it can be done with the modular components, Stadler will do it for you, even if you only want a few.

There is also the option of having more than one power module. You could perhaps have three in a six-car train with two engines in each (allowing more space for cooling kit and potential battery addition).

Multiple power modules is going to eat capacity and platform length though. Are there any space issues with having more motor bogies - I assume you would want more than two if you get longer units than Anglia and start going up hills?

 

[hexagon789]

Multiple power modules is going to eat capacity and platform length though. Are there any space issues with having more motor bogies - I assume you would want more than two if you get longer units than Anglia and start going up hills?

Vy have 5-car 200km/h sets with three motor bogies (1500kW per bogie), so it can be done.

 

[gingertom]

Multiple power modules is going to eat capacity and platform length though. Are there any space issues with having more motor bogies - I assume you would want more than two if you get longer units than Anglia and start going up hills?

Would be interesting for ScotRail to borrow an East Anglia 755/4 for a week and see how it performs over the various routes. Gather some data and make an informed choice. However I think obtaining clearance might prove to be a sticking point, never mind Anglia being able to release one.

 

[MarkyT]

Would be interesting for ScotRail to borrow an East Anglia 755/4 for a week and see how it performs over the various routes. Gather some data and make an informed choice. However I think obtaining clearance might prove to be a sticking point, never mind Anglia being able to release one.

With this train being so popular and flexible, perhaps Stadler and a leasing company should speculatively produce an extra tri-mode version from the end of the TfW order and demonstrate all over the UK.

 

[gingertom]

With this train being so popular and flexible, perhaps Stadler and a leasing company should speculatively produce an extra tri-mode version from the end of the TfW order and demonstrate for all over the UK.

with different internal layouts in the various carriages to show off how it could be set up. Excellent idea, but I'm sure the bean counters at Stadler and leasing company would want to have a firm guaranteed return on the investment.

 

[XAM2175]

We could build a bigger pod, move it to one end of the train, or if needed have one at each end of the train. You’d need a cab in that case and could put traction motors under it.

We could call it a “power car”…

To cover all the bases I'd like to take this moment to propose having two power packs back-to-back in the middle of the train, through which passengers cannot move unless being escorted by staff

 

[ld0595]

Lots more 170 and 158 substitutions between the central belt and Inverness/Aberdeen again today

 

[MarkyT]

To cover all the bases I'd like to take this moment to propose having two power packs back-to-back in the middle of the train, through which passengers cannot move unless being escorted by staff

Do you think tilt capability might have benefits in Scotland?

 

[Trainbike46]

Would be interesting for ScotRail to borrow an East Anglia 755/4 for a week and see how it performs over the various routes. Gather some data and make an informed choice. However I think obtaining clearance might prove to be a sticking point, never mind Anglia being able to release one.

The GA 755 fleet is relatively large, as it was intended operate some extra services that never materialised (hourly Ipswich-Peterborough, for example), so GA could surely temporarily provide one to Scotrail. route clearance might be harder, but then maybe you could get exemptions for testing, and have both a scotrail driver (for route knowledge) and a GA driver (for traction knowledge)

 

[XAM2175]

Do you think tilt capability might have benefits in Scotland?

I reckon yes, actually, and it's an idea that's been knocking around the back of my mind for a while now. Particularly on the Highland Main Line, the ability to take curves at a higher speed (20 to 40% higher was the very general estimate suggested by the APT research, if I remember correctly) would quite likely offer a noteworthy reduction in end-to-end journey times - and this has been conceptually validated by deployments of tilting regional and intercity trains in Japan, Germany, Czechia, and even Australia (plus a number of others that don't spring immediately to mind, I'm sure).

However, the extent of the benefits would depend on a lot of factors, and it's not automatically a given that they could be fully realised once you take into account the constraints of single-line sections and the timing of lower-speed trains. I also wouldn't want to assume that a new tilting train for the UK market could be developed and deployed at a cost that would be justifiable.

 

[ShadowKnight]

I'm not too clued up on the HST issues exactly other than drivers not wanting to drive them soon. Could a short term fix be that the HST sets just be hauled by another locomotive and the power cars just act as hotel power for the coaches?

Sort of like the class 73 + 66 setup on the highland sleeper?

 

[gingertom]

To cover all the bases I'd like to take this moment to propose having two power packs back-to-back in the middle of the train, through which passengers cannot move unless being escorted by staff

Do you think tilt capability might have benefits in Scotland?

Is there an attempt here to recreate the APT? Articulated bogies, tilt, 2x power pods in the centre.

 

[XAM2175]

I'm not too clued up on the HST issues exactly other than drivers not wanting to drive them soon.

The drivers-not-wanting-to-drive-them thing isn't solid other than that it's currently being negotiated.

Could a short term fix be that the HST sets just be hauled by another locomotive and the power cars just act as hotel power for the coaches?

Sort of like the class 73 + 66 setup on the highland sleeper?

It would require significant modifications, as HSTs were never designed to be hauled in service, only dragged (or, at a pinch, shoved) with a bar coupling. You'd also have the same problem of having to find the 30-plus locomotives going spare that could be brought in for the job.

Is there an attempt here to recreate the APT? Articulated bogies, tilt, 2x power pods in the centre.

Hah, well, my reference to back-to-back power packs was indeed an APT joke, but my answer to the tilt question was serious.

However, if we treat the "recreate the APT" point as being serious too, the finished product wouldn't actually have two power cars anyway: that configuration was only selected for the prototypes because the Research and Development Division felt it was essential to test the 250 km/h top speed and a single power car wouldn't have been able to reach that. It was assumed even before the prototypes entered service that the eventual production model would only have one power car, as it wouldn't need to run at above 200 km/h (and the plans for that configuration lead pretty much directly to InterCity 225).

Amusingly enough there was also a fairly serious plan for a diesel-powered APT, which would have used the same top-and-tail setup as the HST - except that each power car would have put out around 3000 hp purely for traction, with ETS supplied by a separate diesel genset in the TGS (or equivalent) coach. Preliminary design studies were reportedly drawn up, but the plan was subsequently shelved on the assumption that ongoing electrification would render it unnecessary.

 

[MarkyT]

Hah, well, my reference to back-to-back power packs was indeed an APT joke, but my answer to the tilt question was serious.

However, if we treat the "recreate the APT" point as being serious too, the finished product wouldn't actually have two power cars anyway: that configuration was only selected for the prototypes because the Research and Development Division felt it was essential to test the 250 km/h top speed and a single power car wouldn't have been able to reach that. It was assumed even before the prototypes entered service that the eventual production model would only have one power car, as it wouldn't need to run at above 200 km/h (and the plans for that configuration lead pretty much directly to InterCity 225).

Amusingly enough there was also a fairly serious plan for a diesel-powered APT, which would have used the same top-and-tail setup as the HST - except that each power car would have put out around 3000 hp purely for traction, with ETS supplied by a separate diesel genset in the TGS (or equivalent) coach. Preliminary design studies were reportedly drawn up, but the plan was subsequently shelved on the assumption that ongoing electrification would render it unnecessary.

I'm not a great advocate for tilt, in Scotland or anywhere else. With the Pendolino/Voyager designs the feature added a lot of weight, mainly in the more substantial bogies required, around 10t extra per car in the case of the 221s compared to the 220s for example. The extra weight is particulary galling for the XC 221s with their former tilt capability now removed while still being equipped with the heavy bogies that have to be accelerated up hills, affect track access charges due to higher axle loading, and performance of course. In any hybrid power proposals there will be competition in the weight budget with batteries, auxiliary engines etc. When Bombardier were promoting their WAKO mechatronic Flexx Eco bogies (a further development of the BREL B5000 as used under the 220s), there seemed hope that some small amount of tilt might be possible using much lighter weight bogies, but the Swiss Twindexx contract proved disastrous and the bogies on that fleet have had their dynamic yaw correction features isolated. That was supposed to be a key feature for higher speeds through Alpine bridges and tunnels due to dynamic envelope concerns and allowed a small amount of tilt as well. If a weight penalty of 20% or so is the price of tilt, I'd rather spend part of that budget on extra installed power so trains can accelerate out of curves and other restrictions more swiftly.

 

[XAM2175]

I'm not a great advocate for tilt, in Scotland or anywhere else. With the Pendolino/Voyager designs the feature added a lot of weight, mainly in the more substantial bogies required, around 10t extra per car in the case of the 221s compared to the 220s for example. The extra weight is particulary galling for the XC 221s with their former tilt capability now removed while still being equipped with the heavy bogies that have to be accelerated up hills ...

Fair enough, and I do agree that tilt is far from a panacea. The weight element was one of the factors that drove the choice of articulation for APT-P.

Re the Voyagers: arguably tilt was entirely wrong for them from the get-go, though I can understand the concerns regarding pathing on the WCML.

If a weight penalty of 20% or so is the price of tilt, I'd rather spend part of that budget on extra installed power so trains can accelerate out of curves and other restrictions more swiftly.

Also fair, and this is obviously something that is more practical with electric traction (and made more reasonable by advances in regenerative braking). Whether this provides journey time advantages that are comparable with a tilting train would vary on a line-by-line basis, though.

 

[MarkyT]

Fair enough, and I do agree that tilt is far from a panacea. The weight element was one of the factors that drove the choice of articulation for APT-P.

Re the Voyagers: arguably tilt was entirely wrong for them from the get-go, though I can understand the concerns regarding pathing on the WCML.

When the XC Voyagers were working on the WCML, it was probably seen as essential to exploit the enhanced speeds with TASS to keep up with the Pendolinos. With hindsight, it might have been possible to provide higher non-TASS speeds in many places, as being progressed now for accelerated non-tilt TPE services, which should also be useful for HS2 services to Scotland in the future. Meanwhile the Avanti 221s that still work extensively on the WCML retain tilt of course, while their replacements being delivered do not. On the originally proposed typical XC diagrams elsewhere for Operation Princess, the 221s couldn't match 220 performance due to the weight penalty on many segments. After that debacle and the redrawing and reletting of the franchise, standard point-to-point timings were adjusted upwards for the worst-case trains, and then some more for resilience.

Also fair, and this is obviously something that is more practical with electric traction (and made more reasonable by advances in regenerative braking). Whether this provides journey time advantages that are comparable with a tilting train would vary on a line-by-line basis, though.

Very much so, and trains with some traction batteries can capture braking energy for reuse in subsequent acceleration. That can be beneficial even under the wires where the line is not guaranteed to be receptive to power input from a decelerating train, although more modern substations could plausibly return some energy to the broader supply grid if other trains can't use it.

Another thing about higher speed in curves enabled by tilt is that bodyshells leaning does absolutely nothing to reduce track forces at the wheel, so both outer rail and wheel tread wear increase significantly. That has to be factored into cost calculations, including downtime and disruption for more frequent wheelset and rail reprofiling and replacement.

 

[Meerkat]

When the XC Voyagers were working on the WCML, it was probably seen as essential to exploit the enhanced speeds with TASS to keep up with the Pendolinos. With hindsight, it might have been possible to provide higher non-TASS speeds in many places, as being progressed now for accelerated non-tilt TPE services, which should also be useful for HS2 services to Scotland in the future. Meanwhile the Avanti 221s that still work extensively on the WCML retain tilt of course,

Were the 221s specced when the WCML was expected to go to 140mph?

 

[RailWonderer]

I'm not a great advocate for tilt, in Scotland or anywhere else. With the Pendolino/Voyager designs the feature added a lot of weight, mainly in the more substantial bogies required, around 10t extra per car in the case of the 221s compared to the 220s for example. The extra weight is particulary galling for the XC 221s with their former tilt capability now removed while still being equipped with the heavy bogies that have to be accelerated up hills, affect track access charges due to higher axle loading, and performance of course. In any hybrid power proposals there will be competition in the weight budget with batteries, auxiliary engines etc. When Bombardier were promoting their WAKO mechatronic Flexx Eco bogies (a further development of the BREL B5000 as used under the 220s), there seemed hope that some small amount of tilt might be possible using much lighter weight bogies, but the Swiss Twindexx contract proved disastrous and the bogies on that fleet have had their dynamic yaw correction features isolated. That was supposed to be a key feature for higher speeds through Alpine bridges and tunnels due to dynamic envelope concerns and allowed a small amount of tilt as well. If a weight penalty of 20% or so is the price of tilt, I'd rather spend part of that budget on extra installed power so trains can accelerate out of curves and other restrictions more swiftly.

I suggested tilting trains for Scotrail a while back and it was shot down for the same reasons as you state - higher track access charges from weight, and extra maintenance costs and lack of infrastructure to support it in many parts. Your solution is a better one for the infrastructure at the moment on the Scotrail network although given investments in line upgrades tilting trains would be beneficial.

Should Scotrail order tilting trains?

I was thinking Scotrail with its low line speeds and long sections of curved track could do with 100mph RegioSwinger type trains to allow 156s to scrap and a cascade of 158 sets and even a send off of the HST short sets. Reducing journey times would be the key to improving many of Scotland's...

www.railforums.co.uk

Were the 221s specced when the WCML was expected to go to 140mph?

I think so. The WCRM with Railtrack was carried out when the order for the Voyagers was placed when tilt was seen as the solution to reduce journey times. Nowadays faster acceleration and slight line speed increases are more attractive to NR and the DfT who fund it, especially in return for what will be a cheaper to order train than anything that tilts.

As much as I believe Scotrail would definitely benefit from tilting trains, the costs are too high especially in these times. Money less of a restriction and I think they'd be a wise choice. Panoramic tilting trains, icing on the cake.

 

[Meerkat]

I think so. The WCRM with Railtrack was carried out when the order for the Voyagers was placed when tilt was seen as the solution to reduce journey times. Nowadays faster acceleration and slight line speed increases are more attractive to NR and the DfT who fund it, especially in return for what will be a cheaper to order train than anything that tilts.

I assume tilt wouldn't have been chosen if the plan wasn't for 140mph?

 

[MattRat]

Re the Voyagers: arguably tilt was entirely wrong for them from the get-go, though I can understand the concerns regarding pathing on the WCML.

Also fair, and this is obviously something that is more practical with electric traction (and made more reasonable by advances in regenerative braking). Whether this provides journey time advantages that are comparable with a tilting train would vary on a line-by-line basis, though.

The Voyagers were just poorly designed. Too short, and too much crammed into the cabin (diesels and tilt). They should have had a rake of MK4 tilt carriages, and a pair of tilt diesel locos top and tail. Would have provided for more space in the cabin for passengers.

Would also work for Scotrail unlike the Voyager proposal that keeps getting thrown about on the forums.

 

[Bletchleyite]

The Voyagers were just poorly designed. Too short, and too much crammed into the cabin (diesels and tilt). They should have had a rake of MK4 tilt carriages, and a pair of tilt diesel locos top and tail. Would have provided for more space in the cabin for passengers.

Wha? I agree that Voyagers waste space, but engines don't affect the space in the cabin and Mk4s have a very similar tilt profile. They're just badly designed.

 

[MarkyT]

I assume tilt wouldn't have been chosen if the plan wasn't for 140mph?

I doubt 140mph was particularly important in the calculation due to:
1. Inability of Voyagers to reach that speed.
2. Low likelyhood of that speed being achievable by Pendolinos, with tilt, over much of the northern part of the WCML to Scotland.

The vast increase in mechanical and control complexity on every bogie is also important when considering tilt. I understand the reliability of XC 221s increased appreciably once the tilt capability was removed.

 

[JamesT]

I doubt 140mph was particularly important in the calculation due to:
1. Inability of Voyagers to reach that speed.
2. Low likelyhood of that speed being achievable by Pendolinos, with tilt, over much of the northern parts of WCML to Scotland.

The vast increase in mechanical and control complexity on every bogie is also important when considering tilt. I understand the reliability of XC 221s increased appreciably once the tilt capability was removed.

I assume the Tilt/Non-tilt calculation was much more focused on the potential costs of straightening out curvy bits of the WCML to be able to do >110mph without tilt.

 

[gingertom]

Hah, well, my reference to back-to-back power packs was indeed an APT joke, but my answer to the tilt question was serious.

Actually it might be a workable solution. A 6-car set with 2 power pods in the middle, each with a pair of diesels and a load of traction batteries would be a good fit. Once the wires arrive the power pods have a cascade path to other routes: Dumfries, Stranraer, Fort William, Mallaig, Oban, Far north, Kyle..?

 

[Mitchell Hurd]

Last months Modern Railways suggested that GWR were eyeing up those 158 (due to ditching 769s) when they eventually become available, so Scotrail may not get first dibs.

Were they??? Phew!

 

[HSTEd]

Perhaps it’s time for the SG to finally bite the bullet and invest in new rolling stock to replace the HST rather than pouring more good money after bad in this failed project.

Well that won't help very much given that that rolling stock will take years to arrive.

And I doubt the business case would provide anything like the capacity the HSTs have now if they are forced to buy new rolling stock for the service.

Will probably be back down to 3 car Turbostar-alikes.

Personally I thought this was probably a doomed effort from the start, but the powers that be wanted "intercity" trains without paying for them.

Now they pay twice.

 

[John Bishop]

Well that won't help very much given that that rolling stock will take years to arrive.

And I doubt the business case would provide anything like the capacity the HSTs have now if they are forced to buy new rolling stock for the service.

Will probably be back down to 3 car Turbostar-alikes.

Personally I thought this was probably a doomed effort from the start, but the powers that be wanted "intercity" trains without paying for them.

Now they pay twice.

Why wouldn’t it? If they went for Azuma, for example, they could run 5 car formations on most services which would be a big increase on the current offering, not withstanding a huge improvement in performance and reliability.

Any more dithering on awarding contracts is just extenuating the problem for longer and making the traveling public suffer even more.

 

[HSTEd]

Why wouldn’t it? If they went for Azuma, for example, they could run 5 car formations on most services which would be a big increase on the current offering, not withstanding a huge improvement in performance and reliability.

26 5-car IEPs is probably going to cost a signifiicantly greater amount to lease than the current fleet.

Does any Scotrail trains currently operate at above 100mph? 2+4 HSTs are limited to 100mph due to brakeforce limits.

 

[43096]

26 5-car IEPs is probably going to cost a signifiicantly greater amount to lease than the current fleet.

Does any Scotrail trains currently operate at above 100mph? 2+4 HSTs are limited to 100mph due to brakeforce limits.

2+4 HSTs are limited to 100mph in Scotland by the fact there’s no routes with >100mph limits. HSTs at other operators have operated at 125mph in 2+4 formation so there is no technical reason why it cannot be done.

 

[hexagon789]

Does any Scotrail trains currently operate at above 100mph?

No.

2+4 HSTs are limited to 100mph due to brakeforce limits.

The sets ran at 125mph on the ECML when delivered.