Avanti IET Speeds

[Railperf]

802s will get to 125mph on diesel. Ive done it between Reading and Paddington. I've also had sets that couldn't manage it, so I think it depends on various factors, probably including which way the wind is blowing and how hard!!!
But to those saying it can't be done, they really need to try a bit harder!!

I had an 802 reach 125mph - from Swindon to Chippenham going down Dauntsey bank - we were doing 115mph at the top and would have needed around 10 minutes to get to 125mph if it hadn't been for the sharp 1 in 100 descent.
But yes - you need a very healthy set of GU's no headwind and a light load. The gradients from Swindon are favourable downhill 1 in 660 until the 1 in 100 at Dauntsey.

In comparison a Class 800 (on different engine settings) on the same stretch of track just hours earlier had only managed 105mph by the top of the bank and 115mph at the bottom. That set eventually managed a peak of 119mph before braking for Chippenham.

You need a decent stretch of track to achieve the 125mph on diesel...i reckon 10 miles or more. Maybe some drivers have some mechanical sympathy for them and don't bother wringing the trains neck for that last few mph. So painfully slow is the acceleration at those speeds.

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It does initially seem plausible that there may be locations where the speed limit could be raised easily enough.

From:

Crewe - Norton Bridge Jn

Colwich Jn - just north of Atherstone

Just south of Atherstone - Kilsby Tunnel

Stowe Hill Tunnel - Watford Junction

The line speed is 125EPS all the way for 390’s (221’s have a 115 through Linslade tunnel and through Berkhamsted).

A lot of these sections are mostly straight with little curvature, are there not points here where the limit could be raised?

If you combine the EPS speeds on straight tracks with the non EPS speeds through the tunnels and more severe curves, then you have an idea of what the profile could look like.
Then it will most likely depend which curves can be banked more to allow the non EPS limit to be raised through them.

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I'm no expert, but I did read on this forum some time ago that HSTs cut the power at 123.5mph, so that they would never exceed 125mph even on a down gradient - as that would cause the brakes to be automatically applied. (It always struck me as a waste of 1.5mph and why didn't they set the overspeed sensors to say 126 mph?) Are we sure that the engine management on 802s will actually permit them to reach 125mph in normal running, even if the raw power is available?

I've seen a genuine 129mph down Stoke Bank on an HST - when i felt a 'jolt' as power was cut - either driver reducing power or overspeed cutting power to one of the power cars. As far as i know, brakes are not applied by the system.

We have seen 125mph + on 800/802 - mainly in electric mode - when the driver is not using the speed set or speed hold device.

In the late HST days at GWR, the HST's would rarely ever run at more than 122/123mph - but that was apparently due to trains having very worn wheel sets - which could cause the ATP equipment to warn of an overspeed. Apparently ATP does not compensate for wheel set wear.

 

[Bald Rick]

Then it will most likely depend which curves can be banked more to allow the non EPS limit to be raised through them.

From my knowledge of the WCML alignment design, there is precious little ability to ‘bank’ (add further superelevation) to any of the track. It is generally sltready at the optimum compromise for high speed running and lower speed freight.

What there is scope for is increasing the cant deficiency at non EPS speeds. That translates directly into a more ‘interesting’ experience for the passenger.

 

[Railperf]

From my knowledge of the WCML alignment design, there is precious little ability to ‘bank’ (add further superelevation) to any of the track. It is generally sltready at the optimum compromise for high speed running and lower speed freight.

What there is scope for is increasing the cant deficiency at non EPS speeds. That translates directly into a more ‘interesting’ experience for the passenger.

Really then, what you are saying is that it is just an exercise about deciding where to run the trains faster without causing too much discomfort to passengers and preventing personal items flying around the cabin as the trains enter those curves. Do the transitions into and out of the curves need some adjustment?

== Doublepost prevention - post automatically merged: 1 Feb 2021 ==

From my knowledge of the WCML alignment design, there is precious little ability to ‘bank’ (add further superelevation) to any of the track. It is generally sltready at the optimum compromise for high speed running and lower speed freight.

Wasn't one of the arguments for being able to increase Non EPS speeds partly to do with the fact that freight speeds are increasing/have increased - and therefore a lower gap between the fastest and slowest trains? Meaning that superelevation could be increased a little more?

 

[LNW-GW Joint]

It does initially seem plausible that there may be locations where the speed limit could be raised easily enough.

From:
Crewe - Norton Bridge Jn
Colwich Jn - just north of Atherstone
Just south of Atherstone - Kilsby Tunnel
Stowe Hill Tunnel - Watford Junction
The line speed is 125EPS all the way for 390’s (221’s have a 115 through Linslade tunnel and through Berkhamsted).
A lot of these sections are mostly straight with little curvature, are there not points here where the limit could be raised?

Some of those sections actually have highly curved bits.
There are steep reverse curves at Whitmore, Rugeley-Armitage, even through Lichfield (on the new TV4 section), through Rugby, at Weedon etc.
They all require maximum tilt, usually both ways is quick succession.
Queensville (Stafford)-Colwich is another awkward stretch, albeit at lower than 125mph.

The route is mostly signed with relatively few deviations from 110/125EPS, with even fewer EPS differentials for 221s.
If there are restrictions at the locations listed there will be a multiplicity of new signage, changing every few miles.
If the limit on the signage is 3 speeds, Avanti/NR will have to wait till all the 221s are off the property before re-signing the middle speed for 80x.
Or alternatively maybe they could limit the 221s to whatever new 80x speed profile is authorised, until they leave the WCML.
There are "slim-line" speed boards in places already where space is restricted - eg on the centre tracks at Colwich and Atherstone.
The OHLE may also have to be realigned in some places for 80x - currently it is optimised for 390 performance.

 

[Nottingham59]

In the late HST days at GWR, the HST's would rarely ever run at more than 122/123mph

That's probably what I remember reading about. Thanks for the explanation.

 

[hexagon789]

I've seen a genuine 129mph down Stoke Bank on an HST - when i felt a 'jolt' as power was cut - either driver reducing power or overspeed cutting power to one of the power cars. As far as i know, brakes are not applied by the system.

The overspeed just cuts the traction power, only the ATP fitted on the GWML would apply any braking effort

In the late HST days at GWR, the HST's would rarely ever run at more than 122/123mph - but that was apparently due to trains having very worn wheel sets - which could cause the ATP equipment to warn of an overspeed. Apparently ATP does not compensate for wheel set wear.

Not that they needed to run at 125 continously anyway, the timings were generally pretty lax. As I recall the two up morning peak services which ran non-stop Swindon-Paddington were timed for only an ~80mph average, hardly quick high enough to need more than modest 100+ running.

 

[greatvoyager]

I’d like to think that all of this would’ve been thought of when the 805/807 was ordered, but based on what’s been brought up here, I’m not hopeful.

 

[southern442]

They will on electric.

Sorry, I should have made myself clear. I meant for Avanti. They might as well have gotten bi-mode 350's.

 

[The Planner]

Really then, what you are saying is that it is just an exercise about deciding where to run the trains faster without causing too much discomfort to passengers and preventing personal items flying around the cabin as the trains enter those curves. Do the transitions into and out of the curves need some adjustment?

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Wasn't one of the arguments for being able to increase Non EPS speeds partly to do with the fact that freight speeds are increasing/have increased - and therefore a lower gap between the fastest and slowest trains? Meaning that superelevation could be increased a little more?

I don't believe any infrastructure interventions are being planned. A line speed profile already exists and has for some time, though it may have altered from the version I have seen.

 

[southern442]

I’d like to think that all of this would’ve been thought of when the 805/807 was ordered, but based on what’s been brought up here, I’m not hopeful.

That's what I think. It almost seems as if they just joined the giddy wave of ordering IEPs without thinking it through properly. My 350 comment above was slightly tongue-in-cheek, but I reckon there is another type of unit out there that might be able to do a better job if one considers the fact that they will never break 110mph for the most part.

 

[hexagon789]

I’d like to think that all of this would’ve been thought of when the 805/807 was ordered, but based on what’s been brought up here, I’m not hopeful.

My understanding was they were ordered on the basis of HS2 - that is they wouldn't be needed to offer as fast as service as the present WCML and so ordering designs based as closely to the existing 80x would be simpler and would suffice.

 

[Railperf]

The overspeed just cuts the traction power, only the ATP fitted on the GWML would apply any braking effort




Not that they needed to run at 125 continously anyway, the timings were generally pretty lax. As I recall the two up morning peak services which ran non-stop Swindon-Paddington were timed for only an ~80mph average, hardly quick high enough to need more than modest 100+ running.

Yes, but even when these were running late they still rarely exceeded 122/123.

 

[Bald Rick]

Really then, what you are saying is that it is just an exercise about deciding where to run the trains faster without causing too much discomfort to passengers and preventing personal items flying around the cabin as the trains enter those curves. Do the transitions into and out of the curves need some adjustment?

In my view the transitions don’t need changing, as the rate of change of cant meets standards (obviously) but I recall someone elsewhere on the forum suggesting they do.

Wasn't one of the arguments for being able to increase Non EPS speeds partly to do with the fact that freight speeds are increasing/have increased - and therefore a lower gap between the fastest and slowest trains? Meaning that superelevation could be increased a little more?

If that was an argument, it was not a good one. The issue is heavy trains at 60mph.

If the limit on the signage is 3 speeds, Avanti/NR will have to wait till all the 221s are off the property before re-signing the middle speed for 80x.

The different profile for the 221s is not signed. The three speeds that are signed are (effectively)

1) freight
2) passenger
3) EPS

 

[greatvoyager]

That's what I think. It almost seems as if they just joined the giddy wave of ordering IEPs without thinking it through properly. My 350 comment above was slightly tongue-in-cheek, but I reckon there is another type of unit out there that might be able to do a better job if one considers the fact that they will never break 110mph for the most part.

Maybe it will all work out.

My understanding was they were ordered on the basis of HS2 - that is they wouldn't be needed to offer as fast as service as the present WCML and so ordering designs based as closely to the existing 80x would be simpler and would suffice.

Ah okay, that makes sense.

 

[CW2]

In my view the transitions don’t need changing, as the rate of change of cant meets standards (obviously) but I recall someone elsewhere on the forum suggesting they do.

If that was an argument, it was not a good one. The issue is heavy trains at 60mph.

The different profile for the 221s is not signed. The three speeds that are signed are (effectively)

1) freight
2) passenger
3) EPS

The transitions will need adjusting, unless somebody takes the pragmatic decision that they can be done whenever the area is next tamped, and we can live with the slight excitement / discomfort in the mean time.

Agreed re the 60 mph freights - and particularly on the hilly sections where going uphill they will be at their slowest, and grinding away at the low rail.

There are a few instances where differential EPS is applied i.e. different speeds for 221s and 390s. Linslade Tunnel on the Up is one, complicated by the fact that the track spacing leaves no room for a full size 3-speed sign, so the 221 differential starts all the way back at Bletchley. (That may have changed in recent years - I haven't double checked the Sectional Appendix).

 

[hexagon789]

Yes, but even when these were running late they still rarely exceeded 122/123.

Well I would say that was for the reason you outlined, no?

 

[LNW-GW Joint]

The different profile for the 221s is not signed. The three speeds that are signed are (effectively)
1) freight
2) passenger
3) EPS

Well eg at Weedon, unless it has changed recently, it's signed as 100 over EPS110/120.
I take that to mean non-tilt is 100mph, 221 is 110EPS and 390 is 120EPS.
There are about 3-4 other such differential signs as far as Crewe.

 

[The Planner]

Well eg at Weedon, unless it has changed recently, it's signed as 100 over EPS110/120.
I take that to mean non-tilt is 100mph, 221 is 110EPS and 390 is 120EPS.
There are about 3-4 other such differential signs as far as Crewe.

They will go for a PS (which will cover the freight), MU and EPS. If 221s go then there won't be a need for split EPS speeds.

 

[Bald Rick]

Well eg at Weedon, unless it has changed recently, it's signed as 100 over EPS110/120.
I take that to mean non-tilt is 100mph, 221 is 110EPS and 390 is 120EPS.
There are about 3-4 other such differential signs as far as Crewe.

I stand corrected, sorry.

 

[Boodiggy]

The transitions will need adjusting, unless somebody takes the pragmatic decision that they can be done whenever the area is next tamped, and we can live with the slight excitement / discomfort in the mean time.

Agreed re the 60 mph freights - and particularly on the hilly sections where going uphill they will be at their slowest, and grinding away at the low rail.

There are a few instances where differential EPS is applied i.e. different speeds for 221s and 390s. Linslade Tunnel on the Up is one, complicated by the fact that the track spacing leaves no room for a full size 3-speed sign, so the 221 differential starts all the way back at Bletchley. (That may have changed in recent years - I haven't double checked the Sectional Appendix).

Yep it change a few years back but as a full size board is needed it is on a gantry by the 42mp so the differential is shorter.

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Well eg at Weedon, unless it has changed recently, it's signed as 100 over EPS110/120.
I take that to mean non-tilt is 100mph, 221 is 110EPS and 390 is 120EPS.
There are about 3-4 other such differential signs as far as Crewe.

This is the same for any EPS differential. Both EPS speeds are still displayed on a single board. Same at Berko, Linslsde and Rugby etc etc.

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They will go for a PS (which will cover the freight), MU and EPS. If 221s go then there won't be a need for split EPS speeds.

as is boarded at Trent Valley Jn - Rugby heading for Coventry.
There was a lot of talk last year or before that even 390s would be classed as MU to take advantage of those speeds when the tilt is having a sulk.... not sure what happened with that.

 

[paul1609]

Clearly it would have been cheaper to have ordered a fleet of non tilt 125mph electric trains than the 390's, but the timetable would have been slower, the running costs higher. The improved journey times gained by 125mph tilt and higher frequency have attracted more passengers = more revenue. You certainly would not have been able to offer London to Glasgow in 4h15mins with a non-tilting 125mph train. And as has been noted on other threads, the design speed was higher than that - 140mph.

In the case of the Pendolinos 140 mph wasn't only the design speed it was the contracted service speed. It was only the network Rail Monkeys that decided it was too difficult, on a project that was already shed loads over budget.

 

[CW2]

In the case of the Pendolinos 140 mph wasn't only the design speed it was the contracted service speed. It was only the network Rail Monkeys that decided it was too difficult, on a project that was already shed loads over budget.

To be fair, I think it was those Railtrack "monkeys" who naively signed up to deliver the undeliverable (within any reasonable sort of budget), and Network Rail who came in and sorted out the mess to deliver something sensible. The fact that Railtrack went bankrupt rather proves the point.

 

[a_c_skinner]

Are not lateral forces proportional to speed squared? I make that a bit less than 30% more going from 110 to 125 without tilt. Is that a clear difference to the passenger experience? This is about ride comfort alone isn't it?

 

[Railperf]

Are not lateral forces proportional to speed squared? I make that a bit less than 30% more going from 110 to 125 without tilt. Is that a clear difference to the passenger experience? This is about ride comfort alone isn't it?

Which is probably why maximum speeds of 115mph have been talked about round curves that Pendolini take at 125mph full tilt.

 

[Bald Rick]

Which is probably why maximum speeds of 115mph have been talked about round curves that Pendolini take at 125mph full tilt.

That would still be very lively. Weedon, for example, is 100mph without tilt, 125mph with. In the ‘good old days’ pre Pendolino (and pre OTMR) I was on a late running up train formed of Mark 3s, doing 110mph, and the driver, ahem, didn’t brake. Whilst the train saved a few seconds, there was a lot of coffee on the floor.

 

[Railperf]

That would still be very lively. Weedon, for example, is 100mph without tilt, 125mph with. In the ‘good old days’ pre Pendolino (and pre OTMR) I was on a late running up train formed of Mark 3s, doing 110mph, and the driver, ahem, didn’t brake. Whilst the train saved a few seconds, there was a lot of coffee on the floor.

Is there a comprehensive list of the curve radii on the WCML?

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That would still be very lively. Weedon, for example, is 100mph without tilt, 125mph with. In the ‘good old days’ pre Pendolino (and pre OTMR) I was on a late running up train formed of Mark 3s, doing 110mph, and the driver, ahem, didn’t brake. Whilst the train saved a few seconds, there was a lot of coffee on the floor.

Weedon may be subject to a slightly lower maximum in that case lol.

 

[Bald Rick]

Is there a comprehensive list of the curve radii on the WCML?

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Weedon may be subject to a slightly lower maximum in that case lol.

There certainly is a list, but it won’t be public!

Weedon isn’t the only one. Linslade, Berkhamsted and Rugby all have 20mph+ gaps between EPS and non EPS. As I’ve said before, Linslade on the Down Fast at 125 scares the wotsits out of me every time.

 

[LNW-GW Joint]

Is there a comprehensive list of the curve radii on the WCML?
Weedon may be subject to a slightly lower maximum in that case lol.

Weedon, as I've pointed out, is 100/110/120 for 350/221/390 respectively.
It's also, from memory, 4 successive curves, which southbound are: hard left, straighten up, hard left again, then hard right through the old station and finally hard left into Stowe Hill tunnel.
It's an extreme case, but the WCML is full of locations like that - Whitmore is another which has sharp reverse curves at 125mph for 221/390 (and no special signs) - what will 80x make of that section?
The question is whether 80x will be allowed 221 speeds at those locations (and elsewhere).
Logic suggests that without tilt, they will not.

 

[Railperf]

Weedon, as I've pointed out, is 100/110/120 for 350/221/390 respectively.
It's also, from memory, 4 successive curves, which southbound are: hard left, straighten up, hard left again, then hard right through the old station and finally hard left into Stowe Hill tunnel.
It's an extreme case, but the WCML is full of locations like that - Whitmore is another which has sharp reverse curves at 125mph for 221/390 (and no special signs) - what will 80x make of that section?
The question is whether 80x will be allowed 221 speeds at those locations (and elsewhere).
Logic suggests that without tilt, they will not.

I was part-watching the Video 125 London to Manchester cab ride - and it is astonishing how twisty the WCML is - and that was just Euston to Bletchley! I, m not sure that many 125mph non-tilt sections genuinely exist - even though i get the cab ride videos generally are zoomed into the distance that seems to magnify the curves.
Anyway, changing the stopping pattern and reducing the amount of intermediate stops saves around 4 mins per stop. So time loss for non-tilt could be offset by reducing the stopping pattern to just key Interchange stations.
The bi-modes will accelerate faster than 221's so there will also be a small time saving for each acceleration from rest to 125mph - even though it might not be more than 20 to 30 seconds per full acceleration. And there won't need to be any performance allowances based on 221's running occasionally with an engine or two out.

 

[hexagon789]

I was part-watching the Video 125 London to Manchester cab ride - and it is astonishing how twisty the WCML is - and that was just Euston to Bletchley! I, m not sure that many 125mph non-tilt sections genuinely exist - even though i get the cab ride videos generally are zoomed into the distance that seems to magnify the curves.

Perhaps also look at the older, pre-tilt Royal Scot Video125 DEV, to get a flavour of the line without any tilt!