Avanti IET Speeds

[DorkingMain]

We have gone backwards. Tilting infrastructure and they ordered a non-tilting train. They might as well have taken surplus class 90s with Mark IV carriages.

What exactly is "tilting infrastructure"?

 

[Railperf]

What exactly is "tilting infrastructure"?

For a start, Balises have to be installed on the track at various locations. These tell the train what speed it can travel at and whether it can tilt over that section of track or not. In the UK at least - no track balises = no tilt.

Also the track geometry would be set up differently if you want non-tilt trains to run at the same speed as a tilting train on the same curve. The track would probably have to have more cant applied - i.e raising the outer rail of the track on a curve to allow a non-tilt train to take that curve. A tilting train doesn't need so much cant in the track because the train body leans into the curve instead.

It does seem a bit crazy to order new trains that will end up running slower. Obviously IETs are basically the default option these days and almost all First operations have them, but how much extra would it have cost to give the west coast ones tilting capabilities? They're already ordering their own spec of them as it is.

I'm not sure Alstom were able to build any more Class 390's. Did i read somewhere that the Class 390 design does not meet the latest standard of crash protection? So a huge redesign would be on the cards.

I'm not sure the cost of redeveloping that design for a handful of trains would have been financially viable for the TOC or manufacturer. So a compromise seems to have been met by ordering a current 125mph tried and tested train.
(Saying that, the Neville Hill crash didn't exactly glorify the class 80x standards of crashworthiness!)

 

[Nym]

And the eurobalises are starting to approach life expiry and would need to be replaced when ETCS is fully rolled out onto the West Coast anyway.

 

[Wapps]

For a start, Balises have to be installed on the track at various locations. These tell the train what speed it can travel at and whether it can tilt over that section of track or not. In the UK at least - no track balises = no tilt.

Also the track geometry would be set up differently if you want non-tilt trains to run at the same speed as a tilting train on the same curve. The track would probably have to have more cant applied - i.e raising the outer rail of the track on a curve to allow a non-tilt train to take that curve. A tilting train doesn't need so much cant in the track because the train body leans into the curve instead.


I'm not sure Alstom were able to build any more Class 390's. Did i read somewhere that the Class 390 design does not meet the latest standard of crash protection? So a huge redesign would be on the cards.

I'm not sure the cost of redeveloping that design for a handful of trains would have been financially viable for the TOC or manufacturer. So a compromise seems to have been met by ordering a current 125mph tried and tested train.
(Saying that, the Neville Hill crash didn't exactly glorify the class 80x standards of crashworthiness!)

Hitachi make titling trains. I don’t know why IET wasn’t, and why HS2 stock won’t be, spec’d to have a tilting option - Class 80T.
Could Alston not have adapted one of their latest tilting trains to the UK network?

 

[Domh245]

Hitachi make titling trains. I don’t know why IET wasn’t, and why HS2 stock won’t be, spec’d to have a tilting option - Class 80T.
Could Alston not have adapted one of their latest tilting trains to the UK network?

Building a tilt 80x would have meant redesigning the entire bodyshell to accommodate the tilt profile, and adding several tonnes to the weight of each vehicle (which are heavy enough as it is). The reason HS2 (and why the rest of IEP) didn't go for tilting stock is because the extra weight has real world implications for maintenance and energy consumption, and away from the WCML, no benefit.

Alstom could have adapted one of their latest tilting trains, but it would have cost significant amounts of money to develop, and would have taken a long time to introduce. There's also no guarantee that they'd be able to offer it as a bi-mode which is rather important to half of the units that have been ordered

 

[Wapps]

Building a tilt 80x would have meant redesigning the entire bodyshell to accommodate the tilt profile, and adding several tonnes to the weight of each vehicle (which are heavy enough as it is). The reason HS2 (and why the rest of IEP) didn't go for tilting stock is because the extra weight has real world implications for maintenance and energy consumption, and away from the WCML, no benefit.

Alstom could have adapted one of their latest tilting trains, but it would have cost significant amounts of money to develop, and would have taken a long time to introduce. There's also no guarantee that they'd be able to offer it as a bi-mode which is rather important to half of the units that have been ordered

Understood. To my mind, having a train that can fulfil the full service on the most important mainline (upgraded to tilt capability at a cost of many billions) is a good enough reason to commission a version of IET or at least HS2 rolling stock that has the tilt profile and heavier infra. The heavier tilting version would only be for the WCML, which already has the heavier 390s and 221s running, so it’s not like the replacement would suddenly be a shock to the WCML maintenance programme.

My presumption is that HS2 rolling stock will be the replacement for the 390s.

 

[Nym]

It wasn't the tilt that cost billions on infrastructure.
Some eurobalises reading via a data diode on the signalling isn't that expensive. The tilt allowed the benefit of a billions upgrade to be felt in real terms.

 

[Railperf]

My presumption is that HS2 rolling stock will be the replacement for the 390s.

Probably for the main destinations: Liverpool, Manchester and Glasgow/ Edinburgh - yes.
But there install a need for people from places such as Milton Keynes, Rugby , Trent Valley etc, that are going to want a service that gets them to these destinations at least as fast as they are now including connections or directly.
Why should the service from these towns be degraded with slower non-tilt services, if the capacity and technology exists to provide a fast interconnecting service.
HS2 is also going to serve Sheffield Leeds and north ECML towns, so it isn't a WCML replacement. More a bypass for the congested southern end of WCML, ECML and MML.

 

[Energy]

I'm not sure Alstom were able to build any more Class 390's. Did i read somewhere that the Class 390 design does not meet the latest standard of crash protection? So a huge redesign would be on the cards.

Yep, the 4 extra units (maybe the extensions to 11 car as well, not sure as they aren't end vehicles so may still be fine) got through as they classified them as replacements for the unit lost at Grayrigg.

 

[Wapps]

Probably for the main destinations: Liverpool, Manchester and Glasgow/ Edinburgh - yes.
But there install a need for people from places such as Milton Keynes, Rugby , Trent Valley etc, that are going to want a service that gets them to these destinations at least as fast as they are now including connections or directly.
Why should the service from these towns be degraded with slower non-tilt services, if the capacity and technology exists to provide a fast interconnecting service.
HS2 is also going to serve Sheffield Leeds and north ECML towns, so it isn't a WCML replacement. More a bypass for the congested southern end of WCML, ECML and MML.

I couldn’t agree more. It’s bonkers to me that we are going backwards.

 

[Ianno87]

Probably for the main destinations: Liverpool, Manchester and Glasgow/ Edinburgh - yes.
But there install a need for people from places such as Milton Keynes, Rugby , Trent Valley etc, that are going to want a service that gets them to these destinations at least as fast as they are now including connections or directly.
Why should the service from these towns be degraded with slower non-tilt services, if the capacity and technology exists to provide a fast interconnecting service.
HS2 is also going to serve Sheffield Leeds and north ECML towns, so it isn't a WCML replacement. More a bypass for the congested southern end of WCML, ECML and MML.

And there'll still be fleet of Pendolinos with at least 10 years left in them that will be looking for use.

Yep, the 4 extra units (maybe the extensions to 11 car as well, not sure as they aren't end vehicles so may still be fine) got through as they classified them as replacements for the unit lost at Grayrigg.

And probably more economic do build 4 trains (plus 11 car extra vehicles) rather than 1 single train.

I couldn’t agree more. It’s bonkers to me that we are going backwards.

But we're not. Pendolinos are staying, and buying a small fleet of non-tilting trains is uneconomic, especially with HS2 part replacing the current Pendolino service in the not too distant future.

 

[hexagon789]

I couldn’t agree more. It’s bonkers to me that we are going backwards.

By not procuring tilting trains?

I'd argue it makes more sense to do exactly that.

 

[Energy]

By not procuring tilting trains?

I'd argue it makes more sense to do exactly that.

Got to find a manufacturer wanting to build them. The 390s aren't compliant anymore and you can't sneak them past like with the 4 extra sets claiming they are replacing a derailed train. If we could order more 390s then those 10 would be. Alstom were willing to build them last time partly because little work was needed (the bodyshells had been built in Italy before) and because the extensions to 11 car meant that is wasn't too small.

 

[hexagon789]

Got to find a manufacturer wanting to build them. The 390s aren't compliant anymore and you can't sneak them past like with the 4 extra sets claiming they are replacing a derailed train. If we could order more 390s then those 10 would be. Alstom were willing to build them last time partly because little work was needed (the bodyshells had been built in Italy before) and because the extensions to 11 car meant that is wasn't too small.

That's what I was saying - that it made more sense to NOT procure tilting trains.

 

[mjmason1996]

Is the acceleration of an IET really that much quicker than a 390, to keep time despite being none EPS though? from the few times ive been on 390s I wouldn't exactly consider them sluggish, I mean their not replacing 91's or HSTs here.

 

[hwl]

Is the acceleration of an IET really that much quicker than a 390, to keep time despite being none EPS though? from the few times ive been on 390s I wouldn't exactly consider them sluggish, I mean their not replacing 91's or HSTs here.

IET weights a lot less which has a lot of advantages for braking as well as acceleration, especially if you have them doing quite a few stops and want some as bi-modes

 

[Bletchleyite]

Is the acceleration of an IET really that much quicker than a 390, to keep time despite being none EPS though? from the few times ive been on 390s I wouldn't exactly consider them sluggish, I mean their not replacing 91's or HSTs here.

They're fairly sluggish. Up to a fair speed a 350 will easily pull ahead.

 

[hexagon789]

They're fairly sluggish. Up to a fair speed a 350 will easily pull ahead.

I think it's about 80 before a 390 starts to take a lead against a 350.

 

[Domh245]

They're fairly sluggish. Up to a fair speed a 350 will easily pull ahead.

They may be sluggish, but as timed by @Railperf there's only 20 seconds between a 390 and an IET to 125mph (post #22)

 

[hexagon789]

Is the acceleration of an IET really that much quicker than a 390, to keep time despite being none EPS though? from the few times ive been on 390s I wouldn't exactly consider them sluggish, I mean their not replacing 91's or HSTs here.

To be fair I thought it was slower!

Going off Virgin publicity if the time the Pendolinos apparently could reach 125 in 3.5 mins (no idea if that's correct or total rubbish), while recent LNER publicity said the Azumas were a minute quicker to 125 than the IC225s - so 4.5 mins.

That would make an IET a minute slower to 125.

 

[Bletchleyite]

I wonder if that meant on diesel?

 

[hexagon789]

They may be sluggish, but as timed by @Railperf there's only 20 seconds between a 390 and a 350 to 125mph (post #22)

I thought they were referring to 390s vs IETs?

I wonder if that meant on diesel?

If what meant on diesel?

 

[Domh245]

I thought they were referring to 390s vs IETs?

Indeed Railperf (and @mjmason1996) were talking about 390 vs 80x - I just wrote the wrong thing!

I wonder if that meant on diesel?

LNER's 800s won't hit 125mph on diesel AFIAK (at least, not without the aid of gradients!)

 

[Bletchleyite]

If what meant on diesel?

The suggestion of 80x being slower to 125 than Pendolinos. They certainly don't feel that way - Pendolinos are a bit slow off the mark, whereas 80x accelerate hard like Desiros. Perhaps they have more low-down grunt?

 

[hexagon789]

Indeed Railperf (and @mjmason1996) were talking about 390 vs 80x - I just wrote the wrong thing!

No worries, I just started wondering if I'd read/interpreted it wrongly!

LNER's 800s won't hit 125mph on diesel AFIAK (at least, not without the aid of gradients!)

I think it's about 117/118 non-uprated 80x manage on diesel on the level iirc? There was an article in Rail Express with some logs when the IETs were new and I believe that was the highest the 800s managed until the software was changed to give them 802 performance on diesel.

The suggestion of 80x being slower to 125 than Pendolinos. They certainly don't feel that way - Pendolinos are a bit slow off the mark, whereas 80x accelerate hard like Desiros. Perhaps they have more low-down grunt?

I understood that would be the case, but I also thought that the 80x had a higher power-to-weight ratio?

 

[Metal_gee_man]

So a Class 801 accelerates at 0.70m/s² or 1.6mph per second
A class 390 accelerates at 0.43m/s² or 0.96mph per second

This means a class 801 with the taps open can hit 125mph in 78 seconds
And a class 390 with the taps open can hit 125mph in 130 seconds

A difference of 52 seconds

So a purely electric 801 is quicker to its top speed

 

[hexagon789]

So a Class 801 accelerates at 0.70m/s² or 1.6mph per second
A class 390 accelerates at 0.43m/s² or 0.96mph per second

This means a class 801 with the taps open can hit 125mph in 78 seconds
And a class 390 with the taps open can hit 125mph in 130 seconds

A difference of 52 seconds

So a purely electric 801 is quicker to its top speed

Those will be maximum acceleration rates, there's no way an 80x makes 125 in under 1 minute 20.

 

[DorkingMain]

And the eurobalises are starting to approach life expiry and would need to be replaced when ETCS is fully rolled out onto the West Coast anyway.

This is exactly my thinking - realistically the cost of building tilting trains was significantly more expensive than the sunk cost of "tilting infrastructure". The idea of tilting trains was to accommodate, if anything, for the lower quality of the infrastructure on the WCML

 

[Domh245]

I think it's about 117/118 non-uprated 80x manage on diesel on the level iirc? There was an article in Rail Express with some logs when the IETs were new and I believe that was the highest the 800s managed until the software was changed to give them 802 performance on diesel.

The whole situation with diesel engine "uprating" (/ceiling removal) is far too complex for me to keep up with!

So a Class 801 accelerates at 0.70m/s² or 1.6mph per second
A class 390 accelerates at 0.43m/s² or 0.96mph per second

This means a class 801 with the taps open can hit 125mph in 78 seconds
And a class 390 with the taps open can hit 125mph in 130 seconds

A difference of 52 seconds

So a purely electric 801 is quicker to its top speed

You've mistaken peak acceleration for acceleration. 80x are designed to hold ~0.75ms/s^2 up to about 45kph, before then tapering off towards higher speeds (which when you plot the power required gives a lovely straight line from about 45kph onwards!)

This shows the acceleration profile that IEP units are supposed to achieve (although when you run the maths, they do slightly better as this profile gets them to 200kph in about 4:20 compared to the timed 3:00

 

[hexagon789]

The whole situation with diesel engine "uprating" (/ceiling removal) is far too complex for me to keep up with!

Good point - I should really have put downrating rather than uprating as 700kW is the normal rating rather than an uprated figure.

I think the difference is purely that GWR 80x are all 700kW, LNER's are the derated 560kW and I presume that as Hull Trains and TPE are both 802 users that their units are thus 700kW.

I.e. only LNER runs 80x with down rated engines?

This shows the acceleration profile that IEP units are supposed to achieve (although when you run the maths, they do slightly better as this profile gets them to 200kph in about 4:20 compared to the timed 3:00

Which would make sense as the source of LNER's one minute quicker to 125mph claim, 4:20 would be around a minute quicker than an IC 225 conservatively estimated.