Avanti IET Speeds

[The Planner]

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

There aren't many locations where 125mph is proposed full stop.

 

[James90012]

Of course one of the extra benefits of improving the profile for non-tilting trains is 390s with tilt faults would not lose as much time.

 

[Railperf]

Of course one of the extra benefits of improving the profile for non-tilting trains is 390s with tilt faults would not lose as much time.

Do they suffer many tilt faults these days? I've only ever experienced a Voyager run from Carlisle to Glasgow that was no tilt and still achieved it in under 70 mins. Otherwise, i've never experienced a tilt failure. On the other hand it is almost guaranteed you will experience a 180, 220, 221, 222, 800/802 with an engine out or running with a low power engine.

 

[hexagon789]

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.

Perhaps it won't.

However, I've always understood the US to be more conservative with cant deficiency than us, and last November I believe it was they passed certain non-tilt stock (Horizons & Amfleets, not sure on Superliners) to run at Tilt speeds on the entire Cascades corridor (Portland-Seattle-Vancouver).

So, if they can do that sort of change perhaps smaller ones here are possible?

 

[a_c_skinner]

The question is whether 80x will be allowed 221 speeds at those locations

I did wonder about that as a partial solution throughout. Northern ECML (and other locations IIRC) allows somewhat higher lateral forces than WCML I think all of which makes me wonder if we are being rather conservative about what is allowed. What about lateral forces on road coaches?

 

[XAM2175]

However, I've always understood the US to be more conservative with cant deficiency than us, and last November I believe it was they passed certain non-tilt stock (Horizons & Amfleets, not sure on Superliners) to run at Tilt speeds on the entire Cascades corridor (Portland-Seattle-Vancouver).

Still limited to 79 mph max regardless though, aren't they?

 

[hexagon789]

Still limited to 79 mph max regardless though, aren't they?

All trains on the route are subject to that ceiling, yes.

Freight is 59mph, Passenger & Talgo are up to 79.

I did wonder about that as a partial solution throughout. Northern ECML (and other locations IIRC) allows somewhat higher lateral forces than WCML I think all of which makes me wonder if we are being rather conservative about what is allowed. What about lateral forces on road coaches?

I think they are, the Continent seems to be more liberal in that way...

 

[Bald Rick]

Of course one of the extra benefits of improving the profile for non-tilting trains is 390s with tilt faults would not lose as much time.

I’ve been a regular Pendolino punter for 15 years, and only ever had one tilt failure, and that was a decade ago. It was also halfway around Weedon, which mean we went round a curve at 120mph with the tilt still partially the wrong way as it recovered to the centre. Noe that was interesting.

I did wonder about that as a partial solution throughout. Northern ECML (and other locations IIRC) allows somewhat higher lateral forces than WCML I think all of which makes me wonder if we are being rather conservative about what is allowed.

It’s an extra 40mm of cant deficiency (from 110mm to 150mm). For comparison, the Pendolino runs at a maximum of 300mm can’t deficiency, with 200mm of it negated to the passenger by the tilt.

So going to the 150mm, which you will definitely know about as a passenger, would give 5mph, perhaps 10mph if the rounding works in your favour.

EDIT
I’ve found some public info, it’s a 26 page technical document so not really quotable. Note it is nearly six years old, and heavily caveated.

Report:

https://www.whatdotheyknow.com/request/396674/response/968390/attach/6/170420%20HS2%20West%20Coast%20Line%20speed%20Study%20Report%20V2.0%202%20NR%20report%20Redacted.pdf

Full request including links to the speed graphs

HS2 Capacity and Tilt - a Freedom of Information request to Department for Transport

In response to a written question from Lord Berkeley on the 23rd February 2017 the written response by Lord Ahmad, dated 9th March 2017, includes the statement :- "HS2 Ltd assumes that tilting rolling stock could achieve a maximum operating speed on the high speed network of 300km/h rather than...

www.whatdotheyknow.com

 

[LNW-GW Joint]

Fascinating stuff, and shows NR is on top of the HS2 requirement at least, to save 10-12 minutes on the PS speed profile of the northern WCML.
It looks like a similar speed profile to EPS is theoretically possible with 75-ish physical interventions on the track alignment (each way), plus 20-odd signage changes.
A price tag of around £100m is quoted, probably to be taken with a large bowlful of salt, and down to HS2 Ltd to fund.
That's for Handsacre-Glasgow, and I would assume Handsacre-Crewe will not actually now be needed if HS2 phase 2a is delivered contemporaneously with Phase 1.

Either way is doesn't consider the southern WCML which is where the 80x requirement is, or who would fund those interventions.
Interestingly, a possible speed profile higher than EPS on some sections is considered, assuming ETCS is implemented.
As Mr Rick says, there are lots of caveats about detailed track design and the constraints of other disciplines (OHLE, signalling, maintenance etc).

 

[a_c_skinner]

So going to the 150mm, which you will definitely know about as a passenger

I've been an ECML regular and not really a noticed a difference. Upthread someone suggests that big country "abroad" works to a less conservative standard. The question of what it is like on a coach or bus remains at the back of my mind too.

 

[Bald Rick]

I've been an ECML regular and not really a noticed a difference. Upthread someone suggests that big country "abroad" works to a less conservative standard. The question of what it is like on a coach or bus remains at the back of my mind too.

Depends which part of the ECML you are on. The 150mm (6 degrees in old money) only applies north of Newcastle (and possibly around Durham, I can’t remember). Same applies on the MML between Bedford and Leicester, and also the Berks and Hants.

As for “Abroad” - the French and Germans use 150mm on some main lines, but absolutely not on the LGVs. Railroads in the US are limited to 76mm (3 inches).

 

[Railperf]

Fascinating stuff, and shows NR is on top of the HS2 requirement at least, to save 10-12 minutes on the PS speed profile of the northern WCML.
It looks like a similar speed profile to EPS is theoretically possible with 75-ish physical interventions on the track alignment (each way), plus 20-odd signage changes.
A price tag of around £100m is quoted, probably to be taken with a large bowlful of salt, and down to HS2 Ltd to fund.
That's for Handsacre-Glasgow, and I would assume Handsacre-Crewe will not actually now be needed if HS2 phase 2a is delivered contemporaneously with Phase 1.

Either way is doesn't consider the southern WCML which is where the 80x requirement is, or who would fund those interventions.
Interestingly, a possible speed profile higher than EPS on some sections is considered, assuming ETCS is implemented.
As Mr Rick says, there are lots of caveats about detailed track design and the constraints of other disciplines (OHLE, signalling, maintenance etc).

By the time the engineers look at it, the cost will have spiralled to around £500m - and half the improvements will be canned because they are too complicated, expensive or some other issue - leaving around 4-5 minutes of real time improvements.

Nevertheless fascinating to see they forecast matching EPS journey times. One wonders why this wasn't done in the first place!! Saying that, the times are based on performance modelling of a specific HS trainset (blanked out) which may have better acceleration than a Pendolino.

 

[Bald Rick]

By the time the engineers look at it, the cost will have spiralled to around £500m - and half the improvements will be canned because they are too complicated, expensive or some other issue - leaving around 4-5 minutes of real time improvements.

Given that this study is nearly 6 years old, I think you can assume that if it was going to happen, you’d have heard something by now.

It also goes show that in the majority of cases it is not as ‘simple’ as changing a few signs.

 

[hexagon789]

As for “Abroad” - the French and Germans use 150mm on some main lines, but absolutely not on the LGVs. Railroads in the US are limited to 76mm (3 inches).

3 inches without tilt that is. Acela and the Talgos are allowed to run with 6" though the BNSF imposes a 5" limit fir the Talgos to allow for less maintenance, they were designed for 9" and 12" respectively but various 'local issues' and the FRA put pay to that.

 

[Railperf]

Given that this study is nearly 6 years old, I think you can assume that if it was going to happen, you’d have heard something by now.

It also goes show that in the majority of cases it is not as ‘simple’ as changing a few signs.

I noticed the transitions into curves were mentioned re: lengthening them.

 

[Bald Rick]

3 inches without tilt that is. Acela and the Talgos are allowed to run with 6" though the BNSF imposes a 5" limit fir the Talgos to allow for less maintenance, they were designed for 9" and 12" respectively but various 'local issues' and the FRA put pay to that.

Indeed - although I understood the FRA limit to be 12” - ie almost the same as our 300mm.

== Doublepost prevention - post automatically merged: 2 Feb 2021 ==

I noticed the transitions into curves were mentioned re: lengthening them.

Indeed. It also said that the existing transitions were to standard (as I recalled).

 

[hexagon789]

Indeed - although I understood the FRA limit to be 12” - ie almost the same as our 300mm.

Yes, I make it 305mm but there is nothing that actually runs to that - Acela is the greatest with 152mm. They also don't tilt as much as they could, I think 4 degrees max instead of the design 7.