Avanti IET Speeds

[craigybagel]

There was no need to be quite so snarky - it's pointless arguing with you so let's leave it at that

TPE (I'm assuming thats you're operator by the mention of 802208) go over the hilly pennines which will undoubtably slow the train down more than flat land, I would imagine the 802s can get to 125mph, just on flatter land and at a push on diesel.

With all due respect, as someone who's experienced similar issues on this forum myself it can be extremely frustrating when you're a member of staff with first hand experience to be told you're wrong by a well meaning, but presumably ill informed enthusiast. This particular guard has access to the speedometer, and can talk to drivers. If they say 802s can't do 125mph on diesel then that's pretty definitive for me.

I would also like to think they're experienced enough to know that trains don't go as fast when going up the kind of hills experienced on the TPE network - and that in any case there is no 125 running West of Leeds anyway.

== Doublepost prevention - post automatically merged: 31 Jan 2021 ==

One thing I don't understand in this talk about infrastructure - surely there are straight parts of the WCML that could have their non EPS speeds upgraded above 110mph without too much effort. I'm thinking Preston - Lancaster for example, or parts of the Trent Valley. Clearly the signalling, track and OLE are already good for higher speeds - so what's stopping non EPS trains running at higher speeds?

 

[Railperf]

One thing I don't understand in this talk about infrastructure - surely there are straight parts of the WCML that could have their non EPS speeds upgraded above 110mph without too much effort. I'm thinking Preston - Lancaster for example, or parts of the Trent Valley. Clearly the signalling, track and OLE are already good for higher speeds - so what's stopping non EPS trains running at higher speeds?

As i understand it, there are some curves which will require further banking to allow non-tilt trains to run faster through them than at present. Tilting trains tapered body profile allows them to lean without fouling the infrastructure, but i suspect there are a number of places that you cannot bank the track too much because a non-tilt train's loading gauge could foul other bits of infrastructure - such as through tunnels etc.

Could it also be that some of the braking distances - while okay for 140mph Pendolino's - might not be sufficient for some other types of rolling stock capable of 125mph.
If so, it could mean relocating some signals too.
There complication in the UK as opposed to some European countries is that we won't post more than two speed limits for any section of track. In Italy for example, there are boards with up to four posted limits for different categories of stock, plus a 'P' Pendolino limit (usually not posted but found in their sectional appendix 'Fascicolo Linea' and on the ''scheda treno' (train schedule).

 

[craigybagel]

As i understand it, there are some curves which will require further banking to allow non-tilt trains to run faster through them than at present. Tilting trains tapered body profile allows them to lean without fouling the infrastructure, but i suspect there are a number of places that you cannot bank the track too much because a non-tilt train's loading gauge could foul other bits of infrastructure - such as through tunnels etc.

Could it also be that some of the braking distances - while okay for 140mph Pendolino's - might not be sufficient for some other types of rolling stock capable of 125mph.
If so, it could mean relocating some signals too.
There complication in the UK as opposed to some European countries is that we won't post more than two speed limits for any section of track. In Italy for example, there are boards with up to four posted limits for different categories of stock, plus a 'P' Pendolino limit (usually not posted but found in their sectional appendix 'Fascicolo Linea' and on the ''scheda treno' (train schedule).

Point accepted with regards to the loading guage issue - but I would have hoped they'd have the foresight to set the breaking distances for the signals at the normal standard for 125mph running used elsewhere on the network?

Also, I can think of at least two locations on the WCML (and I'm sure there are others) where there are 3 different speed limits - two different EPS speeds (higher for pendolinos and lower for voyagers) plus a non EPS. Weaver Junction and Berkhemsted come to mind straight away.

 

[Energy]

With all due respect, as someone who's experienced similar issues on this forum myself it can be extremely frustrating when you're a member of staff with first hand experience to be told you're wrong by a well meaning, but presumably ill informed enthusiast. This particular guard has access to the speedometer, and can talk to drivers. If they say 802s can't do 125mph on diesel then that's pretty definitive for me.

Of course, I was simply pointing out that it can vary depending on the infrastructure. I'm not too suprised they can't quite reach 125mph given the lower amount of power compared to voyagers and adelantes.

 

[hexagon789]

With all due respect, as someone who's experienced similar issues on this forum myself it can be extremely frustrating when you're a member of staff with first hand experience to be told you're wrong by a well meaning, but presumably ill informed enthusiast. This particular guard has access to the speedometer, and can talk to drivers. If they say 802s can't do 125mph on diesel then that's pretty definitive for me.

I would also like to think they're experienced enough to know that trains don't go as fast when going up the kind of hills experienced on the TPE network - and that in any case there is no 125 running West of Leeds anyway.

== Doublepost prevention - post automatically merged: 31 Jan 2021 ==

One thing I don't understand in this talk about infrastructure - surely there are straight parts of the WCML that could have their non EPS speeds upgraded above 110mph without too much effort. I'm thinking Preston - Lancaster for example, or parts of the Trent Valley. Clearly the signalling, track and OLE are already good for higher speeds - so what's stopping non EPS trains running at higher speeds?

I wasn't intended to come across as not believing them per se, I just wondered why some staff say they can and some say they can't. Is the engine management set-up on GWR 800/802s sufficiently different to that on TPE 802s to produce a discrepancy in balancing speed?

 

[Railperf]

Point accepted with regards to the loading guage issue - but I would have hoped they'd have the foresight to set the breaking distances for the signals at the normal standard for 125mph running used elsewhere on the network?

Also, I can think of at least two locations on the WCML (and I'm sure there are others) where there are 3 different speed limits - two different EPS speeds (higher for pendolinos and lower for voyagers) plus a non EPS. Weaver Junction and Berkhemsted come to mind straight away.

Another issue mentioned somewhere was the speed limits for pressure sealed stock vs non pressure sealed - in tunnels.

== Doublepost prevention - post automatically merged: 31 Jan 2021 ==

I wasn't intended to come across as not believing them per se, I just wondered why some staff say they can and some say they can't. Is the engine management set-up on GWR 800/802s sufficiently different to that on TPE 802s to produce a discrepancy in balancing speed?

No. Same diesel settings across the 802 range.

 

[hexagon789]

No. Same diesel settings across the 802 range.

Fair enough, not that then

 

[Nym]

With all due respect, as someone who's experienced similar issues on this forum myself it can be extremely frustrating when you're a member of staff with first hand experience to be told you're wrong by a well meaning, but presumably ill informed enthusiast. This particular guard has access to the speedometer, and can talk to drivers.

Yet those engineers who commissioned the units using calibrated Doppler radar speed sensors can't be right...?

 

[gimmea50anyday]

As i understand it, there are some curves which will require further banking to allow non-tilt trains to run faster through them than at present. Tilting trains tapered body profile allows them to lean without fouling the infrastructure, but i suspect there are a number of places that you cannot bank the track too much because a non-tilt train's loading gauge could foul other bits of infrastructure - such as through tunnels etc.

There is bound to be some sort of compromise limit as to how far the cant can be banked as slower trains unable to attain the speed the track is banked for will be riding against their flanges on the inner rail and that will likely increase track and wheel set wear as a result. WCML has some significant freight flows running at a max speed of between 60 and 75mph which is quite a speed difference in itself, but also significant when considering canting track for 125mph.

 

[Railperf]

Yet those engineers who commissioned the units using calibrated Doppler radar speed sensors can't be right...?

Just revisited my notes. Just to clarify:

Our technical guys reckon the Class 802 has a balancing speed of close to 130mph on level track in diesel mode.

So 125mph should be attainable. But it might take a while to reach it. And all GUs obvs need to be in healthy state.

== Doublepost prevention - post automatically merged: 31 Jan 2021 ==

There is bound to be some sort of compromise limit as to how far the cant can be banked as slower trains unable to attain the speed the track is banked for will be riding against their flanges on the inner rail and that will likely increase track and wheel set wear as a result. WCML has some significant freight flows running at a max speed of between 60 and 75mph which is quite a speed difference in itself, but also significant when considering canting track for 125mph.

I would imagine freight traffic would be planned to run along the relief or slow lines where possible mitigating this issue.

 

[Energy]

And all GUs obvs need to be in healthy state.

Worth pointing out a not healthy engine affects the 80xs more than say a voyager or adelante due to the 80xs having 3 higher output engines per 5 car so if an engine is faulty then it loses a third of the power compared to a fifth of the power.

 

[craigybagel]

Yet those engineers who commissioned the units using calibrated Doppler radar speed sensors can't be right...?

If they are right, then you need to ask the question why the traincrews at TPE aren't seeing 125mph shown on their speedometers when running on diesel.

 

[Domh245]

If they are right, then you need to ask the question why the traincrews at TPE aren't seeing 125mph shown on their speedometers when running on diesel.

If I had to guess, a timetable that doesn't require them to hit 125mph on diesel, and a DAS system telling drivers that they can coast and still maintain the timetable

 

[The Planner]

Could it also be that some of the braking distances - while okay for 140mph Pendolino's - might not be sufficient for some other types of rolling stock capable of 125mph.
If so, it could mean relocating some signals too.
There complication in the UK as opposed to some European countries is that we won't post more than two speed limits for any section of track. In Italy for example, there are boards with up to four posted limits for different categories of stock, plus a 'P' Pendolino limit (usually not posted but found in their sectional appendix 'Fascicolo Linea' and on the ''scheda treno' (train schedule).

Pretty sure no signals require moving, if they do then the cost will spiral. I thought it was three speed limits as the most that can be signed in the UK?

 

[Nottingham59]

why the traincrews at TPE aren't seeing 125mph

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?

 

[hexagon789]

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?)

I don't know where you read that but the overspeed on HSTs is set at 132mph.

If I had to guess, a timetable that doesn't require them to hit 125mph on diesel, and a DAS system telling drivers that they can coast and still maintain the timetable

It's not that, it was definitely stated that they physically wouldn't hit 125mph rather than shutting off before reaching the speed due to running early.

If they are right, then you need to ask the question why the traincrews at TPE aren't seeing 125mph shown on their speedometers when running on diesel.

The only thing I could think of was the ASL being set, but afaik that would impose a 124mph (200km/h) maximum not a figure a good few below 125mph

 

[CW2]

Oh there's so much in this thread!

The reason why HS2 trains are not designed to tilt is the weight penalty. Accelerating to and braking from very high speeds is very energy intensive, so trains need to be as light as possible. Comparison of a 220 (non-tilt) with a 221 (tilt) DMU shows us the weight penalty is about 5 tonnes per vehicle. So on an 8-coach 200m high speed train you would be dragging around an extra 40 tonnes of tilting equipment. For about 95% of its life it would be running on non-tilt routes. The maths made the non-tilt decision very easy.

EPS speeds on the WCML is a virtual minefield. The track infrastructure in the curved sections has been tuned to operate with tilting trains. The amount of cant applied is greater, but also the rate of change of cant is more pronounced, i.e. when entering the curve at speed the train does some of the tilting for you, but if you enter the same curve on a non-tilting train you would experience a sudden lateral change of direction. It is a passenger comfort issue rather more than passenger safety, but it needs consideration.

Multiple speed limits on the same stretch of track (e.g. 390 125mph, 221 115 mph, everything else 90mph) also require sufficient space for the trackside signs - which naturally are larger than normal. As yet we don't have in-cab signalling on the WCML. The stretches of track where there is likely to be the greatest need for multiple speeds are precisely those curved sections where it is most difficult to site the signs.

Aerodynamics in tunnels does play a significant role in the speed restrictions. Some were able to be raised, but others - like Watford - couldn't be done without significant additional expenditure (e.g. boring additional pressure relief shafts).

If I recall correctly, the statement that HSTs shut off at 123.5mph only applies when the wheels are at minimum diameter. So they start off shutting off at about 132(?) mph, and gradually decrease the cutoff speed until the tyres are at scrapping width (because it is measured by axle revolutions).

 

[hexagon789]

If I recall correctly, the statement that HSTs shut off at 123.5mph only applies when the wheels are at minimum diameter. So they start off shutting off at about 132(?) mph, and gradually decrease the cutoff speed until the tyres are at scrapping width (because it is measured by axle revolutions).

Only with the original WSP system, the modern ones compensate for wheel wear and thus the cutoff figure of 132mph applies regardless to power cars so equipped (so not GWR ones I believe for example as I believe there didn't get the upgrades).

 

[43096]

Only with the original WSP system, the modern ones compensate for wheel wear and thus the cutoff figure of 132mph applies regardless to power cars so equipped (so not GWR ones I believe for example as I believe there didn't get the upgrades).

Correct on GWR power cars - except for 43053/056 which got the WSP upgrade when they were with Midland Mainline.

 

[craigybagel]

If I had to guess, a timetable that doesn't require them to hit 125mph on diesel, and a DAS system telling drivers that they can coast and still maintain the timetable

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?

The only thing I could think of was the ASL being set, but afaik that would impose a 124mph (200km/h) maximum not a figure a good few below 125mph

All of these would explain passengers with the ability to measure speed not managing to record any runs at 125mph on diesel - but that doesn't appear to be the case here. This is experienced traincrew who work these units day in day out stating that they're simply not capable of achieving 125mph on diesel.

 

[southern442]

What's the point of getting in fancy 80xs if they are never going to hit 125mph?

 

[Railperf]

All of these would explain passengers with the ability to measure speed not managing to record any runs at 125mph on diesel - but that doesn't appear to be the case here. This is experienced traincrew who work these units day in day out stating that they're simply not capable of achieving 125mph on diesel.

We have measured these doing 125mph on diesel many times.
They are pretty slow at getting there though.

 

[Ianno87]

What's the point of getting in fancy 80xs if they are never going to hit 125mph?

They will on electric.

 

[Bald Rick]

Pretty sure no signals require moving, if they do then the cost will spiral. I thought it was three speed limits as the most that can be signed in the UK?

Correct.

As for the matter in hand - I know a TPE driver, and he has had an 802 at 125 on diesel. Took a while to get there, but it did get there.

 

[David Bullock]

do we know how much time 80x trains are expected to lose over 221s on Euston-Chester/Shrewsbury?

Also surely the more pertinent question for this thread is not whether they can manage 125 on diesel but match 221s up to 90 on the NW coast/Wolverhampton-Shrewsbury.

 

[Railperf]

do we know how much time 80x trains are expected to lose over 221s on Euston-Chester/Shrewsbury?

Also surely the more pertinent question for this thread is not whether they can manage 125 on diesel but match 221s up to 90 on the NW coast/Wolverhampton-Shrewsbury.

I reckon an 802 loses around 20 seconds to a Class 220/1 on each acceleration from 0 to 90mph.

 

[Huntergreed]

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?

 

[gimmea50anyday]

Also surely the more pertinent question for this thread is not whether they can manage 125 on diesel but match 221s up to 90 on the NW coast/Wolverhampton-Shrewsbury.

Up to 90 won’t be an issue although acceleration is slower. it’s above 100 where the power noticeably drops off.

If I had to guess, a timetable that doesn't require them to hit 125mph on diesel, and a DAS system telling drivers that they can coast and still maintain the timetable

Timings are the same on a Sunday as they are during the week. We don’t keep to time on diesel, it simply can’t be done. Don’t forget the use of diesel power on the ECML is only supposed to be a temporary arrangement until the power supply feeders at Hutton Bonville and Marshall Meadows are upgraded.

DAS is not operational on TPE 802s so no advice regarding coasting etc is followed.

I know a TPE driver, and he has had an 802 at 125 on diesel. Took a while to get there, but it did get there.

One particular driver instantly springs to mind, and he is a well known and popular driver, very experienced and well respected. Knows exactly how to throw a train around but isn’t rough. If anyone could manage it, he could.

 

[irish_rail]

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!!

 

[bengley]

If I had to guess, a timetable that doesn't require them to hit 125mph on diesel, and a DAS system telling drivers that they can coast and still maintain the timetable

We don't have DAS at TPE