Do we know what the drag coefficient of them is relative to the HST? Given it follows a power law, less power could quite plausibly still accelerate quicker if it's slippier.
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GWR Class 800
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Do we know what the drag coefficient of them is relative to the HST? Given it follows a power law, less power could quite plausibly still accelerate quicker if it's slippier.
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TheDavibob
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There are some drag coefficients floating around, e.g. in this review paper [annoyingly like most papers pay-to-view, but freer versions are floating around].
Have drag coefficient of HST set quoted as 1.92, c.f. 1.69 for a 9-car class 390. I'll see if there's anything for a 395 floating around, but essentially HSTs aren't anything like as aerodynamic as they look.
Why do you assume it will be quicker?
Distributed power can put more power down simply because you have more points of contact to transfer the power to the rail, once above about 40mph its pure grunt that takes over and the HST has more power available.
I would very much like to see a drag race between a HST and an IET (on diesel), the feeling is that an IET gets away quicker (distributed power) but by 40 mph the HST is accelerating at the same rate (but obviously behind because of its slower pull away), the HsT then pulls back and when the HST is doing 70mph it will be level with the IET but going faster, from then on the HST basically sods off into the distance never to be seen again.
Just because an IET on diesel can reach 120mph doesnt mean it gets there very quickly or is capable of maintaining it.
Actually I would like to see a drag race with the IET on electric as well.
Drag coefficients, physics...blah, blah blah.
The IEPs/80x/AT300 were never intended to run for long periods on diesel power at speeds above 100mph - and the instant that the overhead wires west of Didcot are powered up and passed for passenger services, they won't be doing so, except for the short distance between Thingley junction and Box tunnel and on the odd bit of the Berks & Hants line.
It hasn't been 'cut back' - 140mph running will only be allowed with cab signalling, which requires the installation of ETCS (though in the glorious post-Brexit world it will presumably only be allowed to be called TCS...). If the DfT decides it wants 140mph and will foot the bills, then it can be delivered.
There has never been a plan to wire to Gloucester and Cheltenham, nor to Worcester, Malvern and Hereford, or to the West Country. Or the limited use/diversionary/empty stock routes such as Newport-Gloucester, Newport-Hereford, Bristol-Worcester, Westbury-Bath, etc.
Unless and until all that lot is wired, then GW bi-modes most certainly are justified.
The IEPs/80x/AT300 were never intended to run for long periods on diesel power at speeds above 100mph - and the instant that the overhead wires west of Didcot are powered up and passed for passenger services, they won't be doing so, except for the short distance between Thingley junction and Box tunnel and on the odd bit of the Berks & Hants line.
It hasn't been 'cut back' - 140mph running will only be allowed with cab signalling, which requires the installation of ETCS (though in the glorious post-Brexit world it will presumably only be allowed to be called TCS...). If the DfT decides it wants 140mph and will foot the bills, then it can be delivered.
There has never been a plan to wire to Gloucester and Cheltenham, nor to Worcester, Malvern and Hereford, or to the West Country. Or the limited use/diversionary/empty stock routes such as Newport-Gloucester, Newport-Hereford, Bristol-Worcester, Westbury-Bath, etc.
Unless and until all that lot is wired, then GW bi-modes most certainly are justified.
Yes it has been cut back to 125mph and Severn tunnel Junction-Gloucester-Swindon was considered for electrification. My family owns land either side of this route at former Awre Junction and was told by BR in the 1980s that an occupation crossing was being closed due to electrification to stop hay trailers crossing with bales loaded too high.
Tracked
Established Member
Thanks
Saw them both up close yesterday morning in Doncaster, they pulled in on platform 4 as I was going to Sheffield on Platform 8. The GWR 9(?)-car one was in Platform 1 too, hope one of the people with cameras out there yesterday got a photo they can put on here
800001-2 were operating with pantograph up, not sure about the GWR one.
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Saw them both up close yesterday morning in Doncaster, they pulled in on platform 4 as I was going to Sheffield on Platform 8. The GWR 9(?)-car one was in Platform 1 too, hope one of the people with cameras out there yesterday got a photo they can put on here
My understanding is that the 9 car GWR unit yesterday was the first 9 car 802 (802101) - which then sat down at Finsbury park later in the day.
No it hasn't been cut back to 140mph - the catenary being installed is capable of operation up to that speed if required. There was never a plan to run above 125mph from day one of GW electric operations for the reason I stated - there is no ETCS yet, so no cab signalling, so no 140mph - and the DfT has yet to decide if it does want 140mph running once cab signalling is available.
Whatever your family was told in the 1980s doesn't have anything to do with the current GW electrification scheme, does it?
At no stage has the current GW electrification project - I didn't state it the first time round, as I thought it was obvious that was what I was referring to - included plans to wire several routes that will see regular passengers services, such as Swindon-Gloucester/Cheltenham and the the Cotswold Line, never mind a diversionary route on the north side of the Severn estuary that is only used by South Wales services a few days of the year when the Severn Tunnel is shut.
If 25kv wires were being strung up here there and everywhere, then we wouldn't need bi-modes, but they aren't, so there is a justification for GW bi-modes now and for a long time into the future, unless the government executes yet another u-turn and Network Rail gets its act together on electrification installation.
Peter Sarf
Established Member
Lets not forget. The Bi-Modes where ordered for the planned need to run on diesel beyond the core 125mph Electric Great Western Main Line to places beyond Oxford, Cardiff and Bristol etc. As those are lesser parts of the intercity routes there was no need to have a top speed greater than 100mph. So the diesel engines had their power limited to improve reliability.
All that has changed is that the electrification is now not reaching all the 125mph parts planned so the de-rating of the engines became inappropriate and has been removed. Also bigger fuel tanks required.
The fact that I, along with others, do not like intercity trains with diesel engines under the carriages is neither here nor there in relation to the curtailed electrification. Its just lucky Bi-Modes were ordered in the first place even if they are seen by some to undermine the necessity to fully electrify.
I just want more wires and in the long term perhaps these Bi-Modes will end up moving to Cross-Country when (if ever) that route becomes a candidate for staggered electrification.
All that has changed is that the electrification is now not reaching all the 125mph parts planned so the de-rating of the engines became inappropriate and has been removed. Also bigger fuel tanks required.
The fact that I, along with others, do not like intercity trains with diesel engines under the carriages is neither here nor there in relation to the curtailed electrification. Its just lucky Bi-Modes were ordered in the first place even if they are seen by some to undermine the necessity to fully electrify.
I just want more wires and in the long term perhaps these Bi-Modes will end up moving to Cross-Country when (if ever) that route becomes a candidate for staggered electrification.
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samuelmorris
Established Member
I don't honestly see electrification proceeding at any great pace for the next few years (in other words, no new plans announced and none of the cutbacks reversed) because there's simply too much evidence that the current organisations in charge have too little competence to actually get it done actually providing 'value for the fare payer and taxpayer'. DMUs and Bimodes would seem to be the current railway 'solution' at least of the existing government. I'm hopeful that by this time next decade some sense will have been seen and they will head towards having mainlines electrified with a view to using perhaps bimodal battery units on branch lines that are heavily subsidised. Until that time, it really is high time serious attention is paid to new, regular DMUs - they will clearly get at least a couple of decades' work and are urgently needed - not doing so on the back of emissions regulations is daft when for that reason we have to keep older units which are even worse. It is simply very fortunate that the Class 800 series has proven flexible enough to give the government an escape route from their shortcomings.
I would be very interested to see numerical data on how the 940hp configuration units compare for acceleration performance versus not just the HSTs, but the contemporary high-speed DMUs like the 180s and Voyagers. '14 minute shorter journeys to Penzance' is an unhelpful statistic when there are additional complexities like shorter dwell times.
I would be very interested to see numerical data on how the 940hp configuration units compare for acceleration performance versus not just the HSTs, but the contemporary high-speed DMUs like the 180s and Voyagers. '14 minute shorter journeys to Penzance' is an unhelpful statistic when there are additional complexities like shorter dwell times.
Peter Sarf
Established Member
I am afraid you are correct and I fear there is going to be a significantly longer wait for the next electrification project. Longer than the usual pause to let all the skills evaporate. The current expertise that is forming will be allowed to disband.
Whilst mentioning these versatile 800 series trains I have to caution that, although there are large orders for them, we have not really seen them successfully in action yet - it is all theory !. I cringe when I think that so many have been ordered and wanted soon that the factory in the UK cannot do it all so we are importing from Italy. I suspect that the UK factory will have no further work sooner rather than later once the glut of new trains has arrived. That is unless they build diesel trains !...
Whilst mentioning these versatile 800 series trains I have to caution that, although there are large orders for them, we have not really seen them successfully in action yet - it is all theory !. I cringe when I think that so many have been ordered and wanted soon that the factory in the UK cannot do it all so we are importing from Italy. I suspect that the UK factory will have no further work sooner rather than later once the glut of new trains has arrived. That is unless they build diesel trains !...
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The only part of the GW network where 125mph running is permitted that will not be under 25kv overhead by the end of 2018 - unless Network Rail's latest schedule goes pear-shaped - is, as I said, the few miles between Thingley junction and the east portal of Box tunnel.
Once that happens, along with electric operation as far as Cardiff starting, it could be the case that a decision is taken to switch some or all of the Class 800 fleet to operation with the diesels set at the previously-planned lower power setting. The bigger fuel tanks will obviously still come in handy to allow for the extra mileage on diesel for Swansea services.
Peter Sarf
Established Member
Yes. I would have thought the de-rating will be done ASAP. That will reduce leasing costs and increase reliability which was the whole point of the original de-rating. Of course that assumes that the leasing deal can revert to the original deal once the 800s get de-rated. Pity the "running in" of the engines will have to be done at full power. That will be the only problem long term hopefully.
Mintona
Established Member
The 125 actually begins at the east portal of Middle Hill Tunnel, rather than Box Tunnel, so a couple of miles further west. It is quite a gradient up from Bath to Thingley Jn so will be interesting to see how they get on on this section with the supposed lack of power.
First attempt to run an 800 on Newport-Hereford-Ledbury-Malvern-Worcester appears to have been scuppered on Sunday by overrunning engineering work.
http://www.realtimetrains.co.uk/train/K97270/2017/09/10/advanced
Train plan also included a Worcester-Ledbury trip, presumably for GWR staff to check stopping points on all platforms locally, before running to North Pole via Gloucester and Swindon.
http://www.realtimetrains.co.uk/train/K97270/2017/09/10/advanced
Train plan also included a Worcester-Ledbury trip, presumably for GWR staff to check stopping points on all platforms locally, before running to North Pole via Gloucester and Swindon.
Few days a year? It was weeks and weeks last Autumn. You never know with a tunnel 140 years old, leaking as it does, when it needs to close. The only other route is the original one via Gloucester.
My great grandfather helped build it after building Severn Bridge. His grandson helped demolish it.
In the normal course of things, diversions via Gloucester most certainly are for a few days each year.
As I'm sure you know, the extended closure last autumn was in order for Network Rail to carry out probably the most comprehensive programme of modernisation and repairs to the Severn Tunnel since your great-grandfather helped to build it - including removing 40 tonnes of soot from the brickwork that was left over from steam days.
All that work should mean that in coming years there will likely be rather less need for closures of the tunnel at weekends while engineering teams scurry to do what work they can in 48-hour windows.
'You never know' doesn't look like a business case likely to get past the DFT just now...
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ScottDarg
Member
800001 and 800002 were back at Edinburgh today. Ran to time near enough the whole way up from Doncaster, unlike last Tuesday.
gazthomas
Established Member
Today they did a run from Doncaster to Kings Cross. They left 99 minutes late but recovered a few minutes by the end. Here's my photo at Brookmans Park. I had hoped they would go through the fast line but sadly not, making me wish I had gone to Welham Green instead!
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absolutelymilk
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- 18 Jul 2015
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What times are they set for?
Just a quick heads up but any discussion around the diagrams that GWR SETs are running now that they are approaching service should use this thread. This will hopefully make it a bit easier to keep track of diagrams rather than wading through pages and pages of more general discussion!
Many thanks!
Many thanks!
Class 800 in GWR livery passed through York today heading north.
http://www.realtimetrains.co.uk/train/K01076/2017/09/18/advanced
http://www.realtimetrains.co.uk/train/K01076/2017/09/18/advanced
That was 800004.
Today (Tuesday), 800003+800004 both together doing runs between Peterborough and Darlington in diesel mode.
I've never noticed until now how clunky the driver's door is.
samuelmorris
Established Member
This seems to be a common trend with new stock, I'm not sure why? 345s are the same in that regard.
urpert
Member
Looks a lot like the one on the 345s. That seems to be the new trend...
DarloRich
Veteran Member
Curmudgeon alert: i really cant wait to travel on these. I am sure I will arrive awesome. ( unlike now in relaxed comfort)
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