Pretty much the same way. ATP gets train speed from wheel revolutions; if the wheels are smaller than the size they are calibrated for then warnings and interventions will be at a lower speed. If someone has previously gotten an intervention at 126; they will have had a warning at 123 - and should be adjusting their driving accordingly.
-
Our new ticketing site is now live! Using either this or the original site (both powered by TrainSplit) helps support the running of the forum with every ticket purchase! Find out more and ask any questions/give us feedback in this thread!
GWR Class 800
- Thread starter SpacePhoenix
- Start date
- Status
Pretty much the same way. ATP gets train speed from wheel revolutions; if the wheels are smaller than the size they are calibrated for then warnings and interventions will be at a lower speed. If someone has previously gotten an intervention at 126; they will have had a warning at 123 - and should be adjusting their driving accordingly.
Sponsor Post - registered members do not see these adverts; click here to register, or click here to log in
R
RailUK Forums
TwistedMentat
Member
- Joined
- 2 Oct 2016
- Messages
- 151
So I work nearby to Reading station so I've been getting to see more and more of the Class 800s going through.
And I've got to say, they do look super cool as they glide into the station without a sound. That rounded bullet train nose and the front pantograph up. Makes them look futuristic.
Between the 800s and 387s the GWML from Didcot to Paddington is starting to sound so much quieter.
And I've got to say, they do look super cool as they glide into the station without a sound. That rounded bullet train nose and the front pantograph up. Makes them look futuristic.
Between the 800s and 387s the GWML from Didcot to Paddington is starting to sound so much quieter.
hexagon789
Veteran Member
Presumably they would but as I have never had direct experience of ATP I couldn't say. I know that the ATO system on the Glasgow Subway automatically adjusts for wheelchair wear in its speed calculations - I wonder if the 800s can do this or is this affected by the ATP system and not the train?
No, GW-ATP is a stand-alone system that’s “bolted” onto the train. It’s identical on the IETs, 360s, 180s, 332s and HSTs (the 5 types that have been fitted with it).
It’s set up based on new wheel diameters; such that any wheel wear will cause warnings and interventions at a lower actual speed than new wheels. Wheel wear isn’t necessarily linear, so you would struggle to dynamically calibrate it accurately. The fail-safe nature of the physics behind smaller wheels at same rotation rate = slower is perfectly acceptable; drivers just need to drive to the warnings they get. If it’s warning a couple of mph below 125; then drive a couple of mph below line speed and report it in the defect book.
hexagon789
Veteran Member
Thanks for the expanation, I just wondered if it could be built in seeing as the Glasgow Subway ATO predates ATP by a few years.
A subway system is a very different environment to the mainline railway though - work is very predictable; and it’s not weather-affected. The trains do essentially the exact same thing every day - predicting wheel wear is much easier. On the big railway you get much more wheel slip, and wheel slide, that can cause wear at different rates to general use. The trains are running over very different routes and service regimes; which can also impact rate of wear.
The other reason is that ATO needs to very accurately know position of the train (for stoping correctly in platforms), regardless of the wheel wear. GW-ATP is fed position data as it enters every loop or passes over every beacon - it doesn’t really care about exact position; just how far it is until the signal or speed restriction. While smaller wheels would reduce the real distance; speed would also be proportionally reduced so it’s still not causing an issue.
Finally, such significant changes to the ATP system would probably invalidate it’s safety certification. You’d then have to re-certify a system that is due to be replaced by ETCS in the next few years. Better to stick with what we know.
hexagon789
Veteran Member
Yes. It's fitted with support for ETCS Baseline 3.
hexagon789
Veteran Member
superkev
Established Member
Watched the channel 5 program last night (Mon) mainly concerning the recent winter weather and the over a impression was the 800's fared quite well for a new train. Not sure if that was factual.
K
K
hexagon789
Veteran Member
No idea whether they are better in poorer weather as such but the programme certainly seemed to imply that the HSTs were failing left, right and centre so to speak.
palmersears
Established Member
- Joined
- 20 Sep 2011
- Messages
- 1,487
My first ride on one of these yesterday, from Swansea to Cardiff on 800034. Mixed bag really, with the seats causing me grief almost immediately, but decent viewing afforded by the windows. I also noted the seats smelt rather bad, a mixture of something akin to cheese and onion crisps mixed with off Parmesan. A number of them smelt of this throughout the carriage.
Also, is the clock on the PIS at the end of the carriage supposed to flash when the door close alarms are sounding? I thought my eyes were playing tricks on me when it first happened but it occurred at every stop thereafter so I wasn't going mad.
'Normals' around me commenting on the hard seats and lack of a buffet car, and described the new 'posh' trains as 'mutton dressed as lamb'.
Also, is the clock on the PIS at the end of the carriage supposed to flash when the door close alarms are sounding? I thought my eyes were playing tricks on me when it first happened but it occurred at every stop thereafter so I wasn't going mad.
'Normals' around me commenting on the hard seats and lack of a buffet car, and described the new 'posh' trains as 'mutton dressed as lamb'.
Any report available on the progress of ETCS fitment on the GWML. It has gone awfully quiet !
Wychwood93
Member
I worked for Thames at Reading in the early 90's in Western Tower - I think it was around 10.00 that Concorde headed westwards - compared to the diesels that was NOISY. My time estimate may be wrong but the noise was not!
43096
On Moderation
- Joined
- 23 Nov 2015
- Messages
- 18,735
Back in BR days two Class 56s (56033/039) were fitted with GW-ATP for testing as well.
http://www.traintesting.com/ATP locomotives.htm
43096
On Moderation
- Joined
- 23 Nov 2015
- Messages
- 18,735
It’s also been fitted to a 47 in the past; I was trying to keep it simple.
43096
On Moderation
- Joined
- 23 Nov 2015
- Messages
- 18,735
According to the link, the 47 was fitted with the Chiltern system, not GW-ATP.
palmersears
Established Member
- Joined
- 20 Sep 2011
- Messages
- 1,487
Sadly/fortunately the smell was that strong I didn't need to get too close!That reads like you've been going round sniffing train seats!!!
samuelmorris
Established Member
Lots of 345s seem to smell of weed, including the one I'm on now. I assumed that was the clientele at first, but now you have me wondering...
TractiveEffort
Member
- Joined
- 29 Nov 2016
- Messages
- 290
ATP has an adjustable parameter for wheel size reduction as the wheels reduce in size after tyre turning. The wheel size (as long as the parameter is set correctly) should not affect the speed as the input from the hasler is corrected by the VOBC and gives the correct reading on the speedo and the overspeed.
On a HST power car there is another speed reading, the one that used to supply the original speedo and is still recorded by the OTMR, this is again, kept correct by an adjustable parameter (thumbwheel,on WSP rack). As I said earlier, the overspeed (original, not ATP) is controlled by a fixed resistor which should have a range large enough to accommodate all wheel sizes, but occasionally with small wheels you get overspeed at lower speeds, the only solution is to try another rack and hope that resistor is a bit more forgiving.....
Railperf
Established Member
- Joined
- 30 Oct 2017
- Messages
- 3,683
Getting back to Class 800 ..seems neither 800's or 802's would be a candidate for MML bi-mode stock in their current state of tune. According to Railway Gazette , the National Audit Office found that at the time of the decision to cancel (electrification) there were no bimode trains on the market offering the performance required for MML services, although DfT expected that they could be developed.
I guess that's because they aren't designed for extended running at 125mph off the wires. Surprised though that it isn't possible to replace the trailer carriages with powered carriages to gain the extra performance.
Reliablebeam
Member
- Joined
- 14 Jun 2017
- Messages
- 272
Happy days! But I do enjoy the increasing silence on the GWR.
I've had a couple of trips on these things now and their friends, the 387. I like the 800s, as a buisness train or casual day tripper. I do agree with the sentiment that they might not be the right beasties for long haul bucket and spade stuff, will be interesting to see how they cope come summer.
On a general note, as I've grown older I've become much less tolerant of the endless cacophanous racket from diesels along with their dirty fumes. It's less bothersome bimbling around Welsh market towns where accelerate/decelerate cycles are less frequent. My main complaint about the GWR now? Plenty of wires, not enough 80x's! I don't care about AC motor sound as this is the signal that the Great Western is now a modern railway and not an antique backwater.
I've had a couple of trips on these things now and their friends, the 387. I like the 800s, as a buisness train or casual day tripper. I do agree with the sentiment that they might not be the right beasties for long haul bucket and spade stuff, will be interesting to see how they cope come summer.
On a general note, as I've grown older I've become much less tolerant of the endless cacophanous racket from diesels along with their dirty fumes. It's less bothersome bimbling around Welsh market towns where accelerate/decelerate cycles are less frequent. My main complaint about the GWR now? Plenty of wires, not enough 80x's! I don't care about AC motor sound as this is the signal that the Great Western is now a modern railway and not an antique backwater.
Only been on one 345 and that smelt strongly of weed as well.
Wychwood93
Member
There is a lot of weed smell around in general - not so much in my area (Christchurch) on trains, but certainly buses and pubs. What I may, or may not, have done in the 70's and early 80's seems that much more open nowadays. Somewhat fortunate that being illegal is no real issue in the current climate.
Edit: - no class 800's down here yet! Had 'Spinal Tap' extended, as planned (doubtful in any case), from Reading to Basing and down to Soton, then XC services could have been a candidate. Wires from Soton to Reading and thence to Oxford would see them wireless from Oxford to Coventry and then under the 'dangly bits' up to Manchester. I will probably be dead by the time if even that limited ambition comes to fruition - just might have to live longer and annoy the children in that case!
Last edited:
Pete_uk
On Moderation
How would one know what weed smells like? I'm a good boy so I wouldn't know 
Mordac
Established Member
How would one know what weed smells like? I'm a good boy so I wouldn't know
Just come to Northampton and hang around in the town centre for a while. That smell that permeates the air everywhere? It's weed. :P
Chris125
Established Member
It seems 802003+004 are finally on their way...
- Status