mrfs42
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Post by mrfs42 on May 14, 2007 17:10:18 GMT
I was idly musing at lunchtime if there was a set formula for locating the 15kHz command spots on the Vic.? I'm intrigued by some of the locations - some are obvious and others not so: F'r 'zample Walthamstow - Blackhorse Road. There is a spot in the 1 in 59 fall not far out of Walthamstow. Track continues to fall towards Blackhorse Road at 1 in 59/396 apart from a short 'up' of 1 in 49 before the platforms. I can understand the siting of this spot as it's all downhill apart from when you want to start braking for the next station. However Blackhorse Road - Tottenham Hale Coasting spot towards the end of a 1 in 401 fall before the 1 in 100/150/50 drag up into Tottenham Hale, likewise Tottenham - Seven Sisters Coasting spot about half-way between the two in the climb at 1 in 150ish towards Seven Sisters. I can see the virtue of putting a coasting spot where there is a long falling grade; conversely I can see the merits of putting a coasting spot part way up a long climb to ease the braking at the station stop. Just curious to see if there is actually a developed formula out there - obviously things like rolling resistance as a product of the curves and the rising/falling gradients would need to be factored in. Is there one - or is it a bit of 'white magic' thats been lost in the mists of time?  |
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Tom
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Post by Tom on May 14, 2007 17:55:35 GMT
Not too sure on if there was a formula for where to put it - but it helps to know the background behind it.
Coasting was originally able to be switched on or off depending on how the service was running - there is a 'train late' function for example in Walthamstow IMR which is used to set the S(15)YRs in the IMR.
Later it was switched on or off across the line - most recently it was all on.
Then... coasting was permanently switched off from a number of sections to improve journey time. These sections were: Seven Sisters - Finsbury Pk SB, Oxo - Green Pk SB, Green Pk - Victoria SB, Stockwell -Brixton SB, Brixton - Stockwell NB and Pimlico - Victoria NB.
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mrfs42
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Post by mrfs42 on May 14, 2007 18:04:25 GMT
Coasting was originally able to be switched on or off depending on how the service was running - there is a 'train late' function for example in Walthamstow IMR which is used to set the S(15)YRs in the IMR. From this (remembering that I use Y for 'disengaging' - but am currently away from all my paperwork - may be a later edit from home) - do you mean that 'train late' = coasting off = S(15)YRs 'up' [1] to break code feed to the 15kHz spot? Ta for the gen on the recent coasting amendments - do Regulators still have the 'NB' and 'SB' coasting buttons available to switch on coasting on the sections that still permit it? [1] whichever way it is (back/front contacts) |
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Tom
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Post by Tom on May 14, 2007 18:19:55 GMT
Yes - but I'm not too sure how the train late function was actually used. The people looking at that element of it were all before my time.
When we did the coasting control override works we left the S(15)YR controls alone and just pulled the S(15) fuses.
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towerman
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Post by towerman on May 14, 2007 19:52:31 GMT
Coasting spot at Warren St NB is before the crossing,yet the run to Euston appears to be uphill.
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mrfs42
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Post by mrfs42 on May 14, 2007 23:15:34 GMT
I can understand the coasting spot at Warren St. NB (albeit in very simplistic terms) - its fairly straight (so not much rolling resistance) and there's a hyooge fall of 1 in 50 with the spot halfway down, the comparatively short bit of 1 in 40 up would slow you down nicely for the station stop at Euston. There are a lot of factors that I can think of to use in calculating these positions - but the formulae would be  , I just wondered if there's summat simple along the lines of the calulated overlaps (where the assumption of brake efficiency is 10% open and 12% tube) - wondering if similar assumptions could be made with this calculation - apart from 'we've got a lot of down, not many curves and we need to stop them using juice.'? |
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Post by Deleted on May 15, 2007 20:13:38 GMT
s/b run GPK - VIC appears to be downhill... The way the trains buck and kick over the x-over and the usual 'assisited stop' ;D tells me it's quite a fast run...
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Tom
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Post by Tom on May 15, 2007 22:00:28 GMT
s/b run GPK - VIC appears to be downhill... The way the trains buck and kick over the x-over and the usual 'assisited stop' ;D tells me it's quite a fast run... It is downhill, pretty much all of the way. I can remember the kick over that crossover being far worse... |
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mrfs42
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Post by mrfs42 on May 16, 2007 17:12:33 GMT
s/b run GPK - VIC appears to be downhill... Aye, the coasting spot there is/was [1] about a third of the way between FX406 (Green Pk starter) and Headway Post 404, and a long drop between there and the 'home' for Victoria (VF23). [1] I guess that the feed might still be there to the rail, but there's no means of sending the code unless a technician puts the fuse back? This one I could work out - there's about 600m of 'down' after the spot. |
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Post by lightblueleader on Nov 18, 2007 4:19:09 GMT
s/b run GPK - VIC appears to be downhill... Aye, the coasting spot there is/was [1] about a third of the way between FX406 (Green Pk starter) and Headway Post 404, and a long drop between there and the 'home' for Victoria (VF23). [1] I guess that the feed might still be there to the rail, but there's no means of sending the code unless a technician puts the fuse back? This one I could work out - there's about 600m of 'down' after the spot. As far as I know a lot of the coasting spots were removed well over a year ago at the request of the then SCM. And yes, don't they shift GPK to Vic SB, what a railway! LBL |
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Post by trc666 on Nov 18, 2007 4:59:29 GMT
KGX - SVS northbound is another fast section, particularly on the approach to the latter. |
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Post by railtechnician on Nov 18, 2007 5:16:33 GMT
KGX - SVS northbound is another fast section, particularly on the approach to the latter. Yep Seven Sisters was my nearest station with a decent bus service so in the years I worked days I travelled KGX to SSS (my acronym has always been that!) 5 or 6 days a week. When it was good it was very good and when it was bad it was diabolical. When it was a through train with nowt ahead it was a fair lick into SSS and that was before they upped the top end from 55kph. Brian |
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Post by Deleted on Nov 19, 2007 20:30:22 GMT
Aye, the coasting spot there is/was [1] about a third of the way between FX406 (Green Pk starter) and Headway Post 404, and a long drop between there and the 'home' for Victoria (VF23). [1] I guess that the feed might still be there to the rail, but there's no means of sending the code unless a technician puts the fuse back? This one I could work out - there's about 600m of 'down' after the spot. As far as I know a lot of the coasting spots were removed well over a year ago at the request of the then SCM. And yes, don't they shift GPK to Vic SB, what a railway! LBL The coasting spots were removed as part of the "Interim Victoria Line Upgrade". This was a stop-gap project to improve jourmey times until the VLU proper is completed. It consisted of removal of coasting spots, mods to the 67 stock doors to make them more reliable and close (a bit) faster and New Auto Drive Boxes. The NADB bit is still not finished due to some "teething" problems meaning that only 10 trains are currently fitted. ttr |
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Tom
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Post by Tom on Nov 19, 2007 22:28:19 GMT
As far as I know a lot of the coasting spots were removed well over a year ago at the request of the then SCM. And yes, don't they shift GPK to Vic SB, what a railway! LBL The coasting spots were removed as part of the "Interim Victoria Line Upgrade". This was a stop-gap project to improve jourmey times until the VLU proper is completed. They weren't removed - the spot still has the rail connections trackside and the Spot Frequency Generators are still in the rooms. All that has happened is the fuses for them have been removed. |
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mrfs42
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Post by mrfs42 on Dec 3, 2007 0:15:43 GMT
They weren't removed - the spot still has the rail connections trackside and the Spot Frequency Generators are still in the rooms. All that has happened is the fuses for them have been removed. Ah. Now are the spot frequency generators tuned pendulum things or electronic code generators? (this is in part from a wider set of musings upon cab signalling systems - as in how to get the code from the relay room down to the track? This might be one for tubeprune's much appreciated wisdom. |
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Post by railtechnician on Dec 3, 2007 5:24:28 GMT
They weren't removed - the spot still has the rail connections trackside and the Spot Frequency Generators are still in the rooms. All that has happened is the fuses for them have been removed. Ah. Now are the spot frequency generators tuned pendulum things or electronic code generators? (this is in part from a wider set of musings upon cab signalling systems - as in how to get the code from the relay room down to the track? This might be one for tubeprune's much appreciated wisdom. Spot generators are based on solid state techniques consisting of a tuned oscillator and amplifier. |
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Post by Deleted on Dec 3, 2007 21:26:43 GMT
see i learn something new everyday
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mrfs42
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Post by mrfs42 on Dec 3, 2007 22:58:50 GMT
see i learn something new everyday Yeah, I thought it was just teenage hormones. ;D ;D |
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Post by Deleted on Dec 3, 2007 23:41:22 GMT
wish i was a teenager again
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Post by tubeprune on Feb 5, 2008 12:53:56 GMT
The NADB bit is still not finished due to some "teething" problems meaning that only 10 trains are currently fitted. ttr Has the situation changed to date? Do you happen to know what the teething troubles are? |
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Post by Deleted on Feb 5, 2008 17:56:38 GMT
The NADB bit is still not finished due to some "teething" problems meaning that only 10 trains are currently fitted. ttr Has the situation changed to date? Do you happen to know what the teething troubles are? I haven't checked recently but AFAIK they're now progressively being rolled out. The problems were (I think) something to do with geography files within the NADB, though I think there was more to it than that. I'll do some digging tomorrow and see what I can find out. ttr |
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Post by tubeprune on Feb 6, 2008 9:00:31 GMT
Has the situation changed to date? Do you happen to know what the teething troubles are? I haven't checked recently but AFAIK they're now progressively being rolled out. The problems were (I think) something to do with geography files within the NADB, though I think there was more to it than that. I'll do some digging tomorrow and see what I can find out. ttr Thanks ttr. |
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Post by Deleted on Mar 3, 2008 21:09:49 GMT
I've finally managed to dig up a bit of information. The NADB trial that commenced last year identified some software problems. These caused some occasional idiosyncratic responses which threatened to affect fleet reliability. Since then, the designers have been working to resolve the issues and a new trial is due to commence shortly. Fingers crossed.  ttr |
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Post by tubeprune on Mar 5, 2008 12:30:23 GMT
Thank ttr. I had heard something similar from another "informed source". At this rate, by the time they get it sorted out, the scrapping programme will have started.
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Post by georgedishman on Jun 11, 2008 10:10:14 GMT
I've finally managed to dig up a bit of information. The NADB trial that commenced last year identified some software problems. These caused some occasional idiosyncratic responses which threatened to affect fleet reliability. Since then, the designers have been working to resolve the issues and a new trial is due to commence shortly. Fingers crossed. ttr The key "idiosyncratic response" was that it implemented part of the spec that required the NADB to isolate all outputs if the driver took control. "Operator takes control" can only be determined by seeing air in the brakes (via 15psi) when the NADB isn't requesting any brake, so when an op. briefly fondled the handle to slow the train a tad, the NADB came out of ATO, released all outputs and left the train to the operator. At the next red signal, the op. waited for the NADB to stop the train ... and the NADB waited for the op. to do it ... A change to the requirements resulted! N.G. |
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Post by tubeprune on Jun 20, 2008 21:01:18 GMT
I've finally managed to dig up a bit of information. The NADB trial that commenced last year identified some software problems. These caused some occasional idiosyncratic responses which threatened to affect fleet reliability. Since then, the designers have been working to resolve the issues and a new trial is due to commence shortly. Fingers crossed. ttr The key "idiosyncratic response" was that it implemented part of the spec that required the NADB to isolate all outputs if the driver took control. "Operator takes control" can only be determined by seeing air in the brakes (via 15psi) when the NADB isn't requesting any brake, so when an op. briefly fondled the handle to slow the train a tad, the NADB came out of ATO, released all outputs and left the train to the operator. At the next red signal, the op. waited for the NADB to stop the train ... and the NADB waited for the op. to do it ... A change to the requirements resulted! N.G. Going back to this, it occurred to me that the logical way to disconnect the NADB was when the reverser key switch was taken out of AUTO??? |
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Post by georgedishman on Jul 2, 2008 11:41:57 GMT
The key "idiosyncratic response" was that it implemented part of the spec that required the NADB to isolate all outputs if the driver took control. "Operator takes control" can only be determined by seeing air in the brakes (via 15psi) when the NADB isn't requesting any brake, so when an op. briefly fondled the handle to slow the train a tad, the NADB came out of ATO, released all outputs and left the train to the operator. At the next red signal, the op. waited for the NADB to stop the train ... and the NADB waited for the op. to do it ... A change to the requirements resulted! N.G. Going back to this, it occurred to me that the logical way to disconnect the NADB was when the reverser key switch was taken out of AUTO??? I'm not sufficiently familiar with the switching, I assume you are right, but the aim of the change was not to disconnect the NADB but to keep it active without negating the operator's action. If the op. feels the train is moving too fast, (s)he applies the brakes so, if the NADB then motored as soon as (s)he released braking, it would nullify their decision. The solution is to treat a brief intervention as if a 15kHz spot has been seen so that the train coasts at whatever speed the operator chose but still responds automatically to signalling. |
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