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| Complex track layout 29/01/2013 at 05:08 #40949 | |
clive
2738 posts |
Take a look at this track layout. Make sure you scroll down and read the bit about the track entering from bottom left.
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| Complex track layout 29/01/2013 at 18:23 #40960 | |
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AH1983
8 posts |
Yeap! I have debated in sending him in a picture of Newcastle Central (steam era) for his next challenge!
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| Complex track layout 30/01/2013 at 12:47 #40980 | |
jc92
3630 posts |
" said:Yeap! I have debated in sending him in a picture of Newcastle Central (steam era) for his next challenge!or holgate Junction at york? "We don't stop camborne wednesdays" Log in to reply |
| Complex track layout 30/01/2013 at 13:44 #40983 | |
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kbarber
1712 posts |
" said:" said:Yeap! I have debated in sending him in a picture of Newcastle Central (steam era) for his next challenge!or holgate Junction at york? The old Kings Cross wasn't a bad one either. :evil: Last edited: 30/01/2013 at 13:45 by kbarber Reason: I thought it deserved a smiley Log in to reply |
| Complex track layout 30/01/2013 at 14:16 #40984 | |
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jc92
3630 posts |
" said:" said:with the 8mph speed restrictions over the neck?" said:Yeap! I have debated in sending him in a picture of Newcastle Central (steam era) for his next challenge!or holgate Junction at york? "We don't stop camborne wednesdays" Log in to reply |
| Complex track layout 30/01/2013 at 17:05 #40985 | |
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kbarber
1712 posts |
" said:" said:" said:with the 8mph speed restrictions over the neck?" said:Yeap! I have debated in sending him in a picture of Newcastle Central (steam era) for his next challenge!or holgate Junction at york? That's the one. As torturous a bit of track as ever was (and a right pig for the operator too). Log in to reply |
| Complex track layout 31/01/2013 at 09:56 #40999 | |
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Signalhunter
177 posts |
" said:" said:" said:Why 8mph? Why not 5 or 10? Bearing in mind that (most) steam loco's didn't have a Speedo. how often was 8mph adhered to?" said:Yeap! I have debated in sending him in a picture of Newcastle Central (steam era) for his next challenge!or holgate Junction at york? Log in to reply |
| Complex track layout 31/01/2013 at 10:54 #41005 | |
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DanC
53 posts |
" said:" said:???????" said:" said:Why 8mph? Why not 5 or 10? Bearing in mind that (most) steam loco's didn't have a Speedo. how often was 8mph adhered to?" said:Yeap! I have debated in sending him in a picture of Newcastle Central (steam era) for his next challenge!or holgate Junction at york? Log in to reply |
| Complex track layout 31/01/2013 at 16:56 #41014 | |
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kbarber
1712 posts |
" said:" said:" said:" said:Why 8mph? Why not 5 or 10? Bearing in mind that (most) steam loco's didn't have a Speedo. how often was 8mph adhered to?" said:Yeap! I have debated in sending him in a picture of Newcastle Central (steam era) for his next challenge!or holgate Junction at york? I fear this belongs with why so many people like the Gas Works Railway and how the track circuit really works[sup]*[/sup] as one of the mysteries of the universe. [sup]*[/sup] A rather senior signal engineer I knew, sadly no longer with us, once told me that - according to the laws of physics - the track circuit cannot possibly work in the real world. Log in to reply |
| Complex track layout 31/01/2013 at 20:44 #41026 | |
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jc92
3630 posts |
" said:" said:i think it probably relates to a world which was imperial not metric - theres not 12, not 10 inches to a foot and 16 shillings to a pound! theres a speed restriction of 3mph at the cooperative funeral care outside sheffield PSB (indicated by an old style sign, along with the one at the front entrance to york NRM." said:" said:Why 8mph? Why not 5 or 10? Bearing in mind that (most) steam loco's didn't have a Speedo. how often was 8mph adhered to?" said:Yeap! I have debated in sending him in a picture of Newcastle Central (steam era) for his next challenge!or holgate Junction at york? "We don't stop camborne wednesdays" Log in to reply |
| Complex track layout 31/01/2013 at 20:48 #41027 | |
headshot119
4869 posts |
" said:" said:I'm sure there are a few 3MPH PSRs around the country." said:i think it probably relates to a world which was imperial not metric - theres not 12, not 10 inches to a foot and 16 shillings to a pound! theres a speed restriction of 3mph at the cooperative funeral care outside sheffield PSB (indicated by an old style sign, along with the one at the front entrance to york NRM." said:" said:Why 8mph? Why not 5 or 10? Bearing in mind that (most) steam loco's didn't have a Speedo. how often was 8mph adhered to?" said:Yeap! I have debated in sending him in a picture of Newcastle Central (steam era) for his next challenge!or holgate Junction at york? "Passengers for New Lane, should be seated in the rear coach of the train " - Opinions are my own and not those of my employer Log in to reply |
| Complex track layout 01/02/2013 at 00:56 #41036 | |
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Danny252
1461 posts |
The other place I often see "odd" speed limits is industrial sites such as power stations - 8mph, 13mph, and so on. The reasoning I heard for it was that "everyone knows there's no way you're staying exactly on 8mph - so if you're involved in an incident, they can immediately blame you for not keeping to the speed limit!" Quote: A rather senior signal engineer I knew, sadly no longer with us, once told me that - according to the laws of physics - the track circuit cannot possibly work in the real world.I've heard that quote several times, but I've still yet to see where it comes from. What exactly about a track circuit is so "unphysical"? Log in to reply |
| Complex track layout 01/02/2013 at 10:15 #41043 | |
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kbarber
1712 posts |
" said:
The engineer concerned was the late Dave Wittamore. What he was referring to is the fact that, in the real world, the running rails connected in a track circuit are not perfectly insulated from each other; the sleepers, ballast and the mass of the earth form a high(ish) resistance conductor. Likewise the wheels and axles of a train don't form a perfect short circuit but a medium(ish) resistance conductor. Therefore there has to be some very critical adjustment so the track relay will pick up on the voltage that reaches it with the TC clear but will drop away when that voltage is reduced by the presence of (as few as two) wheelsets in the circuit. What Dave was saying is that the difference between these two voltages and the potential variations, due to such factors as weather affecting the resistance of the leakage path, railhead contamination, just about anything in fact, is such that - if you work it out in full, using Ohms Law on every variable for the whole range of expectable conditions, you can't get an adjustment that works reliably. A few consequences: There are certain vehicles (mainly on-track machines, or they were in my day anyhow) that can't be relied on to operate track circuits and which thus have to be dealt with specially in TCB areas; When the class 158s were introduced, the suspension was so well-tuned that there was no hunting at all. Consequently there was no "scrubbing" action to clean the contact patch and contamination built up until they, too, failed to operate track circuits. In the end they had to fit track circuit actuating units to them all (and I have an idea this became a potent source of train failures, for a while at least). At Biggleswade, in the late 1960s/early 1970s, the track circuit in advance of the up fast home was peculiarly sensitive. There were a number of incidents of the signal reverting to danger just a few yards in front of an approaching train - usually a 100mph inter-city. The box being some 1/2mile in advance of the signal, the train usually came to a stand pretty much outside; the story suggests there were a number of exchanges that were unsually frank even for railwaymen... Eventually the problem was traced to some sleepers that were contaminated with salt and a switch was provided in the box so the voltage on the offending track circuit could be reduced in wet weather (more accurately, when the ground was wet). But as this made the TC unreliable (the lower voltage could result in a failure of the train to shunt it, particularly when the train was short - a wrong side failure) the normal voltage had to be fed whenever ground conditions permitted. In spite of all that, real-life signal engineers have made the track circuit such a solid piece of kit that it still forms the basis of the vast bulk of modern signalling installations (and a vital safety feature in an awful lot of older ones). Log in to reply The following users said thank you: AndyG, postal |
| Complex track layout 01/02/2013 at 11:07 #41044 | |
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Danny252
1461 posts |
Ah, that sounds sensible enough - though I'm not sure I'd go quite as far as saying that physics predicts a TC can't exist! (In fact, any physics lab experiment that works first time is regarded with confusion and amazement, both by students and lecturers!) Log in to reply |
| Complex track layout 01/02/2013 at 21:35 #41059 | |
KymriskaDraken
963 posts |
" said:Ah, that sounds sensible enough - though I'm not sure I'd go quite as far as saying that physics predicts a TC can't exist!The Handy Guide To Modern Science applies here: If it's green or it wriggles, it's biology If it's smelly or explosive, it's chemistry If it doesn't work, it's physics. Log in to reply The following users said thank you: Sam Tugwell, kbarber, Signalhunter |
| Complex track layout 03/02/2013 at 12:22 #41101 | |
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benstafford
88 posts |
And if it's made up it's Economics! (Of course real scientists don't consider that a SCience at all)
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