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Im confused... 21/02/2014 at 18:12 #55938 | |
DanC
53 posts |
Hopefully someone can enlighten me! I work in Manchester and drive along the M602 near enough every day - the Manchester to Liverpool line runs alongside the M602 for a fair while. The other day, I was driving along and a train was going along in the same direction as me, now it went through a Green signal and, as it approached the next signal (not much distance between signals on that stretch) the green signal the train went through reset to a single yellow aspect, not a red. It was my understanding a signal would always revert to red after a train went through? Thanks in advance, Dan Log in to reply |
Im confused... 21/02/2014 at 18:15 #55939 | |
John
884 posts |
Probably a distant signal. Wickipedia said: A distant signal is one that cannot display a 'danger' aspect. It is however able to display a 'caution' aspect, which gives the driver advance warning that the stop signal ahead may be displaying 'danger'. The distant signal is installed roughly at full braking distance on approach to the stop signal to which it applies, taking into account the gradient, the permitted speed, and the braking performance of trains. On sighting a 'caution' aspect, the driver must prepare to stop at the signal ahead. If the distant signal shows a 'clear' aspect, the train may maintain full speed. A single signal may be equipped to function both as a stop signal and a distant signal. Last edited: 21/02/2014 at 18:16 by John Log in to reply The following user said thank you: DanC |
Im confused... 21/02/2014 at 18:44 #55945 | |
DanC
53 posts |
" said:Probably a distant signal.So presumably, the signal preceeding the distant signal would show a danger aspect, ignoring the distant signal aspect? Log in to reply |
Im confused... 21/02/2014 at 19:20 #55951 | |
Steamer
3958 posts |
" said:Yes. There's plenty of examples in SimSig- watch the behaviour of any signal labelled R or RR (the RR variant can show Y, YY or G as opposed to Y or G). In some cases there's a track circuit between the main signal and the distant, in which case the Distant goes back to Y as soon as the train passes it, otherwise the repeater goes back to Y when the main signal goes to R. "Don't stress/ relax/ let life roll off your backs./ Except for death and paying taxes/ everything in life.../ is only for now." (Avenue Q) Log in to reply The following user said thank you: DanC |
Im confused... 21/02/2014 at 19:27 #55953 | |
Lardybiker
771 posts |
If its color lights then it's likely a repeater not a distant (which is a name from the semaphore days and means something completely different). A repeater is typically used in 2-aspect signalling areas and gives advance warning of the signal ahead to give drivers more time to slow down and therefore allowing higher speeds on the line. However, a repeater only has 2 aspects, green and yellow. If the signal the next signal the train reaches after the repeater is green, the repeater will show green. If that signal is red, the repeater, in order to maintain the correct aspect sequence, will show yellow. As the train passes the repeater, TC occupation by the train will force the signal it has just passed to drop to its most restrictive aspect. However, as the repeater has only green and yellow aspects, the most restrictive aspect it can show is a yellow. And that's exactly what you saw. Edit: In fact if you happened to get the signal number, we can tell you exactly what the signal is and what it's doing. Last edited: 21/02/2014 at 19:28 by Lardybiker Log in to reply The following user said thank you: DanC |
Im confused... 21/02/2014 at 22:27 #55966 | |
clive
2766 posts |
Some minor corrections ... On a two-aspect or three-aspect line, a repeater only shows Y or G. On a four-aspect line, it shows Y, YY, or G (Y if the next signal is red, YY if it's yellow, and G if it's YY or G). The RR repeaters only appear on four-aspect lines and show only YY or G. Log in to reply |
Im confused... 22/02/2014 at 07:30 #55977 | |
Forest Pines
525 posts |
" said:If its color lights then it's likely a repeater not a distant (which is a name from the semaphore days and means something completely different).I suspect the vast majority, if not 100%, of distant signals on Network Rail that are on their own post are colour light signals. Log in to reply |
Im confused... 22/02/2014 at 08:21 #55979 | |
Firefly
521 posts |
Quote:I suspect the vast majority, if not 100%, of distant signals on Network Rail that are on their own post are colour light signals.Just to muddy the waters a little the term "distant" applies to any signal not capable of displaying a red aspect. The older ones of us know and love the term "repeater" but that word is only used in association with a banner. So you can have a distant which conforms to semaphore signalling principles or you can have a distant which conforms to colour light signalling principles (what we used to know as a repeater). You'll notice on new schemes the R suffix is never used, the distant signals have their own number and they also have a triangle on the signal id. FF Log in to reply |
Im confused... 22/02/2014 at 10:11 #55986 | |
mfcooper
707 posts |
But the controlled signal on approach to the Distant/Repeater will not be able to show a single yellow, as a train cannot stop at the repeater signal. EG: 4-aspect signalling area, S1 -> S5R -> S5. S5 can show R, Y, YY, G S5R can show Y, YY, G S1 can show R, YY, G - note no single yellow! And in more modern signalling schemes, S5R would be given its own number without the 'R' suffix, so you end up with something like S1 -> S3 - > S5, where S1 cannot show Y, and S3 cannot show R. Log in to reply |
Im confused... 22/02/2014 at 18:24 #56021 | |
DanC
53 posts |
I drove past this signal today and did my best to get a look at the identifier plate below the lamps. It read: MP 5** (Cant remember exact number) R ^ So I'm assuming this means it was a repeater for the following signal (Which I couldn't quite see whilst driving) Its a three aspect signal so I assume it can show G, Y and YY depending on the signal it is repeating? Also I would be interested to know, for what reason would this type of repeater signal be used over and above a banner repeater? Log in to reply |
Im confused... 22/02/2014 at 19:28 #56026 | |
Jan
892 posts |
" said:Also I would be interested to know, for what reason would this type of repeater signal be used over and above a banner repeater? Basically main signals have two functions:
If the signal spacing is approximately equivalent to the maximum required braking distance, both functions can be combined into one signal and you'll get classic three aspect signalling. If you decrease the signal spacing even further, you move over to four aspect signalling, where the full braking distance is provided via the Double Yellow - Yellow - Red sequence of aspects. If on the other hand you increase the distance between consecutive stop signals (mostly because you don't need the full capacity provided by three/four aspect signalling and want to save some money), you reach a point where providing a combined signal for those two functions no longer makes sense - if you've got a five mile long block section, it doesn't make sense to show a yellow aspect to the driver just because the next signal five miles away is displaying a red. Therefore, separate signals are provided in the form of stop signals (red/green) and repeaters (yellow/green). Banner repeaters have a different purpose. When approaching a stop signal at line speed, drivers have to be able to see it properly for a certain amount of time before passing it. Where that is not possible due to the curvature of the line, bridges or anything else obstructing the view of the signal, banner repeaters are provided. Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick. Log in to reply |
Im confused... 22/02/2014 at 20:32 #56031 | |
Danny252
1461 posts |
" said:When approaching a stop signal at line speed, drivers have to be able to see it properly for a certain amount of time before passing it.Well, technically that would apply even to repeaters! However, if your line has few enough signals that you're down to two aspect signalling anyway, you can get away with just moving your repeater back behind whatever obstruction there is - stop signals are somewhat more limited as to their location (e.g. protecting points, stations). There's also the fact that a standard banner repeater (i.e. not one of those funny green ones) doesn't show any difference between the aspects a repeater signal shows! (Cue discussion of banner repeaters for distant signals...) Last edited: 22/02/2014 at 20:32 by Danny252 Log in to reply |
Im confused... 22/02/2014 at 20:33 #56032 | |
Steamer
3958 posts |
" said:I drove past this signal today and did my best to get a look at the identifier plate below the lamps.Doing a bit of Google Maps detective work, I reckon it was MP544R, which appears to be capable of showing Y, YY and G. The signal in rear, ES102 is showing YY, and appears to be capable of showing R, YY and G. "Don't stress/ relax/ let life roll off your backs./ Except for death and paying taxes/ everything in life.../ is only for now." (Avenue Q) Log in to reply |
Im confused... 22/02/2014 at 21:07 #56039 | |
Jan
892 posts |
" said:Well, technically that would apply even to repeaters!Now you're mentioning it, it sounds totally obvious, but somehow it didn't cross my mind at all. Thanks for pointing it out. Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick. Log in to reply |
Im confused... 22/02/2014 at 22:22 #56041 | |
vontrapp
210 posts |
ES is Eccles and MP is Man Picc. Man Picc does have repeater signal/s on the UP-line. R signals cannot show red, as the driver would have to stop at it. Last edited: 22/02/2014 at 22:24 by vontrapp Log in to reply |
Im confused... 23/02/2014 at 10:04 #56058 | |
Forest Pines
525 posts |
" said:R signals cannot show red, as the driver would have to stop at it.I think you have your cause and effect the wrong way round there. Drivers don't. normally have to stop at R signals because they can't show stop, not the other way around. Moreover there are, as I'm sure you're aware, situations in which the driver does have to stop at an R signal if possible. There was also one route which did have repeater signals which did have a red aspect, although I don't know if they had R plates - they're not there in real life any more but they are in a SimSig sim. And of course you can also have R signals which can't show green - an example is Edinburgh signal EY667R, which did (does?) have a standard 2-aspect head with the upper lens aperture blanked out and a yellow lens in the lower one. Log in to reply |
Im confused... 23/02/2014 at 10:27 #56061 | |
Peter Bennet
5377 posts |
M573 on Motherwell (discussed in another thread earlier today) has a 4A head but the top Y is blanked out. There are a fair few around I've found when building Sims. Either they just mounted a head they had laying around spare or a later decision was made to reduce the aspects, presumably as a cost saving. D1001R on Dundee panel. I remember many years ago, just after it was installed, experimenting with night photography to see if I could photograph it with all 3 aspects displaying (it was handily placed to do that). I seem to recall noticing years later the Y blanked and I think the head may have been changed since to a 2A but I'd need to check that. Peter I identify as half man half biscuit - crumbs! Log in to reply |
Im confused... 23/02/2014 at 12:02 #56066 | |
Ron_J
330 posts |
" said:D1001R on Dundee panel. I remember many years ago, just after it was installed, experimenting with night photography to see if I could photograph it with all 3 aspects displaying (it was handily placed to do that). I seem to recall noticing years later the Y blanked and I think the head may have been changed since to a 2A but I'd need to check that.D1001R was formerly Broughty Ferry's Down Home signal (BF2) but became a repeater for a new signal, D1001, when Broughty Ferry box was abolished in 1995. It still has a three aperture head today but is only capable of displaying yellow and green aspects. It has just had LED 'light engine' inserts fitted within the last two months. Log in to reply |
Im confused... 23/02/2014 at 21:26 #56112 | |
clive
2766 posts |
" said:"New Line" signals on SimSig Euston. The signals did have R plates and also had an offset second red lamp to show they were a repeater. Detailed description of the system here. Log in to reply The following user said thank you: Forest Pines |
Im confused... 08/03/2014 at 16:22 #56731 | |
button_pusher
56 posts |
You can't have a Green Signal reading directly onto a red signal in the UK so in 2 aspect signalling areas you have a repeater to stop this from happening (it's either Y onto G or G onto G). " said: " said:Also I would be interested to know, for what reason would this type of repeater signal be used over and above a banner repeater? Log in to reply |
Im confused... 08/03/2014 at 16:30 #56732 | |
Sacro
1171 posts |
" said:You can't have a Green Signal reading directly onto a red signal in the UK so in 2 aspect signalling areas you have a repeater to stop this from happening (it's either Y onto G or G onto G).You can in a semaphore area, you'd have a R/Y distant, reading to a R/G home reading to a R/G starter. Log in to reply |
Im confused... 08/03/2014 at 17:05 #56735 | |
Danny252
1461 posts |
" said:" said:However, the driver will not see the aspect sequence G->R, due to what was Rule 39a, which effectively gives a caution aspect. If a driver receives G onto R, he would be well within his rights to complain loudly.You can't have a Green Signal reading directly onto a red signal in the UK so in 2 aspect signalling areas you have a repeater to stop this from happening (it's either Y onto G or G onto G).You can in a semaphore area, you'd have a R/Y distant, reading to a R/G home reading to a R/G starter. Last edited: 08/03/2014 at 17:06 by Danny252 Log in to reply |
Im confused... 08/03/2014 at 18:01 #56740 | |
kbarber
1723 posts |
" said:" said:" said:However, the driver will not see the aspect sequence G->R, due to what was Rule 39a, which effectively gives a caution aspect. If a driver receives G onto R, he would be well within his rights to complain loudly.You can't have a Green Signal reading directly onto a red signal in the UK so in 2 aspect signalling areas you have a repeater to stop this from happening (it's either Y onto G or G onto G).You can in a semaphore area, you'd have a R/Y distant, reading to a R/G home reading to a R/G starter. Except if there's an exemption in the Sectional Appendix, which the driver would be expected to know before he's allowed to drive that route. Log in to reply |
Im confused... 08/03/2014 at 21:24 #56749 | |
Danny252
1461 posts |
" said:Except if there's an exemption in the Sectional Appendix, which the driver would be expected to know before he's allowed to drive that route.Perhaps some early colour lights may have ended up being G onto R, as semaphore replacements - I'm not sure whether they were required to be operated as per semaphores, though. Log in to reply |
Im confused... 08/03/2014 at 22:12 #56752 | |
clive
2766 posts |
" said:You can't have a Green Signal reading directly onto a red signal in the UK so in 2 aspect signalling areas you have a repeater to stop this from happening (it's either Y onto G or G onto G).Didn't this come up recently? Apparently on the loop line in Liverpool you get G at one station reading straight to R at the next. Log in to reply |