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| 4 Aspect Yellow Lamp Failure? 31/07/2010 at 17:13 #1542 | |
Danny252
1461 posts |
Quick question regarding 4-aspect signals. Obviously, these have two yellow lamps (A and B for the purposes of this discussion), with only one being used for the standard one-yellow caution (let's say A). If Lamp A fails, will the signal switch over to using B instead to show a one-yellow caution (whilst obviously being unable to show double yellow)? Log in to reply |
| 4 Aspect Yellow Lamp Failure? 31/07/2010 at 17:13 #10370 | |
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Danny252
1461 posts |
Quick question regarding 4-aspect signals. Obviously, these have two yellow lamps (A and B for the purposes of this discussion), with only one being used for the standard one-yellow caution (let's say A). If Lamp A fails, will the signal switch over to using B instead to show a one-yellow caution (whilst obviously being unable to show double yellow)? Log in to reply |
| 4 Aspect Yellow Lamp Failure? 31/07/2010 at 17:55 #10373 | |
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Firefly
521 posts |
Hi Dan No it won't. If the bottom yellow fails the signal will be "black" it it should b e showing a single yellow. Kev Log in to reply |
| 4 Aspect Yellow Lamp Failure? 02/08/2010 at 09:00 #10409 | |
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clive
2789 posts |
In relay interlockings, only the bottom yellow is tested in the "signal lit" logic, since a failure of the top lamp is safe (even if it scares the driver a bit). There is a separate "main filament failed" test which does apply to all four lamps and will therefore detect the problem. SSIs are cleverer and could, in principle, use the top yellow for a single yellow aspect. However, there may be sighting issues that make that a bad idea, so I don't think it's done. Log in to reply |
| 4 Aspect Yellow Lamp Failure? 11/08/2010 at 12:57 #10646 | |
Mattyq
259 posts |
This could also be dangerous as the Driver may misinterpret the signal as a Double Yellow with a failed bottom aspect and drive to that assumption.
Not fat ..... fluffy!! (G Iglesias) Log in to reply |
| 4 Aspect Yellow Lamp Failure? 15/11/2020 at 19:46 #133894 | |
9pN1SEAp
1180 posts 
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In SimSig, I don't think I've ever seen a driver reduce speed, and certainly never had a phone call, about losing the second yellow aspect. Would they IRL treat this as adverse requiring signaller attention, or just report later on a form? Thanks Jamie Jamie S (JAMS) Log in to reply |
| 4 Aspect Yellow Lamp Failure? 15/11/2020 at 23:14 #133898 | |
DriverCurran
688 posts |
When I was driving then going green to single yellow when I was expecting at worst two yellows would be straight step 3 / full 50 psi brake application (on the basis that I would be treating it as expecting the next signal to be at red so I would be treating the single yellow as genuine until instructed otherwise) and then on the radio to the signaller to find out what is going on. Paul You have to get a red before you can get any other colour Log in to reply The following user said thank you: 9pN1SEAp |
| 4 Aspect Yellow Lamp Failure? 16/11/2020 at 04:10 #133899 | |
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Chromatix
190 posts |
Indeed, as it could be a "put back" scenario - the kind of thing that SimSig would report as ACOA. Sometimes a "put back" is a necessary evil, but of course best avoided if possible.
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| 4 Aspect Yellow Lamp Failure? 16/11/2020 at 10:39 #133902 | |
Splodge
719 posts |
As ever, there is an exception to this - Manchester South, and its Ansaldo signals. Both apertures can display R/Y/G, with the lower aperture being the default for red and single yellow, and the upper aperture for green. However, should a lamp fail the signal will automatically swap them so it isn't unusual to see red in the top aperture or green in the lower. The system also mitigates for lamp failures that can't be swapped - so if for example a signal can't show either green aspect, it will hold itself on double yellow with the normal sequence leading up to it. If it can't show either yellow, it will hold on red until a green aspect can be displayed. There's the right way, the wrong way and the railway. Log in to reply |
| 4 Aspect Yellow Lamp Failure? 16/11/2020 at 12:51 #133904 | |
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clive
2789 posts |
9pN1SEAp in post 133894 said:In SimSig, I don't think I've ever seen a driver reduce speed, and certainly never had a phone call, about losing the second yellow aspect.At present the second yellow can't fail. Mantis 32064 raised. Log in to reply The following users said thank you: 9pN1SEAp, Trainfan344 |
| 4 Aspect Yellow Lamp Failure? 16/11/2020 at 16:10 #133907 | |
lazzer
634 posts |
DriverCurran in post 133898 said:When I was driving then going green to single yellow when I was expecting at worst two yellows would be straight step 3 / full 50 psi brake application (on the basis that I would be treating it as expecting the next signal to be at red so I would be treating the single yellow as genuine until instructed otherwise) and then on the radio to the signaller to find out what is going on.I remember approaching Airport Junction on the up one day a few years ago, and receiving a single yellow after a green before West Drayton station. It's four-aspect signalling there, so I would have expected a double yellow first. It turns out that the track circuit in advance of what was the red signal failed just after I passed what would have been the double yellow. I was on an HST doing 120mph, and the emergency brake application I gave it just about stopped me before the red signal. There is no way I would have even considered that single yellow as being a double with an aspect failure on one of the lamps. If you see a single yellow with no double before it on four-aspect signalling, the brake goes straight into emergency at that speed. Log in to reply The following users said thank you: 9pN1SEAp, DriverCurran |
| 4 Aspect Yellow Lamp Failure? 16/11/2020 at 16:22 #133908 | |
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DriverCurran
688 posts |
Thankfully mine was at a speed half of that, and at least by step 3 on the Westcode brake did allow a 'relatively' smoothish stop at the red, but indeed much faster and that handle goes past the point of no return so to speak. For those not in the know, a step 3 application can be released and when stopping you were taught to try and stop with a lowering pressure in the brake cylinder for customer comfort (Back in 2002 so may have changed since then), whereas when you hit emergency then until the train has actually stopped you are unable to release the brake in any way, shape or form. You have to get a red before you can get any other colour Log in to reply |
| 4 Aspect Yellow Lamp Failure? 16/11/2020 at 18:22 #133913 | |
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lazzer
634 posts |
DriverCurran in post 133908 said:Thankfully mine was at a speed half of that, and at least by step 3 on the Westcode brake did allow a 'relatively' smoothish stop at the red, but indeed much faster and that handle goes past the point of no return so to speak.As an addition to that, you can bring the brake back from emergency on an HST at any speed by simply bringing the handle back to any other brake position. On a IET you can also get it back, but only after pressing the Train Fault Acknowledge button to cancel the alarm. Log in to reply The following users said thank you: DriverCurran, Trainfan344 |