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| Absolute Block clearing point over points on NX panel 13/01/2014 at 22:07 #53856 | |
john_s
31 posts |
I originally posted this question on the Signalbox forum, but have noticed that the Worksop simulation includes just what I was getting at, so it seems worth mentioning it here. Consider the up section from Worksop (Woodend Junction) to Elmton and Creswell. In reality (as far as I know, I don’t have the exact distances available), the crossover from the Clowne branch lies within the clearing point for acceptance under Absolute Block. If the points were set for the branch, one would have to normalise them before accepting a train from Worksop. Now suppose that E+C was replaced by a route setting system (e.g. NX panel) – with the clearing point still over the crossover. You can’t just set the route from the home signal: this would normalise the points but clear the signal as well, and this is not allowed for AB acceptance. So there would be seem to be three options to accept a train from Worksop with the points initially set for the branch: (a) Use the point switches to normalise the points (b) Slot the section signal at Woodend junction: clearing the slot sets the route to Creswell and normalises the points (c) Have a special button which calls the clearing point (could useful be if several points had to be moved, e.g. including flank protection), then give line clear, then set the route from the home signal. The simulation seems to do (b). My question is: is there - somewhere - a real life precedent for this? (or for (a) or (c)). I can’t think of one – nor could anyone else – and I have a feeling it is unlikely, although theoretically possible. Log in to reply |
| Absolute Block clearing point over points on NX panel 14/01/2014 at 04:15 #53863 | |
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Hawk777
386 posts |
Conceivably, isn’t there also option (d) have the points automatically normalize a few seconds after they are no longer locked? I believe a few points do that.
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| Absolute Block clearing point over points on NX panel 14/01/2014 at 08:17 #53864 | |
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Firefly
521 posts |
Option (e) Move the home signal back. As long as you have a colour light distant signal you only need 180m overlap as apposed to the 440yards you need if you have a semaphore distant signal. Chances are the existing clearing point is based on semaphore signalling. (Not familiar with the location that you're discussing so could be wrong about my last statement) The railways new way of thinking on signalling is that simple is best, so why create a complex method of working when you can just move a signal by a few meters. FF Log in to reply |
| Absolute Block clearing point over points on NX panel 14/01/2014 at 14:01 #53873 | |
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john_s
31 posts |
Firefly - I agree, and of course (e) usually applies. But there have been plenty of one-offs and unusual ways of doing things - so I didn't rule it out entirely. But probably this is one odd arrangement which never existed.
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| Absolute Block clearing point over points on NX panel 15/01/2014 at 10:08 #53902 | |
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kbarber
1742 posts |
I'm pretty certain this would never have been allowed to exist; as Firefly says, the home would've been moved back enough (even in an earlier installation before modern clearing point standards were established) to give a full clearing point before any possible obstruction was encountered. If 'twere a panel, the signal would be a colour light; if the panel were replacing a mech frame there's a high liklelihood the new colour light would be replacing a semaphore in any case so putting it a bit further away would be a no-brainer. (I suspect that would've been done even if the panel were an IFS, I might add - it would make the working far more flexible, quite apart from ensuring the box didn't get extra marks (and thus risk conceding a higher grade) for such things as blocking back.)
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| Absolute Block clearing point over points on NX panel 15/01/2014 at 17:55 #53909 | |
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dwaynedibley
30 posts |
Moving the signal is an option but more likely would be the installation of a second home signal, leaving you with an outer and inner or first and second home depending on the area.
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| Absolute Block clearing point over points on NX panel 15/01/2014 at 18:19 #53911 | |
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Stephen Fulcher
2080 posts |
Colour lights would often be reduced in number relative to semaphores, and placed according to requirements at the time. Total conversion from mechanical to MAS rarely results in every signal being deployed in the same place. Lostwithiel has six stop signals in the up direction at the moment, which would probably be reduced to two or three if they were colour lights. Log in to reply |
| Absolute Block clearing point over points on NX panel 16/01/2014 at 23:14 #53948 | |
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john_s
31 posts |
Thanks for your answers folks. I'm not surprised that a panel (let alone a route setting panel) version of what I originally suggested does not exist, although I suspect there are a few mechanical examples of colour light signalling + AB + points within clearing point (Stockport?).
Last edited: 16/01/2014 at 23:14 by john_s Log in to reply |
| Absolute Block clearing point over points on NX panel 16/01/2014 at 23:38 #53949 | |
headshot119
4869 posts |
" said:Thanks for your answers folks. I'm not surprised that a panel (let alone a route setting panel) version of what I originally suggested does not exist, although I suspect there are a few mechanical examples of colour light signalling + AB + points within clearing point (Stockport?).Rhyl is another example with of the mechanical type. "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 |
| Absolute Block clearing point over points on NX panel 17/01/2014 at 09:24 #53956 | |
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kbarber
1742 posts |
" said:Thanks for your answers folks. I'm not surprised that a panel (let alone a route setting panel) version of what I originally suggested does not exist, although I suspect there are a few mechanical examples of colour light signalling + AB + points within clearing point (Stockport?). I would say it used to be pretty common, sometimes with just the home signal as a colour light and sometimes with rather more. Of course, a lot of the boxes I knew are no longer  but I don't suppose all the examples have gone.
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