UK railway signals- Help lighting this tree

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UK railway signals- Help lighting this tree

Post by leezer3 on Wed Mar 19, 2014 5:45 pm

OK, so I need someone who understands a little more about UK signalling technicalities than I do here.
First, please see the attached image.


The signal tree in question controls the approach to Laira depot. This is as I read it:
* Signal with feather on far right- Controls mainline.
* Subsidiary signal second from right- Shows whether the points on the loop line are set into the depot or into the stabling/ carriage sidings.
* Two aspect- Controls the loop line itself.
* Subsidiary with theater indicator- Gives information to the loop line as to where exactly the points in the depot are set?

Lines from L-R:
Headshunt siding for depot. I believe controlled by a ground signal a little further down.
Depot loop line.
Down Main.
Up Main.

There is also a pair of ground signals that I haven't got as far as adding yet, which I believe control backing movements from the depot onto the two main running lines.

I'm having a headache about exactly what should be lit where; I'm working from some photographs and a video, but none are clear enough to give any real details about the color combinations or exactly what should be lit at any one time on the subsidiarys.

Anyone with any better thoughts than me at the moment?

Cheers

Chris Lees

http://www.bvecornwall.co.uk
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Last edited by leezer3 on Wed Mar 19, 2014 11:00 pm; edited 1 time in total

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Re: UK railway signals- Help lighting this tree

Post by bvetmd on Wed Mar 19, 2014 7:17 pm

Hi Chris, without seeing the track diagram its a little difficult but heres a couple of points.....

The far right signal with the feather and the subsidiary signal 2nd right seem to be conflicting each other, from my experience you wouldnt have a main line signal showing clear along with an associated subsidiary alongside also showing clear. Does the feather grant access into the depot or loop line further along or does it grant access to another route in the distance ?
In my opinion, if the main line signal is set at clear then the subsidiary should be showing a red/white at danger. If the feather is lit granting access to the loop or depot then I'd expect the subsidiary alongside to be lit clear with two white lights, the mainline signal to be lit red at danger and the feathers lit also.
Hope this makes sense...
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Re: UK railway signals- Help lighting this tree

Post by leezer3 on Wed Mar 19, 2014 10:55 pm

Sorry, the lights are just placeholders, so may be a little misleading.
Track diagram:

The signal in question is where the red square is.

The physical configuration is right, but everything else is speculation. I have no real idea exactly of what controls what other than the obvious signal with feather for the mainline. I don't mind simple stuff, but this makes my head spin.
Everything is is supposition and fudge-work, hence why I'm asking before I do anything terminally stupid Razz


Cheers

Chris Lees

http://www.bvecornwall.co.uk

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Re: UK railway signals- Help lighting this tree

Post by bvetmd on Thu Mar 20, 2014 7:09 am

Right that makes more sense now  Smile 

Ideally I'd need to look at the sectional appendix though I reckon what I said before would still stand regarding the mainline signal and its subsidiary, its highly unlikely that to divert away from the mainline a driver would see a clear aspect on the mainline signal and a feather, the only way this would happen would be if there is another subsidiary signal further along protecting the depot/siding itself. So in other words, the only time the mainline signal would show a clear/caution aspect would be if  the route is set for the mainline itself. The subsidiary signal being used with the feather to grant access to the depot/sidings etc.
The confusing bit to me is what happens at the junction of the down/up goods Sutton Hbr branch and the neck into the depot itself, there has to be another signal somewhere in that area to protect movements in and out of the depot and in both directions on the branch.
As for the the other theatre indicator above the extreme left subsidiary signal, I'd expect the indications to be either SDG (for the depot) and possibly GDS or something similar to show the route for the Sutton harbour branch. I'd also suggest that the two aspect signal for the loop would only show a caution aspect if route is set for the Sutton Harbour branch, the subsidiary being used for the depot access only.

I've not had a look yet but the required sectional appendix is here [url=http://www.networkrail.co.uk/browse documents/sectional appendix/western sectional appendix.pdf]http://www.networkrail.co.uk/browse%20documents/sectional%20appendix/western%20sectional%20appendix.pdf[/url]

You should find most of what you require there.
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Re: UK railway signals- Help lighting this tree

Post by leezer3 on Thu Mar 20, 2014 1:53 pm

Yeah, pages 105 & 265.
(301 & 461 in PDF readers)
I don't think that tells me too much about what's going on, other than what I already really know;
* Goods line has a limit of 15mph that then drops to 10mph at the depot entrance somewhere, I'm presuming immediately before this signal.
* 70 limit on main lines

I think you'll find though that most of the signalling has been ripped out by now, which also makes life difficult!
The Sutton Harbour branch & the line to Friary/ Cattewater have all closed, and IIRC all that's down the branch now is the loco wash and availability of the line for use as a turning triangle for specials etc.

Again, not majorly conversant with reading sectional appendicies with regard to signalling mind!

Cheers

Chris Lees

http://www.bvecornwall.co.uk

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Re: UK railway signals- Help lighting this tree

Post by leezer3 on Thu Mar 20, 2014 2:38 pm

Further notes Wink
Trying to find pictures showing signals is a pain in the rear!
Neither my video or the images I have appear to show any further signals on the secondary tracks other than a ground signal at the end of Ocean Siding.

It's possible there's something out of view under the flyover, not sure.
This is taken off the flyover, looking at Laira Junction:
http://www.flickr.com/photos/35663521@N04/4037103045/
There's a single signal (I'm presuming 3-aspect, I haven't come across any 4-aspects in Plymouth) on a post controlling the exit from the Sutton Harbor branch, and what I *think* is a ground-signal controlling the exit from the sidings.
This (I'm reasonably certain) is the current signal situation there:
http://www.flickr.com/photos/didbygraham/4650091431/
I think what they've done is to condense the 3-aspect on the post and the ground signal into a single post. (The top two sidings have also been closed)

A marginally different angle on the first is this one, and possibly shows the signal on a post angled for the sidings?:
http://www.flickr.com/photos/74802869@N03/6841374400/
Makes me wonder if the Sutton Harbor goods line is basically a single section from my initial signal through the depot.

My head now hurts Razz

Cheers

Chris Lees

http://www.bvecornwall.co.uk

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Re: UK railway signals- Help lighting this tree

Post by bvetmd on Thu Mar 20, 2014 5:48 pm


'Makes me wonder if the Sutton Harbor goods line is basically a single section from my initial signal through the depot'

Looking at pages 904 and 905 (pdf) that could well be the case today, as I cant seem to see any other signalling to suggest otherwise, if so it would be possible to be signalled directly off the mainline with a caution aspect on the main signal I'd imagine.
Its been a while since I was down that neck of the woods, I realise quite a bit of track has now gone !

I've sent you a pm with some more info if its of any use ....
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