WS4336 at Penkridge

[driver_m]

Just curious, how far do you take that? What would be wrong with Y-Y on 4 aspect and then Y on 3 aspect? Also, does that mean that you have a 4 aspect signal that only ever shows 3 aspects (or is this the junction where one way is 3 and the other is 4 aspect signalling)?

Nothing wrong with YY in a 4 and Y in a 3 sequence but I've never actually seen it occur. Never seen yellows at Colwich heading to Hixon and doesn't happen at Crewe. Leave on a green (4 aspect) going towards Chester. Get one yellow at the next signal heading towards the steelworks box which is a 3 aspect. Stone does have 3s heading to hixon and 4s to Norton Bridge. Edge Hill goes 3 to 4 aspect on the up and the first 4 aspect signal will show a single yellow when the previous one was a green.

 

[carriageline]

The up lewisham issue previously spoke about is a long standing interlocking issue I believe, but unfortunately I don't know the specifics. I know someone with brilliant knowledge of London Bridge, I'll ask him when I next bump in to him.

When it gets resignalled it might be sorted, that's if it gets a new interlocking. But, it will more than likely be a straight swap/recontrol and any current issues will remain unless they attempt to fix them during the recontrol.

Anything country side of New Cross won't be resignalled, and will probably just be recontrolled, that's if that part of london bridge even gets moved. Apparently the TL project are not paying for that, and it's down to Network Rail. So there's every possibility it might be filed under "too expensive"


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[Crossover]

Nothing wrong with YY in a 4 and Y in a 3 sequence but I've never actually seen it occur. Never seen yellows at Colwich heading to Hixon and doesn't happen at Crewe. Leave on a green (4 aspect) going towards Chester. Get one yellow at the next signal heading towards the steelworks box which is a 3 aspect. Stone does have 3s heading to hixon and 4s to Norton Bridge. Edge Hill goes 3 to 4 aspect on the up and the first 4 aspect signal will show a single yellow when the previous one was a green.

Thanks for that - makes sense. I would have actually thought Stone would have been the other way around - 4 aspect for the faster(?) Hixon route and 3 aspect towards Norton Bridge

 

[ComUtoR]

The up lewisham issue previously spoke about is a long standing interlocking issue I believe, but unfortunately I don't know the specifics. I know someone with brilliant knowledge of London Bridge, I'll ask him when I next bump in to him.

Hugs n kisses xxoo

"Long standing" is an understatement !




Cheers in advance.

 

[Bald Rick]

The up lewisham issue previously spoke about is a long standing interlocking issue I believe, but unfortunately I don't know the specifics. I know someone with brilliant knowledge of London Bridge, I'll ask him when I next bump in to him.

When it gets resignalled it might be sorted, that's if it gets a new interlocking. But, it will more than likely be a straight swap/recontrol and any current issues will remain unless they attempt to fix them during the recontrol.

Anything country side of New Cross won't be resignalled, and will probably just be recontrolled, that's if that part of london bridge even gets moved. Apparently the TL project are not paying for that, and it's down to Network Rail. So there's every possibility it might be filed under "too expensive"


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All of London Bridge is being recontrolled to TBROC as part of TLP.

The Hither Green interlocking area gets resignalled (new interlocking, new ground equipment where required) in 2018/19. Separate renewals project, but delivered by Thameslink.

 

[driver_m]

Thanks for that - makes sense. I would have actually thought Stone would have been the other way around - 4 aspect for the faster(?) Hixon route and 3 aspect towards Norton Bridge

Hixon only had one train an hour either way when they resignalled it. So it's 125mph on 3 aspect signalling! Virtually never see a yellow to be fair.

 

[carriageline]

All of London Bridge is being recontrolled to TBROC as part of TLP.



The Hither Green interlocking area gets resignalled (new interlocking, new ground equipment where required) in 2018/19. Separate renewals project, but delivered by Thameslink.

I see! It's frustrating at our end, we get told a whole array of stuff from a whole array of people!

 

[Joseph_Locke]

numbers of aspects is driven by speed and headway requirement, or by the wish to speed up a 3-aspect railway without moving the signals.

 

[Crossover]

Hixon only had one train an hour either way when they resignalled it. So it's 125mph on 3 aspect signalling! Virtually never see a yellow to be fair.

Ah - thanks for that. I guess even at 3tph either way, it won't be overly congested even then

 

[brick60000]

Thanks all for your replies so far! They've made for a very interesting read.

Can you confirm that it "does not" or that it "did not" ? there is a significant difference between the two.

I noticed it on both occasions I observed the signal following a train passing and then subsequently clearing the next signals. I wasn't sure if I'd seen correctly the first time, so looked on return later on. I watched the OTT map of the area as the train cleared the following signals, and it jumped straight from yellow to green as it the train left the third block ahead.

Sorry I didn't reply sooner!

Brick60000

 

[ComUtoR]

Sounds totally legit. As long as signals step down correct then everything is OK.

Double blocking was mentioned and that's where the sequence can be held by maintaining consecutive signals at red for the section in front to remain clear. Typically this is used where there is a potential colision. Overlaps etc may be smaller or even shared by two signals. We have two such junctions that spring to mind where a YY would be a rare occurrence. One will typically step up as R-Y-G

Just because someone is not seen doesn't mean it doesn't or cannot happen. Bit like bears and their toilet habbits.