Standoff at South Ruislip/Greenford West Junction

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Standoff at South Ruislip/Greenford West Junction 12/11/2021 at 20:20 #142263
Gwasanaethau
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509 posts 		Hi all,

I am currently playing through the December 2013 timetable and have come across a potential issue with the fringe at Greenford West.

I have train 2V35 at South Ruislip awaiting departure towards Greenford West Junction. In the meantime, a very early running 6M22 has entered at Greenford West Junction and has come to a halt at signal ME65. I have requested the slot from Greenford East signalbox in order to send 2V35 towards Greenford, but the 'box is not granting it; I suspect due to the presence of 6M22. Unfortunately, this has resulted in a stand-off, with no way of moving either train out of the way of the other. I have waited/fast-forwarded the sim for half-an-hour (sim time) just to be sure the signal-person isn't just being slow to grant the slot, but it still hasn't been given.

Cheers,

Mark (Gwasanaethau)
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Standoff at South Ruislip/Greenford West Junction 12/11/2021 at 22:25 #142264
wellgroomed
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110 posts
Online 		The same problem exists in real-life. Events in the real world would probably be a conversation between signalboxes. Holding 6M22 back on the Down Branch at Greenford South Junction would/may mean delaying the Greenford shuttle, if 6M22 had run beyond Acton anyway.

If faced with the example, I would ask the driver of the unit to continue to West Ruislip and reverse there. If this meant a significant delay to the unit, then I may just run it back towards Aylesbury. From memory, I think that's what the unit would do when it comes back from the Western anyway.
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Standoff at South Ruislip/Greenford West Junction 13/11/2021 at 13:41 #142290
bill_gensheet
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1431 posts 		I would suggest that the answer is to get the slot before 2V35 is at the point of no return - ie in the Northolt Park area.
Tested and works.

It may seem odd that with the slot given 6M22 happily enters and stops at 'sig 65', yet this is the same 'place' as when GEJ will not give the slot. The on screen appearance of double track beyond suggests the slot should be given with 6M22 at 'sig65'.

However Sig 65 is shown below as being an acceptance switch function between the boxes and not a physical signal.
Without acceptance given at 'sig65' you would assume GEJ would not let 6M22 into the junction.

See below for the details of Greenford:

https://www.roscalen.com/signals/Greenford/Greenford.gif
https://www.roscalen.com/signals/Greenford/index.htm

So should leaving 'sig65' on or collared allow the slot to be given ?
Has the sim simplified the arrangments into a normal one way slot such that 'sig65' is always free, or have there been changes ?

Bill
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Standoff at South Ruislip/Greenford West Junction 13/11/2021 at 22:55 #142314
Gwasanaethau
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509 posts 		bill_gensheet in post 142290 said:
I would suggest that the answer is to get the slot before 2V35 is at the point of no return - ie in the Northolt Park area.
My initial thinking was that I didn't want to request the slot until 2V35 was just about ready to depart. I had it in my head that requesting the slot too early would 'gum up' the works of the neighbouring signalbox. It hadn't occurred to me that that was exactly what I needed to do as it is the only way I have of telling them I could no longer accept a train into my section.

bill_gensheet in post 142290 said:
It may seem odd that with the slot given 6M22 happily enters and stops at 'sig 65', yet this is the same 'place' as when GEJ will not give the slot. The on screen appearance of double track beyond suggests the slot should be given with 6M22 at 'sig65'.

However Sig 65 is shown below as being an acceptance switch function between the boxes and not a physical signal.
Without acceptance given at 'sig65' you would assume GEJ would not let 6M22 into the junction.

See below for the details of Greenford:

https://www.roscalen.com/signals/Greenford/Greenford.gif
https://www.roscalen.com/signals/Greenford/index.htm

So should leaving 'sig65' on or collared allow the slot to be given ?
Has the sim simplified the arrangments into a normal one way slot such that 'sig65' is always free, or have there been changes ?

Bill
This was my original rationale for not requesting the slot immediately, though, I will admit I wasn't totally sure of the track structure beyond the interface with my area of control.

wellgroomed in post 142264 said:
The same problem exists in real-life. Events in the real world would probably be a conversation between signalboxes. Holding 6M22 back on the Down Branch at Greenford South Junction would/may mean delaying the Greenford shuttle, if 6M22 had run beyond Acton anyway.

If faced with the example, I would ask the driver of the unit to continue to West Ruislip and reverse there. If this meant a significant delay to the unit, then I may just run it back towards Aylesbury. From memory, I think that's what the unit would do when it comes back from the Western anyway.
Thank you for that insight into the real-world working here. I'll definitely take Bill's (bill_gensheet's) advice in future; requesting the slot before the 'point of no return', as he put it. ;)

Thank you both! Now please bear with me whilst I unpick this mess I have in front of me! XD
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