Post by mrfs42 on Apr 20, 2007 16:29:42 GMT
Another dose of signalling geekery I'm afraid. ;D
I'm familiar with the Delta Track circuits, but what are Beta points?
There are several in the Vic - letters and numbers for each beta are identical to adjacent track circuits.
Walthamstow:
Beta WK/WN (SB); Beta UB/UC (NB) - these are half-way through the scissors on the Mains.
S.Sisters:
Beta 468E/TC - just before 17 points (depot - plat 5 SB); Beta 453A/453B just after the NB home (VL1).
Finsbury Pk:
Beta 441B/NF NB, just before 3 points from the Picc.
Highbury:
Beta MC/MD. just before the SB - NB xover - I think this one was only in place August - Nov '68 and removed when the NB facing xover was removed: TCircuit MC 'grew' by 12' - the ones above were all shown as 10' long, this one was a 12' beta.
Warren St:
Beta FP/HG - halfway across xover
Victoria:
Same as W'stow half-way over the scissors ED/EJ SB and DN/DP NB. ED/EJ was removed with 17/18 xover on extension. These Beta points were shorter than the others - 9' DN/DP, 8' ED/EJ.
T/Circuit DN has been absorbed into DM, so later it is DM/DP beta.
There aren't any others further south.
What are they - some form of "code isolation"? They're all between 8 and 12 feet long. Wot's their purpose then?
I'm familiar with the Delta Track circuits, but what are Beta points?
There are several in the Vic - letters and numbers for each beta are identical to adjacent track circuits.
Walthamstow:
Beta WK/WN (SB); Beta UB/UC (NB) - these are half-way through the scissors on the Mains.
S.Sisters:
Beta 468E/TC - just before 17 points (depot - plat 5 SB); Beta 453A/453B just after the NB home (VL1).
Finsbury Pk:
Beta 441B/NF NB, just before 3 points from the Picc.
Highbury:
Beta MC/MD. just before the SB - NB xover - I think this one was only in place August - Nov '68 and removed when the NB facing xover was removed: TCircuit MC 'grew' by 12' - the ones above were all shown as 10' long, this one was a 12' beta.
Warren St:
Beta FP/HG - halfway across xover
Victoria:
Same as W'stow half-way over the scissors ED/EJ SB and DN/DP NB. ED/EJ was removed with 17/18 xover on extension. These Beta points were shorter than the others - 9' DN/DP, 8' ED/EJ.
T/Circuit DN has been absorbed into DM, so later it is DM/DP beta.
There aren't any others further south.
What are they - some form of "code isolation"? They're all between 8 and 12 feet long. Wot's their purpose then?
), I see that in 1968 Beta tracks were used/described to actually detect block joints and the code present. Used where there wasn't enough room to ensure code separation - 11' 6" or less. What makes it such a clever bit of circuitry is that if one block joint fails the beta circuit prevents false code feed from the adjacent track across the failed joint, and if the other joint also fails then both adjacent tracks drop. <whisper> I'm quietly impressed. 
