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Post by Deleted on Oct 18, 2009 13:27:31 GMT
Given that the first stage of the Jubilee Line was built around the same time as the Brixton extension of the Victoria and the Heathrow extension of the Piccadilly, is the geometry and curvature of the scissors crossover at Charing Cross similar to the two examples at the former sites?
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mrfs42
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Post by mrfs42 on Oct 18, 2009 14:11:32 GMT
I reckon that Charing Cross is straighter on one side than Brixton:
Brixton = )X(, CHX = )X|, H123 is closer to Brixton than CHX.
However, this is only a subjective guess, nothing more concrete.
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Post by Deleted on Oct 18, 2009 14:15:28 GMT
I reckon that Charing Cross is straighter on one side than Brixton: Brixton = )X(, CHX = )X|, H123 is closer to Brixton than CHX. However, this is only a subjective guess, nothing more concrete. But is the rest of the geometry still such that the physically straight route through the scissors crossover is actually through the diamond crossing, with the signalled straight route being curved slightly? |
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mrfs42
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Post by mrfs42 on Oct 18, 2009 14:24:59 GMT
There is no signalled straight route as such; TG 2 (SB Junction Home) has arbour lights for both routes, and IIRC that the crossover is limited to 25mph.
Entering the straightest route is over the diamond, departing I think the straightest route from platform 4 is *not* over the diamond, but is from platform 3.
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Post by Deleted on Oct 18, 2009 14:32:13 GMT
There is no signalled straight route as such; TG 2 (SB Junction Home) has arbour lights for both routes, and IIRC that the crossover is limited to 25mph. Entering the straightest route is over the diamond, departing I think the straightest route from platform 4 is *not* over the diamond, but is from platform 3. I find it interesting that both routes through the crossover from the s/b line have arbour lights - which way do the lights point for the route to what would have been the s/b platform, had the line been extended? (I forget which platform is numbered which). |
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mrfs42
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Post by mrfs42 on Oct 18, 2009 14:43:12 GMT
\ for the SB; / for the NB.
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Post by Deleted on Oct 18, 2009 14:50:25 GMT
\ for the SB; / for the NB. Thanks! Does the home signal into the crossover have a full overlap into the crossover, or is it a partial overlap? You did say that the crossover was restricted to 25mph but not why; is it because of lack of use or because the signalling dictates it? |
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Post by mrfs42 on Oct 18, 2009 15:08:04 GMT
Moorgate protection; there's a 25mph inductor on the approach.
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Tom
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Post by Tom on Oct 18, 2009 19:37:11 GMT
H123 has a similar arrangement with route lights for both platforms (coming from Hatton Cross).
I remember the geometry of the crossover there to be similar to that at Moorgate, with the nominally straight route cuved and the turnout straight.
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Post by Deleted on Oct 18, 2009 19:57:14 GMT
Can't help with the technical stuff, but if it is of interest, CHX (Jub) originally had moveable angles, removed July 1982. The moveable angles at HR123 were abolished November 1982, and at Brixton August 1983.
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Post by Deleted on Oct 18, 2009 21:07:20 GMT
Can't help with the technical stuff, but if it is of interest, CHX (Jub) originally had moveable angles, removed July 1982. The moveable angles at HR123 were abolished November 1982, and at Brixton August 1983. That was my next question! Given the time period in which it was built I'm not surprised it was initially equipped with moveable angles. |
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mrfs42
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Post by mrfs42 on Oct 18, 2009 23:40:24 GMT
I'm not surprised it was initially equipped with moveable angles. If the same technology existed then that pertains now for swingnose crossings then those moveable angles may still yet be there. |
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Post by Deleted on Oct 19, 2009 0:57:05 GMT
I'm not surprised it was initially equipped with moveable angles. If the same technology existed then that pertains now for swingnose crossings then those moveable angles may still yet be there. But that same technology isn't yet (to my knowledge) in use on LU metals yet, unless it was installed during the Watford South Junction works... |
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Post by JR 15secs on Oct 19, 2009 9:51:26 GMT
If the same technology existed then that pertains now for swingnose crossings then those moveable angles may still yet be there. But that same technology isn't yet (to my knowledge) in use on LU metals yet, unless it was installed during the Watford South Junction works... Waterloo Jubilee has had swing nose crossing since opening. |
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Post by londonse on Oct 19, 2009 12:24:06 GMT
I'm sure that moveable angles are still in use in the Harrow on the Hill area?
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Post by Deleted on Oct 19, 2009 13:04:41 GMT
Indeed they are still at Harrow:
215 and 217 - North Junction
200, 202 and 203 - South Junction
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Post by Deleted on Oct 20, 2009 9:00:41 GMT
Moorgate protection; there's a 25mph inductor on the approach. Given the length of the overrun, I'm surprised that a 25mph speed limit is imposed. Is the speed limit inbound only? |
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Post by mrfs42 on Oct 20, 2009 9:56:07 GMT
AIUI, yes. There is no restriction on leaving.
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Post by North End on Oct 20, 2009 10:45:57 GMT
Moorgate protection; there's a 25mph inductor on the approach. Given the length of the overrun, I'm surprised that a 25mph speed limit is imposed. Is the speed limit inbound only? The overrun isn't that long - both overrun tunnels accommodate sidings, and whilst the sidings finish just beyond Southampton Street, the empty tunnels continue as far as Lancaster Place. At Walthamstow Central, the approach was designed that if the siding was unoccupied, a full-speed approach would be provided. In the event that the siding was occupied by a train, the approach would be restricted to 22mph... until recently when the condition of the crossover was allowed to deteriorate so that all trains are now limited to 22mph. Maybe a more elaborate arrangement was not installed at Charing Cross because it was only intended as a temporary terminus? |
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Post by Deleted on Oct 20, 2009 11:09:44 GMT
until recently when the condition of the crossover was allowed to deteriorate so that all trains are now limited to 22mph. Is this still the case? It seems like pretty poor maintenance if a busy crossover can end up being in a state of such bad condition. |
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Post by North End on Oct 20, 2009 13:22:19 GMT
until recently when the condition of the crossover was allowed to deteriorate so that all trains are now limited to 22mph. Is this still the case? It seems like pretty poor maintenance if a busy crossover can end up being in a state of such bad condition. It's not the only example. Since PPP, many previously high-speed points have now had speed restrictions applied. There are numerous examples on the Metropolitan Line, for example Harrow North Junction. I leave you to infer your own conclusion. |
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Post by Tom on Oct 20, 2009 17:46:35 GMT
Is this still the case? It seems like pretty poor maintenance if a busy crossover can end up being in a state of such bad condition. It's not the only example. Since PPP, many previously high-speed points have now had speed restrictions applied. There are numerous examples on the Metropolitan Line, for example Harrow North Junction. I leave you to infer your own conclusion. The crossover condition did not deteriorate; it was subsequently found that the design speed of the crossover in 1968 was less then the maximum possible speed over it. The end result was not due to poor maintenance under PPP, more a design deficiency that had existed for many years and was only discovered under PPP. |
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Post by Chris M on Oct 20, 2009 20:22:13 GMT
and yet it had operated safely at greater than design speed for ~30 years prior to PPP
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Post by railtechnician on Oct 20, 2009 21:23:51 GMT
I'm not surprised it was initially equipped with moveable angles. If the same technology existed then that pertains now for swingnose crossings then those moveable angles may still yet be there. There are no moveable angles at either H123 or CX, prior to T5 H123 had 3 ends of chairlocks and one end of 4' trailers for the crossover, the single ended 10's was clamplocks (AFAIK this remains so but 10's became 10B and new points, {HW1000?} were fitted as 10A to route to T5) with extended drive (longer turnouts for smoother ride/higher speed) just like 8's turnout at Hatton Cross. Incidentally Hatton X has the same crossover arrangement, 3 ends of chairlocks and one end of 4' trailers. My recollection is that CX was just the same in terms of turnout types at the crossover. I used to do the point maintenance at all these sites. |
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Post by Tom on Oct 21, 2009 19:06:33 GMT
I think it was an M63 machine used for 10A at H123 in the end. I've got the circuits for it somewhere...
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Post by railtechnician on Oct 22, 2009 1:56:30 GMT
I think it was an M63 machine used for 10A at H123 in the end. I've got the circuits for it somewhere... Yes Tom, I am certain that is correct, I simply couldn't remember when I was typing! I recall my former colleagues mentioning it now. |
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Post by Deleted on Oct 23, 2009 10:15:17 GMT
The crossover condition did not deteriorate; it was subsequently found that the design speed of the crossover in 1968 was less then the maximum possible speed over it. Is the issue with the switch blades, or the S curve the train makes through the crossover? |
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