Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 3, 2010 4:19:46 GMT
I put this here because Camberwell isn't likely anymore IMHO, and because the topic here is of no present-day relevance, since the Stanmore branch belongs to the Jubilee.
AIUI the extension to Camberwell was intended to serve the area, but more importantly, to provide a high-capacity, three-track terminus to reverse everything the Watford Junction and Stanmore branches were ramming down the Bakerloo tubes.
I'm just wondering, was it ever considered to triple-track (platform reversal) Elephant & Castle instead? It would have increased the theoretical reversing upper limit to 36tph or so (impossible under traditional signalling), methinks, but not require additional tunnelling to anywhere, just within the E&C area.
AIUI E&C cannot reverse anything more than 24tph, and that this limitation is what crippled the Bakerloo; would tripling E&C have helped? Or would it not have been worth it?
Would this have been feasible? Would it have delayed/negated the need for the Fleet/Jubilee taking the Stanmore line?
|
|
mrfs42
71E25683904T 172E6538094T
Big Hair Day
Posts: 5,922
|
Post by mrfs42 on Nov 3, 2010 10:58:27 GMT
I've seen plans for a centre reversing siding at Lambeth North and a 23 lever frame with 7, 8, 14, 15 and 23 spare.
Lambeth North would have relieved the pressure on Elephant somewhat. There are also plans in existence of the Camberwell extension with and without an intermediate station at Camberwell Gate. I've never seen anything about three tracking Elephant - not even a concept sketch.
Under conventional signalling there were several occasions where less than a 2 minute interval was scheduled out of Elephant, Coronation Day morning springs to mind and (I think) in a number of 'ordinary' WTTs. What is fascinating about the Bakerloo services is that until relatively recently in TT terms the Stanmore services were shewn in the Met. galley - so you've got a lot of data for the services - if you factor in the Watfords which wouldn't appear in the Met. galley then there must have been countless occasions when a 1½ - 1¾ minute service out of Elephant was worked if not scheduled.
I've got some Harsig-type layout drawing to do in the next few days - if I get chance I'll put up the Lambeth North layout. The three-track layout for Camberwell was published recently.
The LPTB invested a lot of time and effort in the Camberwell extension, possibly more so than the Northen Heights in terms of calculations/mile as I've also seen lots of acceleration curves based on a two or three track southern terminus of the Bakerloo - no acceleration curves based on remotoring, which was done as part of the probably F stock and one type of Met. saloon stock (I've seen those graphical results, but can't for the life of me remember the car types involved).
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 3, 2010 11:02:15 GMT
I didn't think of a siding at Lambeth North... Do you have any ideas why tripling E&C was never considered? I rather think that 30+tph is possible only with very low line speeds...  Harsig-type? Would the Jubilee have been built had the need to relieve the central Bakerloo had been negated by a triple terminus and/or other termini? |
|
mrfs42
71E25683904T 172E6538094T
Big Hair Day
Posts: 5,922
|
Post by mrfs42 on Nov 3, 2010 11:10:02 GMT
Harsig-type? I'm surprised that someone who has been a member of this Forum since 2006 is unaware of the excellent signalling drawings provided by my fellow Global Mod - Harsig. |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 3, 2010 11:13:23 GMT
Harsig-type? I'm surprised that someone who has been a member of this Forum since 2006 is unaware of the excellent signalling drawings provided by my fellow Global Mod - Harsig. I know who he is! I was just surprised you called the type Harsig-type... |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Dec 5, 2010 10:15:19 GMT
AIUI E&C cannot reverse anything more than 24tph, and that this limitation is what crippled the Bakerloo; I have seen in many articles which state the Bakerloo once reversed 34tph (sometime mid last Century). |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Dec 5, 2010 10:23:55 GMT
AIUI E&C cannot reverse anything more than 24tph, and that this limitation is what crippled the Bakerloo; I have seen in many articles which state the Bakerloo once reversed 34tph (sometime mid last Century). That must certainly be pre-TETS. Elephant and Castle does have a relatively long overrun. Surely the need for terminus protection would be negated by having an overrun longer than a full speed braking distance. Although it would make sense to have say, a 40mph timed trainstop at entry, to trip any train running faster, for better chance of stopping. Probably rather impractical, though. |
|
Tom
Administrator
Signalfel?
Posts: 4,196 
|
Post by Tom on Dec 5, 2010 22:37:52 GMT
Elephant and Castle does have a relatively long overrun. Surely the need for terminus protection would be negated by having an overrun longer than a full speed braking distance. The overrun on the NB platform at Elephant is extremely short, being dictated by the location of No 28 A points shortly beyond the end of the platform. The timing on the speed controlled trainstop there is quite restrictive, and being tripped on it was not uncommon. As the SB road has further to go before 28 B points, a longer overrun is provided with the speed controlled trainstop positioned further into the platform and an associated less restrictive timing section approaching it. |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Dec 5, 2010 22:43:20 GMT
The overrun on the NB platform at Elephant is extremely short, being dictated by the location of No 28 A points shortly beyond the end of the platform. The timing on the speed controlled trainstop there is quite restrictive, and being tripped on it was not uncommon. As the SB road has further to go before 28 B points, a longer overrun is provided with the speed controlled trainstop positioned further into the platform and an associated less restrictive timing section approaching it. There's a crossover in the overrun tunnel? |
|
mrfs42
71E25683904T 172E6538094T
Big Hair Day
Posts: 5,922
|
Post by mrfs42 on Dec 5, 2010 23:10:22 GMT
Well, from platform 3 you can go into either tunnel beyond the headwall.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Dec 6, 2010 6:58:27 GMT
Well, from platform 3 you can go into either tunnel beyond the headwall. That's very odd... is there less than a train's length overrun on the SB? |
|
mrfs42
71E25683904T 172E6538094T
Big Hair Day
Posts: 5,922
|
Post by mrfs42 on Dec 6, 2010 11:58:05 GMT
No, platform 4 has the longer overrun, because of 28 crossover. Imagine my signature picture and the top line RH end is the end of the siding from platform 4, the siding from platform 3 would end under the N of RND16/17, and there is plenty of room there for a train in both sidings.
If you're still stuck, I'll dig out the 1941 resignalling notice for Elephant which shows the general proportions of the layout as it would have been for the Camberwell extension.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Dec 6, 2010 12:10:55 GMT
No, platform 4 has the longer overrun, because of 28 crossover. Imagine my signature picture and the top line RH end is the end of the siding from platform 4, the siding from platform 3 would end under the N of RND16/17, and there is plenty of room there for a train in both sidings. If you're still stuck, I'll dig out the 1941 resignalling notice for Elephant which shows the general proportions of the layout as it would have been for the Camberwell extension. So is this what you mean?  excuse the poorly drawn-ness. |
|
mrfs42
71E25683904T 172E6538094T
Big Hair Day
Posts: 5,922
|
Post by mrfs42 on Dec 6, 2010 12:45:51 GMT
Yes.  Note that the numbering is from route setting days. This is 2 years later than Harsig's excellent diagram here. |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Dec 6, 2010 13:20:55 GMT
Yes. Note that the numbering is from route setting days. This is 2 years later than Harsig's excellent diagram here. I see. |
|
|
|
Post by Colin D on Dec 6, 2010 14:35:05 GMT
Although it would make sense to have say, a 40mph timed trainstop at entry, to trip any train running faster, for better chance of stopping. Probably rather impractical, though. I worked on the Bakerloo in the early seventies and I seem to remember a curve coming down from Lambeth North that had a 20 or 25mph speed restriction. Also when entering the southbound platform is there not a curve about 1/4 of the way in that requires a slower entry into the station. Around that time period wasn't there a less than 2 min headway south of Baker St in the rush hours due the merging of the Queens Park and Stanmore lines? |
|
mrfs42
71E25683904T 172E6538094T
Big Hair Day
Posts: 5,922
|
Post by mrfs42 on Dec 7, 2010 13:01:18 GMT
I worked on the Bakerloo in the early seventies and I seem to remember a curve coming down from Lambeth North that had a 20 or 25mph speed restriction. Also when entering the southbound platform is there not a curve about 1/4 of the way in that requires a slower entry into the station. Around that time period wasn't there a less than 2 min headway south of Baker St in the rush hours due the merging of the Queens Park and Stanmore lines? Hmm. *wanders into the foothills of the Bakerloo* Must have been quite early 70s - WTT 58 26/1/70 had 37 trains in service MF, and WTT 59 3/5/71 had 42 in service MF. WTT 60 from 1/5/72 also had 42 in service, but this WTT was gradually reduced with C and E variants. Looking at the WTTs 60 was generally 2½ min in the morning busy, and 2 min in the evening busy; WTT 59 was 2 min in the morning busy and quite a few in the evening busy were 1½ min., and it was indeed Stanmores that were 1½ min after Bakerloo (mains). |
|
|
|
Post by Colin D on Dec 7, 2010 16:36:01 GMT
Thanks for that mrfs 42  |
|
Harsig-type?
