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Post by malcolmffc on Jan 30, 2011 10:11:51 GMT
I believe the top speed of the D78s if quicker than the 73ts. Given that, wouldn't it make more sense to have the District be the fast line between Acton and Hammersmith, and the Picc be the slow one?
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Post by phillw48 on Jan 30, 2011 10:33:40 GMT
Probably more to do with balancing the services than the speed of the stock.
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Colin
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Post by Colin on Jan 30, 2011 10:40:36 GMT
I dunno where you get the idea about top speeds from - both the D stock and 73ts use the same size wheels and are technically almost identical - not that top speeds of stock are relevant (signed speed restrictions, signals, etc)......but the obvious starter for ten is that the track layout at both Hammersmith & Acton don't really support your suggestion. All trains would have to cross each others paths which would be an absolute nightmare.
On top of that, only half of the westbound District line service goes towards Hammersmith from Earls Court, and only half again go to Acton - the other half go to Richmond and so must use the "slow" lines, again owing to the track layout. In contrast, the whole Piccadilly line service passes through the area. Your suggestion would see 6 trains per hour going down the "fast" and around 30 trains per hour on the "slow"!!
The two lines customers (yes, I mean passengers!) are very different too - two thirds of the Piccadilly line heading west is going to Heathrow. Those Heathrow people just want to get to the airport and will appreciate the non stop run. Heathrow, even Rayners Lane & Uxbridge, are a lot further west than Ealing Broadway - another reason the Piccadilly customers will appreciate that little bit of a run between Hammersmith & Acton.
Sorry my friend, but there's too many negatives to turn this one around...
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Post by phillw48 on Jan 30, 2011 10:49:05 GMT
And it will get me and a few others to the meet at Acton a lot quicker.
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Post by Deleted on Jan 30, 2011 19:24:47 GMT
The fast service needs to be the one that serves Heathrow, and the tunnels between Hounslow West and Heathrow are built to tube gauge so District trains won't fit! So it has to be the Picc providing the fast service.
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metman
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Post by metman on Jan 30, 2011 20:03:43 GMT
Colin is right. The D and 73 stocks are technically very similar. The wheels and I believe traction motors are the same. The Piccadilly certainly needs to be quicker. The route is such a long run that the non stop services are essential to speed up the journey. This is not a new problem either; Brompton Road, Down Street and York Road were all closed in the late 30s to partly speed up the journey times!
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Post by Deleted on Jan 30, 2011 20:35:23 GMT
The run from Cockfosters - UXbridge is long enough!
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Post by t697 on Jan 30, 2011 23:22:49 GMT
The Piccs are limited by the Piccadilly line signalling primarily. They have to run 'flag down' Acton - Barons Court. Even 'flag up' on all other parts of the Picc there are two further stages of field weakening (go faster!) provided in the equipment design but not enabled to be selected. Probably never will be now, as new signalling and new rolling stock are likely to be a combined upgrade project.
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Post by Colin on Jan 31, 2011 3:38:40 GMT
Now I was under impression the 73ts had their weakfield permanently cut in since refurb owing to the extra weight on board. From what you've said, you appear to be suggesting that isn't the case  .... |
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Post by Deleted on Jan 31, 2011 10:18:40 GMT
Now I was under impression the 73ts had their weakfield permanently cut in since refurb owing to the extra weight on board. From what you've said, you appear to be suggesting that isn't the case .... Colin is correct, weak field is permanently cut in. |
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Ben
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Post by Ben on Jan 31, 2011 11:45:00 GMT
So weak field is perminantly cut in, but when built there was the capacity for two further stages of it which have subsequently never been commissioned?
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Ben
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Post by Ben on Jan 31, 2011 12:08:57 GMT
Just as an aside to the problem alluded to by Colin of the Pic being unable to serve Richmond, quote from 'Reconstructing London's Underground' by Follenfant:
"An underpass under the two westbound tracks west of Turnham Green was constructed for a possible Piccadilly Line service to Richmond - an idea which was considered again, as recently as 1967".
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Post by TMBA on Jan 31, 2011 14:03:24 GMT
If you check this out upminsterthroughtheyears.fotopic.net/p68610906.htmlit proves that the two tunnels are there, but, they were used for the goods round the Acton curves just west of the road bridge before Gunnersbury station, I think the right terminology is Action triangle, and the goods came from there and onto High Street Ken and West Ken goods yards all of course now gone and replaced by buildings. Plus when the goods came up from the Acton triangle they travelled onto the eastbound fast through Turnham Green station and then onto a dedicated siding running parallel to the eastbound Pic and eastboud District - upminsterthroughtheyears.fotopic.net/p68610126.html TMBA. |
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Post by v52gc on Jan 31, 2011 14:11:25 GMT
Great Photos!
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Ben
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Post by Ben on Jan 31, 2011 14:52:13 GMT
Superb! What on earth is wrong with this pic though??  upminsterthroughtheyears.fotopic.net/p68610927.htmlSeems theres a lot of history with the tracks and layouts round there. I'd read about the goods lines from Joe Browns Atlas. It seems the story of its history, purpose and potential is anything but clear cut, however. Perhaps time for a letter to UN!  |
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TMBA
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Post by TMBA on Jan 31, 2011 18:56:25 GMT
Not forgetting though that Gunnersbury used to have 5 platforms upminsterthroughtheyears.fotopic.net/p68610102.html and at the south end trains used to cross over at the Gunnersbury traingle, someone will tell you the junction names and tracks that it used to join, all of course gone now & buildings in place. Quite a large area for railways in general with of course still now the Kew triangle that still exists that still is being used by goods etc. TMBA |
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Ben
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Post by Ben on Jan 31, 2011 21:03:33 GMT
Having a spare platform at Gunnersbury would undoubtably have proved useful over the years. Its interesting to note what platform lines were electrified aswell when the roads were in situe.
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Post by t697 on Feb 1, 2011 0:00:05 GMT
Now I was under impression the 73ts had their weakfield permanently cut in since refurb owing to the extra weight on board. From what you've said, you appear to be suggesting that isn't the case .... Colleagues who worked on 73TS Refurb say the Weak Field 'indicator' was abolished, but not the switch and the switching capability. Maybe Tubelines later removed or disabled it, but the Picc Line Supplement still says you can only use weak field west of Acton Town and East of Arnos Grove. ISTR the east switching point was Barons Court in earlier times. Perhaps someone with current tech info and/or line operating and driving experience can elaborate further? |
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Post by Colin on Feb 1, 2011 5:37:33 GMT
upinthesky is a Picc driver, so it has been confirmed via reply #9 on the previous page.
Just because something is in the line supplement, it doesn't necessarily mean the rolling stock is still so equipped.
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Ben
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Post by Ben on Feb 1, 2011 15:44:50 GMT
Would a suitable analogy be the (until recent) barring of D stock from other parts of the SSR because of suspension system it no longer has?
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Colin
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Post by Colin on Feb 2, 2011 17:22:18 GMT
I wasn't aware that D stock was barred on account of it's suspension - in fact it's my understanding that D stocks are actually quite tolerant to badly maintained track, so if anything their design should work in their favour. I am aware that the bogie design was changed to make it more flexible. That probably ties in with what I said above, but whether it also ties in with your question I wouldn't know .... I would have thought a more logical reason for barring D stocks elsewhere would be for gauging, given that they have longer cars.... |
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Post by causton on Feb 2, 2011 17:26:12 GMT
From CULG: "D stock consists of two 3-car units. Single units have only one cab and may only operate in depots. Because the stock has stiff suspension it may only run on tracks maintained appropriately (the District Line and parts of the Piccadilly Line). 6-car trains will not fit in the stations from Notting Hill Gate to Edgware Road and thus may not carry passengers north of High Street Kensington."
Obviously CULG is not perfect however!
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Colin
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Post by Colin on Feb 2, 2011 17:32:17 GMT
Indeed - about as reliable as wikipedia  However it looks like Ben may have a point.... |
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Post by Ben on Feb 2, 2011 17:33:55 GMT
The relevant passage was in the 'Permitted Running Routes' document. However I won't quote it; rule 7, you know. Whats sensetive is subjective.    Sorry Colin, couldn't resist!  |
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Post by 21146 on Feb 2, 2011 19:37:11 GMT
From CULG: "D stock consists of two 3-car units. Single units have only one cab and may only operate in depots. Because the stock has stiff suspension it may only run on tracks maintained appropriately (the District Line and parts of the Piccadilly Line). 6-car trains will not fit in the stations from Notting Hill Gate to Edgware Road and thus may not carry passengers north of High Street Kensington." Obviously CULG is not perfect however! That restriction went at the time of refurbishment, did it not? |
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Post by t697 on Feb 2, 2011 19:49:24 GMT
Just checked the Permitted Running Routes schedule. The suspension related restriction has indeed been removed. The permitted route is still just the District and small parts of the Picc. I don't think the assurance work for some other areas would be particularly arduous, but it is unlikely to be undertaken unless there's a business need that results in funding it.
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Post by Deleted on Feb 2, 2011 21:20:53 GMT
There are still track based plates at Acton Town w/b instructing Piccadilly Line drivers upon the Weak Field Flag use. I have no idea whether they remain necessary, but they are there.
The reason for the withdrawal of the D stock permissions to run over most of SSR, was indeed due to "Stiff Primary Suspension". This ceased to be a valid restriction many years ago, but remained "on the statute books" so to speak until last year. A detailed business case was made out to restore the approvals for most of SSR (except where there were other issues, such as the car length generating a clearance issue due to the overhangs, eg. Aldgate Inner Rail). This was generally for trains to run empty.
For reasons I don't know despite the case being made out, only the Piccadilly Line branch towards South Harrow was added (D Stock having been running there for ages anyway!) and the reason for the restrictions were removed (as they were now nonsence and had been for ages). I think there may have been some concerns that other changes may have been made to platforms/track during the era D stock was not authorised and therefore were not made to be D stock compatible, because at that time they didn't need to be.
A formal gauge test could no doubt be conducted should a compelling reason be made out for doing so. (There is a potential reason why that may be the case in a few years time, but we will see.)
Sadly the process for generally approving/maintaining/updating stock and track compatability appears to be ludicrously slow or not bothered with at all, hence C stock can go between Barking and Upminster under a derogation, but not in the formal document and not in passenger service. A stock can run between Aldgate East and Upminster but again with even more severe restrictions and not reflected in the general list. A few years back a D stock was borrowed for over night de-icing trips on the Metropolitan Line (I don't however recollect why that was necessary!).
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