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Post by Deleted on Jan 10, 2010 9:17:24 GMT
Is the track layout at Morden approach common on the network? I notice the Jubilee line at Stratford is identical and I wondered how many more station approaches were the same. It obviously offers the most traffic flexibility.
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Harsig
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Post by Harsig on Jan 10, 2010 10:19:38 GMT
Is the track layout at Morden approach common on the network? I notice the Jubilee line at Stratford is identical and I wondered how many more station approaches were the same. It obviously offers the most traffic flexibility. It certainly appears to be the preferred option for a three platform terminus these days. Having said that the opportunity to modify existing track layouts to this ideal is rather limited and so this exact layout is not as common as it might be. High Barnet is basically similar (if you ignore the connections to the sidings). If you look closely you will also find the same layout lurking (for the next five or six weeks) in the approach to platforms 1-3 at Baker St although this layout also has additional connections for platform 4. Edgware and, in due course, Stanmore can be regarded as being mirror images of the arrangement at Morden although to my mind, the layout does not work as well this way round. |
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metman
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Post by metman on Jan 10, 2010 11:57:00 GMT
I was going to ask, what is the plan for Baker Street. We saw a diagram recently, but I would like some clarification on the matter.
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Ben
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Post by Ben on Jan 10, 2010 15:41:29 GMT
Edgware and, in due course, Stanmore can be regarded as being mirror images of the arrangement at Morden although to my mind, the layout does not work as well this way round. Interesting, why so? How does the layout at Uxbridge compare in terms of flexibility? |
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Ben
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Post by Ben on Jan 10, 2010 23:54:48 GMT
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Post by Deleted on Jan 11, 2010 3:57:55 GMT
Edgware and, in due course, Stanmore can be regarded as being mirror images of the arrangement at Morden although to my mind, the layout does not work as well this way round. Interesting, why so? The "singleton" platform at Edgware and Stanmore is on the driver's side of the train (approaching the terminus), which means that exiting the platform requires the conflicting crossing movement to the outbound line. Morden, Stratford and High Barnet have the "singleton" platform on the offside of the train, which means that the conflicting crossing movement is made from the inbound line to enter the platform. If West Ruislip had ever gained its third platform it would probably have been laid out like Edgware. Since Harsig, mrfs42 and stephenk are much cleverer than me they can explain the technicals of this advantage (signalling, dwell times, timetabling, etc). How does the layout at Uxbridge compare in terms of flexibility? It's faster because it's more symmetrical - the conflicting crossing movements to and from the outer roads to and from both lines can be taken at nearly the same speed (keeping in mind protection arrangements on the inbound trip). |
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Oracle
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Post by Oracle on Jan 11, 2010 10:29:05 GMT
Hounslow West had a singelton platform, then an 'island' one from memory. The northernmost was the first to go with the extension works, leaving just a two-platform terminus.
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mrfs42
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Post by mrfs42 on Jan 11, 2010 17:31:52 GMT
*throws hat into the ring*
The only real difference, without resorting to the interesting-but-faintly-excessive mathematics is where you hold the train?
Signalling-wise it makes not much in the way of odds if the geographical set up allows you to stack trains on the approach (without blocking back) - if you can't achieve this, then it is easier to hold trains in the platforms. In fact due to all sorts of 'we can't unduly stress the passenger' then you are less likely to have trains stacking in tunnels even with SPAD mystery shoppers and a lot more in the way of unnecessary announcements. That bit beggars belief and will ultimately affect the thinking behind terminus design.
If you think that sounds farcical, silly and pathetic put on your rose-tinted specs and look how much the Charing Cross Loop managed to reverse and how many passengers were affected by being held in tunnels. All manual, mind.
Hopefully that will stimulate a discussion on the subject. Consider Camberwell. [1] Consider Barking remodelling in 1958. Consider Morden remodelling in 1997.
[1] Bear in mind that the plans were sufficiently advanced that overlaps and block joints were calculated.
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