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Post by mrjrt on Sept 5, 2006 20:07:01 GMT
Saw a passing comment in some interview or another in this morning's Metro about them evaluating double-decker trains a-la Paris to ease congestion, along with the obvious train lengthening and new stocks.
What do you think is best for easing congestion? More frequent smaller trains, or larger beasties? I can only begin to imagine the horror of the works that would be needed to either raise bridges and tunnels or lower trackbeds to accomodate taller trains along the commuter routes...let alone the changes that would probably need to be made to curves due to the higher centre of gravity...
In a similar vein, do you think that at some point in the future the C&SLR upgrade is going to need to be done again for all of the tubes (aka. enlarging the tunnels), or will they just keep adding new lines to try and dilute the problem?
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Post by Chris M on Sept 5, 2006 20:10:41 GMT
I remember reading some years ago now that South West Trains were promising to upgrade some of their routes to take double decker trains in return for a 15 year franchise (which was obviously rejected). Obviously they considered the investment necessary would be recoupable (sp?) over that sort of timescale, which is really just medium-term in public transport terms.
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Post by Deleted on Sept 5, 2006 20:16:56 GMT
The cost of enlarging the tunnels would be astronomical, not to mention the RR Buses that would need to be found. I don't think we'll see tunnels enlarged; the effect on other services [sewerage pipes, telecoms etc] that are often very close to the tunnels, would also have impacts on these services...
New routes to draw traffic away from pinch points may seem a good idea, but that in reality only shifts the problem elsewhere; when the Victoria line opened, it was said to be to releive the strain on services; now we have Victoria as the busiest station....
I for one would love to see more routes and enlarged stations... but I think enlarging the tunnels is a huge pipe dream [pardon the pun].
The CSLR mods cost summat like £3m in 1920's terms... I'd hate to think what the same would cost today....
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Post by Deleted on Sept 5, 2006 21:37:53 GMT
As has been discussed some time ago, it is pretty much impossible to run double-deck trains anywhere in UK because of the restricted clearances. Even in systems which have much larger clearances, such as Sydney, the "double deck" cars have to be single deck at the ends above the bogies. To get sufficient headroom in the double deck section in the middle of the car, the floor of the lower deck has to be close to rail level, reached by going down stairs from the platform level.
This means that it is not possible to have more than two sets of doors on each side. The design significantly increases station dwell times as passengers fight their way off and on through the limited number of doors and the narrow stairways leading to the DD floors. At major Sydney stations in peak hours, dwell times can be as much as 90 seconds. Even if the clearances could somehow be increased, the introduction of DD trains on LU might well lead to a reduction in capacity because fewer trains could be run.
In addition, because the lower floor is close to the rails it is not possible to put train equipment in its usual position under the car. In Sydney this is solved by putting equipment in the car roofs, above the single-deck sections, but this raises the centre of gravity and causes lower speed restrictions over junctions and other sharp curves.
DD cars are useful in Sydney because the system is not really a metro. It is more like Network South East (or whatever it's called this week), running suburban trains, inter-urban electrics, long-distance XPTs*, and freight over the same rails. The signalling is such that around 12 tph is the most that can be run. DD cars make sense in this context, but not on LU.
* XPT = eXpress Passanger Train, similar design to UK IC125.
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Post by Deleted on Sept 5, 2006 23:07:13 GMT
I have read that when Sydney added the double-deck cars, that the resulting increase in dwell time, and thus lower service frequency meant that the overall passenger carrying capacity didn't change.
Paris RER A had to add double deck trains with 3 sets of doors per car side instead of 2 to keep the dwell times down. Still, RER A struggles to keep dwell times below 50secs at the busiest stations required to run the timetabled 30tph (note RER A uses SACEM cab signalling which has similar characteristics to speed control/multiple home signalling which allows for the very impressive frequency with 225m trains).
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Post by mrjrt on Sept 6, 2006 8:00:35 GMT
As has been discussed some time ago, it is pretty much impossible to run double-deck trains anywhere in UK because of the restricted clearances. Even in systems which have much larger clearances, such as Sydney, the "double deck" cars have to be single deck at the ends above the bogies... ....Even if the clearances could somehow be increased, the introduction of DD trains on LU might well lead to a reduction in capacity because fewer trains could be run.... ...DD cars are useful in Sydney because the system is not really a metro. It is more like Network South East (or whatever it's called this week), running suburban trains, inter-urban electrics, long-distance XPTs*, and freight over the same rails. The signalling is such that around 12 tph is the most that can be run. DD cars make sense in this context, but not on LU. My apoligies, the reason I stuck this in this forum and not the LU one was that I was of course referring to suburban heavy rail commuter services, a-la Silverlink County, Thameslink, GNE, etc. Double-decker tube trains would of course be nigh-on-impossible given the clearances the tube have to work within. The tunnel enlarging comment ( which I take it may have confused the issue) was a bolted-on thought that came to me just before I hit submit  I was thinking along the lines of enlarging tube tunnels to standard-stock size or even slightly bigger. Though of course, even with more doors to handle the increase in capacity, stations would then become the bottleneck. |
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Post by donnytom on Sept 6, 2006 16:15:11 GMT
Better than a proposal in an official paper that examined the problem of capacity- "wider" trains!
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Post by Deleted on Sept 6, 2006 16:16:38 GMT
well the Vic will get wider trains with the 2009 tube stock.
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Post by Deleted on Sept 6, 2006 16:59:22 GMT
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Post by Deleted on Sept 6, 2006 19:22:01 GMT
Oh yes, the SR 4-DD trains. Now the problem was solved by extending the platforms, firstly to 10 cars, now to 12... They were a good idea, but Bullied overlooked three important matters, access and egress from the upper deck, not to mention the cramped conditions and ventilation problems on the upper deck...
Two cars survive as far as I know; one is at Northampton and the other is on a farm near Ashford in Kent.... the latter is in a terrible state.
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Post by Deleted on Sept 6, 2006 22:32:13 GMT
The Southern cars were not really DD in the sense of having two decks extending along the cars: they had a rather strange system of compartments on two levels. But they are a good example of the problems of DD cars, as the dwell times were so extended that BR gave up on the idea and instead spent large amounts on extending platforms.
The Sydney DD cars may not have resulted in an increase in total capacity, but at least there are more seats.
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I was thinking along the lines of enlarging tube tunnels to standard-stock size or even slightly bigger. Though of course, even with more doors to handle the increase in capacity, stations would then become the bottleneck.
