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Post by Deleted on Feb 24, 2005 11:03:06 GMT
Why is it that a pair of double-ended units are never coupled together to form a service train? Are the couplers incompatible in some way?
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Post by Admin Team on Feb 24, 2005 11:27:44 GMT
I have seen trains formed in that way, but it is rare.
I believe the depot staff avoid forming trains thus, as it reduces flexibility to make trains up from combinations of available units.
I'm not aware that there's anything that says they can't be formed like that (I've just checked our Line Supplement and can find no reference to it), but I *think* that DM's are slightly longer, so having a total of four cabs means that a train formed in this way will be longer than the 'norm' - another reason why it may be avoided.
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Post by Deleted on Feb 24, 2005 11:37:02 GMT
How much longer is a double-ended-unit train compared to a double-single or a single-single?
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Post by Admin Team on Feb 24, 2005 11:57:39 GMT
The quick answer is that I don't know the exact dimensions, and a check of Brian Hardy's 'London Underground Rolling Stock' book and a check of a few websites hasn't revealed the answer!
Perhaps someone else has got them to the nearest mm........
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Post by Dstock7080 on Feb 24, 2005 15:38:20 GMT
The 2002 (15th Edition) of Brian Hardy's LONDON UNDERGROUND ROLLING STOCK book reveals: DM cars- 18372mm UNDM cars- 18119mm.
When the D Stock was new the double-ended units were the first to be delivered, so that ALL service trains for a while were formed DM-T-DM+DM-T-DM.
I can see no operational reason why two double-ended units of D Stock can't run together. On tube stock the problem of door spacing, especially '73 Stock, make this more of a 'shouldn't do' situation.
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Post by Deleted on Feb 24, 2005 17:07:38 GMT
but I *think* that DM's are slightly longer, so having a total of four cabs means that a train formed in this way will be longer than the 'norm' - another reason why it may be avoided. This was the reason I was given. The rear door of a train formed of one single and one double ended unit will only just fit Gloucester Road WB platform as it is.
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Post by Admin Team on Feb 24, 2005 17:08:45 GMT
Thanks for that - I missed the appropriate section in Brian's book.........
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Post by Dstock7080 on Feb 24, 2005 18:03:28 GMT
Looking into this, the length difference between 2x DM and 2x UNDM is 506mm (19.9ins), so it's not a lot really!
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Post by Deleted on Feb 24, 2005 19:33:30 GMT
Looking into this, the length difference between 2x DM and 2x UNDM is 506mm (19.9ins), so it's not a lot really! As I previously posted, the rear door only just fits in at Gloucester Road WB, 19 inches would leave it in the tunnel.
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Post by Deleted on Feb 24, 2005 20:01:32 GMT
As I previously posted, the rear door only just fits in at Gloucester Road WB, 19 inches would leave it in the tunnel. I never knew Gloucester Road WB was so short - are there any other places where a double-ended-unit-formed train would be squeezing into the available space?
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Post by Admin Team on Feb 24, 2005 21:52:37 GMT
Certainly Gloucester Road w/b is the 'Big One'(or should that be the short one?).
But here are several others that are 'tight', and you need to stp in the 'right' place so as not to compromise the ramp at the rear of the train.
Ravenscourt Park springs to mind - it's marginal.
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Post by Deleted on Feb 24, 2005 22:15:47 GMT
Will the new plastic stock have similar issues with platform lengths on the District?
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Post by Admin Team on Feb 25, 2005 8:56:29 GMT
As I understand it the new stock will be made up of 'conventional' 50ft (or metric equivalent) cars and there will be seven to a train, which - if my sums are correct - makes 350ft, whereas the existing D Stock are 6 x 60ft, making 360ft.
So - at least in theory! - the new trains will be shorter by +/- 10ft and will fit Gloucester Rd a bit better, but they'll still need to ne halted with the front in the tunnel or, if at the mirror, with rear doors cut out.
However at other locations it will allow a little bit of a margin.
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Post by Deleted on Mar 7, 2005 0:26:33 GMT
So - at least in theory! - the new trains will be shorter by +/- 10ft and will fit Gloucester Rd a bit better, but they'll still need to ne halted with the front in the tunnel or, if at the mirror, with rear doors cut out. As the trains will have in cab CCTV we will presumably be stopping with the cab just in the tunnel as the mirror will be completely obsolete.
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Post by Admin Team on Mar 7, 2005 17:20:41 GMT
As the trains will have in cab CCTV we will presumably be stopping with the cab just in the tunnel as the mirror will be completely obsolete. Oh yes - the 'in cab' OPO monitors, I'd forgotten about them! I'm sure they'll be part of the cab though - it seems the norm now. I've never used them 'in anger' but have ridden in cabs so fitted. It'll make it very important to get the stopping marks 100% in some locations though - Bayswater as well as Gloucester Road springs to mind - to ensure the whole train is properly berthed.
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Post by James on Mar 9, 2005 20:15:29 GMT
This was the reason I was given. The rear door of a train formed of one single and one double ended unit will only just fit Gloucester Road WB platform as it is. Incidentally, why are trains allowed to "just" platform at Glouc Rd WB, whilst at Charing X Strand (Northern) SB, the last set of doors are locked out, despite just fitting onto the platform (and indeed the first set NB)?
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Post by Deleted on Mar 9, 2005 20:42:48 GMT
Incidentally, why are trains allowed to "just" platform at Glouc Rd WB, whilst at Charing X Strand (Northern) SB, the last set of doors are locked out, despite just fitting onto the platform (and indeed the first set NB)? IIRC, the platform there is very narrow which creates a risk of dragging someone along
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Post by James on Mar 9, 2005 21:06:10 GMT
IIRC, the platform there is very narrow which creates a risk of dragging someone along It doesn't seem any worse than the extreme front of Waterloo Northern NB (which I use quite frequently when going to Birmingham - gets me right next to the exit at Euston and people seem to have an aversion to walking to the front of the train on the Northern). Incidentally, the platform which always gets me for being far too narrow is Euston (Northern CX SB) - it would be okay if all the idiot Northerners didn't reach the platform and stop dead at the foot of the stairs. As it is, they do stop dead and it becomes almost lethal to move past them along the platform.
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Post by Deleted on Apr 10, 2005 18:15:48 GMT
Why is it that a pair of double-ended units are never coupled together to form a service train? Are the couplers incompatible in some way? Certainly on a 73ts nothing stops it happening, but they do not do it because it can cause problems with the electrics and the such like!
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