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Post by grahamhewett on May 15, 2017 8:19:38 GMT
<<rincew1nd: Posts made before 20th May were initially made in this thread>>crusty54 - the trouble with extending the DLR anywhere but the more lightly used areasis that it runs (much) shorter trains than a modern tube; if you're going to spend a few big ones any way, a few more gives you a step up in capacity.
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Post by Chris M on May 15, 2017 12:12:45 GMT
The capacity of the DLR train is actually comparable with a tube train, and the new trains will have greater capacity than the existing ones.
Each car has (according to Wikipedia) a capacity of 284 passengers, meaning 852 for a three-car train. The new stock is expected to increase capacity by about 10%, so about 935 people per train.
Again according to Wikipedia, an S7 stock has a capacity of 865 people, an S8 1003 and a 1996 stock 875.
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Post by crusty54 on May 15, 2017 13:21:21 GMT
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Post by philthetube on May 16, 2017 1:00:59 GMT
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Post by norbitonflyer on May 16, 2017 6:24:59 GMT
according to this a crush loaded S stock can carry 1524 passengers Aren't you double-counting the tip-up seats? The crush standing capacity is, surely, with those seats folded up. The Wikipedia article contradicts itself, since the side bar gives a total capacity of 1,003 but the full text gives a standing capacity of 1,226, suggesting the number of seats is a negative number! Neither figure is referenced. (There is a link at the end of the relevant paragraph, but the linked web page gives no information about seating, and in any case it relates to 2009 tube stock) |
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Post by class411 on May 16, 2017 8:46:07 GMT
according to this a crush loaded S stock can carry 1524 passengers Aren't you double-counting the tip-up seats? The crush standing capacity is, surely, with those seats folded up. What it your evidence for saying that? I have never ever seen, on any underground stock that uses tip up seats, anyone suggest that people should stand up and let the seat tip up, to increase capacity. As anyone who actually uses the underground will tell you, use is made of the entire seating capacity long before you get to crush level. It is, of course, conceivable that, during crush loading, a vacated tip up seat will not be re-used, although that is by no means a given (depending, I would imagine, on how many stops the person standing against the seat has to travel). In reality, though, it would depend on how the manufacturer (or end user) chooses to measure capacity, but without specific evidence to the contrary I can see no reason to just assume that tip up seats are not considered to be used during crush loading. |
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Post by norbitonflyer on May 16, 2017 9:04:27 GMT
The maximum theoretical capacity is, surely, with the seats folded away, as a seated passenger takes up more floor area than a standing one. The way the accommodation is used in practice may well be different.
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Post by brigham on May 16, 2017 9:54:27 GMT
I take it the DLR hasn't placed any withdrawn carriages on the 'duplicate' list, in case of demand outstripping growth?
Does nobody learn any more?
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Post by norbitonflyer on May 16, 2017 13:07:18 GMT
I take it the DLR hasn't placed any withdrawn carriages on the 'duplicate' list, in case of demand outstripping growth? Does nobody learn any more? Whilst it would be prudent to do so on lines with spare capacity (a lesson Beeching didn't understand), there would be little point in maintaining rolling stock to meet demand unless there is spare capacity on the infrastructure on which to run them. In any case, the only DLR rolling stock withdrawn so far have been the 21 units of P86 and P89 stock, which were unsuitable for the tunnel sections*. All of them have found further use elsewhere. *The P89 stock was fireproofed for use on the Bank extension, but because of the lack of end doors they may not operate in tunnels except as single units. |
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Post by Chris M on May 16, 2017 13:42:45 GMT
The DLR are in the process of procuring new trains to replace the stock that is becoming life expired and at the same time meet the foretasted increase in demand. The oldest stock currently in service dates from 1992, and so will be 30 years old by the time the new trains arrive and are increasingly unreliable (5,000-8,000 km MDBSAF*, desribed as "very low" - see Latest figures for LU stock (PDF page 15) which range from ~7,000km on the W&C to just over 43,000km on the Victoria. The new stock is specified to run at 50,000km MDBSAF) The TfL board paper states "A minimum base order of 43 new three-car equivalent trains is required; 33 to replace the life expired B90/92 LRVs and 10 to support housing and employment growth in the Royal Docks." The official procurement notice posted here notes "The initial requirement is for 43 new trains." and "In addition to the initial requirement, the contract for manufacture of the new trains will include options to purchase up to 34 additional trains." *MDBSAF = mean distance between service-affecting failures |
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Post by peterc on May 16, 2017 14:19:03 GMT
Only because they have got rid of most the seats. I have seen passengers unable to board trains with transverse seats due to crush loading despite empty seats. This was a particular problem with the 3+2 seating on the A stock but certainly not unique to the Met.
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Post by brigham on May 16, 2017 15:24:35 GMT
I take it the DLR hasn't placed any withdrawn carriages on the 'duplicate' list, in case of demand outstripping growth? Does nobody learn any more? Whilst it would be prudent to do so on lines with spare capacity (a lesson Beeching didn't understand), there would be little point in maintaining rolling stock to meet demand unless there is spare capacity on the infrastructure on which to run them. In any case, the only DLR rolling stock withdrawn so far have been the 21 units of P86 and P89 stock, which were unsuitable for the tunnel sections*. All of them have found further use elsewhere. *The P89 stock was fireproofed for use on the Bank extension, but because of the lack of end doors they may not operate in tunnels except as single units. I was referring to this statement mentioned in the link: "The DLR is seeing annual growth around 8% yet no additional trains are expected until 2022, as covered here..." Which suggests that extra stock, not capacity, is the problem. |
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Post by norbitonflyer on May 16, 2017 17:04:29 GMT
That article is not an official source, but it suggests to me that if there is any spare track capacity it is on the Beckton line. Longer trains, or trains which make better use of space, may improve the capacity of each train. (as in the various ten and twelve car projects on National Rail, and the switch from 6-car C stock to S7s on the H&C and Circle). As explained above, the original units would not now be allowed to operate except as single units, so they would not be able to form longer trains. And the proposed new trains will each be one long walk-through multi-articulated unit, rather than the three separate short units each train is formed of currently, so will make much better use of space as the gaps between units will be eliminated.
But the initial premise was that the DLR should have held its withdrawn stock in reserve, rather than selling it on to another operator - note that they were not scrapped. Since the original stock is not capable of running on most routes in longer than single unit formations, their contribution to solving the capacity problems would be quite likely to be negative. They are also incompatible with the new signalling system, so would have needed a lot of work done on them anyway.
Finally, the P86 and P89 units, which are the only ones which could have formed such a reserve as the B92s and all subsequent builds are still in service, are now well past their design life of 25 years. It does not improve capacity if the extra unit you put on then breaks down and stops anything else running.
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Post by Chris M on May 16, 2017 18:15:22 GMT
Even if you ordered some new build stock to the same design of the most recent units (which are themselves rapidly approaching 10 years old) tomorrow, and Bombardier still have the necessary tools (unlikely) and capacity you wouldn't likely see any in service until very late 2018 at the absolute earliest, and wouldn't really be a very good use of public money.
Should they have ordered the new trains earlier. Possibly, but remember that planning ahead for the long term isn't something the previous mayor was noted for, that a not insignificant part of the DLR's budget was diverted to the cable car, and that various extensions that would (of necessity) have come with new rolling stock have been repeatedly kicked down the line or cancelled. The DLR has also had to wait its turn for access to TfL's pot of new train money while the 09 and S stocks were being built.
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Post by crusty54 on May 16, 2017 19:07:44 GMT
There is also the problem of depot capacity for the additional trains.
Considerable reworking is needed at Beckton to make space for them.
This all takes time.
I imagine some design work is also needed to ensure that the new fully articulated trains will not hit any infrastructure. Some of the bends are very tight.
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Post by Chris M on May 16, 2017 19:27:44 GMT
If the trains are the same overall length as three current cars and the bogie spacing is the same there shouldn't, in theory, be a problem with gauging. However there is not a lot you can do until the design of the train is finalised - when you can start doing your calculations, but really you can't be completely certain until you get an actual vehicle to test with.
Perhaps a passing admin or moderator could split the discussion of DLR rolling stock into a new thread, as while it's good we've rather digressed from the thread title! Done! rincew1nd
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Post by norbitonflyer on May 16, 2017 20:55:10 GMT
If the trains are the same overall length as three current cars and the bogie spacing is the same there shouldn't, in theory, be a problem with gauging. If the elements are articulated in pairs like the existing units then that is true, but if the articulation is different (three elements or more) then some of the bogie centres will, of necessity, also be different. |
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Post by crusty54 on May 16, 2017 21:07:30 GMT
If the trains are the same overall length as three current cars and the bogie spacing is the same there shouldn't, in theory, be a problem with gauging. If the elements are articulated in pairs like the existing units then that is true, but if the articulation is different (three elements or more) then some of the bogie centres will, of necessity, also be different. If you travel in the front seat in a trailing unit the movement in the leading unit can be seen and is quite significant. |
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Post by Chris M on May 16, 2017 21:54:22 GMT
If the trains are the same overall length as three current cars and the bogie spacing is the same there shouldn't, in theory, be a problem with gauging. If the elements are articulated in pairs like the existing units then that is true, but if the articulation is different (three elements or more) then some of the bogie centres will, of necessity, also be different. If you travel in the front seat in a trailing unit the movement in the leading unit can be seen and is quite significant. I did say "if the bogie spacing is the same", but just because the articulation is different doesn't mean that the bogie centres necessarily will. There are (very generally speaking) two types of articulation - that used by the current DLR stock where there is a bogie beneath the articulation point, and that used by the S stock where the articulation is between two bogies. I see no reason why, in theory, a combination of both types could not be used on one train allowing continuation of bogie spacing. Just because this is possible in theory though doesn't necessarily mean that it will be the chosen design. Yes, I'm very familiar with the amount of movement (when I lived in Woolwich, the front of the second car was where I usually travelled as that is closest to the exit I used). I don't think though that a fully articulated unit - even if using the more flexible S-stock articulation - will allow more movement than the existing couplings so, again in theory, this should not produce any issues for gauging. |
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Post by norbitonflyer on May 17, 2017 6:30:34 GMT
There are (very generally speaking) two types of articulation - that used by the current DLR stock where there is a bogie beneath the articulation point, and that used by the S stock where the articulation is between two bogies. There seems to be some confusion here: S-stock is not articulated. This is articulation The middle car will have a different gauging profile to the other two, as the bogie pivots are further apart (or the middle car has to be shorter to compensate) |
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Post by class411 on May 17, 2017 7:48:06 GMT
There are (very generally speaking) two types of articulation - that used by the current DLR stock where there is a bogie beneath the articulation point, and that used by the S stock where the articulation is between two bogies. There seems to be some confusion here: S-stock is not articulated. Nope. Articulated simply means "having a joint"; all underground passenger stock is articulated. You may be confused by the fact that all (as far as I know) articulated lorries use a common set of wheels for the tractor and the front of the (first) trailer, but 'articulation, there, applies to the flexible join between the tractor and the trailer, not the way that join is achieved. Definition here |
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Post by brigham on May 17, 2017 7:49:23 GMT
The other system, where each vehicle has a full complement of wheels to itself, is called 'coupling'.
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Post by class411 on May 17, 2017 9:05:38 GMT
The other system, where each vehicle has a full complement of wheels to itself, is called 'coupling'. It's an articulated joint that may be coupled and uncoupled without in any way dismantling the items being coupled. |
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Post by norbitonflyer on May 17, 2017 9:25:39 GMT
The dictionary definition is "having joints" (as in an articulated skeleton). In that sense any vehicle carried on bogies is articulated.
However, in a railway (or road) context the term has a more specific meaning, relating to vehicles in which one or more wheelsets carry part of the weight of two adjacent bodies. Thus an articulated lorry, where part of the weight of the trailer is taken by the tractor unit. The only trains articulated in that sense operating in the UK are the Eurostar class 373 units and (if they count as trains) the DLR and Tyne & Wear units (class 994). Most trams are also articulated.
The confusion appears to have arisen because of the similarity in internal appearance between the typical articulated bus (which is, beneath the skin, similar to an articulated lorry) and trains such as the S stock and class 378s. But it is not full-width gangways which make a bus articulated.
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Post by class411 on May 17, 2017 10:10:41 GMT
The dictionary definition is "having joints" (as in an articulated skeleton). In that sense any vehicle carried on bogies is articulated. However, in a railway (or road) context the term has a more specific meaning, relating to vehicles in which one or more wheelsets carry part of the weight of two adjacent bodies. Thus an articulated lorry, where part of the weight of the trailer is taken by the tractor unit. The only trains articulated in that sense operating in the UK are the Eurostar class 373 units and (if they count as trains) the DLR and Tyne & Wear units (class 994). Most trams are also articulated. The confusion appears to have arisen because of the similarity in internal appearance between the typical articulated bus (which is, beneath the skin, similar to an articulated lorry) and trains such as the S stock and class 378s. No, I think the confusion arises in the minds of people who are using a 'back construction' and, because lorries and buses that are articulated (almost) always have a trailer sharing wheels with the cab, think that this is a necessary condition for articulation. It is not. To be articulated something merely needs a moveable joint. Indeed it is not. It is the fact that they have a moveable joint. |
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Post by norbitonflyer on May 17, 2017 13:21:51 GMT
because lorries and buses that are articulated (almost) always have a trailer sharing wheels with the cab, think that this is a necessary condition for articulation. It is not. Not almost - always. If the trailer's weight is carried on its own wheels, it is known as a drawbar combination  In what way is the connection between S-stock cars (/coaches/carriages) different from that of any other gangwayed stock? More articulated rolling stock. No moveable joints between the vehicle bodies, other than the conventional gangway connection in the Eurostar. Gangway connections are of course commonplace in passenger rolling stock, although they did not exist on the Underground until the introduction of the S stock.    Where locomotives are concerned, the definition is a bit fluid. A Fairlie type steam locomotive has two powered bogies (carrying the pistons) pivoted to the main frame (carrying the boiler, firebox, and cab). This is usually considered a form of articulation. But any modern double-bogie diesel or electric locomotive, from Sarah Siddons to the latest Class 88, also has two powered bogies pivoted to the main frame, and they are not usually considered to be articulated. |
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Post by brigham on May 17, 2017 15:41:29 GMT
S-stock gangways are remarkably wide; that's how they differ.
I was only used to seeing such wide gangways on articulated stock using the Tyneside loop. That is why I first of all believed the S-stock to be articulated.
I was amazed to find that it was not; and was shown (on here) the diagrams which prove this.
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Post by class411 on May 17, 2017 15:55:56 GMT
because lorries and buses that are articulated (almost) always have a trailer sharing wheels with the cab, think that this is a necessary condition for articulation. It is not. Not almost - always. If the trailer's weight is carried on its own wheels, it is known as a drawbar combinationI think we need a bit of background on the use of hierarchical classification here. In most languages there is the ability to describe something in more and more specific ways: e.g. A carp is: an animal cold blooded a fish fresh water a tiger is An animal A mammal A cat In the same way a railway coupling is: A joint Articulated <any other subordinate classifications> "If the trailer's weight is carried on its own wheels, it is known as a drawbar combination"It may well be, but that does not stop it being: A joint Articulated A Drawbar connection. Various ways, but that is not the point. Each carriage is joined to at least one other and that join is articulated - otherwise it would not be able to go round curves in the track. I don't know how long you want to keep flogging this dead horse, but a joint that moves is articulated, and S-Stock is joined together by moveable joints. The confusion was yours, not Chris M's. |
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Post by brigham on May 17, 2017 16:07:12 GMT
ALL trains are 'articulated' in some way or another, assuming that they consist of more than one vehicle.
The TYPE of 'articulation' is the point here.
As far as passenger rolling stock is concerned, 'articulation' refers to the mounting of the ends of two underframes on a shared bogie. This is what is meant by 'articulated', and to use the word for any other form of 'articulation' without specifying that fact can only lead to confusion.
So it's best not to.
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Post by Chris M on May 17, 2017 16:18:23 GMT
And this is all quite beside the point I was trying to make!
There are two methods of making a train with permanently coupled cars (or carriages or coaches or vehicles or units or whatever else you want to call them) fully walk through.
1. Place the bogies under the joint between permanently coupled cars, supporting part of the weight of the cars either side and directly supporting the connecting bit. This is the method used on the current DLR vehicles.
2. Place the bogies under the car such that each bogie supports (part of) the weight of only one car and the weight of the connecting bit is jointly supported by the cars (and thus bogies) either side. This is the method the S stock uses.
If the new DLR vehicles (which haven't even been designed yet) use either of the above methods it is very likely (but not guaranteed) that the bogie centres will be differently spaced to the current stock and thus end and centre throw will be different and gauging works may be needed.
If the new DLR vehicles use a combination of the methods (e.g. pairs connected using method 1 connected to each other using method 2) then it is more likely (but not guaranteed) that bogie centres will be the same and gauging not required.
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