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Post by zbang on Jan 2, 2021 18:36:20 GMT
Stephenson's gauge is too narrow. Brunel knew that, Hitler knew that, and Stephenson himself knew it. It prevails because of legacy, not merit. It arose from the need to use existing wagons, and not from any engineering-based calculation. I'm not sure I buy that. IIRC the Gauge Act (1846?) recommended standard gauge, so there was probably a decent understanding of the effects of narrow/wide even then, or at least of compatibility between companies; and since new rolling stock were being built for new companies, they could be built for whatever the company wanted. Even if Stephenson though it wasn't optimum*, that's what he built. Sure, companies did continue to build other gauges, but I suspect that was not from rational engineering considerations.
* I haven't turned up anything along those lines, would love to hear of any.
There has never been a lack of observers who thought 4 feet 8-1/2 was suboptimal - men as disparate as James J. Hill, David P. Morgan, and Adolf Hitler, to name three. Essentially, this interpretation is based on the fact that area-volume ratios of cylinders become more favorable as size increases. As a consequence, large boilers produce their output at a lower average cost than small ones
Certainly, by the time the tubes were being dug, standard gauge was well established and there wouldn't be much reason to consider otherwise.
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Post by zbang on Dec 31, 2020 18:29:07 GMT
I can see the value of staying with standard guage as it reduces the need for bespoke equipment but is it really the optimum?
Optimum in what sense? Certainly, it's optimum cost-wise (even bespoke equipment uses some standard parts). There may be a consideration of track geometry, and how curves & points, but I can't see that from here.
(doing this largely as an excersize because it interested me)
About the only other factor would be expected center-of-mass (CM) of the load. Since humans average under 6' tall and under 11-12 stone, it becomes difficult for the CM to get over maybe 2-2.5m above the rail. For the sake of discussion, if we assume a non-driving motor car weighs 20t and holds 270 people (~20t), the CM would only be maybe 1.8m above the rail (that's a guess) and centered. If only one side of the car had heavy riders (15 stone? each), that might be 60-70 people and 6-7t, but with respect to the overall weight the CM is still between the rails and relatively low (and that can be managed by super-elevating rails on higher-speed curves).
Feel free to check my assumptions, I'm not through my first cup of coffee. (Yes, I was intentionally mixing units ).
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Post by zbang on Dec 28, 2020 17:59:26 GMT
Overhead rail or wire, probably a somewhat higher voltage (750v? 1000v? higher?). Or a covered 3rd rail (many metro's use them).
But.... even with speculative H&S requirements, I think exposed conductors would be allowed in some controlled circumstances.
Possible a greater question is whether it would be DC or AC. I'd expect DC since the drive electronics would be somewhat easier, but I could be wrong.
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Post by zbang on Dec 25, 2020 22:19:26 GMT
At the other end of the scale- Washington Metro's map is very much like the actual system; not that it's a complex system at all.
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Post by zbang on Dec 19, 2020 21:37:18 GMT
Given all of the systems (tube, sub-surface, overground, dlr, trams, etc), how many days would it take to stop at each station (let alone exit/reenter each)? If nothing else, you're going to get hit by the train frequency problem. (If my numbers are correct- if a end-to-end route takes 35 minutes and has 14 stops... at 30 tph that's going to be 30 + 2*13 = 56 minutes to cover one direction. Of course, then you're out in the weeds and need to get back to a transfer point. My reasoning may be faulty here.)
Passing through every station, or covering every revenue route, w/o alighting would be a lot faster, although that runs into the pesky once-a-week sort of route knowledge moves. Scheduling this would be more than just a headache.
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Post by zbang on Dec 15, 2020 18:15:41 GMT
But then what do you do about the counter-weight, which is heavier than the lift; leave that at the top?
If the ropes are cut, it'll find it's way to the bottom . Safe thing would be to carefully lower it down and then unload the weights.
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Post by zbang on Dec 9, 2020 21:10:21 GMT
It rather depends on whether or not the train management system is written to run under an operating system, or rather communicate directly with the hardware. (Sorry, I'm late.) I don't know specifically, but depending on all the tasks it handles, it's quite likely that the TMS does run with an operating system, but that OS is more likely to be a real-time OS like QNX or VxWorks than a general-purpose one like linux or WinCE. Very few systems run "on the metal" anymore.
If it were me, and it isn't, I'd put the passenger info/announcements/etc on a completely separate platform from actual train operations/management.
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Post by zbang on Nov 13, 2020 17:39:41 GMT
When it comes to bridge strikes I really do not think there is great merit in focusing attention on somehow automatically monitoring the track alignment and triggering the signals to red if/whenever they happen. [...] So what happens if a dozy driver smashes his overheight truck into a bridge travelling fast enough to distort the track. Your automatic laser monitoring system will instantly detect the problem and set signals to red. BUT it will really only help if can garantee that there are no trains within 0.8 miles of the bridge - as there is a risk that any trains within that distance are going to reach the defective track even using maximum braking. [...] The answer must be to bite the bullet and make sure we prevent any over-height vehicles hitting the bridge in the first place. [...] You're mixing the apples of real-time action with the watermelon of active prevention.
No, a red signal will not stop the train that's already within stopping distance of the problem, but then this is true for anything that will put up a Danger (like a broken rail). The purpose is to alert the trains (and signalers/controllers) that there is a problem ahead (like a broken rail). And even if the train can't fully stop, any energy dissipated in braking won't have to be dissipated in a crash. (Railways in areas of avalanche or rock slides often spend a fair bit know that one has occurred, better to send out a plow or digger to clean up than send a goods train at 60kph.)
And we know from long experience that even with training, fines, etc, humans make mistakes. A simple (and relevant) example is Correct Side Door Enable- a trained driver would never (I hope) intentionally open the wrong side, but it's happened enough to warrant adding CSDE to the trains. Heck, most of signaling is to prevent things that shouldn't happen anyway.
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Post by zbang on Nov 13, 2020 0:08:40 GMT
Impacts that cause multiple days worth of disruption to the railway seem to happen on average about once every 1-2 years based on the same far from perfect google search. Possibly skimming RAIB report titles would also yield some info, I expect they'd look at anything like that; not offering to do so at the moment.
(Topic drift- whatever happened with that 100m+ section of brick wall that fell down on some tracks?)
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Post by zbang on Nov 11, 2020 20:56:48 GMT
Indeed it was possible to run out of air using the Westinghouse brake. Each coach has an auxiliary air reservoir which has enough capacity for 3 applications. Air flow to the brake cylinders was via a triple valve, a rather complex bit of kit which I won't try to explain here! The single brake pipe reservoir-exhaustion problem led to both the multi-pipe systems and to electrically-controlled triple-valves (of which, IIRC, there are several competing systems). Single-pipe also has the difficulty on longer trains that brake application (and recharge) depends on the speed of air movement in the single pipe; a US-length goods train could take over 20 minutes to charge the entire system from empty.
*with some very bad letterspacing, sigh
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Post by zbang on Nov 10, 2020 17:24:31 GMT
One issue I see with the 11'8" bridge is that the overheight warning sign is between a pair of traffic signals that show a green light to approaching traffic!
Large signs alert driver to the low clearance several blocks before the bridge. Half a block before the trestle, a sensor detects overheight vehicles and triggers an LED blackout warning sign that was installed in May 2016. That same sensor also triggers a red-light phase at the traffic light directly in front of the trestle (installed in March 2016), so the driver has 50 seconds to read the warning sign next to the red traffic light and consider their next move.
AFAICT, there is still no remedy for willful ignorance, only consequences (like paying for a new truck body, insurance won't cover it).
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Post by zbang on Nov 9, 2020 21:23:11 GMT
The famous 11foot8 bridge was recently raised 8", which I believe put the track at the same elevation as the level crossings either side. The bridge, well, the crash beam, still gets hit, just not as often.
Drivers routinely ignore warnings and occasionally lose their bet with physics.
People complain about the low bridges but don't even think about the cost to raise them. (11foot8 has a sewer running under the road and level crossings on the rail line within about half a mile of the bridge.... don't want to know the cost to jack it up to spec height.)
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Post by zbang on Nov 9, 2020 5:04:00 GMT
When feeding energy back into "the grid", yes, it must be sync'd, however this is possible with modern power electronics which can track both the frequency and the flows in/out; a type of engineering that I presently consider some sort of Dark Magic. (Solar/wind power feeds are much easier than transit/etc supplies as their flow is one-way- see "grid-tie inverter".)
IIRC one of the main early problems with regen braking is that unless there were enough loads to soak up that energy and the converter regulators fast enough, the DC bus voltage could rise excessively (again, more modern controllers limit this).
BTW (from memory), the Norfolk & Western RR (West Virginia, USA) did regen braking probably 90 years ago into their AC system (25Hz 11KV), but the motors were synchronous so it wasn't such a problem.
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Post by zbang on Nov 3, 2020 0:03:50 GMT
Will the old wagons be offered for sale . I'm not sure anyone will want them! The knackers would (the scrap still has value).
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Post by zbang on Oct 28, 2020 22:57:46 GMT
BTW, this is also known as "rebar rot", and yes, water ingress to uncoated rebar will do that.
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Post by zbang on Oct 28, 2020 22:55:29 GMT
It's probable that you and your friends were just travelling in a different unit to the PSA.
I'm fairly sure when I say 'only ones on the train', that's what I mean; and I think they were one-unit trains at that time. However, none of that precludes a PSA from hiding somewhere in the train and occasionally pushing buttons.
Why am I pushing this? Because I remember the novelty of seeing a PSA at a door control panel when I hadn't seen any before, and as a railfan I do tend to look around.
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Post by zbang on Oct 28, 2020 5:09:29 GMT
Every DLR train has a staff member on board at all times. Was that always the case? ISTR from 2014(?) that the later-in-the-night trains didn't- leaving the ExCeL center/Prince Regent station after 2200 our group were often the only ones on the train heading west. (My memory is a bit fuzzy on this.)
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Post by zbang on Oct 27, 2020 16:14:52 GMT
A minor point- GoA 3 Driverless (DTO); Starting and stopping are automated, but a train attendant operates the doors and drives the train in case of emergencies. As used on DLR<abbr>.</abbr> My recollection is that DLR does/did have TAs during the busy times but not early/later in the day. Is this still the case?
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Post by zbang on Oct 27, 2020 4:13:43 GMT
All roads can now only accommodate one S7 train, the only named roads are: - 'Whiteley's siding' , runs parallel to exit road towards Olympia - 'electric road' , between main siding and outlet to West Kensington - 'steam road' , alternative route main sidings and outlet to West Kensington
(coming to this late) Why those particular names? How common is/was it to name roads/sidings at all (in the TfL realm)
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Post by zbang on Oct 22, 2020 20:26:28 GMT
The primary concerns of the travelling public are: - where the train is going, and which route it'll take to get there, and to a lesser extent
- how fast the journey will be and how frequent trains are.
As someone who only has the chance to visit every couple of years, I'll add one more: - can I touch on/off or do I need a "paper" ticket?
In recent visits and other than inter-city rail (e.g. Bristol or York), I think I only bought two "paper" tickets (Bedwyn and Whitchurch) and used touch card PAYG the rest of the time, including Teddington, Rochester, and probably some I've forgotten. Surely, I do know the difference between the systems, but that doesn't matter in the grand scheme unless I want a particular stock or route.
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Post by zbang on Oct 2, 2020 16:35:02 GMT
Complaining about the noise is a tradition probably going back, oh, let's call it 200 years now. And these same people would rent a flat over a pub or next to the fire brigade and complain about that noise, too.
Vaguely back to the original- how common are time-based whistle restrictions? Or "no-blow" level crossings? We've had some enormous fights over them 'round here ("CalTrain", if anyone's interested).
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Post by zbang on Aug 5, 2020 16:35:26 GMT
hobbayne , I'd say the main plus point is the accessible map which at last gives something approaching usable to those with access requirements. Well, the paper maps have indicated if a station is "step-free" for a while, and ISTR a friend using an iPhone app 3-4 years ago that had all of the accessibility info, including where on each platform to board/alight. Have they added anything past that? (not having an iThing, I can't look myself)
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Post by zbang on Jun 28, 2020 6:02:07 GMT
To be shovel ready you need to have been out to tender and have potential contractors lined up.
Maybe, or maybe not.
From wikipedia-
At least in the US, projects aren't put out for bid/tender if the money isn't there to spend; contractors aren't going to do the formal process if they know it's not going to be awarded (no funding).
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Post by zbang on May 13, 2020 21:21:06 GMT
Not sure if the original question related only to lines underground, or the whole LT system. Still as one who regularly passes Chalfont & Latimer station and chuckles to see a large UNDERGROUND roundel where the line crosses on a bridge up above, I suppose Underground can mean whatever one wants it to mean. Yes, the whole system although was was originally thinking only about the more classic Underground of tube, sub-surface, and maybe trams.
(I'm not much interested the buses, but I'm sure some readers are. Probably the only thing I'd exclude is main-line/long-distance trains; and with the line to Reading run by TfL (yes? no? in-between?)....not sure how that fits.)
"Bargain Basement Shop - 1st floor"
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Post by zbang on May 9, 2020 17:11:12 GMT
The original question (9 May 2020) Maybe not a simple question- Of all that's been published about "The Underground" in all its forms, what are the top volumes for someone interested in more than just pictures of trains (e.g. history, technical, etc)?
[.... one year later .....]
10 May 2021 Wow, that took a while. I've collected all of the suggestions from comments below and from others, attempted to correct the titles & authors as needed, and attempted to organize the works into some sensible groupings... (Doubtless I've also introduced some errors along the way.) This is not intended to be an all-encompassing list of books about the Underground and related lines, only the ones someone has recommended. Some of these books appear in multiple editions, occasionally published with slightly different titles (and even authors! e.g. London's Underground). Because of this, I've generally omitted publishers and dates; searching just the title and author will turn them up. That said, be diligent, you may find one title attached to completely different works; you may also find same work with slightly different titles for the exact same ISBN. GeneralLondon's Underground (For the Modeller and Historian) - originally by H. Howson, later editions by John Glover (some prefer the earlier editions) London's Lost Tube Schemes - Antony Badsey-Ellis How the Underground Works - P.E. Garbutt Tube Trains Under London - J. Graeme Bruce London's Underground: The Story of the Tube - Oliver Green Handling London's Underground Traffic - J.P. Thomas ("if you can get your hands on it, is well worth a read. It's fast approaching a hundred years old, but has stood the test of time. Much of LU's current management would benefit from a copy.") Frank Pick's London - Oliver Green London's Local Railways - Alan A. Jackson London Railway Atlas - Joe Brown
History & peopleThe Man Who Built London Transport: a biography of Frank Pick - Christian Barman Rails through the Clay: A History of London's Tube Railways - Alan A. Jackson & Desmond F. Croome Steam to Silver - J. Graeme Bruce Working the London Underground: 1863 to 2013 - Ben Pedroche London Underground's Strangest Tales - Iain Spragg Romance of London's Underground - W.J. Passingham Building the systemRails Through the Clay - Desmond Croome & Alan A. Jackson Reconstructing London's Underground - H.G. Follenfant London's Local Railways - Alan A. Jackson Semi-Detached London - Alan A. Jackson London's Lost Railways - Charles Klapper Underground Movement - Paul Moss The Subterranean Railway: How the London Underground was Built and How it Changed the City Forever - Christian Wolmar StationsTiles of the Unexpected - Douglas Rose London's Disused Underground Stations - J.E. Connor Mr Beck's Underground Map - Ken Garland Underground Maps after Beck - Maxwell Robert Underground Architecture - David Lawrence Original London Underground Lift Stations - Jim Wright The Underground Stations of Leslie Green - David Leboff Do Not Alight Here: Walking London's Lost Underground and Railway Stations - Pen Pedroche Tube Station Trivia - Geoff Marshall (added 17 August 2022)
Specific linesLondon's Metropolitan Railway - Alan A. Jackson History of the Metropolitan District Railway Company to June 1908 - Alexander Edmonds History of the Metropolitan Railway Vol.1-3 - Bill Simpson The Metropolitan Line: London's First Underground Railway - Clive Foxell Hammersmith & City Line 150 years - Mike Horne The Jubilee Line Extension - Kenneth Powell ("mainly a photobook but I really like it") By Tube Beyond Edgware - Tony Beard The Aldwych Branch - Antony Badsey-Ellis The History of the Bakerloo Line - Clive D.W. Feather The Big Tube: A Short Illustrated History of London's Great Northern & City Railway - J. Graeme Bruce London's District Railway: A History of the Metropolitan District Railway Company vol: 1 & 2 - Mike Horne The First Tube: the Story of the Northern Line - Mike Horne & Bob Bayman (These appear to be the same) Northern Wastes : The Story of the Uncompleted Northern Line ExtensionsNorthern Wastes: Scandal of the Uncompleted Northern Line - Jim Blake & Jonathan James Lines of the London Underground (Charles Edward Lee) Series (separate volumes for Central, District, East London & Thames tunnel, Met, Northern, Picc.) www.goodreads.com/series/80846-lines-of-the-london-underground-charles-edward-leeTrains & stockUnderground Train Overhaul - J. Graeme Bruce The London Underground Tube Stock - J. Graeme Bruce London Underground Rolling Stock - Brian Hardy Workhorses of the London Underground - J. Graeme Bruce (added 17 August 2022)
Not directly TfL related but interesting anywayWorking to Rule: Railway Workshop Rules: A Study of Industrial Discipline - Kenneth Hudson ("I find this fascinating") London's Historic Railway Stations - John Betjeman London's Termini - Alan A. Jackson -- "Both are concerned with the mainline termini, but there is plenty of Tube interest within the stories." Frank Julian Sprague: Electrical Inventor and Engineer - William D. Middleton (among many other things, Sprague invented interconnected electric multi-unit operation; Middleton was a fairly prolific writer on electric American railroads) (added 17 August 2022) I heartily encourage readers, when you can, to purchase from your local independent bookseller, most will order almost any new book and it helps keep them in business. For used editions, www.bookfinder.com does an excellent job of finding who has a specific edition and what it will cost, and many independent sellers appear in the listings (even though they may use Amazon/eBay/alibris/etc to process the orders); you can even then contact the shop directly. Places to Look Things UpAuthor listings at goodreads.com--
J Graeme BruceJ E ConnorPiers ConnorAntony Badsey-EllisClive FoxellJohn GloverOliver GreenAlan Arthur JacksonMike Horne (aka M. A. C. Horne, see also www.metadyne.co.uk/Books.htm)(at times wikipedia has a better list of an author's works than goodreads, check both)
17 August 2022 A couple of additions & updates.
z!
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Post by zbang on May 7, 2020 19:21:32 GMT
I said further up the thread that the maps used to be printed with individual solid colours for each line. It was very, very expensive. [...] If you just wanted to create a diagram for a single line you would need to produce a new set of films. Was. On an 8-stand web press, you can put any eight colors; granted that running more than 6 would be very uncommon.
[...]
Of course, although the printer might be using computer-to-plate and completely bypassing any actual film (new plates was never a question, but they're relatively cheap). The point is- this is not a difficult process and not uncommon at all, and what's really an editorial change happens far above the platemaking stage. (Oh, and often the plates aren't kept, a new one being made for each press run. Negatives/mats might be kept, but aren't hard to remake either.)
In deference to topic drift (into printing technology), I'll stop now.
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Post by zbang on May 7, 2020 17:04:45 GMT
The layers are separated for 4 (sometimes 6) colour printing so black is only only solid colour. Colour separations are done in "pre-press"; actual content changes like dropping a train line or adding text would be done at the much higher content-manipulation level and with different tools. (BTW, I have some maps are seven colour- CMYK, medium brown, light blue, metallic silver.)
All that's neither here nor there, if TfL wanted to print maps showing only certain lines, it would not be difficult; I used to do similar things a couple of times a year. It only requires the inclination and the money.
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Post by zbang on May 6, 2020 21:21:41 GMT
Not a simple task to break out an individual line and you would have to include the black layer for the station names and interchange rings.
With modern composition tools, it could be fairly easy. Depends on whether the lines are kept on separate layers and how crossovers and shared connections/stations are resolved (such as Leicester Sq or Bond St). (And the station names aren't in black on the map I was just looking at, they're a medium blue.)
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Post by zbang on May 4, 2020 17:47:52 GMT
Having spent time working with industrial controls and designing/building test systems, I understand the need for proving a system and the basic methods involved. Also for monitoring unintended consequences ("Hey, flow at pump #5 and motor not running, is that right?", "Um, no, close the valves and raise an alarm").
What I'm interested in here is how those principles are applied to a lever frame/interlocking plant. "Every possible scenario" on a 50 lever frame is quite a lot. It's easy to check simple things, such as if a FPL prevents the associated points being moved, but does that procedure also include whether it affects an genuinely-unrelated signal at the far end of the station?
There's also the concept of "implied trust" where simple sequences are proved correct and then become a single component in a more complex sequence. This can limit the amount of direct action to prove a sequence by avoiding what could be come a recursive problem.
Or one let's be it be an n-squared problem and gets on with the work.
When Theory meets Practice, what actually happens?
FPL- Facing Points Lock
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Post by zbang on May 4, 2020 16:57:42 GMT
Out of the the GCR discussion elsewhere-
At least in the context of non-computerized schemes, how is an lever frame/interlocking plant "proved" to be correct? That is, the correct locks are applied and sequence enforced? Also that one lever doesn't affect things it shouldn't.
On the face of it, most locking should be fairly simple combinatorial logic with the occasional timer, however when moving from a worksheet/book to a physical manifestation, it's almost easy to put a peg in the wrong place or a wire on the wrong terminal. At first glance, testing is an n^2 problem trying every combination of levers, however that can't directly work because of enforced sequences and it becomes a huge number rather quickly. Likewise, it's easy to try the expected sequences but are seemingly unrelated actions checked at the same time? How is this documented?
Or is a frame only visually checked that the locks match the book?
(Normally this would send me into a pile of books, but I have neither the time nor brain power at the moment.)
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