[go: up one dir, main page]
Jump to content

Talk:Third rail

Page contents not supported in other languages.
From Wikipedia, the free encyclopedia

Change title of page? plus no overhead third rail

[edit]

There needs to be at least some disambiguation. This page should be titled "Third rail electrification" or "Third rail (railways)", or something similar.

Furthermore, there is no mention of the use of overhead third rail, especially on the B&O, and in Grand Central Terminal to allow electric locomotives to bridge gaps at interlockings.

70.105.217.151 (talk) 17:52, 25 August 2009 (UTC)[reply]

3rd rail lubrication

[edit]

Does anyone know what the black coloured liquid is that is used to lubricate the rail and the pick-up shoe?--Screen42 11:18, 14 September 2006 (UTC)[reply]

There is, to the best of my knowledge, no specific fluid used to "lubricate" the rail. Certainly, the regular trains do not carry and liquids for such a purpose, and do not have any means of "squirting" it on to the rails. What you might be thinking of is de-icing fluid. This is placed on the conductor rail to prevent it from icing over when the temperature falls below freezing. This is applied by a "departmental" train as opposed to a regular passenger train. I think they put so called "Q" paths into the working timetable (that is the timetable used by the railway operators) which include for the running of a deicing train should it be required (the train runs "as required", but has a path in the timetable). Olana North (talk) 22:49, 10 January 2008 (UTC)[reply]
There is no need for lubrication due to low friction coefficent of steel on steel. De-icing fluids must not be corrosive and has developed into oil. Oil will not freze or allow water to settle directly to the conductor rail. This prevents ice bonding to the rail and allows any ice to be readily knocked off by the "shoe". —Preceding unsigned comment added by 86.18.88.149 (talk) 23:06, 29 December 2008 (UTC)[reply]
I have seen a heavy black build-up of some substance that looks like dried-out oil on the third rail at South West Trains stations in southeastern England. However, I don't know how it got there unless it was deposited by a special maintenance vehicle. The third rails are definitely not as shiny as the ordinary rails on this network, which suggests that they are made of something different or may be coated with something. I too have been trying to find out why the shoes don't wear out, rubbing continuously along the rails. (A car's pistons would soon lock up without lubricant, so I don't buy the previous commenter's remark about steel-on-steel.) EWAdams (talk) 23:02, 6 June 2009 (UTC)[reply]
The pistons is a car engine are moving at hundreds of revolutions per minute. If we assume an average of 2000 rpm and a two hour journey, then thats a total of 240,000 movements. It would take years for the conductor rail to reach the same number of passes, even on a busy railway. The comparison is flawed. Conductor shows do wear out, but slowly, and do get replaced during train maintenance. Also the conductor rail wears out, but again, very slowly. The southern region of england has conductor rail that is over 50 years old. The rails are not lubricated in general, but the application of de-icing fluid does cause the build-up of greasy deposits over time. Bhtpbank (talk) 06:51, 8 June 2009 (UTC)[reply]
That is correct; there is no lubrication of the shoe to rail contact, and the pressure of the shoe is minimal. Moreover it is a large lump of metal. The piston to cylinder clearance in a car engine is ciritical to thousands of an inch. The black sludge is the residue of deicing fluid over the years. --Afterbrunel (talk) 05:44, 4 August 2009 (UTC)[reply]
Indeed it is de-icing fluid. While present on the rail, the fluid collects the steel dust thrown off the brakes (which are cast iron on steel). The dust can often be seen accumulating on parts of the railway that are not regularly cleaned as a brown deposit (where the steel dust has rusted). When it is absorded into the deicing fluid, the fluid inhibits the rusting and the fluid takes on a black sludge like appearance.
Incidentally, although the conductor rail is steel, the collector shoe is cast iron. Cast iron is self lubricating and so runs over the steel rail easily. The self lubricating effect is lost when it used as brake shoes as the substantially higher contact pressure causes the dissimilar materials to 'stick' to each other (the 'Blish effect' (for which Wikipedia does not have an article)). –LiveRail < Talk > 13:30, 27 September 2014 (UTC)[reply]

Safety section

[edit]

I replaced the sentence "However, such incidents are usually the result of carelessness on the part of the victim" since it was not cited, and conjecture. I replaced it with another statement, "However, the hazard can be mitigated by use of signage or safety barriers", I think that is in the same spirit of the original sentence, and wholly supportable without citation. Also I removed "The principal hazard is probably associated with level crossings (grade crossings)". "Probably" does not belong in an encyclopedia, it could be added back in if it can be cited. Zatoichi26 (talk) 16:53, 1 April 2009 (UTC)[reply]


For now the Wikipedia article looks like the "third rail" could be the only option (or somebody just doesn't want to inform people about other options existing in the other countries, which by the way are considerably better and safer). Why there isn't even one word mentioned about the third rail (poor)safety comparing to overhead line electrification safety? I lived in Soviet Union (Latvia), we had electric trains about 40 years ago with "overhead line electrification" and I've NEVER heard in 30 years about somebody electrocuted on the rail (!) while living now in UK, I see it in news at least couple times a year. "The public, trespassers and track workers are at ten times more risk of being electrocuted on third rail lines than by OLE systems." citate from Network Rail A Guide to Overhead Electrification 132787-ALB-GUN-EOH-000001 February 2015 Rev 10. http://www.bathnes.gov.uk/sites/default/files/sitedocuments/Planning-and-Building-Control/Planning/nr_a_guide_to_overhead_electrification.pdf

Section Added

[edit]

I added the section: Technical Advances Lowers Running Costs Waterspaces (talk) 13:19, 3 April 2009 (UTC)[reply]

"Myth" are you people CRAZY???

[edit]

What on earth were you thinking writing that part about people urinating on the third rail? To urinate on a live high voltage conductor is EXTREMELY DANGEROUS and the fact that it will harm you is NOT A MYTH. Have you tried peeing on an electrical fence, if not then I can tell you that is WORSE than touching it. Urine is highly electical conducting due to the concentration of ions in it. It's important that WikiPedia doesn't contain such reckless statements that may mislead people. You cannot base WikiPedia on shallow TV programs such as mythbusters. M99 87.59.103.226 (talk) —Preceding undated comment added 14:44, 23 April 2009 (UTC).[reply]

I agree. This article verifies that even the Mythbusters don't always get it right. www.thelondondailynews.com. Bhtpbank (talk) 06:45, 8 June 2009 (UTC)[reply]

The article does not verify it. The article merely states that the guy went to take a whiz not that he did. Touching the third rail is harmful. Stating that people will get electrocuted by urinating on the third rail cannot be in a Wikipedia article until it is verified. Without scientific or other forms of actual evidence, it is a statement of conjecture. Anecdotal evidence is also inappropriate, and all stories that I can find of this nature seem to be anecdotal, or of the "I heard about a guy who pissed on a railroad track and got killed" I am removing the sentence from the article and placing it in this section as, whether true or not, does not have any supporting evidence. Mrschwen (talk) 03:14, 19 October 2012 (UTC)[reply]

This is the statement as originally in the article under cost/benefits in the Supreme court case section. " In such an action the stream of liquid forms in essence a wire, transmitting a severe (and if not fatal, at very least debilitating and painful) electric current to the person's body via the penis." Once scientific research or a verifiable case occurs of this, then it can be added back to the article along with proper citation. Also, the supreme court case mentioned in the article does not state that the guy was urinating on the tracks, merely that he was going to urinate. He was found facing parallel to the tracks, with his foot near the third rail. His urine would be hitting the ground near the rail. Mrschwen (talk) 03:19, 19 October 2012 (UTC)[reply]

And that's where this ended? Really? I was wondering if there was a WP article with a section about people attempting to lick frozen outdoor objects, and whether we could start a "Stupid Things People Do With Their Bodies" links page pointing to this, that, and any number of as-yet innumerable acts of body-related lunacy, which people could check before considering doing anything about their common sense is trying to warn them not to do—or even if it isn't, which, when you look around online, seems more likely, doesn't it. You'll notice that wasn't a question. – AndyFielding (talk) 07:44, 20 November 2023 (UTC)[reply]

Bordeaux system

[edit]

I think the description of the Bordeaux system here is inaccurate. Where the system runs along streets the third rail is flush with the road surface and is exposed. There is a system in operation which makes the rail live when and only when a vehicle is above a particular section. I found this information some time ago on the Web, but I'm sorry I can't cite references now. I don't want to get involved in changing anything, but I thought I would flag this in case someone else might like to. 89.240.47.42 (talk) 12:01, 2 May 2009 (UTC)[reply]

Flow of page

[edit]

I am worried about the flow of the information on the page, where after a cursory introduction, we launch into a huge history section. A reader coming here for information would be put off by having to wade through that first. I will alter the sequence so that the description comes higher up. Also there are a lot of anecdotal statements that do not add to understanding and are not encyclopedic, and I will thin them down a little. --Afterbrunel (talk) 05:49, 4 August 2009 (UTC)[reply]

100mph maximum speed test

[edit]

The only speed tests that have taken place for third rail technology happened on the London to Brighton line during the introduction of the Gatwick Express. This line has a maximum of 100mph and so there has not been any tests above 100mph. The paragraph

"The end ramps of conductor rails (where they are interrupted, or change sides) present a practical limitation on speed due to the mechanical impact of the shoe, and 160 km/h (100 mph) is considered the upper limit of practical third-rail operation. The world speed record for a third rail train is 174 km/h (108 mph) attained on 11 April 1988 by a British Class 442 EMU." contradicts itself by stating 100mph and then suggesting a faster time.

Unless someone can provide evidence for the above, the statement should be changed to state it has never been tested above 100mph —Preceding unsigned comment added by Sailor iain (talk • contribs) 12:05, 27 August 2009 (UTC)[reply]

The practical upper limit is not exactly 100 mph. This is merely the conveniently rounded figure that is considered to be the upper limit. A train travelling at 108 mph on a line that has a line speed of 100 mph is not considered to be exceeding the speed limit because UK mainland railways allow a leeway of 10% before a driver will be disciplined. –LiveRail < Talk > 13:24, 27 September 2014 (UTC)[reply]

Platform height

[edit]

Third rail systems require high-level platforms. 121.102.47.215 (talk) 14:14, 14 March 2010 (UTC)[reply]

FALSE. The platforms on the southern region of British Rail are no different in height to any other. Please provide evidence to support your statement. The standard hight of a platform on British Rail is 915 mm (ARL) and this does NOT change in third rail areas. Furthermore, the height the height is not lower is areas where overhead electrification is installed. Bhtpbank (talk) 13:15, 15 March 2010 (UTC)[reply]
What happens is that in stations the third rail is placed further away from the platform edge (in the "six foot"). This means that if a person were to fall from the platform onto the track it is less likely that they will also be electrocuted. Bhtpbank (talk) 13:17, 15 March 2010 (UTC)[reply]
I know of plenty of examples of stations where the third rail is adjacent to the platform. If I was able to upload pictures, I could supply plenty. 86.139.78.218 (talk) 17:58, 23 January 2014 (UTC)[reply]

Halving of Italian voltage

[edit]

The article claims that the voltage of tha Italian side was halved which in turn halved the power of the trains. This cannot be the case. In general electrical terms, halving the voltage also halves the current. This means that only a quarter of the power is drawn. With DC electric motors the position is complicated because the lower back e.m.f. of the slower running motor means that the current is a bit larger than half. The power will still be reduced by more than half though. –LiveRail < Talk > 13:18, 27 September 2014 (UTC)[reply]

Top-contact and covered?

[edit]

We've got a sentence that says, some of the earliest systems used top contact, but later developments use side or bottom contact, which enabled the conductor rail to be covered. The NYC Subway has a top-contact third rail, and it has a cover over it. There's a good illustration of this at [1]. So, some rewording of that sentence is probably called for. -- RoySmith (talk) 04:02, 5 February 2015 (UTC)[reply]

Fewer feeds for smaller third rail?

[edit]

"The Docklands Light Railway (DLR) uses a third rail which is tiny in section compared with the usual; thus fewer substations are required." This is counter-intuitive. If it is somehow correct, would someone please explain why? The Wikipedia article for the DLR has no mention of this feature. — Preceding unsigned comment added by 38.122.49.58 (talk) 14:54, 17 February 2015 (UTC)[reply]

I agree, so I have added a "citation needed" tag. Biscuittin (talk) 21:59, 30 November 2015 (UTC)[reply]

Shoe vs. wheel

[edit]

Why are sliding shoes commonly used instead of metal wheels? It seems like this would generate a lot of friction and thus wear and tear. Would wheels overheat due to the smaller area of contact?? -- Beland (talk) 01:21, 21 February 2015 (UTC)[reply]

This has already been answered above. The contact shoe is made out of cast iron. Cast iron has a very useful property in that it is self lubricating when run in contact with the steel rail. They do, of course, wear out just very slowly. –LiveRail < Talk > 18:20, 19 March 2015 (UTC)[reply]
Besides, even if you went to a wheel, you would then have to have something in sliding contact with the wheel, like the brushes that bring power to the rotor in an electric motor. You'd just be moving the sliding contact point to someplace else and adding complications (bearings, etc.) that are proven to be unneeded. Jeh (talk) 07:28, 23 November 2015 (UTC)[reply]

"There are a number of cases"

[edit]

From the Gregg Reference Manual, 10th edition, by William A. Sabin, page 266:


Also, from this example at oxforddictionaries.com, showing proper use of a phrase including the word "number":

I've found further distinction drawn depending on whether the noun that follows "the number" is a "count noun" or a "mass noun". E.g. correctly, you would say "there are a number of people", or "there are a lot of people", because even though "people" is a group noun, the "people" in the group can be counted one by one. (In fact, it is hard to see how you would use "a number of" with other than a countable noun.) But you would say "there's a lot of dirt" because "dirt" is a mass noun. You would never say "there are dirt", right? Nor would you say "there is people". Sticking "a number of" in front of a count noun doesn't change it to a mass noun. --Jeh (talk) 07:24, 23 November 2015 (UTC)[reply]

It doesn't matter if the people can be counted one by one, because even in examples like "there is a group of apples over there" or "There is a pile of boogers on your desk," which can be counted individually, you're still saying "there IS." You don't say "there are a pile of boogers on your desk," right?
So you think that people should say "there are a group of cats over there"? "There are a pack of dogs over there"? No, that doesn't make sense. Why should those words be any different from "number"? 174.23.104.46 (talk) 09:27, 23 November 2015 (UTC)[reply]
I explained why already; let me try it with slightly different wording: "A number of" is not descriptive of a mass of things. It's a handy substitute for a specific number. We would write "There are cases"; we would write "there are 23 cases"; we would even write "there are more than 20 cases"; we would also write "there are a number of cases".
Examples involving other words like "group" or "pack" or "pair" (a special case if ever there was one) are not on point.
Anyway, it doesn't matter what you or I "think," what "sounds right", what we "would do", or what "makes sense", or what we think is "always taught". What matters is what's in authoritative references. I've found two (ed.: now three four; see below) that say that "there are a number of cases" is correct. Can you find one that says "There is a number of cases" is correct? (No substitutes for "number" allowed.) If not, then it goes back to the way it was before your edit.
Another reference, this one from the BBC:


Jeh (talk) 09:43, 23 November 2015 (UTC)[reply]

Why should "number" be any different from other grouping words? 174.23.104.46 (talk) 09:49, 23 November 2015 (UTC)[reply]

I'm not a grammarian, so I'm really not sure why. But it is. My guess is that the reason is that it (like several others) can only be used with count nouns. e.g. you can't say "a number of dirt". It's not as if English isn't riddled with special cases, you know? But anyway, authoritative references say that "there are a number of..." is correct. Have you found any that say otherwise? Jeh (talk) 09:55, 23 November 2015 (UTC)[reply]
Here's a fourth reference, this one archived from oxforddictionaries.com - alas they seem to have removed the "askoxford" section of their pages, but archive.org saves the day. [2]
Jeh (talk) 10:33, 23 November 2015 (UTC)[reply]

"A lot"

[edit]

Aside from the reference I gave in my edit summary, see also this website for an explanation of the usage of "a lot" with countable nouns. At best, both singular and plural usage are acceptable, in which case, you shouldn't change the status quo in the article; but really, plural verb with plural nouns is preferred, so I suggest just dropping this silly edit war. LjL (talk) 14:03, 23 November 2015 (UTC)[reply]

Briefly, the subject of "There are a number of (countable objects)..." is not "a number". The subject is "(countable objects)". Thus the subject is plural. Sticking "a number of" in front of it doesn't make it singular any more than would "23". Subject-verb agreement therefore requires that the plural form of the verb be used. Jeh (talk) 20:44, 23 November 2015 (UTC)[reply]


But words like "group" and "pair" represent countables too. You don't say "there are a group of..." do you? You don't say "there are a pair of shoes," do you? So your logic that "the contents are countable and therefore the container word should be treated as a plural in all cases" is flawed. — Preceding unsigned comment added by 97.117.51.136 (talk) 20:03, 24 November 2015 (UTC)[reply]

People most certainly do say "there are a group of". Just check Google hits count. The "there is a group of" prevails slightly, probably because that tends to be more common in American English while the former is more widely used in British English. LjL (talk) 01:47, 28 November 2015 (UTC)[reply]
ANYway, we're not talking about "a group of" or "a pair of". We're talking about "a number of", and I can find NO authoritative references supporting the notion that "a number of (countable objects)" should take a singular verb. Sever references supporting plural, however. (edit-added: I've improved the formatting above to call more attention to the quotes from these sources.) Have you found any references for singular? Jeh (talk) 02:53, 28 November 2015 (UTC)[reply]
Further research: These "grouping nouns" come in two flavors: "partitive" and "non-partitive". "non-partitive" also seems to be equivalient to a "quantifier". The difference is that you can express more than one of a partitive, but never of a non-partitive. For partitives, the verb agrees with the number (singular or plural) of the partitive. For example, "A pack of wolves often attacks as a unit" - singular subject, singular verb. "Two packs of wolves rarely attack as a unit" - plural subject, plural verb. Right? But while you can write "A number of males in a pack may compete for 'alpha male'", you can't write "Two numbers of males in a pack may compete...".
Again, consider replacing "A number of" with a specific number like "6". You could write "6 wolves in a pack may compete...", but you would never write "Two 6 wolves in a pack may compete..."
Re "A lot", nor would you write "two lots of males in a pack may compete...". So "A lot" is a quantifier; the subject is wolves, plural, competing, the quantifier just says that not all of the pack, but probably more than one, are competing. And here's the key point: Quantifiers act differently from partitives in that they do not determine the "pluralness" of the subject. Instead the main verb in the sentence must agree with the main subject (wolves), not its quantifier ("a number of").
Re "a lot of": Yes, you would write e.g. "A lot of people wear shoes." You could not write "Two lots of people wear shoes." Therefore "A lot of" is a quantifier. So we need the plural form of the verb.
Reference: [3]
I know the adjacency of "are" with "a" (as in "There are a number of...") just sounds wrong, but again... I have references, and English is often more complex than what "sounds right". Jeh (talk) 10:03, 28 November 2015 (UTC)[reply]


Benefits and disadvantages

[edit]

Is the section highly biased? Although the name is "Benefits and disadvantages", the texts in the section are most disadvantages and potential problems of third rail. I noticed User:LiveRail (currently the account is blocked) removed one paragraph about the advantages of third rail. Should the paragraph be reverted to main article or someone write something about the benefits of third rail in the main article? — Preceding unsigned comment added by 155.69.115.184 (talk • contribs) 07:52, 25 January 2016 (UTC)[reply]

"Electric rope"?

[edit]

Talk:Third rail/Archive 1#"Electric rope"? catenary should have read overhead catenary Peter Horn User talk 22:26, 21 April 2020 (UTC)[reply]

Coverboard

[edit]

The Coverboard with its supports needs an article or a section in this article Peter Horn User talk 20:14, 28 March 2021 (UTC)[reply]

  • Third rail layout. 1:Cover 2:Power rail 3:Insulator 4:sleeper 5:Rail
    Third rail layout. 1:Cover 2:Power rail 3:Insulator 4:sleeper 5:Rail
  • Third rail (top) with cover at Bloor-Yonge station
    Third rail (top) with cover at Bloor-Yonge station
  • Shoe of NYC Subway car making contact with third rail. Showing coverboards
    Shoe of NYC Subway "e" train car making contact with third rail. Showing coverboards
  • This safety cover is not a coverboard
    This safety cover is not a coverboard
  • Bottom contact third rail in the sheath insulator
    Bottom contact third rail in the sheath insulator

Peter Horn User talk 20:52, 28 March 2021 (UTC)[reply]

Safety cover may be more appropriate because not all covers come in the form of a board. Peter Horn User talk 21:23, 28 March 2021 (UTC)[reply]
See also Shroud#Safety shroud Peter Horn User talk 04:17, 6 April 2021 (UTC)[reply]
Shroud#Safety shroud → sheath insulator Peter Horn User talk 16:53, 29 April 2021 (UTC)[reply]

"Safety" section — dubious-discuss

[edit]

The {{dubious}} comment voltage in itself is not dangerous, so this doesn't make sense. Power (volts times amps) is dangerous, but the same amount of power is always used, whether at 2000 V or 20,000 V. What's really going on? confuses working power to the train and shock power to a trespasser, which, assuming constant resistance of the body, is proportional to the square of the voltage (P = V² / R by one of the forms of Ohm's law). The higher the voltage, the higher the risk of electrocution to someone touching both the third rail and the current-return rail. I rewrote the relevant sentence in an attempt to make the difference clearer. Another thing which I didn't compute in, but should also be of concern, is the risk of dielectric breakout at the skin, which also increases with increasing voltage. — Tonymec (talk) 03:36, 13 April 2023 (UTC)[reply]

Retrieved from "https://en.wikipedia.org/w/index.php?title=Talk:Third_rail&oldid=1235990947"