Talk:Speed limit/Archive 1

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Archive This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

DO NOT EDIT OR POST REPLIES TO THIS PAGE. THIS PAGE IS AN ARCHIVE.

This archive page covers approximately the dates between the article's beginning to Sept. 31, 2005.

Post replies to the main talk page, copying the section you are replying to if necessary. (See Wikipedia:How to archive a talk page.)

Please add new archivals to Talk:Speed limit/Archive02. Thank you. Novasource 20:51, 28 December 2005 (UTC)

Contents

Crash vs. Accident

This is a stub for a discussion of the terminology of crash vs. accident. Please discuss here before further edits. User:Novasource

Note that it is my opinion that "crash" is the correct terminology. The original poster, 66.25.47.88, is correct in that government agencies, including the NHTSA and Federal Highway Administration (a clearly pro-highways agency, unlike the NHTSA which sometimes appears to be in cahoots with anti-highway forces and insurance industry), are preferring the term crash over accident. "Accident" makes a judgment because it implies an unpreventable crash, whereas "crash" includes both preventable and unpreventable crashes. User:Novasource

Okay. Provided the main article describes "crash" as a superset of "accident," I will drop my objection. --24.107.227.12 16:33, 6 August 2005 (UTC)
Thanks. I am sure that the distinction and commentary on crash vs. accident would be great. Only question is whether. Speed Limit is the right place? Would other places work? 66.25.47.88 21:27, 6 August 2005 (UTC)
Speed limit is one place, but perhaps an ideal place would be an article about car crashes, including politics, crash forces, safety, insurance, etc. What do you think? --24.107.227.12 22:51, 10 August 2005 (UTC)
That sounds like a great idea. Could you start the article? Novasource 14:05, 11 August 2005 (UTC)

Merge with 30 mph

I've done a preliminary merge of the two pages, as indicated in the article. Comment and modify to your heart's desire. Josh 05:22, Apr 13, 2005 (UTC)

Where is Canada's speed limit?

Each province in Canada has its own speed limit laws. Most provinces have a speed limit on freeways of 110km/h except for Ontario and Quebec which have freeways (and toll highways) at 100km/h. Also rural two-lane roads in Canada have a speed limit of 100km/h (as is standard also in Europe and Australia) but in Ontario and Quebec it is only 80-km/h and 90km/h in rural northern areas. Generally Ontario and Quebec have the lowest speed limits not just in Canada, but in North America. I feel that the Paragraphs in the Article on Canadian Speed Limits is best under the circumstances.

What's an example of a rural two-lane road in Canada with a speed limit of 100 km/h? -rak

Most rural two-lane roads in Alberta, Saskatchewan, and Manitoba are signed at 100km/h. Many but not all rural two-lane highways in B.C. are also signed at 100km/h. I know for a fact it is the default two-lane rural speed limit in Alberta and most rural highways are signed at 100km/h.

Mph in US and UK only?

Am I right every country in the world uses Kph speed limits except the US and the UK? if so, this article should probably say this interesting fact more clearly. Seabhcán 00:50, 8 Jan 2005 (UTC)

Nobody uses "Kph." They use kilometres per hour whose legal symbol is "km/h". SI units do not have abbreviations, they use symbols that do not vary with language or type.


Hold your horses there, there's another 12 days to go until us Irish finally change our speed limits to km/h (or kph as the signs will say)! zoney ♣ talk 13:35, 8 Jan 2005 (UTC)

The conversion is complete and the signs show km/h not kph. Kph is wrong, wrong, wrong!!!

There may be a few others, but I can't think of them. The US, in fact, doesn't use metric for anything!

Incorrect. 40 % of US industry is metric. Automobile manufacturing is the most visible. With some industries using metric parts and others not, it creates an added cost burden to Americans who have to maintain duplicate inventories of parts to serve both sides.

To make it easier to convert in the real world, the converted speeds here should be listed as follows:
Metric to Imperial: 10 = 5, 20 = 10, 30 = 20, 40 = 25, 50 = 30, 60 = 40, 70 = 45, 80 = 50, 90 = 55, 100 = 65, 110 = 70, 120 = 75, 130 = 80, 140 = 90, 150 = 95.
Imperial to Metric: 5 = 10, 10 = 20, 15 = 25, 20 = 30, 25 = 40, 30 = 50, 35 = 55 (or 60), 40 = 60, 45 = 70, 50 = 80, 55 = 90, 60 = 95 (or 100), 65 = 100, 70 = 110, 75 = 120, 80 = 130, 85 = 140. 24.146.12.62 03:15, 11 Jan 2005
The UK (Where I live) also rarely uses Metric. Milk still comes in pint and two pint bottles, which, due to EU law, are labled as "1.136 l"! Seabhcán 15:13, 11 Jan 2005 (UTC)
I just read in Pint that "The UK pint is officially defined as 0.56826125 litres precisely". So whats the point of using it, if its defined in terms of litres anyway??? Seabhcán 15:16, 11 Jan 2005 (UTC)

UK industry is fully metric as are the majority of prepackaged goods in the shops. Weather is predominately reported in metric, petrol and oil are sold in litres, length products are sold by the metre and most shops use kilogram scales when selling produce to customers, etc. Some milk is sold in litres, others in pints, but the remaining non-metric products compose a remnant not the norm

convenience, and especially tradition. The convenience because there are lots of bottles, etc, made in this size, and also because they are frequently very nicely sized units. Thryduulf 16:36, 11 Jan 2005 (UTC)
Maybe, but when I buy a half litre of milk in Ireland, I don't notice the missing 0.06826125 litres. Personal preference I suppose. ;-) Seabhcán 20:47, 11 Jan 2005 (UTC)

It is what you want to be use to. In Australia milk is sold in 600 mL and 1200 mL sizes. Thus you get 32 mL and 64 mL more. The UK can do the same. BTW, why dis you say "missing 0.06826125 litres", instead of saying "missing 68 mL"? Maybe in imperial that type of nonsense works because imperial doesn't employ user friendly prefixes to scale numbers, but metric does. Maybe you and other luddites might find metric more convenient if you took advantage of its user friendliness instead of trying to incorporate bad imperial practices when using metric. 17:01, 30 Jan 2005 Ametrica

Touché. :-) Seabhcán 20:38, 30 Jan 2005 (UTC)

Interesting. When I visited England more than 20 years ago, the signs were all in metric. Did anything change? Or does Northern Ireland still use the traditional system of measurement? 64.50.192.206 14:11, 31 July 2005 (UTC)

Proposed reorganisation of article

I think the current layout of the article is a little hap-hazard - without a good logical structure. I propose a reorganisation here: Speed limit/proposed, along with some new sections which need to be writen, such as a proper history section (Speed limits must be a 20th Century invention? Were there limits before the automobile?) and Speed limit enforcement, which must vary greatly from country to country. We're also missing info on many regions of the world, such as Central and South America, Africa, and Russia. What do you think? Seabhcán 01:39, 21 Jan 2005 (UTC)

First thing to do is to throw "kph" out of your vocabulary. Gene Nygaard 01:48, 21 Jan 2005 (UTC)
Why? Its perfectly understandable, and serves as a link to the correct article: Kph. Seabhcán 12:03, 21 Jan 2005 (UTC)
Although I prefer km/h, it doens't really matter to me which is used. However, you should pick one and use it consistently, not mix and match. Thryduulf 12:34, 21 Jan 2005 (UTC)
Wrong. That Kph merely redirects to Kilometre per hour (do slashes work in article names and Wikipedia search engine?), and if you had clicked on that link, you would have learned what the proper symbols are. Even in the United States, our speedometers don't say "kph"—they use the proper "km/h". Gene Nygaard 13:18, 21 Jan 2005 (UTC)
km/h redirects to Kilometre per hour, so yes it does work in the article name and search engine. Thryduulf 13:26, 21 Jan 2005 (UTC)
For what it's worth, km/h is the abbreviation used on our spanking new metric speed limit signs in Ireland. zoney ♣ talk 13:29, 21 Jan 2005 (UTC)
By the way, if you are worried about parallelism, "mi/h" is acceptable, and redirects to Miles per hour (for some reason that one is plural, probably from before preference for singular expressed). Lots of latitude there; English units are like old software, no longer supported and updated--nobody really making any rules for them any more. Gene Nygaard 13:31, 21 Jan 2005 (UTC)
I've made several edits and comments on the /proposed page, along with a couple of typo and spelling fixes. Thryduulf 13:11, 21 Jan 2005 (UTC)
I'm happy with replacing all "kph" with "km/h". Seabhcán 17:04, 21 Jan 2005 (UTC)


"Forces increase exponentially"

Yesterday, I removed the word "exponentially" from the claim that "crash forces increase exponentially as speed increases." Today, Coolcaesar reverted my deletion with the note "Looks like Coneslayer wasn't paying attention in high school physics!" I would like to point out that I hold a B.S. in physics, in addition to a Ph.D. in astrophysics. I will therefore use this space to explain my deletion.

First, understand what is meant by "exponentially." If a force increases exponentially with speed, we're saying: F \propto {\rm e}^v. So let's see if that's the case. The original statement is a bit vague, but let's say it's referring to the average deceleration force, which occurs over a fixed distance d travelled (e.g. the crush zone of the car). We will assume constant deceleration during this interval.

We have then that the car decelerates from an initial velocity v0 over a distance d at a constant acceleration a. From basic mechanics, x = at2 + v0t (taking x(t = 0) = 0). Now, the end-state occurs when v = 0, also at which time x = d. This is when v0 = atfinal, or tfinal = v0 / a. Substituting, we have d=at_{final}^2 + v_0 t_{final}, or d = a(v0 / a)2 + v0(v0 / a), or finally d=2v_0^2/a and hence a = 2v_0^2/d

Thus, the deceleration (and hence force, since the car's mass is constant) increases with the square of the initial speed. It does not increase exponentially.

You may be able to get different dependences with different assumptions, such as a fixed time, instead of distance, over which the deceleration occurs, but I don't see how to get an exponential dependence, with any reasonable choice of assumptions. If you can, please feel free to illustrate, but don't just point us to the force and acceleration articles, like you did in your edit. -- Coneslayer 22:11, 2005 Mar 24 (UTC)

Oops! Okay, I concede you have analyzed the underlying mathematics quite clearly. I was using exponential (and I believe whomever originally inserted that word also meant the same) in the sense that the relationship is not a simple first-degree or linear function, which is the most intuitive relationship for most people. That is, neither F nor a equals v times some constant.

Of course, having reread several Wikipedia articles on algebra to refresh my own memory, I also concede that exponential is inappropriate since v itself is not the exponent. Perhaps "nonlinear" may be more appropriate. --Coolcaesar 02:00, 25 Mar 2005 (UTC)

Actually, "quadratically" would be most appropriate. --yermo 06:13, 26 Mar 2005 (UTC)

I also immeidately recognized that the use of "exponentially" as incorrect. However, I did NOT see it in the WikiPaedia article (since I read the article after the correction was made). I saw it used incorrectly in the article that was referenced. That must be how it ended up in WikiPaedia. It was used it to describe to the rate of increase in two things relatvie to speed: 1. probability of injury and 2. severity of injury. However, I think they gave no emperical evidence for either claim. They should have posed the claims as an interesting challenge to anybody who wishes to refine and extend the research. Either claim might be true. -dw

US Speed Limits

I will post a US State by State highway speed limit chart. I will also credit the list to the site I found it on, and I hope people occasionally update the chart from time to time.

i replaced the canadian speed limit sign example. the new image is better quality and it is a better example. I hope thats okay. bjj

Mexico speed limits?

Does anyone know what the speed limit is on various classes of roads in the country of Mexico?

85th Percentile Speed

<<Traffic engineers are taught the 85th Percentile Rule, which claims that maximum speed limits should be set to the speed at which 85% of vehicles are traveling. (Thus 15% of vehicles are speeding.) The rule has a mathematical basis; the 85th percentile almost exactly corresponds to one standard deviation above the mean of a normal distribution. This rule has been used for many years, yet no scientific evidence has been produced that this particular rule is safer than any other. >>

Is this true? If speed limits were set to the 85th percentile of drivers, then that would mean setting a speed limit would actually raise the average speed at which people take a road, since (at least in the United States) many more than 15% of drivers are speeding at a given time, and most feel compelled to be doing at least the speed limit. In practice (this is just anecdotal observation) the average seems to be 5 to 7 mph over the speed limit, and I'd guess 85th percentile's about +10-15. 137.22.11.145 04:22, 1 Apr 2004 (UTC)

Yes, it's true. Worldwide studies on driver reaction to speed limits go both ways, but many United States studies show little or no clear relationship between actual speeds and speed limits except that 85th percentile speed limits can affect speed dispersion. The prevailing theory is that speed dispersion (i.e., speed difference between fastest and slowest drivers) is reduced with 85th percentile limits, but empirical evidence of this is spotty.

Europe in-town speed limits

What about in-town speed limits in Europe? AFAIK, it's 50 km/h in most countries, often 30 km/h in residential areas, sometimes even only 20 km/h. Switzerland changed from a general in-town limit of 60 km/h to 50 km/h in 1984, just as it did switch from 100km/h outside towns to 80 km/h and from 130 km/h on highways to 120 km/h in 1985 ([1]). Also, isn't there a minimum speed a car must be able to attain if it is to be driven on a highway (Autobahnen, Autostrade, Autoroutes) in many European countries? I thought it was 60 km/h... Lupo 14:57, August 8, 2005 (UTC)

American vs. British English

I have reverted this article to American English from a recent conversion to British English. Per the varieties of English clause of the Wikipedia Manual of Style: "If an article is predominantly written in one type of English, aim to conform to that type rather than provoking conflict by changing to another."

This article is predominantly American English, and American subjects are by far the largest in the article, so let's keep American English.

By the way, "Interstate" is a proper noun when referring to the US Interstate Highway system, so it is correc to capitalize it. Novasource 17:05, 8 August 2005 (UTC)

Safety

This section needs to be reworked. Much of it is opinion and partially thought out theories. There is some good info here, but it needs to be extracted and the whole section rewritten.

I agree. Do you have any thoughts on how to do this? Novasource 21:56, 12 August 2005 (UTC)


Perhaps requiring sources for some of the theories presented. Also, simply eliminating some of the wordiness might help. I can try and pare it down, let me know how it looks after. 17 August 2005

Changed it, and moved some things to a new category--enforcement.

POV deletions

I just deleted everything contributed by 83.196.194.166. Virtually everything this person wrote was POV, completely uncited, or or made logical errors like a hasty generalization (e.g., the implication that heresay from one radiology unit of a hospital has broad meaning on a country's entire road system).

The person is invited to recontribute without POV and with better documentation. I feel that the speed limit article has benefited from many recent improvements in citations, and I don't want to loose this through unsubstantiated commentary.

Novasource 22:12, 23 September 2005 (UTC)

I concur with Novasource's reasoning.--Coolcaesar 04:26, 24 September 2005 (UTC)
The same guy did it again, anonymously. I found grammar and spelling erorrs, plus even more POV information. Whoever you are, please provide citations for your quotes. Also, please consider working on it over here in the Discussion page before you post it. Thanks, Novasource 02:15, 26 September 2005 (UTC)
What you are doing here, Novasource, is not good at all. You have deleted article content together with supported references, including The UK Transport Research Laboratories. In your edit comment, you are describing it as spam.
Furthermore, the impression I get from reading the page as is, is that it is has a degree of POV, toning down the importance of speed as a problem. See especially the Safety and Enforcement sections, as well as the External links (which begins with two links to Association of British Drivers, which is highly POV). Novasource actions maintains that POV. The content added by this anon seems to be valid counterpoints to what was claimed in the article. The claims were, at least for the most part, supported by the references that Novasource deleted. The amount of grammar and spelling errors, were certainly not enough to exclude this content. -- Egil 06:54, 26 September 2005 (UTC)
I added an introduction to safety that aims to be more NPOV, and also summarize findings of various studies. I also removed much of the Isle of Man material. There seems to be a conflict between the income brought to the island due to 'speed tourism' and the problem with road safety, but more references are required to cover it properly. -- Egil 08:08, 26 September 2005 (UTC)