Talk:Speed limit/Archive 1

message: 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)
replies: text: 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)
replies: text: 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)
replies: text: That sounds like a great idea. Could you start the article? Novasource 14:05, 11 August 2005 (UTC)
thread_title:  Crash vs. Accident 

message: 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)
replies: text: First thing to do is to throw "kph" out of your vocabulary.  Gene Nygaard 01:48, 21 Jan 2005 (UTC)
replies: text: Why? Its perfectly understandable, and serves as a link to the correct article: Kph. Seabhcán 12:03, 21 Jan 2005 (UTC)
replies: text: 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)

text: 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)
replies: text: 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)

text: 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)

text: 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)

text: 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)
replies: text: I'm happy with replacing all "kph" with "km/h". Seabhcán 17:04, 21 Jan 2005 (UTC)
thread_title: Proposed reorganisation of article

message: 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 v_0 over a distance d at a constant acceleration a.  From basic mechanics,
x=at^2 + v_0 t (taking x(t=0) = 0).  Now, the end-state occurs when v=0, also at which time x=d.  This is when v_0 = at_{final}, or t_{final}=v_0/a.  Substituting, we have d=at_{final}^2 + v_0 t_{final}, or d=a(v_0/a)^2 + v_0(v_0/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)
thread_title:  "Forces increase exponentially" 

message: <<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)
thread_title: 85th Percentile Speed

message: 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)
thread_title:  American vs. British English 

message: I live in Utah, and it seems like everyone goes exactly 9 mph over the speed limit, no matter what kind of road. the only exception are school zones when the lights are flashing. and whats more, the cops never pull anyone over, and in fact they usually go 9 over. so if thte limit is 55, more than half of the people on the road go 64, and the police could care less. but go 10 over, and they are on your case so fast. you don't fail your driving test in utah if you go + or - 9 mph, but go + or - 10 over, and you'll fail. i think the police follow that principle or something. what do you think? Vandalism destroyer (talk) 05:49, 9 April 2008 (UTC)
thread_title:  Utah 

message: Amazing that the same sign is used for km/h and mph. - Patrick 10:38 18 Jun 2003 (UTC)
: I always thought they use a round sign with a red border for km/h, and a rectangular white sign with a black border and black lettering for mph. 64.50.192.206 14:12, 31 July 2005 (UTC)
replies: text:  The white circle with red border and black text seems to be standard, for both miles/hour and km/hour.  Rather confusing as you say, albeit slightly less so than having to drive on the wrong side of the road ;)  Ojw 18:45, 16 October 2005 (UTC)
thread_title:  Same sign for kmh and mph 

message: One time a police officer in our area said that he stopped an older man for going 28mph on the interstate when the limit at the time was 55mph.  He said that was an accident waiting to happen, that someone going the limit would have come upon him and been unable to slow down or move aside in time.
JesseG 02:34, Nov 20, 2004 (UTC)
: Apparently, driving slower than average traffic speed is just as dangerous as driving faster than the average traffic speed (relative speeds, etc.) and I wouldn't be surprised if it was common to pull over drivers who are at the posted limit.
: It's certainly bloody scary to be driving at the 50mph speed limit (through some motorway roadworks) while everyone else is doing 75/80mph on both sides of you... Ojw 18:45, 16 October 2005 (UTC)
replies: text: IIRC, it's forbidden to drive slower than 30 km/h on motorways in Sweden. Also, the wikipedia article on Hsuehshan Tunnel claims there's a formal lower speed limit of 50 km/h there. Perhaps the article should contain a separate section on lower speed limits? --213.50.52.226 17:23, 4 December 2006 (UTC)
thread_title:  Driving too slow 

message: I think we should move the speed limit stuff off of Interstate Highways and to speed limit. If you compare the two, you'll see that speed limit is far more thorough, covers more road types, and is more accurate. Given that speed limits are by far the most pervasive and probably the most contraversial road regulation, I think we are best served by keeping the speed limit info on its own page.
I suggest linking to the United States anchor on speed limit.
Novasource 16:29, 6 October 2005 (UTC)
thread_title:  Moving Interstate Highways Speed Limit content to here 

message: Is there an article for variable speed limit that we should link to? If not, it's worth noting that the UK has them (first one was M25 I think, which lowers its speed limit to keep the traffic moving rather than start-stop). Ojw 18:45, 16 October 2005 (UTC)
thread_title: Variable speed limits

message: I have moved several statements that need more references to this page. I could not find documentation backing them up.
=== Opposition ===
However, it is noted that the Autobahns have twice the fatality
rate of Britain's (speed limited) motorways, and that increasingly
Autobahn speeds are being limited.

I cannot find any clear documentation of this statement.
* It's in IRTAD. - Just zis Guy, you know? [T]/[C] :: AfD? 19:06, 5 November 2005 (UTC)
replies: text:  Thanks for the updates. I look forward to these statements being re-introduced to the main text once they are referenced. Novasource 03:04, 7 November 2005 (UTC)
replies: text: Examples: a survey of British drivers found that 40% rated the overall standard of driving as bad, but only 2% rated their own driving as bad; 24% rated the overall standard as goo, 75% rated themselves good (Lex Motoring Plc, 1989); A survey of motorway drivers found that, on a scale of 1 (poor) to 5 (good) drivers rated themselves at an average 3.9, and rated other drivers at a mean 2.7 (Gallup for General Accident Insurance, 1989); see also McCormick I, et. al., "Comparitive perceptions of driver ability - a confirmaiton and expansion" Accident Analysis and Prevention, Vol. 18 no. 6, 1986 (these are from the refs in a 1989 book).  According to Davis, the tendency of drivers to see themselves as better than other drivers is one of the most stable features of informed debate on road safety. - Just zis  Guy, you know? [T]/[C] (W) AfD? 22:18, 8 December 2005 (UTC)
thread_title:  Statements that need references 

message: However, it is noted that the Autobahns have twice the fatality
rate of Britain's (speed limited) motorways, and that increasingly
Autobahn speeds are being limited.

I cannot find any clear documentation of this statement.
* It's in IRTAD. - Just zis Guy, you know? [T]/[C] :: AfD? 19:06, 5 November 2005 (UTC)
thread_title:  Opposition 

message: (text about increasing or lowering speed limits)...sometimes by
(perversely) reducing average speeds: drivers are more willing
to obey a limit they see as "reasonable" (although it should be
noted that there is solid evidence that most drivers overestimate
their own skill).
Needs documentation.
Novasource 18:22, 5 November 2005 (UTC)
replies: text:  Thanks for the updates. I look forward to these statements being re-introduced to the main text once they are referenced. Novasource 03:04, 7 November 2005 (UTC)
replies: text: Examples: a survey of British drivers found that 40% rated the overall standard of driving as bad, but only 2% rated their own driving as bad; 24% rated the overall standard as goo, 75% rated themselves good (Lex Motoring Plc, 1989); A survey of motorway drivers found that, on a scale of 1 (poor) to 5 (good) drivers rated themselves at an average 3.9, and rated other drivers at a mean 2.7 (Gallup for General Accident Insurance, 1989); see also McCormick I, et. al., "Comparitive perceptions of driver ability - a confirmaiton and expansion" Accident Analysis and Prevention, Vol. 18 no. 6, 1986 (these are from the refs in a 1989 book).  According to Davis, the tendency of drivers to see themselves as better than other drivers is one of the most stable features of informed debate on road safety. - Just zis  Guy, you know? [T]/[C] (W) AfD? 22:18, 8 December 2005 (UTC)
thread_title: Safety

message: This article (like so many in Wikipedia), while interesting, omits any context of why & how speed limits developed... For instance, Br's Ref Flag Law, or New York's first limit, 1904...?  Trekphiler 10:42, 16 December 2005 (UTC)
replies: text: Hey, thanks for volunteering to create a history section! :-) Novasource 03:58, 17 December 2005 (UTC)
thread_title: History?

message: According to the Shell Book of Firsts. The first speed limit in the UK and was 2 mph in the country or towns under the Locomotives and Highways Act on th 5th July 1865
I concur with Senior Moments. In Britain The Locomotives on the Highways Act 1865 imposed a limit of 2 m.p.h. in towns and 4 m.ph. in the country. It also required motor vehicles to be preceded by a runner carrying a red flag which is why it was known as 'The Red Flag Act'. The law was repealed in 1896 when a new urban speed limit of 12 m.p.h was introduced with 14 m.p.h for the country. This was further revised in 1903 when the limit became 20 m.p.h. 
*1904 -- The maximum speed limit in most cities was 10 mph.
http://www.ci.nyc.ny.us/html/nypd/html/transportation/newpage5.html
http://www.iihs.org/research/qanda/speed_limits.html#12
*14th November, 1896, Motorcar speed limit raised from 4mph to 14mph
The Locomotive and Highways Act 1896 was the first improvement in motoring laws to encourage motor vehicles. It lifted the retrictions set by the 1865 act and the then famous 'man with a red flag' who would walk 60 yards ahead of each vehicle, enforcing a walking pace of between 2 and 4mph.
==== Ohio ====
 1908 -- The first speed limit was 20 mph outside municipalities, 8 mph inside municipalities
 1926 -- 35 mph
 1940 -- 45 mph
 1941 -- 50 mph
 12/1/42 -- Gas rationing and a 35 mph speed limit on all roads that had been in effect along the 
  East Coast for 7 months was extended nationally to conserve gasoline and rubber during
  World War II
 8/15/45 -- 50 mph speed limit reinstated
 1958 -- 60 mph daytime, 50 mph speed limit at night
 1963 -- 70 mph for cars and 55 mph for trucks and commercial tractors on interstates;
  60 mph daytime and 50 nighttime on noninterstates
 1974 -- 55 mph for all vehicles on interstates and most other highways
 1987 -- 65 mph for cars on 900 miles of rural interstates, 55 mph for commercial vehicles weighing
  more than 8,000 lbs.
 1991 -- 65 mph for cars on another 246 miles of interstates
 1992 -- 65 mph on 209 miles of rural noninterstates
 1996 -- Speed limits raised to 65 mph on designated urban interstates and rural highways for
  passenger vehicles and commercial buses
Source: Ohio Historical Society
Gam3 17:44, 26 February 2006 (UTC)
thread_title: notes

message: 1908 -- The first speed limit was 20 mph outside municipalities, 8 mph inside municipalities
 1926 -- 35 mph
 1940 -- 45 mph
 1941 -- 50 mph
 12/1/42 -- Gas rationing and a 35 mph speed limit on all roads that had been in effect along the 
  East Coast for 7 months was extended nationally to conserve gasoline and rubber during
  World War II
 8/15/45 -- 50 mph speed limit reinstated
 1958 -- 60 mph daytime, 50 mph speed limit at night
 1963 -- 70 mph for cars and 55 mph for trucks and commercial tractors on interstates;
  60 mph daytime and 50 nighttime on noninterstates
 1974 -- 55 mph for all vehicles on interstates and most other highways
 1987 -- 65 mph for cars on 900 miles of rural interstates, 55 mph for commercial vehicles weighing
  more than 8,000 lbs.
 1991 -- 65 mph for cars on another 246 miles of interstates
 1992 -- 65 mph on 209 miles of rural noninterstates
 1996 -- Speed limits raised to 65 mph on designated urban interstates and rural highways for
  passenger vehicles and commercial buses
Source: Ohio Historical Society
Gam3 17:44, 26 February 2006 (UTC)
thread_title:  Ohio 

message: I removed the two pictures of a road in Texas.  We have far too much about Texas in this article (Texas is not the world!) and the captions were POV and they could as OR since no verifiable evidence is presented that either picture was representative of the general conditions at either time.  On the M25 in the UK use of variable speed limits has substantially improved traffic flow by slowing traffic at times of high volume.
:I am moving United States content to a different article. Novasource 16:01, 24 December 2005 (UTC)
thread_title: Pictures removed

message: I have moved the US Speed Limit information to Speed limits in United States. It is clear that US speed considerations were dominating the article, and it is also clear that US practices are much different than in other countries, causing unnecessary contentious disucssions.
In the move, I removed the following statement due to the fact that it are no longer relevant in a US-only article:
:In the UK, on non-motorway dual carriageways trucks are limited to 50mph and cars to 70mph.  On motorways cars are subject to 70mph limits on and trucks are limited to 60mph by law (and often 56mph by mechanical governor).
Novasource 16:19, 24 December 2005 (UTC)
replies: text: This is probably reasonable. What is important is that the discussion of libertarian opposition to speed limits does not overwhelm the balance of the article. Per policy, Wikipedia documents the balance of informed opinon.  The balance of informed opinion on speed limits is that they are necessary. - Just zis  Guy, you know? [T]/[C] AfD? 16:48, 24 December 2005 (UTC)
thread_title: Separate article for US speed limits

message: I appreciate the information added to Essential Physics about motorways, but I am concerned about it for a few reasons:
*It duplicates content already on road safety. This setup can cause concurrency problems: if the motorways information on road safety is edited, then who guarantees that the same content on speed limit is edited, and vice versa?
*It is not 100% related to speed limits. The study of motorways is one that involves many disciplines, and vehicle speed regulations are just one of these disciplines.
I think it may be better to have a quick summary that wiki-links over to the Road Design section of Road Safety rather than to copy everything.
Novasource 19:38, 24 January 2006 (UTC)
thread_title:  Motorways section of Essential Physics 

message: Is it possible to get a different photo for this section or failing that just remove the manipulated one that is currently in the article? I think that a  has no place here. Softgrow 11:44, 16 February 2006 (UTC)
replies: text: I agree. I removed it. :-) Now why don't you create your own true 140 MPH photo? Nova SS 15:39, 16 February 2006 (UTC)
thread_title: Roads without speed limits photo