How Should Speed Limits Be Set?
February 29th, 2008 Posted in Bonnie Sesolak, Speed LimitsBy Bonnie Sesolak, NMA Development Director
“Realistic” speed limits should invite public compliance by conforming to the behavior of normal responsible drivers. This results in the safest and most efficient use of streets, roads, and highways.
Traffic engineering research has determined that speed limits should be established according to the 85th percentile of free flowing traffic. This means the limit should be set at a speed that 85 percent of people are driving at or below.
Numerous studies have shown that the 85th percentile is the safest possible speed limit. It recognizes that most drivers voluntarily adjust their speed to the total roadway/roadside environment (width, alignment, surface condition, roadside development, pedestrian activity, weather, light conditions).
It is not appropriate to set a limit below the 85th percentile to accommodate factors that are obvious to road users. Drivers are already taking these factors into account with their existing speed decisions.
Main Factors Used to Set Speed Limits:
Engineering Study
Speed zones are established on the basis of an engineering study. The engineering study includes an analysis of the current speed distribution of free- flowing vehicles.
85th percentile speed
The speed at or below which 85 percent of the sample of free flowing vehicles are traveling. This speed should be determined by conducting a speed survey following the procedure contained in the Manual of Transportation Engineering Studies.
Advisory speed limits
These should be implemented when certain features, such as sharp corners, require a momentary reduction of speed.
Additional Notes:
Each speed zone should be periodically restudied to determine that the established speed limit is appropriate. The suggested maximum interval is five years.
In addition, an engineering study should be conducted whenever there is a change in the roadway that would affect the prevailing speed. Such changes would include elimination of parking, added lanes, signal coordination and changes in roadside development.
According to an Institute of Transportation Engineers Study, those driving 10 mph slower than the prevailing speed are six times as likely to be involved in an accident.
For more information, studies, and articles on speed limits, visit the speed limit section of the NMA’s website.
Other Related Articles
Tennessee Supreme Court says speed limits not valid without traffic engineering survey
http://piratenews.org/OakRidge-v-speed-limit-OPN.pdf
Pastor Rick Strawcutter preaches How Any Idiot Can Beat a Radar Speeding Ticket in Michigan
http://video.google.com/videoplay?docid=-5186628884102899588&hl=en
download ASAP since Google Video is banning and deleting all videos in 6 months
http://piratenews-tv.blogspot.com/2009/04/case-of-censored-videos.html
Schwinn writes((As for me doing my job as poorly as I interpreted the study, I’ll have you know that I am still rather gainfully employed, and doing a pretty good job at my R&D engineering work in the high-tech industry. The R&D job supports my knowledge and scientific reasoning ability every day, as I couldn’t possibly succeed without those skills.))
Phil replies((I find this rather surprising considering the conclusion I reached was the same as a possible conclusion the author of the study mentioned. That this possible conclusion doesn’t support your agenda as an NMA member doesn’t negate it as possible.))
Schwinn asks((What is it that you do, then?))
Phil replies((You should have assertained this prior to acting like such an ass. Maybe you’d have had a little more respect for my opinion. However since you already hold contempt for my opinion what my occupation is holds no relevance to our conversation.))
First off, the NMA offers no “classes” or specific “training” for my stance. My stance is based on reading, science, and whatever info I can find.
First off, you conclusions simply make no sense. As the study states very clearly, “Changes in the measured average travel speeds in the 65 MPH zones were found to experience nominal differences compared to prior 65 MPH conditions, as some locations increased and some decreased, generally less than 2 mph.” In other words, even though the posting was 65MPH, the speeds generally remained the same. In fact, they even said “The change to the 65 MPH speed limit during the study period had minimal impact on actual travel speeds.”
If travel speeds changed oh-so-minimally, then how come there were suddenly more accidents and fatalities?
I have no problem dealing with insults from you… I can take it.
As for me doing my job as poorly as I interpreted the study, I’ll have you know that I am still rather gainfully employed, and doing a pretty good job at my R&D engineering work in the high-tech industry. The R&D job supports my knowledge and scientific reasoning ability every day, as I couldn’t possibly succeed without those skills.
What is it that you do, then?
I would say that the answer to your question “If travel speeds changed oh-so-minimally, then how come there were suddenly more accidents and fatalities?” lies within this portion of the text:
((Some roadway sections in the 65 MPH zones appear to be very favorable for the 65 MPH speed limit; however, with other roadways, the information is mixed. The data is not conclusive. Therefore, it is recommended that any conclusive long-term decisions on the 65 MPH speed limit cannot be made at this time. Rather, it is recommended to extend the study period another 18 months, in order to perform a more detailed analysis that is completed in a time frame more acceptable for professional practice in the area of transportation safety))
This passage implies that my conclusions are correct more crashes with more injuries is a reason to recomend that the study be extended before a conclusive long-term decision on the 65mph speed limit be made. It was expected that all the sections of roadway would react favorably to the 65mph speed limit but because not all the roadways reacted favorably to the speed limit increase further study needs to be done before a conclusion can be reached.
Or maybe this passage would be easier for you to comprehend “As noted previously, accident rates fluctuate over time. In periods between 1984 and 1996, rates vary as much as 12 percent per year. The study captured data for a fixed 18-month period. Accordingly, it is not possible to determine whether the increase in accidents in 65 MPH zones represents a normal fluctuation in accident rates OR suggests that increased speed contributes to increased accidents.”<——–(READ THIS VERY SLOWLY TO FULLY COMPREHEND IT)
Did you not read that far down the study or were you intentionally misdirecting us?
Phil writes((You interpret the study to say one thing while I see something else. You can say that is a lack of scientific priciples and reading comprehension on my part and I can say you are interpreting the data incorrectly. what does any of it prove? That you are a brainwashed NMA member who will lie to further the NMA agenda while I remain objective as a non NMA member.))
Schwinn writes((This is called science and engineering. It’s a concept lost on many people, and only taught in limited fashion in high schools, unfortunately. As an engineer, I do this type of proper testing all the time, so I’m very familiar with it.))
If you do your job as poorly as you interpreted that study then you must be homeless and hungry.
The 12.0 in 65mph compared to the 12.9 in ADJACENT 55mph zones was pointed out and implied that there was spillover from the 65mph zones onto the 55mph adjacent zones. The control group was the portions of highway PRIOR to the 65mph increase both the portions that were raised and the portions adjacent that remained 55mph. To compare the 12.0 increase in crashes in zones that were raised to 65mph to the adjacent zones that remained at 55mph and suffered a 12.9% increase in crashes in an attempt to make it appear as if the portions that were raised to 65mph would have suffered an additional .9% increase if the had remained as a 55mph zone is intellectually dishonest. I will not concede that you have sucessfully made a point because your assertions are a farce.
quote from study “Notably, accidents on sections of highways with 65 MPH speed limits increased 18.3 percent. Accidents with injuries increased by 9.4 percent, and the total number of people injured increased by 5.9 percent from a comparable time period.”
Phil writes((CFrom a comparable time period (this is known as a control group) when compared to the control group of a similar time period prior to the increase in speed limits 18.3% more crashes 9.4% more crashes with injuries and 5.9% more people suffering injuries nwere experienced.
Of course if you want to concede the point that after the increase to 65mph there were more crashes that injured more people I’d be willing to move on to your next misinterpretation if that is your wishes.))
Side note: Insulting me will gain you no respect and only be met with insults from me aimed at you. We can disagree on the material without any personal insults being exchanged. Does the NMA give classes on how to try and intimidate anyone who has a view that differs from the NMA because every one of you NMA Idiots I have tried to have a discussion with ends up trying the same Dumbass tactics of insulting me, my education and my understanding of the principles. I don’t expect you to agree with me nor should you expect me to agree totally with you. That being said there is no reason we can’t discuss the issue without you making it a win/lose debate.
So, your true lack of scientific principles and reading is showing much more clearly now. Now I can understand why you aren’t getting it.
The 12.0/12.9 matter: Scientifically speaking, the 12.0 increase in the “data” group of 65MPH zones is telling, but to do any proper scientific study, you must have a control group to compare it to. The idea being that since every study has variation from time to time, the control group can pretty reasonably account for any such variation in the data. By this metric, the 12.0/12.9 are showing that the data is relatively comparable, and that even if you do nothing, the accident rate increased by 12.9%, as per the control group… due to other uncontrolled variables. Therefore, the 12.0% increase on the 65MPH zone is showing no significant deviation from the control. In other words, the one thing “changed” between the two zones (65 vs 55) shows no significant effect on accident rates.
This is called science and engineering. It’s a concept lost on many people, and only taught in limited fashion in high schools, unfortunately. As an engineer, I do this type of proper testing all the time, so I’m very familiar with it.
Notice I have not mentioned the NMA or anything here… because its basic science and experimentation. The NMA doesn’t have to “twist” numbers in any way here, because this is how real engineering is done. Everything else is BS and misdirection. If you don’t have a control group in your study, a lot of questions can arise making the “study” relatively moot.
Before I continue on your other ranting, can we at least consider this point made? I don’t want to go off on any more tangents with this matter until we solve each and every point you wish to contest… you seem to lose track of the information I am providing too easily. I’m happy to continue onto the next point as soon as this one is clear.
Schwinn says((have read many papers from the NMA and other sites. To date, all of the other misinformation has been just that – improper conclusions.))
Phil replies(This says it all! papers from the NMA and other sites(likely other sites that the NMA has linked you to). There are so many studies out there concerning so many aspects of speed limits and safety yet the only 1 that you believe is the one that the NMA tells you to believe, all the others are “misinformation” and contain “improper conclusions”)
Like the good little follower of the NMA you seem to like to lie with the science. The study says one thing but you twist it and interpret it to say something entirely different.
Schwinn writes((that the accidents in the 55 zone increased by 12.9%, while those in the 65 zone increased by 12%… that’s a net DECREASE if you know how to read the data scientifically.))
Phil replies((I have to laugh at this because it shows just how brainwashed you are by the NMA. If I get what you are trying to say it is that because the 55mph zones experienced a 12.9% increase then the increased speed limits experiencing only a 12% increase is actually a .9% decrease? Does the NMA give classes on how to manipulate and twist data like that?
quote from the article((An analysis of certain 65 MPH zones and ADJACENT 55 MPH zones were made for comparison basis with accidents from the 12-month period before 65 MPH was implemented, to the 12-month period after 65 MPH was implemented. The highways analyzed were I-78, I-80 and I-287. The findings showed that accidents increased in the 65 MPH zones by 12.0%, and increased in the 55 MPH zones by 12.9%.))[emphasis added]
Phil replies((Note I emphasized the word adjacent. The word adjacent is there not because they were comparing the 12.9% and 12% respectively but because they were showing a causual link of spill over of the increased 65mph limits onto ADJACENT 55mph highways. Therefore my conclusion was correct that they did increase 12% and 12.9% respectively. Understadably Accident rates fluctuate over time. In periods between 1984 and 1996, rates vary as much as 12 percent per year. The word flucuation implies both increases and decreases and also it says it would be impossible to distinguish if the 12 and 12.9% were part of that normal fluctation. best case scenario is an even in 65mph zones and a .9% increase in the 55mph zones. worst case scenario is 12% increase in the 65mph zones and 12.9% in the adjacent 55mph zones. in actuality the scenario is propably somewhere in between. Which BTW Equates to a net increase. ))
Phil writes((Oh yeah you must have missed the portion where it said “An analysis of CERTAIN 65 MPH zones and adjacent 55 MPH zones were made for comparison basis with accidents from the 12-month period before 65 MPH was implemented, to the 12-month period after 65 MPH was implemented.” NOTE it says CERTAIN not ALL so it would be a moot point for you to suggest that an overall increase wasn’t present given studywide roadways that recieved the increased sped limit yielded an 18.3% increase in crashes. That would be some 6.3%-18.3% above the normal fluctuation.))
Schwinn writes((As for the severity issue, you’ll note the study showed a DECREASE in fatal accidents as well… making that entire paragraph of yours rather moot.))
Phil replies((You are joking right? You can’t be that ignorant and be an engineer too. Fatal injuries can’t happen without injury. “Accidents with injuries increased by 9.4 percent, and the total number of people injured increased by 5.9 percent from a comparable time period.” fortunately there were fewer life threatening injuries. “It should be noted, however, that fatal accidents comprise less than one percent of all reported accidents and may not be a statistically relevant indicator of safety.”))
Phil replies((Studywide results “Notably, accidents on sections of highways with 65 MPH speed limits increased 18.3 percent.Accidents with injuries increased by 9.4 percent, and the total number of people injured increased by 5.9 percent from a comparable time period.” This tells us there were more crashes and more people were injured in those crashes no matter how you try to twist it.))
schwinn writes((The only choice I am making is to not waste any more time with your empty data sets. If you have read the data, you must have it… if you have it, why do you refuse to show your work?))
I want to see how long you’ll hang your hat on the “why are you affraid to show me” BS if you are still suggesting that in 6 months I’ll show you what I have. However we both know that to be your red herring. You know those studies say exactly what I posted from the summary of each but being a member of the NMA knowing you can’t discredit those studies you ignore them. When they are brought up you discredit the messenger because most aren’t as educated as you pretend to be. If all you have is I won’t show my copy of a study your position is already weak. I too have been down the road where some anonymous person doubts everything you offer and keeps asking for more information. I made a statement you said it was incorrect but can’t prove it incorrect so you are trying to waste my time here. I gave you the study authors and dates published if you REFUSE to view the material it is on you not me. We have already seen that if you had the study in hand you’d interpret it incorrectly anyway so why are you here? Run along and remain ignorant as long as you want. I gave you the tools to expand your mind but I can’t force you to use them.
I have read many papers from the NMA and other sites. To date, all of the other misinformation has been just that – improper conclusions.
Once again, you aren’t reading me right. Your right, I don’t want to research everything all over again… because every time I do, I find that the NMA’s statements hold water, while the other data is misunderstood or misinterpreted.
Anytime ANYONE contradicts the NMA’s stance, they spew forth supposed data, but never actually reference it… so I have to go off and research it all again. Why is that? I mean, if the other person claims to have studies that prove their point, then why are they never provided?
I already posted one link of a source which contradicts your statements, and you still don’t seem to want to rebut it directly… instead, you want me to go off on a research expedition for data you supposedly have already read… yet refuse to show.
You say you read the 18-month study I posted, yet you seem to be missing the text. You state that there were “more crashes”… yet the study says “The findings showed that accidents increased in the 65 MPH zones by 12.0%, and increased in the 55 MPH zones by 12.9%. Accident rates fluctuate over time. In periods between 1984 and 1996, rates vary as much as 12 percent per year. The study captured data for a fixed 18-month period. Accordingly, it is not possible to determine whether the increase in accidents in 65 MPH zones represents a normal fluctuation in accident rates or suggests that increased speed contributes to increased accidents.”
In other words, your statement of them increasing is an improper conclusion. If anything, you can say there was no difference, but making a statement of INCREASE is a lie, at best, since even the study says it’s likely not statistically significant… but even still, that the accidents in the 55 zone increased by 12.9%, while those in the 65 zone increased by 12%… that’s a net DECREASE if you know how to read the data scientifically.
As for the severity issue, you’ll note the study showed a DECREASE in fatal accidents as well… making that entire paragraph of yours rather moot.
The only choice I am making is to not waste any more time with your empty data sets. If you have read the data, you must have it… if you have it, why do you refuse to show your work?
You have really started to show the true color of your wool..
Let’s examine what you have told us:
You just told us you don’t have the time, inclination, or see the fruitfulness of this debate. You don’t have the time to look up all the material and websites that contradict what I offered.
You haven’t looked up anything, researched anything, or tried to find the entire truth about what you have been commenting on, You read what the N.M.A. wrote here and you RAN with it.
You haven’t looked up anything because you don’t have the inclination to, You haven’t studied any reports because you don’t have the time.
You’ve just exhibited exactly what I was talking about, not doing any research for yourself…just following blindly like a sheep.
Thing is if you posted anything as far as a list of sources that contradict what I am saying I’d do the research and find them so that I can disprove your assertions. If the evidence was compelling enough it may alter my opinion.
Yes you did link to an 18 Month Study Report on 65 MPH Speed Limit in New Jersey done by the New Jersey Department of transportation. I read it and formed a conclusion to what the EVIDENCE said. It tells me that the change from 55-65mph created a driving enviroment where more crashes happened and more people in those crashes were injured but fortunately those injuries included fewer life threatening injuries. It is evidence that the raise from 55mph to 65mph in New Jersey had a negative result on traffic safety.
When I brought forth the severity issue, you did as any good little NMA member would do and say it really isn’t an issue if you decrease the number of crashes so too you decrease the number of injuries and fatalities. Unless you eliminate the possibility of crash entirely severity of the existing crashes is an issue. Since you can’t eliminate crashes entirely the severity of the crashes must be considered. To say that severity isn’t an issue is a complete lie. It is possible to have 1/2 as many crashes all with increased severity and end up with 1/2 the number of actual crashes but twice the number of injuries or fatalities. As witnessed in the EVIDENCE you supplied, raising the speed limit doesn’t always accomplish fewer crashes.
(In fact in that case:
” Fatal accidents in 65 MPH zones have decreased since the implementation of the 65 MPH speed limit. There were ten fewer deaths, representing a 9.6 percent decrease, on the sections of highway that now have the 65 MPH speed limit and seven fewer fatal accidents, representing a 7.9 percent decrease, than on those sections of highway for a comparable time period. It should be noted, however, that fatal accidents comprise LESS THAN ONE PERCENT of all reported accidents and MAY NOT BE a statistically RELEVANT indicator of safety.
Notably, accidents on sections of highways with 65 MPH speed limits INCREASED 18.3 percent. Accidents with injuries INCREASED by 9.4 percent, and the total number of people injured INCREASED by 5.9 percent from a comparable time period. An analysis of certain 65 MPH zones and adjacent 55 MPH zones were made for comparison basis with accidents from the 12-month period before 65 MPH was implemented, to the 12-month period after 65 MPH was implemented. The highways analyzed were I-78, I-80 and I-287. The findings showed that accidents INCREASED in the 65 MPH zones by 12.0%, and INCREASED in the 55 MPH zones by 12.9%.”)
It is a choice you are making that you will not view any of the evidence that I supplied in a nice neat list for you to refer to. so for your reference to data that supports my opinion simply reread the evidence that you supplied a link to and then refer to the list of studies I supplied and see how many of them have similar results of increased crashes, injuries, or deaths resulting from higher posted speed limits. If you choose to NOT view those studies that is on you not me I have already discredited your argument using your own evidence. Anything further from you without viewing those studies is a blatant waste of both our time, so you may as well use that time to view a study or two.
Well, as far as I’m concerned, you don’t have any evidence… you’ve mentioned a few studies, but then refuse to provide any links, meaning we have to do the research on it all over again (if you read the articles, why don’t you have copies of them?)
I can post up a bunch of “evidence” in that manner, but it’s not evidence… it’s heresay.
You say, I didn’t provide data, yet I linked you DIRECTLY to the NJ DOT report… you haven’t provided a single similar reference.
It’s not that I don’t choose to look it up… it’s just that, in the past, I’ve been vindicated with improper conclusions from the study, and then met with silence. I have better things to do than convince someone on the internet of their misunderstandings AGAIN. I am confident that I’m right, yet (as an engineer) I’ll always objectively assess an opposing point… if there is enough detail to determine that the data is valid.
So, bottom line – I provided a DIRECT linked reference to a study that proves my point. Once again, to date, you have not provided a single direct-reference to any thing supporting your point… the ball is in your court.
I really don’t care if you are objective or not. The abusiveness of NMA members towards someone who is supportive of higher speed limits but doesn’t fall 100% in line with the thoughts one MUST have to be a true supporter is astonishing. If you want to consider the NMAs stance valid and true that is fine with me, I know differently. You came at me after I posted calling me an Idiot and saying I had no evidence. I replied with a comprehensive list of evidence now you want me to find sources of this evidence online and provide you a link for your convenient viewing. You haven’t provided me with links to full text and raw data supportive of your opinion(you haven’t even listed your sources)but expect me to spoon feed all that I have read on this subject and used to develope my opinion to you so you can say you don’t care what my studies say and I would have wasted my valuable time. I too have been around the block with this issue. If you choose to not view evidence that may alter your opinion I really could careless but don’t expect that your criticisms of my position will be taken lightly with respect to that choice.
Well, if you can’t provide the info, then I really don’t have the time to spare to dig it up – two jobs, plenty of projects… it’s getting out of hand. I realize this isn’t a very good excuse, but if you can’t provide the references (obviously you have read them, so you must have them) then I can’t waste my time digging them up. Of course, this also means that I will consider the NMA’s stance valid and true, since no one has ever provided me references for their data… it seems to be a pattern of people. I used to go through and dig up the info, but I’m just too tired to bother to try to convince one person every time…
So, the ball is in your court… if you truly want me to be objective about this, then I need the data. Otherwise, you can carry on with your belief, and I will carry on with mine which I have proven with references… as far as I am concerned, I’m still in the clear with my statements…
Well one of your NMA buddys has made it abundently clear his opinion of me. I could provide it but I am not feeling very generous to the NMA at this point. You seem Intelligent enough to research for yourself and I would only like to impose on you believe very little that the NMA tells you, even if it is a so called unrefuted fact.
Good response… still need some data references. I figure, if you know where the data came from, then it should be easy enough for you to provide it…
Normally I would agree with you that maybe the limits are outdated and need updating… but that’s really not the case most of the time. We know for a fact that speed traps exist, and that ticketing rates increase when money is low, or when the quota says they must… proving again that it’s not about safety… and it’s about money. Sure, maybe these are the “bad apples” in the bunch, but I know here in MA on route 128, the speed limits are well below 85% levels… which automatically makes them illegal… yet they won’t bother to fix them. In fact, in the past, I recall an article which said that MA decided (on their own) that they weren’t subject to the federal MUTCD… so they could do whatever they want. How’s that for ignoring science?
The NMA is continuosly ignoring science. If you don’t believe me then ask someone about the severity of crash issue. As an engineer I am sure you are very familiar with Kinetic Energy. After asking about the severity of crash issue ask them about Ke=1/2M(v)squared. and you’ll see just how much the NMA feels science should be used.
The kinetic energy discussion is moot if one scenario reduces accidents (ie, no KE to be determined).
As for ignoring science, who’s the one ignoring it when the MUTCD (a government body, no less) which uses scientific principles, states that the 85% speed should be used in numerous cases (including speed limit setting)… yet the states refuse to do this?
Prove to me this is the case… with references.
Schwinn writes((Thank you for FINALLY posting some data to look at… note that this is the FIRST time you have posted such information… until now, we were just supposed to take your word for it.))
Phil Writes(I have offered all the same information on other threads and get tired of spoonfeeding information to people most of which have no intent on reading anu of it anyway, They just want me to provide proof)
Schwinn writes((The problem with your data is that we don’t know anything about the surrounding situations with each of these stories. You haven’t linked up any reference documents for me to look at, so I have to go and research each and every one individually, assuming I can even find them.))
Phil replies(My posting here is an attempt to get people to do just that and NOT take the NMA at it’s word because I have found a wealth of disinformation and misinformation filling thier site.)
Schwinn writes((What’s more, the current discussion is based on the 85% speed guideline, which you have constantly opposed… so the data you provide is largely irrelevant unless we are told what the 85% speed was on each of them, relative to the posted speed. Of course, the assumption here is that these are straight and clear highways, without any specific reason to reduce speed in that area… again stuff we don’t know. Heck, none of these references even list a single roadway to reference!))
Phil replies(Sort of like the NMA referencing the Parker report. Sure they link to the alleged text posted on the NMAs old site which appears to be entered by hand and is missing all the attached documents, data panels and figures but we are to simply take the NMA at it’s word that this is an accurate depiction of the text from the document and believe them when they tell us what the data panels show and the figures show because we can’t view them for ourselves.)
Schwinn writes((So, while I applaud you for being the first person I have ever seen here with SOMETHING to show for evidence, I’d like more information. To simplify, can you at least point me to the USA study references? I would be happy to read them and see what they say…))
Schwinn writes((Keep in mind, NO ONE here says that raising speed limits EVERYWHERE is the answer… the fact is that most speed limits today are below the 85% for no good reason… and therein lies our complaint.))
Phil replies(On the contrary James Young and an article I read on another thread implys not only that nationwide speed limits are severely under posted but also that they are under posted purposefully for revenue gathering purposes. 1 Good reason I can think of is they are simply outdated and need to be adjusted to meet up with our current technology.)
Phil writes( What did you think of my rebuttal?)
Thank you for FINALLY posting some data to look at… note that this is the FIRST time you have posted such information… until now, we were just supposed to take your word for it.
The problem with your data is that we don’t know anything about the surrounding situations with each of these stories. You haven’t linked up any reference documents for me to look at, so I have to go and research each and every one individually, assuming I can even find them.
What’s more, the current discussion is based on the 85% speed guideline, which you have constantly opposed… so the data you provide is largely irrelevant unless we are told what the 85% speed was on each of them, relative to the posted speed. Of course, the assumption here is that these are straight and clear highways, without any specific reason to reduce speed in that area… again stuff we don’t know. Heck, none of these references even list a single roadway to reference!
So, while I applaud you for being the first person I have ever seen here with SOMETHING to show for evidence, I’d like more information. To simplify, can you at least point me to the USA study references? I would be happy to read them and see what they say…
Keep in mind, NO ONE here says that raising speed limits EVERYWHERE is the answer… the fact is that most speed limits today are below the 85% for no good reason… and therein lies our complaint.
Since you seem to be a typical NMA member who’s approach to convincing me is set by your narcasistic overtones and the assumption that I have not read anything on this issue before I posted. Let me ask you, how many of the following have you read?
1)Nilsson (1990) Sweden, Speed limits lowered from 110kph to 90kph(68 mph to 56 mph) caused Speeds to decline by 14kph and Fatal crashes to decline by 21%
2)Engel (1990) Denmark, Speed limits lowered from 60 kph to 50 kph(37 mph to 31 mph) caused Fatal crashes to decline by 24% and Injury crashes to decline by 9%
3)Peltola (1991) UK, Speed limits lowered from 100kph to 80kph(62mph to 50mph) caused Speeds to decline by 4kph and Crashes to decline by 14%
4)Sliogeris (1992) Australia, Speed limits lowered from 110kph to 100kph
(68mph to 62mph) caused Injury crashes to decline by 19%
5)Finch et al. (1994) Switzerland, speed limits lowered from 130kph to 120kph
(81mph to 75mph) caused Speeds to decline by 5kph and Fatal crashes to decline by 12%
6)Scharping (1994) Germany, Speed limits lowered from 60kph to 50kph
(37mph to 31mph) caused Crashes to decline by 20%
7)NHTSA (1989) USA, Speed limits increased from 55mph to 65mph(89kph to 105kph) Caused Fatal crashes to increase by 21%
8)McKnight, Kleinand Tippetts (1990) USA, Speed limits increased from 55ph to 65mph(89kph to 105kph) caused Fatal crashes to increase by 22% and Speeding to increase by 48%
9)Garber and Graham (1990) USA, Speed limits increased from 55mph to 65mph
(89kph to 105kph) caused Fatalities to increase by 15% in 28 of 40 states and Decrease or no effect in 12 of 40 States.
10)Streff and Schultz (1991) Michigan, Speed limits increased from 55mph to 65mph(89kph to 105kph) caused Fatal and injury crashes to increase significantly
on rural freeways.
11)Pant, Adhami and Niehaus (1992) Ohio, Speed limits increased from 55mph to 65mph(89kph to 105kph) caused Injury and property damage crashes to increase but not fatal crashes
12)Sliogeris (1992) Australia, Speed limits increased from 100kph to 110kph(62mph to 68mph) caused Injury crashes to increase by 25%
13)Iowa Safety Task Force (1996) Iowa, Speed limits increased from 55mph to 65mph(89kph to 105kph) caused Fatal crashes to increase by 36%
Schwinn writes((In other words:
1) People already were driving 65, so setting the limit higher only reduces the number of violations… which implies that violations are a poor indicator of safety (which is what we/the NMA have always said).
2) Environmental and noise impacts were insignificant (as expected, due to the insignificant rise in speeds)
3) ACCIDENT RATES DECREASED AS DID FATALITY RATES. What’s more this is in stark comparison to HIGHER accident rates “over a similar 18-month period prior to the study period” and HIGHER accident rates in “adjacent 55 MPH zones”. So, when compared apples-to-apples with time or location, the higher limit reduced accident AND fatality rates.))
Phil replies(When you say in “other words” is that code for you are going to write whatever you want? I notice your list #3 says accident rates in general decreased yet what you posted from the summary says there was an 18.3% increase. The NMA also claims that such raises in speed limits will decrease the number of crashes yet in this study there was some 18% increase in the zones that were increased and a slightly higher increase on adjacent 55mph zones. apparently from the spill over that the NMA keeps telling us won’t happen. so apples to apples the higher limit decreased fatalities while increasing accident experiences. I notice that you didn’t list injury crashes so I will Accidents with injuries increased by 9.4 percent, and the total number of people injured increased by 5.9 percent from a comparable time period. What does this tell us? It tells me that the change from 55-65mph created a driving enviroment where more crashes happened and more people in those crashes were injured but fortunately those injuries included fewer life threatening injuries. This helps us as roadway users in NJ how? At least the cops couldn’t issue as many tickets.)
Now that I rebutted your example let me let you know where I stand. I support speed limit raises In fact I support speed limits raised to the top of the pace. I speak out here on this site because when I read some of the crap that is written in articles and posted as facts for internet users to read. I get annoyed at an organization that was developed to counter the lies of the NMSL era which is now supplying unknowing motorists with equally bad information. I am not here to stop progress or higher speed limits I support both. However, I have the education level to make an informed decision based on information readily available on the internet. The target demographic for this sites users is apparently the lesser educated Americans or the Lazy Americans who can’t or won’t check the facts.
As a typical stubborn engineer, I’ll keep at this, for the simple task of proving the point, since you don’t seem to be reading any of the studies we (and the NMA) have already presented.
so, let’s keep this dead simple. You want proof… ok, let’s start with accident rates vs. speed limits. Here’s a simple, short study done by the NJ DOT about a few sections of road which were increased from 55 to 65mph: http://www.state.nj.us/transportation/about/press/2000/65mpg/
The summary, as quoted directly from their “recommendations” section:
“Average increase in travel speeds of 1 mph, on the various roadway sections in the 65 MPH zones, with the exception of the Turnpike which increased 3-4 mph, on various segments. The “after” speeds on the Turnpike ranged from 63 to 68 MPH, falling in line with the “after” speeds on the other state highways.
Environmental impacts regarding air quality and noise were only nominally affected due to the nominal change in the travel speeds.
Fatalities decreased 9.6% and fatal accidents decreased 7.9% in the 65 MPH zones over a similar 18-month period prior to the study period.
Reported accidents increased 18.3% in the 65 MPH zones over a similar 18-month period prior to the study period. Adjacent 55 MPH zones had slightly higher increases in the number of reported accidents than the 65 MPH zones during a similar time period.”
In other words:
1) People already were driving 65, so setting the limit higher only reduces the number of violations… which implies that violations are a poor indicator of safety (which is what we/the NMA have always said).
2) Environmental and noise impacts were insignificant (as expected, due to the insignificant rise in speeds)
3) ACCIDENT RATES DECREASED AS DID FATALITY RATES. What’s more this is in stark comparison to HIGHER accident rates “over a similar 18-month period prior to the study period” and HIGHER accident rates in “adjacent 55 MPH zones”. So, when compared apples-to-apples with time or location, the higher limit reduced accident AND fatality rates.
Note that this is a NJ DOT study… not one by the NMA or even associated in any way with the NMA. The data speaks for itself.
Still, this data is just one example of similar findings all around the world… and it’s what is the basis for the MUTCD states, which is that you should set limits to the 85% level. Heck, if you spend even a little bit of time on the MUTCD, you’ll see that they mention the 85th percentile in a number of applications for guidelines… because it’s so effective and accurate.
Dwight Kingsbury’s post seems to point to some relevant history of this matter here: http://knowledge.fhwa.dot.gov/cops/opspublic.nsf/discussionDisplay?Open&id=F3B7136D152BE3FF852571CB0072BE0C&Group=MUTCD%20General&tab=DISCUSSION
So, there’s some proof. If you care to rebut THIS statement, then I’d love to see your PROOF of the contrary. If you’re just going to say you don’t believe it, then we can’t help you.
There has been a link that has been established which shows the least amount of crashes at or near the mean traffic speed. There are also numerous studies that show that the likelyhood of injury or fatality in a crash rapidly increases at speeds above 60 mph and then increases sharply at speeds above 70mph.
Yeah, we engineers… we get all the money, don’t we? Idiot.
The point is, the system is designed to make decisions based on logic and science and engineering. Unfortunately, the politics prevent this from happening.
In MA, for example, they have (in the past) refused to do traffic studies because they felt somehow they “magically” knew the best speed limit to set on a roadway. Needless to say, if you ever travel on any major highway in MA, you’ll rarely see anyone driving at the speed limit… everyone is almost always speeding. Makes for a good revenue stream… but has nothing to do with safety.
Like an old Subaru commercial had said: The best way to keep from getting hurt in an accident… is to never get into one in the first place. In that line of thought, if people are going at a high speed, and one person decides to go too slow… who do you think is the one causing the accidents?
Increased business and increased financial gains from the proposed restudy of the roadway for future adjustments to the speed limits sounds like a motivation for an engineer to want speed limit changes. The cause of the accident would be a direct result of the misinformation used to brainwash the vehicle drivers who chose to speed up. Filling the public’s heads with crap like No speed limits in America are set scientifically and if they were we’d have limits at 75 or 85mph, and that the main reason for keeping limits low is to create a revenue stream only serves to speed some drivers up while others continue to obey the limit that is posted. All that this accomplishes is a formula for unsafe driving conditions. Whereas if the NMA was truly about as they claim “Safe Roads & Intersections” they would be telling thier flock that by complying with the posted speed limit we lose the battle for higher speed limits but gain safety through having less disparity in the speeds of traffic. They don’t do that because thier goal isn’t Safe Roads & Intersections it’s increased speed limits. Even according to your Subaru approach the best place would not be the 85th percentile speed it would be within the Pace somewhere, where the largest portion of the speed distribution is at about the same speed. How does increasing travel speeds and creating a larger variance in the speeds of traffic within the traffic stream along with the relaxation of drunk driving laws do anything to further the claim that they are working for Safe Roads & Intersections. Yeah I’m the idiot, but at least I don’t buy the brainwashing crap of the NMA. Here is a task for you Mr engineer: read some of these articles and then check the facts that they are claiming within those articles. You’ll find an astounding number of misrepresentations, misquotes, and 1/2 truths. If thier claims were sufficient on thier face they wouldn’t have to lie to you to get your support.
If you bothered to mention even a single statistic, then maybe your argument would make sense… but you’re just stating things which have no evidence whatsoever. As yet, you still haven’t presented a single study that proves your point. If you don’t want to believe me, then fine… I’d understand that, since you don’t know me from a hole in the wall. But, when many studies prove the NMA’s stance (hint, traffic studies are rooted in science, not politics or heresay)… who’s the person stating half truths?\
Put it this way… forget the studies and theories. When the NMSL was repealed, people like you kept telling everyone that we’d have may more deaths, and that highway fatalities would skyrocket because of the higher speed limits in use around the USA. Have you ever looked into the statistics since the NMSL repeal? I think you’d be surprised to find out what happened.
Pretty much I have produced just as much evidence of the things I have said that the NMA has provided us about thier claims. Being an engineer tell us the place where the largest percentage of drivers is grouped within a speed survey?
That’s what I thought!
Sorry for not answering sooner… some of us have jobs and can’t post all day long.
I’m not going to bother with your nonsense. You have provided nothing to backup your claim, the NMA’s stance is based on traffic engineering studies and best practices, which (by the way) are also federal law via the MUTCD. What’s more, we have already provided data showing that speed doesn’t kill… hell, I even showed how when the NMSL was repealed we DIDN’T see the “thousands more” deaths that people like you claim we would have had.
So, it’s clear you’re not reading anyway, so I’m not going to bother to prove you wrong anymore. If you can’t handle a logical discussion, then enjoy your life of ignorant bliss. I have better things to do than teach you basic logic.
Schwinn writes((I’m not going to bother with your nonsense. You have provided nothing to backup your claim, the NMA’s stance is based on traffic engineering studies and best practices, which (by the way) are also federal law via the MUTCD. What’s more, we have already provided data showing that speed doesn’t kill… hell, I even showed how when the NMSL was repealed we DIDN’T see the “thousands more” deaths that people like you claim we would have had.))
The 1000s more deaths was an estimate but you NMA idiots like to quote it as if it was a written in stone gonna happen event that was spouted to create fear of higher speed limits. what would have happend if twice that amount actually became reality the following year? You apparently haven’t read anything I have written or you’d know more about my position on speed limits. You because of your limited mind capacity have a need to lump everyone that doesn’t agree with you 100% as having a position in line with the so called safety radicals. I do advocate a standard of practices that all traffic laws in the U.S should adhere to that includes speed limits. I am not onboard for the 85th percentlie but I do support a number that I can tangibly see such as the top of the pace speed. You have no idea where I stand on these issues other than your assertion that it is in line with anti speed limit increases so I await for you to begin to (”so I’m not going to bother to prove you wrong anymore”) prove me wrong. It would be an easy task if my position was as you assume but it isn’t so comemce at will.
Schwinn((If you can’t handle a logical discussion, then enjoy your life of ignorant bliss. I have better things to do than teach you basic logic.))
If you have something to offer beyond assuming that everything is you are either for us or against us. I would love to discuss where you feel speed limits should be set and why. I will even respond with where I believe they should be set and why. I just get so tired of the NMA propaganda machine stuffing thier beliefs that there is some big conspiracy against the public in the way of traffic laws. I have in several threads found blatent misrepresentations of what the laws state, what other organizations think this study is good that one is bad because it doesn’t support the NMAs predetermined position on where speed limits should be set. If all you are going to do is further the NMA propaganda machine by spouting propaganda like “when the NMSL was repealed we DIDN’T see the “thousands more” deaths that people like you claim we would have had.” or “What’s more, we have already provided data showing that speed doesn’t kill”
You have no proof of any such thing. You may have some data that shows that speeding doesn’t kill. However, as an engineer I would expect you to be familiar with Isaac Newton’s laws of motion and that as speed increases so too does the kinetic energy of the mass at an exponential rate. Without the things like airbags and seatbelts which function to control you deceleration every crash at todays speeds would be fatal.
Schwinn writes((people like you kept telling everyone that we’d have may more deaths, and that highway fatalities would skyrocket because of the higher speed limits in use around the USA.))
Phil replies(I am nothing like these people and this is a function of you lumping me with them as against you. BTW the people who uttered that phrase have been replaced by the likes of the NMA saying things like we have proof that speed does not kill. Two sides of the same coin)
Scwhinn writes((In MA, for example, they have (in the past) refused to do traffic studies because they felt somehow they “magically” knew the best speed limit to set on a roadway. Needless to say, if you ever travel on any major highway in MA, you’ll rarely see anyone driving at the speed limit… everyone is almost always speeding. Makes for a good revenue stream… but has nothing to do with safety.))
Magically setting the speed limits would be more in line with lets set them so that 85% of the vehicles are traveling at that speed or slower. Why did they choose the 85th percentile and not the 80th or 90th for that matter? I am very aware of the 85th percentile theory so there is no need for you to explain it in full beyond why the 85th and not the 80th or 90th. Not an easy question but as an educated man they have you convinced that at the 85th percentile speed is where it would be best for all traffic even if the speed distribution doesn’t support that the 85th percentile is where the limit should be.
I have driven in Mass. on the Mass pike and when we had the MNSL 67-72 was the speed of traffic now that 65 is the limit 90+ mph is common so did the magical raise help us or hurt us?
Quotes from above:
((Engineering Study
Speed zones are established on the basis of an engineering study. The engineering study includes an analysis of the current speed distribution of free- flowing vehicles.))
((85th percentile speed
The speed at or below which 85 percent of the sample of free flowing vehicles are traveling. This speed should be determined by conducting a speed survey following the procedure contained in the Manual of Transportation Engineering Studies.))
((Each speed zone should be periodically restudied to determine that the established speed limit is appropriate. The suggested maximum interval is five years.))
((In addition, an engineering study should be conducted whenever there is a change in the roadway that would affect the prevailing speed. Such changes would include elimination of parking, added lanes, signal coordination and changes in roadside development.))
Phil responds((With all these traffic studies and speed surveys every 5 years and then when something changes will only serve to make the traffic engineers rich and increase our County, State, and Federal taxes to pay for them. I guess if you follow the revenue stream you’d find an Engineer benefiting every time. You may be able to decrease the revenue collected by speeding citations but at the cost of increasing other taxes to pay for not only services not covered because of the decrease but also to pay for all these studies and surveys.))
Read this passage By James Baxter, NMA President:
((MADD’s current excuse for existing is to make DUI violations a felony, the most serious of criminal convictions. A felon, along with going to prison, loses the right to vote, the right to possess firearms, any professional licenses, scholarships, and many employment opportunities. Given that two or three drinks and a typically inaccurate BAC test will yield a DUI conviction, any normal, responsible person who drinks moderately has a good chance of becoming a felon, if MADD has its perverted way.
The standard incremental approach is to first attach the felon status to persons with multiple DUI convictions and then whittle the number of convictions down to two or even one where the felon status will be assigned. The elephant in the room that no one is mentioning is that once a person has a DUI conviction on their record it’s like having a big sign on the back of their car that says “stop me, I’m a good candidate for a DUI.” A second or third DUI conviction is much easier to acquire than is the first.
Combine .08 percent BAC laws with inherently inaccurate Breathalyzers and politicized enforcement and normal responsible individuals who drink in moderation will achieve the status of “drunk driver felon,” without ever reaching the point of meaningful impairment, or causing and accident. The prohibition movement is alive and well and residing in Texas.))
Phil challenges James Young((Then go to the MADD website and quote for me where it says that they want to make a first offense DUI a Felony let alone a first offense DUI with only a .08 BAC))
From the M.A.D.D website((Enhanced/Escalating Penalties For DUI/DWI Based On Blood Alcohol Content (BAC) Level
As part of the progressive sanctions approach to impaired driving and in an effort to impact the higher risk driver, Mothers Against Drunk Driving (MADD) supports legislation that would provide for enhanced or escalating penalties for drivers convicted of DUI/DWI whose blood alcohol content (BAC) at the time of arrest was .15 or higher))
Phil writes(Although they do support more severe penalties for those convicted a second time or those convicted a 1st time with a BAC above .15, I found nothing in thier mission statements or proposals that even resembled what the NMA attributes M.A.D.D. as wanting. As stated above “1st time convictions for .08 BAC to be a felony”. Looks like the NMA propaganda machine strikes again. Hasn’t any of the NMA members and/or supporters ever checked the things that the NMA tells them? I have found so much bad information on the NMA’s website that it makes it hard to discern what the good information is telling us. You have to question an organization that feeds so much misinformation about what it is really trying to accomplish.)
Phil writes: {Please point me to the STUDY that shows that.} [spelling corrected by James Young in all quotes for clarity even though no spelling errors were present]
James replies((Phil, this is not a study; it is the process and the accumulated work of an entire discipline. This is not a one-time fad but a well-founded regimen based on sound engineering principles and practices.))
Phil responds(The above article said ”NUMEROUS studies have shown that the 85th percentile is the safest possible speed limit.”[emphasis added] When I ask you to provide such a study you tell me I don’t understand because there is no such study but rather it is the process and accumulated work of an entire discipline and it is a well-founded regimen based on sound engineering priciplels. So then what you are saying here is that Bonnie Sesolak, NMA Development Director who wrote the above article blatently lied to the readers when she said there was Numerous studies?)
Phil wrote{ I have seen studies that relate safest to the mean speed. I have also seen the curve showing the safest point related to the mean speed where someone added a line at the curves lowest point and wrote 85th percentile speed next to it. It was an NMA sponsored link so I have no doubt the NMA just added the line and created their own evidence.}
James replies((Show us what you’ve got. I would like to see that because I have never seen any legitimate independent traffic survey that used the mean (or even its cousin, the median). Further, since you are once again accusing NMA of lying, it’s time for you to put up or shut up. Exactly where was this magical curve “related to” the mean speed? You claim it is an “NMA sponsored link” so it should be easy for you to direct us to it.))
Phil responds(It was something that you directed me to while you were explaining how educated you are and implying that I know nothing on another thread. Surprising you don’t remember it. But I will search for a link to it and provide it for you if I saved it.)
Phil writes: {Well if the lowest point is AT the 85th percentile speed why do the studies related via deviations from the mean speed?}
James replies((Aside from the confusing construction, I think you are asking why the studies relate the crash incidence curve by standard deviations from the mean. The fact is, they don’t. The mean has no real meaning in traffic engineering.))
Phil responds(The mean traffic speed has no meaning in your personal brand of traffic engineering. Your credentials as a traffic engineer are?)
Phil writes{ It rises slower than it descended from the mean speed but, slower than the curve below the mean speed?}
James replies((I have no idea what you’re trying to say here.))
Phil responds(You said “since the C-I curve rises less steeply above the 85th percentile, it is actually safer to travel 10 mph over the 85th than 10 mph below it.” according to Solomon, Cirillo and Fildes, the risk of crash above the 85th percentile speed rises quicker than it fell below the 85th percentile , as I have outlined in another response.)
Phil writes{ The picture that I am familiar with from these studies that I have been directed to shows that the curve rises slower than it fell for a very very short time then rises quickly.}
James young writes((I don’t know where you got that but it certainly does not describe the “flattened elongated reverse ‘J’” that traffic engineers use to describe it.))
Phil responds(maybe you can direct me to the reverse “J” curve you are referring to. I already pointed to 3 studies that show a curve where risk of crash rises faster, for speeds above the 85th percentile, than it fell at speeds below the 85th percentile speed. I refer to the 85th percentile here because you previously said the lowest risk was at the 85th percentile speed so where I refer to the 85th percentile I am referring to the lowest point on the curve.)
Phil writes: {When did they come out with the device that stops your internal organs from continuing forward after your body has stopped suddenly? Oh they haven’t invented it yet. Therefore the physics argument still holds water.}
James replies((I’m always inwardly pleased when the safety cabal resorts to the physics argument because it means that the argument is over, that they have exhausted all of their other “evidence,” scare tactics, threats, emotion-laden rhetoric and appeals to phony authority.))
Phil responds(Unless you can prove that a device exists that will stop the internal organs from continuing to move after the body has suddenly stopped. Since you can’t do that because no such device exists as crash speeds increase so too does the amount of damage to the body and it’s internal organs. I realize that in the world you live in the laws of physics don’t exist and the kinetic energy a moving vehicle possesses before crash magically disappears when that vehicle crashes. Yet you call me uneducated and confused.)
James wrote((Please note that I wrote “mitigate the likelihood of injury or fatality” and not the “elimination of injury or fatality.” The difference is palpable.))
Phil responds(Increasing travel speeds and increasing the velocity at which cars are crashing does nothing to make crashes or injuries less severe.I’ll bet in your world that even the distortion of the vehicle doesn’t happen anymore when it crashes. I’d go so far as to think that you believe that a crash at 150mph is safer than a crash below the 85th percentile speed, at least that is the way you are presenting your case.)
Phil writes{but just because we make an advancement in that area it isn’t reasonable that we now increase the effects of the interior by adding more velocity into the mix.}
James replies((Certainly, it is reasonable. More egregious, your argument (emotional appeal) also a strawman. We already have much higher speeds across the nation, just as Jim Walker pointed out and that I see whenever I travel throughout the West. The physics and the mitigation apply equally to a car legally at 80 mph in Texas or illegally at 80 mph in a 65 mph zone in Wisconsin. The issue is not slowing traffic down but speeding the limits up to reflect reality. There is no societal benefit from arbitrarily defining one-half or more of our drivers as criminals and there is very real damage done by slowing them all down to some arbitrary speed.))
Phil responds(Just because we have higher speeds accross the nation the argument that higherspeeds cause more property damage and more injuries and fatalities is not negated. Higher speeds do cause more property damage, injuries and fatalities there is no way around that. You can try to say that at the 85th percentile speed traffic is subjected to fewer chances for conflict but what happens once the traffic that is within the 10mph pace begins to spread upward and the pace moves closer to the 85th percentile? what happens when the 85th percentile creeps upward? now the speed where the least number of conflicts was is no longer the same and according to YOUR curve risk of crash is now increasing as well as risk of injury or death.)
Phil writes: {I pointed to this statement because it is irresponsible to point out that it is more likely to be involved in a crash at 10mph below the “prevailing speed” without also pointing out that above the prevailing speed risk also increases. By only showing the increased risk below the “prevailing speed” you imply that as your speed increases so too does your safety. That is a lie and you know it.}
James replies((No, it is not a lie but you don’t know it because you don’t understand what the curves mean as evidenced by your incorrect description of them. Nobody has said that risk does not increase in both directions from the minimum point (by definition) but you go wrong when you think that the “mean” is the prevailing speed. Further, the magnitude of change is greater below the 85th percentile (the “prevailing speed”) than it is above the 85th. Finally, it is true that your safety does increase with an increase in speed up to the minimum point speed or the 85th percentile, which are, of course, the same thing.))
Phil responds(Prevailing speed is the TERM that By Bonnie Sesolak, NMA Development Director used when she wrote the article. Thank you for pointing out that that the term “prevailing speed” wasn’t correctly used. I think the study said something like “the crash risk for vehicles traveling much faster or slower was six times the average rate.” The NMA took that out of context and misquoted it to say “those driving 10 mph slower than the prevailing speed are six times as likely to be involved in an accident.” it is a lie not only are you just as likely to crash at 10mph above the 85th percentile speed as you are to crash at 10mph below it but you are more likely to crash at 10mph above than you are at 10mph below.)
Phil writes: {This is very compelling but you are simply trying to throw a lot of manure to try to get it to stick. If I get what you are saying here is that the Risk curve and the speed distribution are two separate things and you simply overlay the risk curve onto the speed distribution. apparently YOU do it so that the 85th, 90th or 95th percentile speed corresponds with the lowest point of the curve.}
James replies((No, because the C-I curve is calculated based on the number of crashes occurring at a given speed. It is very easy to coordinate those speeds with the exact same speed on the speed distribution and that is exactly what traffic engineers do.))
Phil responds(The C-1 curve is as unique to the roadway as the 85th percentile speed simply overlaying any crash curve over a speed distribution of any random roadway tells us nothing.)
Phil writes: { In almost every article that I have read posted here by the NMA there were lies, 1/2 truths and misdirecting information which is designed to brainwash readers into believing the NMA is here to help when they only have a self serving agenda, Faster driving without having to be responsible for the decision of choosing that speed.}
James replies((First, since you are once again asserting NMA lies, you need to point out exactly where those “lies, ½ truths, and misdirecting information” are so that we may examine the same evidence that you are. Perhaps you have insights that the rest of us lack. I believe the best explanation is that your reading comprehension is deficient as evidenced by other things that you have messed up.))
Phil responds(Have you been paying attention? I started this entire discussion by posting 1 such 1/2 truth “those driving 10 mph slower than the prevailing speed are six times as likely to be involved in an accident.” and I pointed out that it was also just as likely for someone traveling at 10mph over the “prevailing speed” to be involved as a crash. I have since modified that after examining Solomon, Cirillo and Filde to say that it is actually MORE likely that someone traveling 10mph over the “prevailing speed” to be involved in a crash as someone traveling 10mph under.
Phil writes{ If there were 1 or 2 errors I could see it happening but as many misstatements as I have seen here is only possible if it is deliberate.}
James replies((Then they should be easy for you to point out.))
Phil replies(This discussion started by me pointing 1 out once you recognize it as an error and it is corrected so that other who visit can read accurate information I’ll point out the next. Since you have no authority to make that happen you are wasting your time berating me.)
Phil writes{ want to convince me otherwise drop the attitude towards me and provide me with things showing how the crash incidence curve is derrived and overlayed to the speed distribution.}
James replies((You are the one upon whom the attitude is predicated. You come in here to tell all of us that we are a bunch of nitwits being led astray by a deliberately mendacious website but can’t provide any examples, much less significant examples, of it. Further, I believe that your appearance was predicated upon an intent to divert or disrupt this website because you or your peers don’t like the message. While I believe you’re a cop, there is no doubt that you reside somewhere solidly in the revenue stream of traffic citations. Then you want me to show you the work of an entire discipline in a single post or link. You might as well ask for the link that will make you a surgeon.))
Phil responds(That you berate me because I point out factual errors in context contained within the website only furthers my beliefs that you are a bunch of nitwits being led astray by a deliberately mendacious website. I have told you and others on here that I am not a cop. Now I am expanding that to include that I am not employed anywhere in the revenue stream generated by traffic citations. I am impartial, nonpartisan, objective, unbiased, unprejudiced in this matter unfortunately the NMAs constant use of 1/2 truths, lies, misquotes and misdirecting statements caused me to speak out and bring notice to thier brainwashing of readers.)
Phil writes{It is Ironic how I can go to a forum and have an intelligent conversation with a traffic engineer but any and all NMA members will only catch an attitude with me because I disagree with them.}
James writes((I don’t believe that the problem is that you disagree with them but two other things: You claim things that just ain’t so and you have done it in a virulent in-your-face attitude. Virulence bounces off me like water off a duck’s ass but as a dedicated academic, dishonesty bothers me greatly and your credibility is currently negative. It also does not help you to misunderstand/misstate rather simplistic concepts and assertions, much less label some of them as lies[content corrected for clarity]. They ain’t lies; you just can’t read.))
Phil responds(There is no malice in my intent to point out the factual errors that I have seen. One can only find malice if one intended the context to be inaccurate to purposefully misinform the readers and regards my pointing them out an attempt to subvert thier misinformation strategy.)
Quote from the NMA website((”I received a speeding ticket at the start of my vacation, in late May… The state sabotaged its case against me by causing the Highway Patrol officer to miss the hearing — they claimed he was investigating a traffic accident. Case dismissed! Thanks NMA. I could not have prepared a defense without your guidance over the years!”
- S. Swanke, NMA Member since 1987))
This guy needed the NMA’s help to get his case dismissed. I should sign up now so they can charge me dues, then advise me to do what I could have done by myself? makes sense to me!
Quote from above”Numerous studies have shown that the 85th percentile is the safest possible speed limit.”
Define safest? There has been a link that has been established which shows the least amount of crashes at or near the mean traffic speed. There are also numerous studies that show that the likelyhood of injury or fatality in a crash rapidly increases at speeds above 60 mph and then increases sharply at speeds above 70mph.
Quote from above”According to an Institute of Transportation Engineers Study, those driving 10 mph slower than the prevailing speed are six times as likely to be involved in an accident.”
It is also true that a vehicle traveling at 10mph above the prevailing speed(AKA mean speed) is also six times more likely to be involved in a crash(The mean speed which is always below the 85th percentile. The risk curve is calculated by deviation fron the Mean speed not the 85th percentile speed). I use the word crash and not accident because accident implies that nothing could have been done to avoid the crash when most often driver error is the cause. Many times that driver error is manifests itself in overconfidence to drive at high speeds. That overconfidence is a result of institutions such as the NMA not acting responsibly and telling the whole truth but rather instead filling motorist’s heads with lies or 1/2 truths like the one quoted directly above.
Phil writes: {Define safest?}
“Safest” means the point on the speed distribution where the crash-incidence curve minimizes. That is almost always at the 85th percentile for urban and suburban roadways; new evidence is emerging that for Interstate-grade roadways the crash-incidence curve may minimize between the 90th and 95th percentiles.
{There has been a link that has been established which shows the least amount of crashes at or near the mean traffic speed.}
Sorry, that is just not true and is indicated in multiple reports from ITE, academic institutions, even NHTSA. Since the mean and the 85th percentile are never the same, it is impossible to have the lowest crash-incidence at two different points. The crash-incidence curve *declines* from the mean until it reaches the minimization point – at the 85th percentile – and then rises, although more slowly than it descended from the mean.
{There are also numerous studies that show that the [likelihood] of injury or fatality in a crash rapidly increases at speeds above 60 mph and then increases sharply at speeds above 70mph.}
That was actually true at some time in the past. However, we have expended vast time, energy and resources to mitigate the likelihood of injury or fatality, even at high speeds. We have softened dashes without protrusions, collapsible steering columns, airbags and cross-over belts, crumple-zones built into the frame/bodywork, and engines and transmissions designed to move *down* as well as back, thus moving them away from the passengers. We have done all these things so that drivers could drive faster because higher speeds are extremely valuable, not only to drivers but to society as a whole.
{Quote from above ”According to an Institute of Transportation Engineers Study, those driving 10 mph slower than the prevailing speed are six times as likely to be involved in an accident.” It is also true that a vehicle traveling at 10mph above the prevailing speed(AKA mean speed) is also six times more likely to be involved in a crash.}
This is wrong. First, “prevailing speed” has no specific legal meaning other than its ordinary English usage, i.e., common, frequent or dominant, although traffic engineers use it to refer to the 85th percentile. It has nothing to do with the mean or the median. Further, since the C-I curve rises less steeply above the 85th percentile, it is actually safer to travel 10 mph over the 85th than 10 mph below it.
{The risk curve is calculated by deviation from the Mean speed not the 85th percentile speed.}
Nope. This is just flat wrong. The crash-incidence curve – what you call the “risk curve” – is calculated independently of the speed distribution, based on actual crashes at different speeds. It is overlaid onto the speed distribution but does not derive from it. Further, since it changes in relation to the particular speed where it minimizes, it can be measured – although not calculated – by deviation from that minimum speed but not from the mean. Note also, the mean has no useful significance in traffic engineering – nothing important happens at the mean – nor does its close cousin, the median.
{ That overconfidence is a result of institutions such as the NMA not acting responsibly and telling the whole truth but rather instead filling motorist’s heads with lies or 1/2 truths like the one quoted directly above.}
Bullshit. NMA is not the irresponsible party here. That is your role. You keep assigning lies and malfeasance of all sorts to NMA but your allegations are not worth the bandwidth they use up. You have misread or misinterpreted – ignorantly or maliciously – many things NMA and posters have said, creating strawmen or diverting attention to minutiae. Proof of your poor comprehension or malfeasance is right above, where you get multiple things wrong, misconstrue concepts and draw incorrect conclusions.
Simply put from James’ far more complete response (excellent job James!):
Phil – where is your data? The article quotes ITE (and James follows up with NHTSA and other data) as proof… you simply provided… nothing. Show us ANY data backing up your claim, and then we can believe that you are speaking with some sense of real knowledge.
So far, the only real data provided is in defense of this article and the statements therein… so it looks like you’re the one spreading half-truths and lies…
And please don’t tell me “common sense dictates…” If science were based on common sense, we wouldn’t need engineers and all these science books would we? Real science and engineering requires real data… SOMETIMES this matches with “common sense”… but often it does not.
Phil writes: {Define safest?}
James replies((“Safest” means the point on the speed distribution where the crash-incidence curve minimizes. That is almost always at the 85th percentile for urban and suburban roadways; new evidence is emerging that for Interstate-grade roadways the crash-incidence curve may minimize between the 90th and 95th percentiles.))
Phil replies(Please point me to the STUDY that shows that. I have seen studies that relate safest to the mean speed. I have also seen the curve showing the safest point related to the mean speed where someone added a line at the curves lowest point and wrote 85th percentile speed next to it. It was an NMA sponsored link so I have no doubt the NMA just added the line and created thier own evidence.)
Phil says{There has been a link that has been established which shows the least amount of crashes at or near the mean traffic speed.}
James replies((Sorry, that is just not true and is indicated in multiple reports from ITE, academic institutions, even NHTSA. Since the mean and the 85th percentile are never the same, it is impossible to have the lowest crash-incidence at two different points. The crash-incidence curve *declines* from the mean until it reaches the minimization point – at the 85th percentile – and then rises, although more slowly than it descended from the mean.))
Phil replies(well it is obvious that the LOWEST point can’t be at two separate places along a single curve. Well if the the lowest point is AT the 85th percentile speed why do the studies related via deviations from the mean speed? It rises slower than it descnded from the mean speed but, slower than the curve below the mean speed? The picture that I am familiar with from these studies that I have been directed to shows that the curve rises slower than it fell for a very very short time then rises quickly.)
Phil writes{There are also numerous studies that show that the [likelihood] of injury or fatality in a crash rapidly increases at speeds above 60 mph and then increases sharply at speeds above 70mph.}
James replies((That was actually true at some time in the past. However, we have expended vast time, energy and resources to mitigate the likelihood of injury or fatality, even at high speeds. We have softened dashes without protrusions, collapsible steering columns, airbags and cross-over belts, crumple-zones built into the frame/bodywork, and engines and transmissions designed to move *down* as well as back, thus moving them away from the passengers. We have done all these things so that drivers could drive faster because higher speeds are extremely valuable, not only to drivers but to society as a whole.))
Phil replies(When did they come out with the device that stops your internal organs from continuing forward after your body has stopped suddenly? Oh they haven’t invented it yet. Therefore the physics argument still holds water. Yes we have made major advancements to prevent an occupant from recieving injury from striking parts of the vehicle inside when he crashes. but just because we make an advancement in that area it isn’t reasoning that we now increase the effects of the interior by adding more velocity into the mix.)
Phil writes{Quote from above ”According to an Institute of Transportation Engineers Study, those driving 10 mph slower than the prevailing speed are six times as likely to be involved in an accident.” It is also true that a vehicle traveling at 10mph above the prevailing speed(AKA mean speed) is also six times more likely to be involved in a crash.}
James replies((This is wrong. First, “prevailing speed” has no specific legal meaning other than its ordinary English usage, i.e., common, frequent or dominant, although traffic engineers use it to refer to the 85th percentile. It has nothing to do with the mean or the median. Further, since the C-I curve rises less steeply above the 85th percentile, it is actually safer to travel 10 mph over the 85th than 10 mph below it.))
Phil replies(I pointed to this statement because it is irresponsible to point out that it is more likely to be involved in a crash at 10mph below the “prevailing speed” without also pointing out that above the prevailing speed risk also increases. By only showing the increased risk below the “prevailing speed” you imply that as your speed increases so too does your safety. That is a lie and you know it.)
Phil writes{The risk curve is calculated by deviation from the Mean speed not the 85th percentile speed.}
James replies((Nope. This is just flat wrong. The crash-incidence curve – what you call the “risk curve” – is calculated independently of the speed distribution, based on actual crashes at different speeds. It is overlaid onto the speed distribution but does not derive from it. Further, since it changes in relation to the particular speed where it minimizes, it can be measured – although not calculated – by deviation from that minimum speed but not from the mean. Note also, the mean has no useful significance in traffic engineering – nothing important happens at the mean – nor does its close cousin, the median.))
Phil replies(This is very compelling but you are simply trying to throw alot of manuer to try to get it to stick. If I get what you are saying here is that the Risk curve and the speed distribution are two separate things and you simply overlay the risk curve onto the speed distribution. apparently YOU do it so that the 85th, 90th or 95th percentile speed corresponds with the lowest point of the curve.)
Phil writes{ That overconfidence is a result of institutions such as the NMA not acting responsibly and telling the whole truth but rather instead filling motorist’s heads with lies or 1/2 truths like the one quoted directly above.}
James replies((Bullshit. NMA is not the irresponsible party here. That is your role. You keep assigning lies and malfeasance of all sorts to NMA but your allegations are not worth the bandwidth they use up. You have misread or misinterpreted – ignorantly or maliciously – many things NMA and posters have said, creating strawmen or diverting attention to minutiae. Proof of your poor comprehension or malfeasance is right above, where you get multiple things wrong, misconstrue concepts and draw incorrect conclusions.))
Phil replies(I misinterpreted or misread?? I don’t think so Jimmy! In almost every article that I have read posted here by the NMA there were lies, 1/2 truths and misdirecting information which is designed to brainwash readers into believing the NMA is here to help when they only have a self serving agenda, Faster driving without having to be responsible for the decision of choosing that speed. If there were 1 or 2 errors I could see it happening but as many misstatements as I have seen here is only possible if it is deliberate. want to convince me otherwise drop the attitude towards me and provide me with things showing how the crash incidence curve is derrived and overlayed to the speed distribution. If all you want to do is tell me how it is without showing me how it is derrived or calculated you are wasting your time. I feel that if the NMA was about what they claim to be about they wouldn’t have to lie, misinform or misdirect readers to gain support. It is Ironic how I can go to a forum and have an intelligent conversation with a traffic engineer but any and all NMA members will only catch an attitude with me because I disagree with them. I have given you a specific request on something you can show me here but I expect only to get the reply that it isn’t your responsibility to provide me with that. If that is the case then you can forego the response.
Phil writes: {Please point me to the STUDY that shows that.} [spelling corrected in all quotes for clarity]
Phil, this is not a study; it is the process and the accumulated work of an entire discipline. This is not a one-time fad but a well-founded regimen based on sound engineering principles and practices.
{ I have seen studies that relate safest to the mean speed. I have also seen the curve showing the safest point related to the mean speed where someone added a line at the curves lowest point and wrote 85th percentile speed next to it. It was an NMA sponsored link so I have no doubt the NMA just added the line and created their own evidence.}
Show us what you’ve got. I would like to see that because I have never seen any legitimate independent traffic survey that used the mean (or even its cousin, the median). Further, since you are once again accusing NMA of lying, it’s time for you to put up or shut up. Exactly where was this magical curve “related to” the mean speed? You claim it is an “NMA sponsored link” so it should be easy for you to direct us to it.
Phil writes: {Well if the lowest point is AT the 85th percentile speed why do the studies related via deviations from the mean speed?}
Aside from the confusing construction, I think you are asking why the studies relate the crash incidence curve by standard deviations from the mean. The fact is, they don’t. The mean has no real meaning in traffic engineering.
{ It rises slower than it descended from the mean speed but, slower than the curve below the mean speed?}
I have no idea what you’re trying to say here.
{ The picture that I am familiar with from these studies that I have been directed to shows that the curve rises slower than it fell for a very very short time then rises quickly.}
I don’t know where you got that but it certainly does not describe the “flattened elongated reverse ‘J’” that traffic engineers use to describe it.
Phil writes: {When did they come out with the device that stops your internal organs from continuing forward after your body has stopped suddenly? Oh they haven’t invented it yet. Therefore the physics argument still holds water.}
I’m always inwardly pleased when the safety cabal resorts to the physics argument because it means that the argument is over, that they have exhausted all of their other “evidence,” scare tactics, threats, emotion-laden rhetoric and appeals to phony authority.
Please note that I wrote “mitigate the likelihood of injury or fatality” and not the “elimination of injury or fatality.” The difference is palpable.
{but just because we make an advancement in that area it isn’t reasoning [reasonable?] that we now increase the effects of the interior by adding more velocity into the mix.}
Certainly, it is reasonable. More egregious, your argument (emotional appeal) also a strawman. We already have much higher speeds across the nation, just as Jim Walker pointed out and that I see whenever I travel throughout the West. The physics and the mitigation apply equally to a car legally at 80 mph in Texas or illegally at 80 mph in a 65 mph zone in Wisconsin. The issue is not slowing traffic down but speeding the limits up to reflect reality. There is no societal benefit from arbitrarily defining one-half or more of our drivers as criminals and there is very real damage done by slowing them all down to some arbitrary speed.
Phil writes: {I pointed to this statement because it is irresponsible to point out that it is more likely to be involved in a crash at 10mph below the “prevailing speed” without also pointing out that above the prevailing speed risk also increases. By only showing the increased risk below the “prevailing speed” you imply that as your speed increases so too does your safety. That is a lie and you know it.}
No, it is not a lie but you don’t know it because you don’t understand what the curves mean as evidenced by your incorrect description of them. Nobody has said that risk does not increase in both directions from the minimum point (by definition) but you go wrong when you think that the “mean” is the prevailing speed. Further, the magnitude of change is greater below the 85th percentile (the “prevailing speed”) than it is above the 85th. Finally, it is true that your safety does increase with an increase in speed up to the minimum point speed or the 85th percentile, which are, of course, the same thing.
Phil writes: {This is very compelling but you are simply trying to throw a lot of manure to try to get it to stick. If I get what you are saying here is that the Risk curve and the speed distribution are two separate things and you simply overlay the risk curve onto the speed distribution. apparently YOU do it so that the 85th, 90th or 95th percentile speed corresponds with the lowest point of the curve.}
No, because the C-I curve is calculated based on the number of crashes occurring at a given speed. It is very easy to coordinate those speeds with the exact same speed on the speed distribution and that is exactly what traffic engineers do.
Phil writes: { In almost every article that I have read posted here by the NMA there were lies, 1/2 truths and misdirecting information which is designed to brainwash readers into believing the NMA is here to help when they only have a self serving agenda, Faster driving without having to be responsible for the decision of choosing that speed.}
First, since you are once again asserting NMA lies, you need to point out exactly where those “lies, ½ truths, and misdirecting information” are so that we may examine the same evidence that you are. Perhaps you have insights that the rest of us lack. I believe the best explanation is that your reading comprehension is deficient as evidenced by other things that you have messed up.
{ If there were 1 or 2 errors I could see it happening but as many misstatements as I have seen here is only possible if it is deliberate.}
Then they should be easy for you to point out.
{ want to convince me otherwise drop the attitude towards me and provide me with things showing how the crash incidence curve is derrived and overlayed to the speed distribution.}
You are the one upon whom the attitude is predicated. You come in here to tell all of us that we are a bunch of nitwits being led astray by a deliberately mendacious website but can’t provide any examples, much less significant examples, of it. Further, I believe that your appearance was predicated upon an intent to divert or disrupt this website because you or your peers don’t like the message. While I believe you’re a cop, there is no doubt that you reside somewhere solidly in the revenue stream of traffic citations. Then you want me to show you the work of an entire discipline in a single post or link. You might as well ask for the link that will make you a surgeon.
{It is Ironic how I can go to a forum and have an intelligent conversation with a traffic engineer but any and all NMA members will only catch an attitude with me because I disagree with them.}
I don’t believe that the problem is that you disagree with them but two other things: You claim things that just ain’t so and you have done it in a virulent in-your-face attitude. Virulence bounces off me like water off a duck’s ass but as a dedicated academic, dishonesty bothers me greatly and your credibility is currently negative. I also does not help you to misunderstand/misstate rather simplistic concepts and assertions, much less label some of them as lies. They ain’t lies; you just can’t read.
Schwinn writes((Simply put from James’ far more complete response (excellent job James!):
Phil – where is your data? The article quotes ITE (and James follows up with NHTSA and other data) as proof… you simply provided… nothing. Show us ANY data backing up your claim, and then we can believe that you are speaking with some sense of real knowledge.
So far, the only real data provided is in defense of this article and the statements therein… so it looks like you’re the one spreading half-truths and lies…
And please don’t tell me “common sense dictates…” If science were based on common sense, we wouldn’t need engineers and all these science books would we? Real science and engineering requires real data… SOMETIMES this matches with “common sense”… but often it does not.))
Just another mutual masterbation cerimony of the NMA members(good job James you showed him). someone doubts so they are the enemy. The NMA misquotes, lies and misdirects people to believe that speed limits are set politically low purposefully to generate revenue. They point to the 85th percentile speed and say this is where the speed limits should be set even though you can have two entirely different speed distributions that share a common 85th percentile speed. They deny that the 85th percentile speed changes when a speed limit changes even though there is evidence to the contrary. It matters not the studies that I could provide to present my case because according to the NMA the only study that matters is the 1992 Parker. They even go as far as to discredit the later Parker of 1997. It is ironic that James mentioned NHTSA because the NMA deems them as liars and part of the grand conspiracy to keep speed limits lower than they should be so that the government can extract a speeding tax.
http://euroris.swov.nl/knowledge/content/20_speed/speed_and_accident_risk.htm
If James is refering to the crash incididence curve from Solomon 1964 or Cirrilo 1968 we can see that on freeways the lowest point is approx 10mph above the average speed and that the number of crashes increases as we go outward from that point . In fact the curve is shaped so that the number of crashes at 15mph above the lowest point is equal to the number of crashes at 20mph below the lowest point. The curve continues to climb to a number of crashes at 25mph above the lowest point which is equivalent to the number of crashes at nearly 35mph below. One can clearly see that the curve rises quicker above the lowest point than it does below the lowest point. Yet the NMA and James will have you believe that it is just opposite of that. On the curve for daytime rural roadways the curves lowest point is less than 5mph above the average speed and climbs to a point approx 25mph above that where the number of crashes is equal to a point 28mph below. this is the most symetrical curve. The lowest point on the night time rural roadway curve appears to be at 5mph above the average speed the curve climbs to a point 20mph above the lowest that is equal to the number of crashes at 23mph below. None of these curves resemble that which james referred to. In 1993 Fildes and Lee came up with a surprisingly similar curve. Kloeden et al. (1997) found that the risk of being involved in an injury crash was lowest for vehicles traveling near or below the median speed and increased exponentially at higher speeds. the risk of being involved in an injury crash was lowest for vehicles traveling near or below the median speed and increased exponentially at higher speeds. Vehicles exceeding the 90th percentile speed or traveling more than 7 km/h faster (4 mi/h) than the speed limit and median speed had above average injury crash involvement rates. The curve for injury crash rates is more of a backwards “L” staying almost flay until it reaches 64kph(40mph) and then rises sharply.
This is a great way to start building a defense!
An independent company maybe the ones actually performing the test, but in the end, I believe the state is required to keep this data on file. I know for me, in MA, I can send a letter to the state highway department to ask them for any prior “traffic studies” that are related to the speed of traffic on the highways. This can be done under a FOIA (Freedom of Information Act) request, and they are supposed to reply within a certain time. (as mandated by the FOIA).
Although it’s an MA specific page, the NMA page here is pretty helpful, and has an example FOIA request for you to build from: http://www.motorists.org/ma/oldmanews2.htm
Keep in mind, the statements made there are MA-specific. You’ll need to find out the specific rules in TX to properly defend your case. May I suggest getting the Legal Defense Kit from the NMA? It’s an excellent resource (for rent) that provides all the state-specific info, and defense info in one big package. (See http://www.motorists.org/ldk/ )
Man, do I sound like a commercial?! Still, I’ve used the LDK before… excellent resource for the first-time defender!
I want to find out who conducts and gets the average speeds limits for Blue Ridge Tx., because I am going to court in a few weeks and I need to find out when the last test was done in that area for fm455. I was told an independent company conducts a test to get the average speed, which must be done every 3 to 5 years. How do I come up with this information for my court case.
[...] could argue the speed limit was set unusually low, provided that a speed survey bears that out: How Should Speed Limits Be Set? Could one invest the time to conduct one to scientific standards to which the court would give [...]
By definition, a traffic study states that it cannot be done during any adverse situation, such as a police presence or construction.
I am sure that most traffic studies are performed properly, but it’s the politics and brainwashing with “speed kills” that sets speed limits artificially low, which is more of a safety hazard than proper speed limits (as proven EVERY DAY since the repeal of the national speed limit.)
Translation: The faster you drive, and the faster everyone drives, then the higher the speed limit. Traffic engineering surveys don’t count when under the influence of a speed trap. So when you see a cop, speed up! “Necessity” for safety is always a valid legal defense.
James Young writes:
{darrel writes:
{ Generally though, officers are aware of the situation and don’t punish the public for poorly marked speed zones. In fact, Myself and other officers that I currently work with, have complained about poorly marked speed zones or enforcement practices.}
You have no idea how rare that is. The overwhelming majority of LEOs working traffic just trigger the radar, flash the lights and write the citation.}
Well said. What’s more, under such a system, leaving the decision on whether to give or not give a ticket up to the officer leads to an unfair situation and to discrimination and emotion. If it’s REALLY unsafe, then just give the ticket – period. The fact is, that it’s NOT unsafe. Yet, you pulled them over… why? Just to harass the driver into “being good”? Do you honestly think that this works, when it’s proven that even the ticket itself isn’t a deterrent to speeding?
The fact is, it’s not about safety – it’s about making money. I don’t disagree that LEOs are underpaid, overall, for a dangerous line of work. However, fleecing the public while sitting on the side of the road, and trying to make quotas on speeding tickets has NOTHING to do with safety… it’s all about the money.
Anyway, back to the original point, let’s look at the original argument in a different way: On the highway, what causes accidents? Well, by definition, it’s when one car hits another. Aside from vehicle failure-related accidents, and inattentive drivers sideswiping each other, or skidding out of control. In the latter case, speed has little to do with the problem, unless the car was hydroplaning, in which case EVERYONE wouldn’t be doing it. In the case of hitting an ice patch, no amount of speed reduction can replace attentive-ness to the road conditions, etc. Yet, how often do you see speeding tickets in adverse conditions? No, it’s usually on the sunny, clear, warm days that police hand out tickets. Again, it’s not about the safety, otherwise you’d see more tickets in the winter here in the north… but you don’t.
So, ignoring those cases, accidents happen when two (or more) cars were going at different speeds in order to hit each other (front to rear). These are the most common accidents on the highways. Put another way, if everyone drove the same exact speed, we wouldn’t have these types of accidents, because it’s simply impossible. Again, how often do you see people getting tickets for driving too slow? If one person is driving slow on the highway, I guarantee that one of the faster cars will get the ticket instead. Heck, the radar gun doesn’t even show you the speed of the slowest vehicle… yet that person is likely the MOST unsafe! (Samuel C. Tignor and Davey Warren. “Driver Speed Behavior on U.S. Streets and Highways.” Institute of Transportation Engineers: 1990 Compendium of Technical Papers, 1990 August, p. 85.
“The accident involvement rates on streets and highways in urban areas was highest for the slowest 5 percent of traffic, lowest for traffic in the 30 to 95 percentile range and increased for the fastest 5 percent of traffic.”)
Ok, so what about the onramps and offramps? You have to slow down for those, right? Very true. This is one of the reasons that the left lane is for passing, and the right is slower for exiting/entering. Again, not so many tickets for lane-laws, are there?
Additionally, on/off ramps have speedup/slowdown sections to allow the cars to speed up and slow down as necessary OFF the highway. Yet, I know in Massachusetts, many such lanes are horribly maintained, horribly short, or simply missing. What’s worse, there are STOP signs on them, totally defeating the purpose of the lane in the first place! Even when there isn’t a stop sign, many dangerous drivers stop AT THE END of these lanes, or simply refuse to speed up to traffic speeds before merging. Again, not many tickets out there for these people, are there?
So, as a win-win, I propose to the LEOs that they go after the unsafe acts that we see every day, and ticket those people more often. That way, you get to continue making your money, AND you make the roads safer. Heck, if you want to be totally lazy, pick an onramp, and just watch the dumb people stopping at the end of it… you don’t even have to move to give them a ticket, and don’t need to point a laser or radar gun at all. I guarantee you can make TONS of money this way, but more importantly, you’ll make it safer for the people on the highway. What a concept.
In other words, there are plenty of ways to improve safety that are going COMPLETELY overlooked.
Lastly, just to reinforce James’ statement above, as well as mine: Keep the emotion out of it, and look at the real data. Speeding does NOT cause more accidents. 85% speed limits are totally safe in most highway cases, because, as you’ll note, most of the people are driving at that speed… and as I mentioned above, if everyone drove at the same speed…
darrel writes:
{ Generally though, officers are aware of the situation and don’t punish the public for poorly marked speed zones. In fact, Myself and other officers that I currently work with, have complained about poorly marked speed zones or enforcement practices.}
You have no idea how rare that is. The overwhelming majority of LEOs working traffic just trigger the radar, flash the lights and write the citation.
{ And in regards to the 85th percentile formula that the article speaks about, try this formula in an area that doesn’t get worked by law enforcement for an extended period of time and see what “safe” speeds the public drives. Its been my experience that most drivers on highways drive at or close to the speed limit. These areas are worked routinely by law enforcement though. If you take law enforcement out of the picture and do your 85th percentile formula to leave it up to the drivers to determine the appropriate speed, you will find that many will drive faster than is safe for conditions, and cause more dangerous driving environments.}
Commonly, approximately half the drivers on the highway drive over the posted limit because the 50th percentile (median) is usually very near the posted limit. A critical characteristic of the 85th percentile is that it is calculated in the absence of enforcement, that is all those drivers that you accuse of near suicidal behavior DON’T do those things. Further, there is emerging engineering data that lead us to believe that on Interstate-grade and rural highways, the 95th percentile is the optimal and safest speed.
{Not everyone anticipates an animal running out in front of them, how many intersections there are, or what’s over the next hill.}
Interstate-grade roadways don’t have intersections and rarely do animals intrude. The risk of a meteor hitting the roadway is very real but we should not build public policy around it.
{Serious injury accidents will also increase. I dont need a statistic to tell me that, I have seen it with my own eyes.}
Your own statistics do not support that assertion, which has been made by the anti-destination league for about 40 years.
Speeds, drivers, vehicles and roads are all increasing; injury crashes are decreasing.
Schwinn you drive a good point. I’ve wondered about this for a long time. I work for a major air carrier and we had a bad crash many moons ago. As part of the investigative team the CO. picked several from our maintenance facility. One was a inspector mechanic. After he finished his assignment and came back on normal duty he was so traumatized it took him several months before he could start doing his job again. He was so afraid to sign anything off. I believe this “human factor” might be a problem as it pertains to traffic enforcement. It may cause an officer to over enforce as a result of some trauma he/she received as a result of working a bad accident. Therefore I’ve always felt that if possible the enforcers and the accident team should be two different parties.
And your right about the zillion miles driven annually across this country under all kinds of conditions with all kinds of equipment and frankly I’m surprised we don’t have more accidents. If all you see are accidents all day long your thinking is going to trend toward this as the norm instead of the exception.
As you so eloquently stated, we must look at the facts and quit making rules and enforcement based on emotions. Lets start with a first class drivers education course for our youth. Something more along the lines of what the Germans do.
And for darrel’s sake in my driving envornment left lane hogs form a whole lot worse safety scenario then speeders but that’s not what gets enforced. It’s the easy pickings, the low hanging fruit …..speeders. On one of these blogs, when confronted, one LEO explained that he believed in his patrol area that rear-enders in rush hour was probably the most prevalent accident he observes. It’s unlikely someone is going to be speeding when creeping along in rush hour traffic. Lets face it, the ratio of accident causation to speeding citations is way out of proportion. Fact is radar just don’t find bad drivers.
LEO or not, you are grossly misinformed. Traffic studies have already been done to show that 85th percentile speeds are SAFER than lower speed limits. Did you even bother to read the article?
Keep in mind, the 85th percentile number is based on FEDERAL studies on HIGHWAYS. This can extend a little bit into major state routes, but no one ever says that this is totally applicable to city streets. So, your argument over intersections and such is moot. Please stay on topic.
As for “anticipating an animal running out in front of them”… that’s silliness. Accidents WILL happen – you can’t eliminate ALL of them. Such is the nature of life. So, whether an animal pops out while you are doing 55 or 75 doesn’t really make much of a difference, since you simply will not be able to predict their actions, nor the ability of the driver to see the action any better at either speed.
The bottom line is, take a look at the highway fatality rates before and after the 55mph NMSL was repealed… people who believed 55 was safer said we would have “thousands more deaths” per year and that the roadways would become extremely dangerous. Guess what – it didn’t happen. Why? Because it’s nonsense.
Sure, you, being an LEO, see only the bad side of accidents, but do you get to see the millions of cars that go by without incident? You need to put these things in perspective, and look at them in the larger picture. Your one or even 10 datapoints are irrelevant in the grand scheme of things, and making a judgement on the entire population based on such a tiny slice of evidence (that is biased because it’s your job to look at accidents) is hardly a scientific study.
I am a LEO, and I can tell you that speed has a lot to do with traffic accidents.
I am not just talking about people going over the speed limit, but those going too fast for conditions. Higher speeds mean less reaction time, less control, and more distance covered in the event a hazard presents itself. I agree, there are areas where the speed limit is incredibly slow. Generally though, officers are aware of the situation and don’t punish the public for poorly marked speed zones. In fact, Myself and other officers that I currently work with, have complained about poorly marked speed zones or enforcement practices. There has to be a standard, or some will take advantage and cause more dangerous driving environments.
You must also remember not everyone has the same driving skills or sense. Some drivers are better or worse than others. And in regards to the 85th percentile formula that the article speaks about, try this formula in an area that doesn’t get worked by law enforcement for an extended period of time and see what “safe” speeds the public drives. Its been my experience that most drivers on highways drive at or close to the speed limit. These areas are worked routinely by law enforcement though. If you take law enforcement out of the picture and do your 85th percentile formula to leave it up to the drivers to determine the appropriate speed, you will find that many will drive faster than is safe for conditions, and cause more dangerous driving environments.
Not everyone anticipates an animal running out in front of them, how many intersections there are, or what’s over the next hill. Serious injury accidents will also increase. I dont need a statistic to tell me that, I have seen it with my own eyes. The only exception to this is obvious conditions, such as weather.Though many speed related accidents occur during inclement weather, when you compare that number to how many drivers are on the road, generally the majority of the public does a good job of policing themselves in driving an appropriate speed.
You will never have a speed limit system that is perfect for everyone.
@P Candida: Besides the fact that your post is totally irrelevant to an article about HIGHWAY speed limits: Slower does not always mean safer. Maybe if people stop jaywalking everywhere, and maybe if people actually LOOK BOTH WAYS before crossing, we’d have fewer accidents, too? But, there is no money in enforcing those laws.
Anyway, regarding the article – I’d love to see more references to this “six times” value that is mentioned in the article. In fact, I advise that you post more references to the actual articles in the future. Now, I realize that this particular one has not been published, but I can’t find any reference at the ITE site, nor at the linked article with NMA headers, to the “6-times” value that is provided in the article…
On average 45000 die in traffic accidents a year in the US. What I would like to see is a device for cars so that it regulates the speed in residential, business and retail districts to 25 mph.
SORRY FOR THE DOUBLE POST BUT I FORGOT.
WHE I DRIVE 50 – 55 MPH ON HIGHWAYS OR PARKWAYS I TEND TO NOD OFF YOU KNOW FALL ASLEEP, IT IS A REAL SRUGGLE TO STAY AWAKE. ITS HARD TO DRIVE WHEN IT IS COLD WITH ALL WINDOWS OPEN TO TRY AND STAY AWAKE.
BY THE WAY THERE WAS A STUDY DONE YEARS AGO THE RESULT WAS THIS ‘WHEN TRUCKERS ARE DRIVING THE OPEN ROAD AT 55 MPH THEIR BRAIN IS IN THE CLOSEST STATE TO SLEEP AS IT CAN BE WITHOUT ACTUALLY SLEEPING’
TRAFFIC SAFETY BULL
SAVING LIVES BULL
PROTECTING THE PUBLIC BULL
WHAT ELSE IT IS ALL BULLSHIT
SIMPLY THESE AND ALL OTHER ‘TICKETS’ ARE PROFIT CENTERS FOR THE CITIES/TOWNS/STATE, THE FEDS HAVE YET TO GET IN ON THIS WINDFALL.
YOU FIGURE IT OUT AT ABOUT $50.00 + A TICKET AN OFFICER DOES ANYWHERE FROM 10 TO 50 A DAY THAT IS $500.00 TO $5000.00 A DAY PER OFFICER(WHEN THEY COULD BE SOLVING REAL CRIMES) MINUS THEIR SALARY YOU ARE LOOKING AT A LOT OF PROFIT FOR TOWNS ETC. WAIT TILL THEY GET LIKE GERMANY (AT LEAST IN THE TICKET DEPARTMENT ONLY) THEY CHARGE SLIDING FINES ACCORDING TO THE WEALTH OF THE OFFENDER HA HA HA HA. GERMANY HIGHEST SPEED LIMITS IN THE WORLD LOWEST ACCIDENT/DEATH ON THE ROADS. GO FIGURE
BUT DONT FORGET ‘PROFIT CENTER’
How do you go about getting limits increased? On both the main roads I travel to work daily, most cars are going 10mph above the posted limit. Can a local agency or gov’t office be contacted? If so, which office? Do they have to honor the request to re-evaluate the posted limits?
EVERY TIME I SEE CONSTRUCTION OF A NEW TRAFFIC LIGHT SYSTEM AT SOME GOD-FORSAKEN INTERSECTION,, I CAN’T HELP BUT WONDER WHICH POLITICIANS HAVE THEIR DIRTY MITTS IN ON THE COMPANY(S) WHO SUPPLY THOSE DAMN THINGS.
SEEMS TO BE A VERY LUCRATIVE BUSINESS TO BE IN ON. AND WHO BETTER THAN TO STEER OUR MONEY IN THAT DIRECTION. WONDER IF ANYONE HAS EVER DELVED INTO THAT SITUATION???