RE: Final Report 551: Actual Speeds on the Roads Compared to the Posted Limits October 2004

Prepared by:

Sherry L. Skszek

505 N. Tanque Verde Loop Rd.

Tucson, AZ 85748


Rebuttal by,

Charles E. Dornsife, Founding Director

Best Highway Safety Practices Institute

December, 2004


To Sherry L. Skszek,

Yes this is a rebuttal to a purported finding of fact. A report that if it recommendations and conclusions were to be actually used as policy for setting speed limits and/or enforcement policies by anybody, ever, we would all loose.

Your name is on this, and yes you just stepped on a landmine in the battle between best practice and special interest.

Rather than focusing on the good data published here: the actual speeds as compared to the posted limits, a survey of existing practices, and the implied research into the actual causes of accidents - which was not done at any locationŠ and the conspicuous by it absence mention of the governing federal law regarding how speed limits should be set or an explanation on why Arizona had not complied with these mandates. Significant omissions, no, for the same reason the other 49 states are getting it wrong – the lack of FHWA oversight! So if the US DOT already knows the answer, why this study?

The why is responsible for the very tone of this effort as commissioned by the US DOT. Did the people participating in it know they were being used, I donıt think so. Nevertheless the US DOT wanted a report that delved into social engineering, urban myth, mixing faux research at face value and referenced inappropriate related statistics to dilute best practice. The ²why² it preordained speed as the leading safety problem on our highways; there is an overwhelming need to control an out of control public by subjecting them to more efficient ways to fine their otherwise safe driving, with photo radar?

My question would be, why did you rely so heavily on publications supplied by and/or sources that are infamous for using grossly misstated data as fact; NHTSA, IIHS, as well as the byproducts of this influence, the TRB report. The cited TRB is a classic example of the direct correlation in a finding, to the source of its funding and/or sponsor (NHTSA this time). I have first hand knowledge of this report, why and how it was initiated, the process and how its outcome was controlled.

Moreover if 48 states that replied to your survey are setting speed limits wrong, it is of great interest to have this documented, but the engineering body of knowledge already has the answer on how we should post speed limits. In fact, this ³best practice² made it into the Millennium Edition of the MUTCD, Section 2B.11, Speed Limit, based solely on an engineering study, applying best practice, and the starting should be the 85th percentile speed raised to the next 5 mph increment! If the engineer thinks it is warranted because speed limits are not required under federal safety standards if they provide no safety benefit. This is the standard by law that we are supposed to be applying. The FHWA even offered grant money to get posting authorities to apply it, to no avail. And none of these major relevant facts were mentioned at the Speed Limit Workshops either, workshops cosponsored by NHTSA. Wonder why, it was relevant, and it is the law?

The ³why² we arenıt applying it is because those professionals whom under law have been given this responsibility, havenıt been given the power to act and worse yet, where removed from standards oversight. Therefore our unsafe roads are a matter of choice by the systemıs overseers. And your report appears to have been commissioned in manner to solidify their powerbase, and the unsafe practices needed to sustain these efforts.

This is why it is extremely important that reports like this have someone in charge that understands who the players are; and more importantly, the legacy of the information being referenced.

Case in point, place subject matter of choice in between the GAO quotes and the following best describes NHTSA in regards to everything it produces on highway traffic safety issues, universally untrustworthy or distorted to garner attention via large numbers.

US GAO Quote on NHTSA practices: Š²While NHTSA characterized the studies as conclusively establishing² ... &ldquo:The studies had limitations and raised methodological concerns calling their conclusions into question or reported mixed results."

What the GAO didn't say publicly would be even more troubling to Congress and the We the People, is that NHTSA (US DOT) simply quashes research initiatives and/or withholds from discourse those studies that do not support their agenda. Dissenting views are not allowed or are they ever posted on their subject matter resource sites.

NHTSAıs charter of protecting the citizens on the Nationıs highways was short lived. In the early 70ıs, after it became the lead advocate for National Maximum 55 mph Speed Limit, it metamorphosing almost immediately into a propaganda agency whose constituents were its own self interest first, then the enforcement agencies, courts, government entities and insurance companies whom profit from these enterprises.

In quoting or referencing materials from an agency, it is helpful to under stand its legacy, self-interest, and primary function in the area you are researching. The NHTSA Traffic Law Enforcement Division is staffed with officers on detail from their respective agencies learning how to write and administer enforcement grants, and coming up with new programs.

NHTSA "Traffic Law Enforcement" (TLE) Division

The Traffic Law Enforcement Division anticipates and responds to the needs, and develops innovative products that law enforcement will seek and use to reduce traffic crashes, deaths, and injuries. This is accomplished by collaborating with law enforcement, prioritizing program delivery, marketing, expanding partnerships, and establishing new partnerships, technology, and research.

NHTSA in support of its TLE Division, has an ad agency that is under contract to aid in inventing crises, funding studies or institutions to produce forgone supporting results, launch press campaigns to build public consensus that something must be done, and then the need to intervene, the PR materials for launch, its time schedules and strategies. At launch, each agency that signs up to participate is rewarded money, equipment and supplemental income opportunities for its officers.

This is a billion dollar industry and those in charge are true professionals at shaping public opinion, and are not to be underestimated! Does this look like what you were commissioned to produce here, a study to support a new initiative on speed enforcement; an outcome that will assist in the elimination the 85th percentile, reasonable limits, as the primary consideration? It sure does to me.

This type of subterfuge is not new to Arizona either. In 1995 NHTSAıs Road Rage effort got headlines but didnıt solve their problem. Even though the NMSL was repealed, the equipment and infrastructure was still in place, so their agency came up with new marketing initiatives: &ldquo:Aggressive Driving² and ²Zero Tolerance². Problem #2, aggressive driving, the replacement for road rage, required new state laws to be viable, and here in 1998 Congress had just barred them from lobbying the states to promote their agendas.

Here is how they solved this dilemma; if they were barred from lobbying legislatures the agencies within the TLE were not. So they provided a substantial cash reward/bribe offer to the Arizona Department of Public Safety if they could get an aggressive driving law passed. They simply bought a poster child to sell this programıs viability to other states.

Arizona legislators apparently couldnıt discern fact from fiction either, so they passed a bad law because they were mislead by an in depth organized effort as presented to them by a clean cut ADPS officer; complete with printed materials and slide shows expounding false facts, supplied by NHTSA. All proscribed acts - to pass a new law; speed enforcement with a new name, look, increased penalties and money from Congress for all.

Sidebar: Irony of ironies, when I went through the presentation at a regional transportation meeting, I asked a question about some of the obvious misstatements and unfounded assertions, and the ADPS officer making the presentation asked me seriously, are you with the AZDOT? I answered no, why? His answer, because they had the same objections!

The Transportation Equity Act for the 21" Century (TEA-21), which was enacted in 1998, included a new lobbying restriction that prohibits the use of NHTSA funds for:

any activity specifically designed to urge a State or local legislator to favor or oppose the adoption of any specific legislative proposal pending before any State or local legislative body.

This restriction imposes additional lobbying restrictions on NHTSA, such as by prohibiting agency officials from:

Visiting or sending letters to State or local legislators, urging them to favor or oppose specific State or local legislation pending in those jurisdictions; or

Developing and providing to anyone (including lobbyists) materials developed specifically to advocate for the enactment or repeal of specific pending State or local legislation.

Here is another example from the Federal Register in 1995 citing a NHTSA notice where they explicitly refused to condition speed enforcement aid on reasonable speed limits. This mindset is pervasive throughout this agencyıs actions.

&ldquo:The agencies have not adopted West Virginia's suggestion to include a statement that enforcement funding be preceded by engineering evaluations of existing speed limits. To do so would hinder enforcement efforts, based on a blanket presumption that existing speed limits are not reasonable. The agencies are neither willing to accept that presumption nor to place conditions on enforcement efforts, which we view as a vital tool for effective speed control.²

This comment related to adoption of the "speed control" guidelines and their use of the word &ldquo:presumption² was, at best, duplicitous. Why? When this statement was made in the federal register, NHTSA had also been aggressively impeding the publication of the largest body of work/research ever done on &ldquo:The Effects of Raising and Lowering Speed Limits². This study, which was initially published in 1992, took 7 years to compile, with 3 years of before and after data being collected at each site, on sites spread throughout 22 states. And in 1995 when this federal register entry was made it still hadnıt seen the light of day. In fact, those with copies were being threatened with job sanctions if any more copies of the 1992 version were distributed.

This study was published only after the author was ordered/agreed to change the conclusion to a very misleading, innocuous one, thereby quashing the significance of his findings. It was changed from showing an &ldquo:overall increase in accident rates when limits were unreasonably lowered², and an &ldquo:overall reduction when they were raised to reasonable levels² to &ldquo:changing limits had no affect on accident rates².

We have both versions of this report, the only large scale research project done in modern times that looked into the relationship between speed, speed limits and accident rates; and it found the exact opposite to be true from what this AZ report purports to be fact!

The real tragedy here is after the Parker study content ramifications became apparent, NHTSA immediately implemented plans to never let something like its result ever happen again, and they have succeeded!

Here is an outtake from a study that was spawned by a state that wanted to verify its practices after it participated in the Parker study, amazing this isnıt in the US DOT subject matter database either.

Nebraska Department of Road, NDOR

University of Nebraska Lincoln,

Department of Civil Engineering College of Engineering and Technology:

Research Report No. TRP-02-26-92

Evaluation of Lower Speed Limits on Urban Highways:


The results of the analysis of the accident experience in speed zones indicate that zones with posted speed limits equal to the reasonable speed limits proposed by the NDOT method of speed zoning are safer than zones posted with limits that are 5 and 10 mph below the reasonable speed limits. Speed zones with speed limits 5 mph below the reasonable speed limits were found to have 5 percent more accidents than zones with reasonable speed limits. Speed zones with speed limits 10 mph below the reasonable speed limits were found to have 10 percent more accidents than zones with reasonable speed limits. Therefore, the speed zones on state highways in urban areas should be posted with reasonable speed limits proposed by NDOR method in order to minimize the numbers of accidents in the speed zones. Speed limits lower than the reasonable speed limits should not be posted.²

Nationally accepted practices:

Are those practices that are articulated as standard or guidance within the national MUTCD or adopted by reference therein. Adopted by reference are those that have been peer reviewed, accepted as guidance or recommended by AASHTO, FHWA and the ITE etc. It is not the personal opinion of an engineer or local practice, the engineerıs duty is to apply accepted national practice to the best of their ability and be able to articulate which practice they applied and why.

Here are a few guidance examples, most &ldquo:missing in action² in the subject matter database;

Federal Highway Administration

Report No. FHWA/RD-85/096 Technical Summary, "Synthesis of Speed Zoning Practice" which states:

"Based on the best available evidence, the speed limit should be set at the speed driven by 85 to 90 percent of the free-moving vehicles rounded up to the next 5 mph increment. This method results in speed limits that are not only acceptable to a majority of the motorist, but also fall within the speed range where accident risk is lowest.²

&ldquo:No other factors need to be considered since they are reflected in the drivers speed choice.²


A 1969 &ldquo:Resolution of the annual meeting of the American Association of State Highway Officials²

&ldquo:The review of existing practices revealed that most of the member departments use, primarily, the 85th percentile speed. Some agencies use the 90th percentile speed, and of secondary consideration are such factors as design speed, geometric characteristics, accident experience, test run speed, pace, traffic volumes, development along the roadway, frequency of intersections, etc.²

&ldquo:On the basis of the forgoing review, the Subcommittee on Speed Zoning recommends to the AASHTO Operating Committee on Traffic for consideration as an AASHTO Policy on Speed Zoning that:

The 85th percentile speed is to be given primary consideration in speed zones below 50 miles per hour, and the 90th percentile speed is to be given primary consideration in establishing speed zones of 50 miles per hour or above. To achieve the optimum in safety, it is desirable to secure a speed distribution with a skewness index approaching unity²

Institute Of Transportation Engineers; (urban highways)

ITE Committee 4M-25, Speed Zone Guidelines:

&ldquo:Thus, the overriding basis (from a safety perspective) for speed zoning should be that the creation of the zone, and the speed limit posted, results in an increase in the percentage of motorists driving at or near the 85th percentile speed.²

&ldquo:A third rationale is the need for consistency between the speed limit and other traffic control devices. Signal timing and sight distance requirements, for example, are based on the prevailing speed. If these values are based on a speed limit that does not reflect the prevailing speed of traffic, safety may be compromised.²

&ldquo:2. The speed limit within a speed zone shall be set at the nearest 5 mph increment to the 85th percentile of free flowing traffic or the upper limit of the pace of the 10 mph pace.² &ldquo:In no case should the speed limit be set below the 67th percentile speed of free flowing traffic.²

1990 ITE PUB# PP-020 (sponsored by FHWA and AASHTO)

&ldquo:It would be premature to draw any firm conclusions since the research is still underway. However the findings to date suggest that, on average, current speed limits are set too low to be accepted as reasonable by the vast majority of the drivers. Only about 1 in 10 speed zones has better than 50 percent compliance. The posted limits make technical violators out of motorists driving at reasonable and safe speeds.

For the traffic law system to minimize accident risk, then speed limits need to be properly set to define maximum safe speed. Our studies show that most speed zones are posted 8 to 12 mi/h below the prevailing travel speed and 15 mi/h or more below the maximum safe speed. Increasing speed limits to more realistic levels will not result in higher speeds but would increase voluntary compliance and target enforcement at the occasional violator and high risk driver.

One way for restoring the informational value of speed limits requires that we do a better job of engineering speed limits. Hopefully, the result of this research will provide engineers with the knowledge and tools needed to set maximum safe speed limits that are defensible and accepted by the public and the courts.²

There was another study done on urban interstates in Indiana where the researchers were trying to determine if you should set speed limits at the 85th raised to the next 5 mph increment, or the 90th percentile raised to the next 5 mph increment. The conclusion was the 85th raised to the next 5 mph increment as the best solution for urban interstates. This too is no longer distributed or available? All I have left is photocopied excerpts.

Or maybe the states got it wrong too, maybe, but at least the engineering portions of their websites got it right.

Chapter 8, California State Traffic Manual:

&ldquo:Speed limits established on the basis of the 85th percentile conform to the consensus of those who drive highways as to what speed is reasonable and prudent, and are not dependant on the judgement of one or a few.²

&ldquo:Further studies have shown that establishing a speed limit at less than the 85th percentile (Critical Speed) generally results in an increase in accident rates.²

Washington State DOT website:

"people don't automatically drive faster when the speed limit is raised, speed limit signs will not automatically decrease accident rates nor increase safety, and highways with posted speed limits are not necessarily safer than highways without posted limits.

When compared to the unanimity of all prior engineering findings, and the law - MUTCD, the following from your report highlights how wrong a conclusion outcome can be when pseudo research and irrelevant related data is given equal value to actual research.

While there is no clear consensus on the impact that raising or lowering speed limits has on the number of crashes; studies seem to show number of crashes decreases when speed limits are lower and the number of crashes increases or remains unchanged when speed limits are raised.

Another interesting sidebar to limits set too low, and severe unintended consequences: According to the FHWA's own data &ldquo:Work Zone² fatalities are up 52 percent since the double fine and hyper enforcement practices have been implemented. That kind of increase should demand that traffic safety officials stand down this new widely promoted practice, and reevaluate what best practice really is! Nope, that is not an option because it is extremely popular, so we are expanding this practice? At what real cost in lives we ask?

If you read the Parker Study you apparently didnıt understand the charts because if you had, you would have noticed the disparity between the data and the conclusion. Luckily for those who do engineering research, they left his data and charts unaltered. The chart below and the others in the report speak for themselves.

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One question, if in excess of 90 percent of the motorists are exceeding a posted limit, then what function does the value posted represent. Particularly when engineering 101 says the public consensus as to what is safe is determined by measuring their actions, as opposed to the opinions of one or a few. Meaning well in excess of 90 percent of the drivers in Arizona have voted by their actions that the limits are set unreasonably low on some sections of your highways, and that they have no merit from a safety perspective.

In this paper you represented the traffic engineering community, Traffic Engineers are not Social Engineers. Instead of placating the uniformed, they must attempt to educate them regardless of how daunting a task this may appear.

They are licensed professionals and their profession demands that they apply vetted best practice as determined by their professionıs body of knowledge. Itıs important also because under federal law if they do otherwise as licensed engineers they can be held personally liable, though this is rarely done. Each roadway needs to be examined on its own merit: accidents, prevailing speeds by time of day, signage and delineation, flow conflict/friction points, site distances, special conditions etc.. Then the engineer is to review the data and the site to ascertain the problems and potential remedies, and then they are to apply &ldquo:nationally recognized² best practices.

Here is the crux of the problem, determining what best practice is has become a serious challenge because the process is no longer under the control of engineers or their institutions. Their sources have been hijacked by special interest groups that have been exchanging at will best practice with unfounded conjecture, read unsafe practices.

When vetted best practice is applied accidents are significantly reduced, yet we do not fund these efforts. Worse, we have been spending literally billions on NHTSA programs that either have zero, or negative effects. Moreover, because best practice represented a clear threat to NHTSA programs, the US DOT in violation of their charter removed key elements from the FHWA federal standards, so that there is no longer any safety standards to met. And since the 1990ıs, all new research has had forgone agenda driven conclusions built in which are designed to further undermine engineering best practices.

NHTSA now decides what traffic engineers can study and/or report on in regards to speed limits, including sponsoring regional best practice speed limit conferences that contain no factual engineering findings or subject matter experts. And for those that do speak out - retaliation!

The following statement cost renowned researcher Julie Ann Cirillo her jobŠ she was demoted/transferred after this!

In an interview in the June/July, 1999 issue of LANDLINE, the magazine of O.O.I.D.A., Julie Cirillo, new program manager at the FHWA Office of Motor Carriers and Highway Safety, said,

" . The more you have differential speed the more you have accidents.

.... We have fallen into a situation where for a variety of reasons we are setting speed limits that are not realistic. They are setting speed limits that are too low. We're legislating them, and once you legislate speed limits, invariably the speed limit is at about the 50th percentile. So, here you have a traffic regulation that's enforceable by law and half of the people are exceeding it when you put it in place. That makes no sense to us. So, what we're trying to do is get the states to agree that they will set speed limits in accordance with the 85th percentile, which is where most people travel. Most people are sane. Most people will not put themselves in undue hazard. . . .

. . . We have deteriorated the value of speed limits and now find the disregard for speed limits is spilling over into other traffic-control devices -- disregard of red lights, disregard of stop signs.

If we have any hope of moving the population back to where it ought to be, we have to set reasonable speed limits."

Sidebar on Julie Ann Cirillo study:

The thesis of the day that she was trying to document that there is a direct correlation between speed differential and accident rates. On urban interstates her charts show that the vehicles traveling 12 mph faster than the mean of the flow had the lowest accident rates, least likely to be involved.

An incongruity of outcome, if in fact speed differential is the threat it is professed to be. I also found similar problems with Solomon that made me reevaluate this thesis of risk for the above average speed vehicles, and speed differential accidents. In all studies the faster moving vehicles were the least likely to be involved, likewise with the 85th percentile rule which is also the safest speed, so the question became what is the real source of the collisions?

After examining her data I came to a very different conclusion, and here is how I stated it in 2001,


By Chad Dornsife, 8/11/2001;

&ldquo:Since the 70ıs studies on the effects of the 55 mph limit documented speed enforcement has no long-term effect on speeds or accident rates. The presence of a police vehicle only temporarily slows traffic regardless if theyıre writing a citation or not. Traffic immediately returns to the speed they are most comfortable with as soon as the threat is perceived to be gone.

In terms of accident risk, there is a direct correlation between accident rates and flow conflict points - converging highways and interchanges. The accident rates at these locations are primarily a design question regarding methods used to allow traffic to egress and ingress into the stream or converge. If they are too close to each other, rates increase exponentially. Once the traffic stream clears these conflict points, accident rates drop precipitously.

The speed of traffic is self-regulating, flow becomes uniform as congestion increases and the speed of traffic is not effected or influenced by posted speed limits nor are the nature and type of accidents that do occur.

Conversely, when the conditions become light, you do see increases in speed differentials, and during these light free-flowing periods, accidents for any reason drop to negligible rates. Also during these periods of the lowest risk is when the bulk of the citations are written which leads us to this safety conundrum. If a hundred percent of your assets are targeted at virtual zero causes – safest drivers, on the safest highways, on the sections where accidents for all reasons are low. You canıt escape the fact that sum of these efforts can never exceed zero effect.² (Automated or not!)


Source of accidents: In addition to this and the poor design legacy of most rural highways, universally traffic control throughout the nation on urban roads is not set to meet the needs of traffic. We have the money to enforce traffic laws on these roads, but we donıt have the money to do the safety audits/engineering studies to quantify the safety problems, let alone the money to correct the unsafe traffic control or unsafe locations: delineation, guard railings, attenuators, warnings, sight distance etc? We do have the money to repaint the striping, but no funds to correct when and where it should be painted? We know that another leading cause is fatigue and sleep deficit, but we donıt have the money to keep the rest areas open? Our unsafe roads are a matter of choice!

Primary Engineering Tenets and Rationales in regards to Speed Limits:

The following is an excerpt from a speech given to engineers about their responsibilities in establishing proper and realistic speed limits. The following was accredited to Mathew C Sielski; bestowed the highest honor that the Institute of Transportation Engineers can give for lifetime achievement to their profession. The often-quoted text below can be found in many state DOT handouts and websites.

&ldquo:One of the most important responsibilities of traffic engineers is the establishment of proper and realistic speed limits. Our profession has long recognized that most citizens will behave in a reasonable manner as they go about their daily activities.

Thus, traffic laws that are based upon behavior of reasonable motorist are found to be successful. Laws that arbitrarily restrict the majority of motorist encourage wholesale violations, lack of public support, and usually fail to bring about desirable changes in driving behavior. This is especially true of speed limits².

&ldquo:Our profession, since the early 30ıs, based its speed zoning techniques on several concepts deeply rooted in our American system of government and law, namely:

1. Driving behavior is an extension of our social attitude, and the majority of drivers respond in a safe and reasonable manner, as demonstrated by their good driving records.

2. The careful and competent actions of a reasonable person should be considered legal.

3. Laws are established for the protection of the public and the regulation of unreasonable behavior of an individual.

4. Laws cannot be effectively enforced without the consent and voluntary compliance of the public majority.²

&ldquo:Our profession also recognizes that an emotionally aroused public will reject these fundamentals and will rely on more comfortable and widely held misconceptions, such as:

1. Speed limit signs will slow the speed of traffic.

2. Speed limit signs will decrease accidents and increase safety.

3. Raising a posted speed limit will cause an increase in the speed of traffic.

4. Any posted speed limit must be safer than an unposted speed limit, regardless of the prevailing traffic and roadway conditions.

Before and after studies have proven conclusively that these are definitely misconceptions. Unfortunately, in too many instances influential pressures succeed in the application of such unrealistic regulations.²

Here are the guidelines, per my compilation of all research regarding best practice in establishing speed limits.

Guide to choosing the numeric value of regulatory speed limits (R2-1, R2-2):

Prima facie: The average of the 24-hour free-flowing speed.

Absolute: The highest two-hour segment of the 24-hour free-flowing speed.

Free flowing: Minimum 4-second headway, no vehicle queues, 500 Πfrom flow impediments and no vehicles impeded within zone.

Contiguous sections: Minimize speed limit changes, set limits at predominate prevailing speed uniformly for all the included segments.

Measurement method: Not apparent to vehicles being monitored, measuring 24-hours of traffic. Radar/lidar subjective, sample too small, known to reduce registered speeds, measurement angles greater than 15 degrees unusable.

Interstates/Urban: 85th rounded up to next 5 mph increment.

Interstates and Secondary Highways/Rural: High volume highways 90th rounded up to next 5 mph increment; on low volume highways there is no justification for speed limits unless an accident pattern is present that speed limits would reduce.

Highways, business districts and arterials: 85th or upper end of pace speed rounded up to the next 5 mph increment, but in no case less than the 67th.

Minimum: 10th percentile or bottom of pace rounded down.

Residential, hospital, parks etc: 85th rounded down to the next 5 mph increment but in no case less than the 67th.

Truck: No separate limits, not to exceed 75 mph maximum. Exceptions, special limits on downhill sections or grades determined by that locationıs experience or design features. Generally it should begin at onset of the grade and shall end when the grade no longer presents a runaway vehicle threat. Ideally on grades trucks should be restricted to special slow vehicle lanes and on all other highways the right two lanes except in convergence zones, or when directed otherwise by traffic control devices. Also there are special limits needed on some bridges where weight is a factor, post accordingly.

Suggestions and observations:

Minimum speed limits need to posted on some the major roadways, &ldquo:slower traffic keep right² needs to be emphasized, and dedicated lanes need to be built on grades for slow moving vehicles because on some of your highways the slow vehicles represent a clear and present danger. Minimum speed limits have been shown to reduce dangerous overtaking and accident rates.

Safety is found in flow management and assuring that motorists are informed in a timely manner as to the conditions ahead, exits et al and/or hazards – for the speeds they are driving!

Flow conflict points are where the majority of your preventable accidents occur; examine all locations as to remedies to reduce flow friction and improve guidance.

The truth is of those accidents that are preventable, engineering solutions represent the only true solutions because enforcement has proven to be ineffectual or a negative. You cannot correct a design error with enforcement. If there is a problem area, then the engineer needs to act on it to determine what is contributing to the problem, what remedies may be indicated to correct it, and then place it on the action list accordingly.

Fact: those traveling faster than the average, regardless of roadway classification, have the lowest accidents rates. The 85th percentile is the safest speed yet it is the primary target of enforcement too? Focusing our scarce resources on those that are the least likely to be involved on our best roadways is pure folly and will never reduce accident rates. Particularly when by definition to be speeding their path has to be unencumbered or they are traveling with the flow, exhibiting lowest risk behavior.

Conversely a slow moving vehicle creates flow conflict and chaos for its entire trip and these uniformed or passive aggressive drivers are clearly the highest risk to public safety. And this unsafe behavior is lauded? Slow driving DOES NOT equate to safer driving!

Maximum speed limits DO NOT meaningfully affect driver behavior as to speed choice, but the expectation of higher speed traffic does affect driver behavior and travel lane choice, resulting in fewer flow conflicts and lower accident rates. Contemporary real world examples were documented in Montana and on the German Autobahn. Whereas under posted limits result in greater flow friction and conflicts, and improperly applied (unsafe) traffic control - to the detriment of safety.

It is the traffic engineer's responsibility to determine what this safe for conditions public consensus is by recording their actions, and to assure that the traffic control meets that need.

In regards to some the reports showing high before and after results from speed limits changes, a few of the cited studies used divergent data, data that wasnıt collected with the same criteria. Whereas I have before and after data that was collected by the FHWA on interstates showing before and after speeds by time of day, 85th, average, volumes, all traffic and free flowing et al, by vehicle classification. It was amazing how stable the before and after data was, regardless of where it was collected in the nation. Likewise for the locations they tracked before and after to be used as controls for trends where the limit wasnıt changed.

As for the studies that claim small increases in speeds after a change in limits, a portion of this is natural creep that has been going on since the automobile was invented, about ½ mph per year. An unrelenting phenomenon that continues unimpeded even in the face of decades of hyper enforcement of systemic unrealistic low limits.

1966 Law, Best Guide for 21st Century

Safety and Setting Speed Limits

By Charles E. Dornsife

Presented to TRB Speed Limit Workshop

Transportation Research Board Annual Meeting

Workshop - Restoring Credibility to Speed Limits:

Washington D.C., January 9, 2000

The 1966 law was the &ldquo:Highway Safety Act of 1966²

&ldquo:In 1966, Congress passed a law that required all traffic control devices on public roadways in the nation be based on sound engineering principles, practices and have a common &ldquo:basis in fact² determination, appearance and application. These mandates are found in Title 23, United States Code, Section 109(d) and Title 23, Code of Federal Regulations (CFR), Part 655.601 through 655.603. The MUTCD (Manual on Uniform Traffic Control Devices) is where these requirements are specified.

The goal was to return safety decisions to those that base their decisions only on findings of fact that have proven to make us safer; with uniform nationwide continuity of meaning and expectation. They expanded the FHWA domain over construction of the nationıs highways to include all traffic control on them. Entrusting this responsibility solely to the licensed traffic engineering professionals and their institutions, because the tenets of their profession require studies to test a thesis, peer review and verification before a standard, practice, procedure or principle can be incorporated into their engineering body of working knowledge.

This law outlawed the old practice of each political entity in the nation, based on local tradition or conjecture, deciding the appearance of &ldquo:traffic control devices² and what, where and how such devices would be used in their town, county or state.

In describing where the process went wrongŠ

&ldquo:After 25 years of enormous cost to the nation, NHTSA created an Urban Myth that equated lower speed limits with safety. The evidence at every stage of the process was indicating neither speed limits, nor their enforcement had any meaningful effect on traffic speeds and accident rates.

Speeds have been going up and accident and fatality rates have been going down and they have continued to do so since the automobile was invented – year after year the speeds continue to increase and the death rate falls.

The public after 25 years propaganda has accepted the slower speed equates to safety myth; but assume it is targeted at the other crazies because when they drive over the posted limit they are driving safely – which they are.²

&ldquo:This speed myth that NHTSA created has become so pervasive that traffic engineers trying to do what they know is best (raising limits to reasonable levels), are vilified and attacked by politicians, the press and citizen groups demanding lower limits because they wrongly believe they are safer.

It is time to accept the fact that increases in speed is the natural byproduct of advancing technology. Therefore, the focus needs to be on flow management and making sure traffic control devices are only used when they have a real expectation of accomplishing their desired effect.²

The problem here is the assumption of this paper, which assigns speed in and of itself as the leading safety villain, whereas the true object of the exercise should have been to reduce accidents while improving flow. Each location should have been examined on its own merit by dispassionate researchers applying their professional skills to ascertain cause and contributing factors. This project appears to have been funded to show speed as the preordained villain, rather than a site-specific determination as to what part speed (related to a speed limit and its enforcement could alter) contributed to the accidents.

Moreover using the R word (speed related) has no place in the report when there is no direct correlation with the facts. It is used to inflate statistics and for dramatics. When you look at the accident data in regards to posting speed limits, excessive speed is only relevant when that event involves a vehicle that was exceeding the prevailing speed of traffic, during optimum traffic conditions and this act caused the accident – posted speed limits are for free-flowing optimum conditions!

There is something here you can really be proud of; your survey of the states documented how dysfunctional the FHWAıs stewardship of best practices has become. With the adoption of the 1988 MUTCD, Title 23 mandated national uniformity in traffic control standards: uniform appearance, application and expectation on all roads open to public travel regardless of jurisdiction type or classification. You had 48 responses, and 48 divergent answers applying local practice, not counting the tens of thousands other posting authorities in the US and its territories the MUTCD covers, all each doing their own thing too. With no evidence whatsoever that a uniform national standard is in effect 18 years after each state began certifying compliance on all roads open to public travel regardless of jurisdiction type or classification, in exchange for federal highway funding.

None of the states in the survey is in compliance with this safety mandate, some are closer than others, but none comply. And as best as we can determine, this is greatest cause of fatalities and injuries we have.

Since the FHWA took over stewardship of the MUTCD from the NCUTCD, their championship of best practice has been a complete failure. Unsafe practices and conditions are your greatest threat as a motorist, not speed, drunk drivers, road rage et al and these unsafe conditions couldnıt exist, except with the acquiescence (inaction) of the US DOT. In 2004 AAA estimated 5000 preventable deaths a year from poor engineering practices, we believe this is too low a number, particularly when you add in the omnipresence legacy of poor roadway design.

Worse these poor design elements (killers) are still being built into projects under construction today, SAFTEA increases funding for unsafe practices that increase both accidents and pollution. And more billions were earmarked for ineffectual programs to support political/agency constituencies, while true safety programs only received token attention. Why? This bill was called $AFTEA, not Safety!

Therefore the only conclusion one can come to is our unsafe roads are a choice by the US DOT and politicians whom control the funding, they're your number one killer, not the motorists. I see &ldquo:We the People² as a pawns whose lives have become fodder for special interest.

Sorry to say it, but your report has all the earmarks of a program that was explained to me some time ago that was going to be sponsored by the US DOT. FHWA researchers working under NHTSA were discussing the funding of this new research in the near future.

The very wording of this effort preordained speed as the villain, and it really wasnıt structured to document the source and nature of accidents, by lane, location and contributing factor.

An approach I objected to at the time because it was another obvious effort to further degrade best practice to support of the enforcement constituencies. Rather than providing helpful information, it would provide none, but would reinforce enforcement justifications? If this isn't the case in your report I apologize, but quite frankly I can't tell the difference.

Here is some food for thought from my 2001 Montana Paradox follow up regarding enforcement:

&ldquo:Notice of Defect is defined below. It is very clear in its meaning. Just because a minimum statutory requirement has been met, if by any means a problem becomes known to the engineer or agency, it is their professional duty to examine and mitigate it with the tools they have available through their application of engineering judgment; applying those nationally accepted practices that have been identified that may meet this need.

Traffic Control Devices Handbook, 1983, FHWA, "Notice of Defect

"An agency has a duty to correct a dangerous condition when that agency has actual or "constructive" notice of the hazard.²

Taking advantage of the Notice of Defect, another obvious method of identifying and reporting otherwise unknown problem areas became apparent - via an electronic citation database. The following email spawned the idea.

From, Bernard J. Michel, To: FHWA

&ldquo:If you are at all familiar with industrial practices you will recognize the truism that ŒYou canıt inspect quality into your product. It must be designed in.ı If safe highways are your product, then enforcement is your inspection. I maintain that properly designed and engineered speed limits and signal timing are the right long term solution.²

Couldnıt agree more. All literature regarding highway safety refers to the 3 Eıs: Engineering, Education and Enforcement. Enforcement as utilized provides little safety benefit except in flow impediment mitigation, but in this there is an untapped opportunity to improve safety. Itıs called, Notice of Defect via Enforcement. Traffic officers are tasked with writing citations and they readily find the easiest place to write citations in their respective beats. The norm of these locations is an under posted limit, confusing traffic channelization or some other engineering defect. Therefore any location that produces noticeable repetitive citations be deemed a probable engineering &ldquo:Notice of Defect², to be reviewed.²

Thanks again for the informative data, it will be very helpful. It quantifies our observations. Our effort to return traffic control to licensed professionals needs all the hard data we can find.


Charles E. (Chad) Dornsife, Founding Director

Best Highway Safety Practices Institute

673.1926 San Diego Office

800.708.5723 Fax                  

775.721.2423 Cell