The effectiveness of speed traps - No Dosh {P}   Mon 27 Oct 03 21:06

>> btw I seem to recall that Idris Francis contributed to this >> site some time back? Didn't he suffer a rather hostile or >> doubting reception? Around the Bogush era I think... >> I think Bogush was the hostile reception

The effectiveness of speed traps - Mark (RLBS)   Tue 28 Oct 03 06:32

Actually I think it was me.

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The effectiveness of speed traps - Dynamic Dave   Tue 28 Oct 03 10:18

I think nearly everybody was hostile toward Bogush because of his eccentric and political views; and no doubt part of this thread will end up being replicated in his own forum.

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Eccentric views?

Yet another "expert" who doesn't know about the 85th percentile speed limit.

So "eccentric" are my views that they are shared by all true traffic engineers the world over.

And, as Arizona State says:

WHY SPEED LIMITS?

Since most citizens can be relied upon to behave in a reasonable manner as they go about their daily activities, many of our laws reflect observations of the way reasonable people behave under most circumstances. Traffic regulations are invariably based upon observations of the behavior of groups of travelers under various conditions.

Generally speaking, traffic laws that reflect the behavior of the majority of vehicle operators are found to be successful, while laws that arbitrarily restrict the majority of drivers encourage wholesale violations, lack public support, and usually fail to bring about desirable changes in driving behavior. This is especially true of speed zoning.

Speed zoning is based upon several fundamental concepts deeply rooted in our American system of government and law.

1. Driving behavior is an extension of social attitude, and the majority of drivers respond in a safe and reasonable manner as demonstrated by their consistently favorable driving records.
2. The normally 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 on the part of individuals.
4. Laws cannot be effectively enforced without the consent and voluntary compliance of the public majority.

Public acceptance of these concepts is normally instinctive. However, the same public, when emotionally aroused in a specific instance, will often reject these fundamentals and rely instead 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 the accident rate 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 traffic and roadway conditions prevailing.

PS For those that missed it, those last four items were:

Misconceptions !

"Before and After" studies consistently demonstrate that there are no significant changes in traffic speeds following the posting of new or revised speed limits. Furthermore, no published research findings have established any direct relationship between posted speed limits and accident frequency, although short-term reductions have resulted from saturation enforcement efforts directed at speed and other traffic law violations.

Police agencies necessarily rely on reasonable and well recognized speed laws to control the unreasonable violator whose behavior is clearly out of line with the normal flow of traffic.

Contrary to popular belief, speed in itself is not a major cause of accidents. In fact, there is a consensus of professional opinions that many speed-related accidents result from both excessively low and high speeds.

It is accepted within the traffic engineering profession that there is a demonstrated need to produce as much uniformity as possible in the traffic flow and to eliminate the so-called speed trap. A speed trap may be defined as a street or road which is wide enough, straight and smooth enough, and sufficiently free of visibility limiting obstructions to permit driving a certain speed, but where the law nevertheless calls for a much lower speed.

 

Or:

"Comparison of Speed Zoning Procedures and their Effectiveness: Final Report."

Michigan Department of Transportation - Traffic and Safety Division

Martin R. Parker. 1992 September, pp. vii, 31:

"The available evidence suggests that posting limits in the region of the 85th percentile minimizes accident involvements and provides acceptable driver compliance. There is no information that suggests including other factors in setting speed limits would provide additional safety or compliance benefits."

 

"Effects of Raising and Lowering Speed Limits: Final Report."

U.S. Department of Transportation, Federal Highway Administration

Martin R. Parker. 1992 October, p. 54.

"Accidents ... where speed limits were lowered increased by 5.4 percent."

"Accidents at the ... sites where speed limits were raised decreased by 5.4 percent."

"Lowering speed limits more than 5 mi/h (8 km/h) below the 85th percentile speed of traffic did not reduce accidents."

 

Texas State Department of Highways and Public Transportation, 1990. "Speed Zoning on Texas Highways"

"Laws are written to single out the unreasonable behavior of a minority of the population... The Texas speed law is written so that the reasonable actions of the majority are considered legal."

 

And a few excerpts from Washington State:

Speed Limits

The setting of speed limits on streets and highways is a technical science backed by many years of research and experience on what works and doesn't work for the safety and benefit of the motorist.

....what is the purpose of having speed limits?
Safety is always a factor, but the setting of speed limits is, for completely practical reasons, more fundamentally influenced by some basic principles of human behavior. When setting speed zones, traffic engineers base decisions on several fundamental concepts proven over the years to be true:

• The majority of motorists drive in a safe and reasonable manner
• The normally careful and competent actions of a reasonable person should be considered to be legal
• Laws are established for the protection of the public and the regulation of unreasonable behavior of a few individuals
• Laws cannot be effectively enforced without the consent and voluntary compliance of the majority

Research and experience have shown that effective speed limits are those that the majority of motorists naturally drive, and that raising and lowering speed limits doesn't substantially influence that speed.......

What do you mean by "realistic" speed laws?
Realistic speed laws are desirable for a number of reasons:

1. They invite public compliance by conforming to the behavior of the majority and by giving a clear reminder to the non-conforming violators.
   
2. They offer an effective enforcement tool to the police by clearly separating the occasional violator from the reasonable majority.
   
3. They tend to minimize antagonism toward police enforcement of unreasonable regulations.
4. They inject an element of logic and reason into an otherwise arbitrary and often emotional issue.

What is the law?
All 50 states have adopted a basic speed law which recognizes that driving conditions vary widely from time to time, and place to place. No set of fixed driving rules will ever adequately serve all conditions. Motorists must constantly adjust their driving behavior to fit the conditions they meet.

Individuals need to learn this with a minimum of assistance from law enforcement. The basic speed law is founded on the belief that most motorists are able to modify their driving behavior properly as long as they are aware of the conditions around them.

Just a selection from thousands of links on 85th Percentile Speed.

 

All, of course, just:

"eccentric and political views"

Forgot to mention, it's from:

The Speed Camera Thread XIV

 

Oh, and a typical run of posts here:

Speeding (mostly excl cameras) X

All about how if you increase the speed limit:

speed limits - a case for change - volvoman   Mon 13 Oct 03 11:27

The average car is easily capable of well over 100mph. If you increase the speed limit to say 80 this will not satiate anyone, all it will do is encourage more people to drive at inappropriate speed as they do now - i.e. 70 is regarded as the minimum rather than the maximum speed limit. So instead of tailgating at 80 these people will tailgate at 90 and so on. There'll always be someone along in a minute who wants to go faster than the limit wherever it's set.

And:

speed limits - a case for change - Andrew-T   Mon 13 Oct 03 11:36

v - you have taken all the words out of .. The only point I might add is that I suspect many drivers (however 'good') interpret a speed limit as an indication of how fast a road can be driven safely. In their nice new car, and with their superior skills, it must be OK for at least 10mph more than that. Sadly that is not what a limit means.

 

And how the government sets limits:

speed limits - a case for change - SR   Mon 13 Oct 03 12:39

I think the reason many speed limits seem artifically low is that the authorities accept many people will break them, so they're set with this in mind - i.e. if they want to limit traffic on a particular stretch of road to 50mph, they'll post a 40 limit and hope most people don't exceed it by more than 10mph.

 

Yeah, right.

Do these "motorists" know ANYTHING?!

 

Oh dear.......don't these bods remember the 1960's?

I used to breeze past plod cars at 120mph.

They never blinked.

I never caused a crash.

So, what's changed?

Gullibility has reached epidemic levels and brainwashing is so very, very easy.

And competence has been sacrificed so the inept can flourish........they seem to be alive and well and breeding in the Back Room..............

 

More (less) speed on the M4 - SR   Wed 29 Oct 03 13:31

But do these "most accidents" account for "most damage", "most injuries" and "most deaths"? Brilliant hypocrisy to condemn use of statistics while using statistics..... Agreed more should be done in built-up areas, but it never ceases to amaze me how certain people who know nothing of the background are that speed limits have been lowered just to fleece them, and it has absolutely nothing to do with the 40 injuiries and 3 deaths over the last 3 years, has it?!?!.......... [Where?!] People know the law, they know the limit, they know their own speed, they know where the cameras are, and they know the consequences. If they're still stupid enough to get caught then they deserve all that comes to them (or gets taken from them)....... [I suppose he always went to archery practice after Church on Sunday!]

 

[My Emphasis and comments!]

 

From:

http://www.honestjohn.co.uk/forum/post/index.htm?f=2&t=16582

 

A selection of quotes from Googling 85th Percentile Speed:

 

Federally sponsored studies have repeatedly proven that the safest and most efficiently enforced speed limits are those based on the '85th Percentile Rule' - a speed limit that reflects and considers legal actions of normally prudent and reasonable drivers.

The setting of speed limits below those acceptable to responsible motorists leads to large scale noncompliance, misallocation of enforcement and judicial resources and safety problems caused by erratic traffic flow.

 

Some surveys were conducted on Ottawa, Canada on the same section of road over a number of years. During this time, the speed limit was increased from 50 to 60 to 80.

What was the net result?

Speed limit 50km/h (85th percentile speed 84km/h)

Speed limit 60km/h (85th percentile speed 86km/h)

Speed limit 80km/h (85th percentile speed 85km/h) NB IT DROPPED!

 

Contrary to popular belief, speed in itself is not a major cause of accidents. In fact, there is a consensus of professional opinions that many speed-related accidents result from both excessively low and high speeds.

 

Where speed limits were lowered accidents increased by 7 percent.

Where speed limits were raised accidents decreased by 11 percent.

 

the same public, when emotionally aroused in a specific instance, will often reject these fundamentals and rely instead on more comfortable and widely held misconceptions

 

No wonder they try to suppress the truth!