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Thread: Why Don't Speed Limits Make Sense

  1. #1
    gail
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    Why Don't Speed Limits Make Sense

    As seen on the NMA web site - borrowed by permission:

    Why Don?t Speed Limits Make Sense?
    I have often wondered why speed limits and the speed of traffic seem so disconnected. Most of the time traffic is moving five, ten or fifteen miles per hour faster than the posted speed limit. I have heard supposedly knowledgeable people say ?no matter what the speed limit is, drivers will always drive ten miles per hour over that limit.? I?ve wondered, so if the limit was 100 MPH would everyone drive 110 MPH? I don?t think so, I know I wouldn?t come close to driving 100 MPH, even if it was legal. That tells me there is a point where motorists curtail their speeds, regardless of the speed limit.

    As it turns out, I was right.

    After researching federal, state, and university studies I learned that speed limits work if they reflect the speeds normal responsible people typically drive on any particular road or highway. If most of the traffic on a given road travels between 50 and 55 miles-per-hour and the speed limit is set at 55-MPH almost all the traffic will be in compliance with the speed limit. If the speed limit is set at 45-MPH traffic speeds will remain at 50 to 55 miles per hour and almost everybody will be in excess of the speed limit.

    Traffic engineering experts have found that most of us drive at speeds we feel are safe and comfortable for the existing conditions. If it?s clear and sunny we drive faster. If it?s raining or snowing we slow down. If we?re on a multi-lane Interstate we speed up. If we?re on a city street or winding country road we slow down. This isn?t magic, it?s just self-preservation and common sense at work.

    Reality turns out to be quite the opposite of prevailing opinions. It?s not that we all drive 10 miles-per-hour over the speed limit. Rather, the problem is that speed limits are set 10 miles per-hour-slower than most people drive. The solution seems obvious, set speed limits at levels that represent existing normal (free flowing) traffic speeds and traffic speeds will be in sync with speed limits. This may upset the fans of command and control government, but we?ve tried their approach and it doesn?t work. Let?s use the knowledge we?ve gained and set rational speed limits that reflect the actions of normal responsible drivers.

  2. #2

    Re: Why Don't Speed Limits Make Sense

    The above article does not apply to MD.
    I live in a van... DOWN BY THE RIVER

  3. #3
    gail
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    Re: Why Don't Speed Limits Make Sense

    Quote Originally Posted by l3it3r
    The above article does not apply to MD.
    And this is because????? ???

  4. #4

    Re: Why Don't Speed Limits Make Sense

    The speeding in MD is always higher than that.. I'll be 'speeding' and still getting passed. In a 55MPH zone like 495, 80-85MPH is normal. I95 and 695 are similar. The backroads in MD have higher speed limits than VA too.. I'll be on road here in VA that is 35-40MPH and people might go 10MPH over, in MD, the same road would be 45-50MPH, and people would still be going faster.
    I live in a van... DOWN BY THE RIVER

  5. #5
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    Re: Why Don't Speed Limits Make Sense

    Quote Originally Posted by l3it3r
    The speeding in MD is always higher than that.. I'll be 'speeding' and still getting passed. In a 55MPH zone like 495, 80-85MPH is normal. I95 and 695 are similar. The backroads in MD have higher speed limits than VA too.. I'll be on road here in VA that is 35-40MPH and people might go 10MPH over, in MD, the same road would be 45-50MPH, and people would still be going faster.
    A lot of that is perception. Actual speed measurements before and after speed limits are increased tell a different story. When speed limits are increased, compliance goes from around 80 percent non compliance to 40 percent non compliance. In some rare cases, when the speed limits are raised to the 85th percentile, non compliance is 15 percent.

    Speed limits should be reevaluated every 5 years and adjusted accordingly. There is speed creep of about 0.5 mph per year. So, in 20 years, people are driving 10 mph faster than they were 20 years ago. That is seen mostly on interstates. Speed limits have not caught up with reality, therefore, people are still driving 10 over.

  6. #6
    gail
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    Re: Why Don't Speed Limits Make Sense

    Quote Originally Posted by swamprat
    Quote Originally Posted by l3it3r
    The speeding in MD is always higher than that.. I'll be 'speeding' and still getting passed. In a 55MPH zone like 495, 80-85MPH is normal. I95 and 695 are similar. The backroads in MD have higher speed limits than VA too.. I'll be on road here in VA that is 35-40MPH and people might go 10MPH over, in MD, the same road would be 45-50MPH, and people would still be going faster.
    A lot of that is perception. Actual speed measurements before and after speed limits are increased tell a different story. When speed limits are increased, compliance goes from around 80 percent non compliance to 40 percent non compliance. In some rare cases, when the speed limits are raised to the 85th percentile, non compliance is 15 percent.

    Speed limits should be reevaluated every 5 years and adjusted accordingly. There is speed creep of about 0.5 mph per year. So, in 20 years, people are driving 10 mph faster than they were 20 years ago. That is seen mostly on interstates. Speed limits have not caught up with reality, therefore, people are still driving 10 over.
    Very good. I couldn't have said it better myself. 8) Thanks for your input.

  7. #7
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    Re: Why Don't Speed Limits Make Sense

    Swamprat,

    Wow, very well said. You are 100% correct. Could not have said it better myself.


    Chris,

    The MD/VA beltway (I495) around DC (with the exception of the area around the Mormon Temple in Silver Spring, MD - since it zig-zags around all the established neighborhoods), was intended to be driven up to 85 mph safely. The beltway opened in 1964 when the speed limit was 75 mph. Cars and trucks now handle better 43 years later, and yet the speed limit is stuck at 55 mph. This is why so many people speed on the beltway because the speed limit is artificially low.

    Another example is the Greenway from Leesburg, VA to the Toll Road the speed limit is 65 mph (average speed is 65 - 70 mph) once it hits the toll road, it turns into 55 mph all the way in to I66. Everyone still goes 65 - 70 mph on the Toll Road. This is why the VA troopers sit on this road since the speed limit at 55 mph is artificially low and it's a great revenue generator. The VA troopers also love to go after the HOV violatiors, since they are easy prey.


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    Re: Why Don't Speed Limits Make Sense

    Quote Originally Posted by Pete
    Swamprat,

    Wow, very well said. You are 100% correct. Could not have said it better myself.


    Chris,

    The MD/VA beltway (I495) around DC (with the exception of the area around the Mormon Temple in Silver Spring, MD - since it zig-zags around all the established neighborhoods), was intended to be driven up to 85 mph safely. The beltway opened in 1964 when the speed limit was 75 mph. Cars and trucks now handle better 43 years later, and yet the speed limit is stuck at 55 mph. This is why so many people speed on the beltway because the speed limit is artificially low.

    Another example is the Greenway from Leesburg, VA to the Toll Road the speed limit is 65 mph (average speed is 65 - 70 mph) once it hits the toll road, it turns into 55 mph all the way in to I66. Everyone still goes 65 - 70 mph on the Toll Road. This is why the VA troopers sit on this road since the speed limit at 55 mph is artificially low and it's a great revenue generator. The VA troopers also love to go after the HOV violatiors, since they are easy prey.
    I had no idea that the beltway had a 75 mph speed limit. I thought it was 70 back in the good old days.


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    Re: Why Don't Speed Limits Make Sense

    swamprat,

    You may be right. I was too young to remember, but I have heard both 70 and 75 mph thrown out there as the former beltway speed limit before the Jimmy Carter era national 55 mph limit.

  10. #10
    Vulture of The Western World Eric's Avatar
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    Re: Why Don't Speed Limits Make Sense

    "I had no idea that the beltway had a 75 mph speed limit. I thought it was 70 back in the good old days."

    I'm not sure which it was, either. However, whether it was 75 or 70 - it still shows the extent of the pile of BS that descended upon us - and which is still a mile deep even today.

    Consider: If a big highway such as the Beltway was deemed by its designers and the traffic safety engineers (and even the politicians and lawmakers, who ultimately dee-cided) to be safe to travel at 70 mph some 40 years ago, how come today, nearly 40 years later, we're still not permitted to go even that fast? The limit ranges from 55 to 65 mph - so it's still lower by at least 5 mph than the former limit - despite nearly 40 years of advances in car design that, surely, have rendered it at least as safe to drive 70 mph as it was circa 1970. When you consider the enormous strides that have been made in terms of vehicle stability at high speed, braking capacity, tire grip (and ability to handle high speed without failure), the vastly superior crashworthiness of modern cars, the presence of electronic aids, etc, etc. it's just absurd on its face to impose limits that are actually lower than they were when cars had drum brakes, bias-ply tires, shitty steering and so on.

    Even taking into account the low skill level of today's average driver, the cars themselves are so good that highway speed limits could be raised to 80-85 mph without negatively affecting the accident/fatality rate. Hell, on many highways, this is close to the 85th percentile speed/natural flow of traffic.

    But that's probably why the speed limits are left where they are. If they were raised to reasonable levels, the number of "speeders" would drop dramatically - and with it, the number of tickets that could be issued.

    That's the bottom line.

    Not saaaafetyy. Money.




  11. #11
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    Re: Why Don't Speed Limits Make Sense

    Here is the speed limit information for the beltway. It was 70 mph.

    http://www.capital-beltway.com/Capit...l#Speed-Limits

  12. #12
    Vulture of The Western World Eric's Avatar
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    Re: Why Don't Speed Limits Make Sense

    Quote Originally Posted by swamprat
    Here is the speed limit information for the beltway. It was 70 mph.

    http://www.capital-beltway.com/Capit...l#Speed-Limits
    Cool - thanks for digging this up!

    Isn't it FUBAR that we're still stuck with limits that are at least 5 mph below what they were 30-40 years ago?

    Oh yeah, I forgot.... it's all about the chyllllldruuuun!

  13. #13

    Re: Why Don't Speed Limits Make Sense

    well.. after all.. you don't even have first ammendment rights in this country anymore..
    I live in a van... DOWN BY THE RIVER

  14. #14
    Vulture of The Western World Eric's Avatar
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    Re: Why Don't Speed Limits Make Sense

    Quote Originally Posted by l3it3r
    well.. after all.. you don't even have first ammendment rights in this country anymore..
    Yep; we can discuss all this when we're rounded up and put into FEMA gulags!

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