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Devon Glass
Devon Glass
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Why Speeders on the Highway Cause More Serious Accidents


So it goes that we have a third party to add to our blog series. I think I speak for both Steve Lombardi at the Lombardi Law Firm, and myself at the Church Wyble, P.C. law firm, when I extend a hearty welcome to Wayne Parsons from the Wayne Parsons Law Offices in beautiful Honolulu, Hawaii.

Yesterday, both Wayne and Steve wrote about the dangers of speeding on interstate highways. No matter the state, whether that state is Michigan, Iowa or Hawaii, speeding drivers cause a huge danger to others. As Wayne so aptly stated, people love to speed on the Interstate Highway System, going as fast as they can and getting upset with those who choose to follow posted speed limits.

Steve mentioned that when he first learned how to drive, he was instructed that for every ten miles an hour, you need at least one car length to safely stop without rear ending the driver in front of you. Additionally, as Steve pointed out, drivers are more distracted than what they were even 10 to 15 years ago. With the advent of texting, drivers cannot possibly be as focused, and therefore as safe, as they were before texting existed. In fact, driving while texting increases the risk of collision by 23 times compared to when a driver is completely focused on the road. I cannot begin to imagine what the increased speeds of the interstate highway contribute to those omnipresent dangers.

Speed limits on the interstate vary to upper and lower extremes across the country. Michigan and Iowa represent the higher extremes of 70 mph, while Hawaii tends toward the lower at 60 mph. I’m not sure if these are still accurate for Iowa and Hawaii, so perhaps Wayne and Steve can correct me if I’m wrong. Nevertheless, the Insurance Institute for Highway Safety argues that some of these new, higher speed limits in the Midwest and elsewhere are costing lives. In fact, it estimates that deaths on highways and the interstate freeways have increased 15% due to the higher speed limits. Some researchers, such as those in the AOL article link I provided, will argue that speed actually decreases the number of accidents. However, these aren’t the pure facts. While higher speeds may keep some slower drivers off of the interstate, it boils down to the truth of the matter that higher speeds cause more serious injuries, including death. Indeed, speed influences the risk of crashes and crash injuries in three basic ways:

· It increases the distance a vehicle travels from the time a driver detects an emergency to the time a driver reacts.

· It increases the distance needed to stop a vehicle once an emergency is perceived.

· It increases the “crash energy” by the square of speeds—when an impact speed increases from 40 to 60 mph, the energy that needs to be managed increases by 125%. In other words, the crash impact is going to be astronomically greater than if you were going at a slower speed.

Anyway, enough about physics. The point is speed does kill. It may be faster (and more fun) to speed, but it just isn’t safe. Slow down and follow the posted speed limits.

Here’s a video on the impact of speed. Albeit a video created in the UK, but speed doesn’t discriminate who it will kill by country of origin.


If you just joined our series, here’s a recap of what you’ve missed:

Are Double-Bottomed Semis More or Less Dangerous to You?

Who wins and loses when a Ford Focus and a fully-loaded semi-truck crash?

Hawaii Freeway Chronicles #1: What Are The Danger Points On H-1, H-2 and H-3?

The Interstate Highway Graveyard, “Speed Kills”


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  1. Jim Walker says:
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    To Devon Glass, Steve Lombardi and Wayne Parsons,

    Are you aware of any of these facts?

    1. The posted speed limit has almost no effect on actual travel speeds (+/- up to 3 mph). In addition, the lowest accident rate tends to occur when the posted speed limits are set at the 85th percentile speed of free flowing traffic under good conditions. In Michigan and most of the midwest, that speed would round off to 80 mph in most places — that is, if the posted limit were set at 80, about 85% of the vehicles would be below or right at the limit. In the midwest, the posted 65 and 70 limits tend to be around the 30th percentile speed, thus defining about 70% of all drivers as illegal. This counterproductive methodology started with the National Maximum Speed Limit in 1974 and persists today. Posting correct 85th percentile limits would reduce our rates of crashes, injuries and fatalities – nationwide.


    2. The fatality rate per mile traveled on an Interstate highway is two to four times lower than on a surface highway. If we can draw more traffic to our safest roads – the Interstates – we can reduce fatalities nationwide. HOW is this done? One way is to stop defining about 70% of all drivers as criminals and post the safest possible speed limits which are consistent with normal safe driving behavior – usually the 85th percentile speed. After 1987 when rural Interstate speed limits could go to 65 mph (from 55), the states that adopted 65 had a greater drop in their fatalities than the states that retained 55 limits.


    3. Many states, including Michigan, publish documents about the speed limit setting process and why the 85th percentile speed is usually the correct place for the limit. Unfortunately, many state legislators set arbitrary statutory limits for some classes of roads, thus preventing the police and traffic engineers from posting the safest speed limits. With rare exceptions, the legislators are not qualified to determine the safest speed limits, so their statutory limits often reduce safety for all of us. Michigan’s booklet is the most descriptive, you can download it here “Establishing Realistic Speed Limits”


    4. The fatality rates today have dropped by almost two-thirds of what they were in 1974 with 55 mph speed limits. In 1974, the fatality rate was about 3.50 fatalities per 100 million vehicle miles traveled. For 2008, it was about 1.27. (NHTSA data) Michigan is closing on a fatality rate of 1.00 and the Michigan State Police are strong proponents of using correct 85th percentile posted speed limits.

    If state legislatures, state departments of transportation, state police departments and other interested parties could jointly decide to use the known principles of traffic safety engineering to set posted speed limits, we could make some faster progress in reducing our rates of crashes, injuries and fatalities.

    So long as the myth prevails that the arbitrarily smaller number, rather than the CORRECT number, on the speed limit signs is better, our progress toward traffic safety is slowed down.


    Jim Walker
    JCW Consulting (automotive consulting)
    Member – National Motorists Association http://www.motorists.org
    2050 Camelot Road
    Ann Arbor, MI 48104

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    Hi Jim,

    Thanks for your great comment. I found it veryy informative and interesting. To me, common sense about physics would seem to imply that the slower you go, the lower the likelihood of injury or fatality, but it’s not really the case when you think in terms of the relative speed of vehicles one to another (see my Grama merging onto the Interstate for example – a harrowing experience for everyone). I hadn’t considered the point of “realistic limits” before.

    With about 50K deaths per year annually due to auto accidents, and the fact that collisions are one of the highest causes of death in some age groups, you’d think Americans would be more concerned with addressing driving safety.

    I’m a bit of a car nut who has spent a lot of time on the road. I’m always aghast at how badly so many people drive and how poorly regulated some highly trafficked high-speed roadways are.

    Simple things like aggressively enforcing “slower traffic keep right” regulations would undoubtedly prevent many high speed accidents (and road rage incidents).

    I had the chance to drive through parts of Western Europe a few years ago and the differences in common driving courtesy between here and there were astounding. It was a really pleasant experience. It would be great if we could get lawmakers and citizens to better understand the science of driving in this country, given how much time we spend in our cars.

  3. Andrew Gregory says:
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    Seems the 3 lawyer types found a great way to get Google hits, and not offer any real or fact based advice just rely on anecdotes. Course, that would cost a certain amount per hour, wouldn’t it?

    So, here’s just one free real fact: Car lengths can’t be measured with any real accuracy. Try the 3 second rule, learned thru the National Safety Council Defensive Driving Course.

    I’m not a lawyer, and don’t play one on tv or on a weblog. Neither should mssrs Glass, Lombardi or Parsons.

  4. Devon Glass says:
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    Thanks for your comments. I never claimed to be the end all, be all, expert on safe driving. My intent is to inform people how to prevent and avoid dangerous accidents. The articles I cited provide support for the suggestions I made. Also, the immutable laws of physics back up the tips about why it’s dangerous to travel faster. I am open to hearing all sorts of ideas on how to best achieve the goal of safer highway travel, so please let me know more of your thoughts on this important matter.

    As for the issue of Google hits, the more people know about these topics, the safer the roads will be. I see nothing wrong with trying to reach as many people as possible to warn of the dangers of unsafe highway travel. Would you rather I kept these safety tips to myself? That does not sound reasonable at all.

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    Exactly right, Devon. Thanks to your post I, for one, learned something valuable today. I am sure other readers have too. We shouldn’t be quick to jump to broad conclusions about driving speed or lawyers, I guess.

    The video makes a good point about braking (and understand your car’s limits). Before someone else jumps in to point it out, I think it (based on the accent and Monash University’s location) may have been produced in Australia. Thank Crocodile Dundee and Steve Irwin for my noticing that.

  6. Henry Stowe says:
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    Closer to home and the subject at hand, posted speed limits have very little effect on accident rates. Between 1996 and the middle of 1999, Montana had no posted speed limit on its rural highways. Actual operating speeds on their highway system were actually below those in comparable states with posted limits of 75 mph or less. It is true that western states have a higher fatality rate than crowded eastern or southern states. That is because of long distances from emergency responders. Back to Montana – when speed limits were imposed on their rural roads, fatalities doubled on those sections of roads. Google “Montana Paradox” and you will understand the phenomenon.

    Using statewide fatality rates between 1993 and 2004 using actual NHTSA/FARS data, fatality rates in states posting speed limits of 70 mph or higher dropped by 17-27%. Those keeping 65 mph rural interstate speed limits dropped by 17%. This confirms the phenomenon that traffic transfers to safer highways and that higher speed limits smooth traffic flow. The fatality rate is the only acceptable way to measure traffic safety as it normalizes the statistics in terms of incidents per mile traveled. It also smooths out fluctuations in individual data that can be taken out of context.

    It should also be noted that the Northern Territory of Australia imposed a speed limit on its rural roads. Fatalities more than doubled.

    To avoid accidents on roads, people should focus on driving, not on adhering to an arbitrary number. Police need to redirect their resources to identify reckless drivers who aren’t paying attention, not to ticketing people for exceeding an arbitrary number. In fact, arbitrary limits need to be removed from highways as much as possible, as no correlation has ever been found between speed, speed limits and highway fatalities.

  7. Steve Lombardi says:
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    I’m not sure if the poor economy has anything to do with it but driving on I-80 from Iowa City to Des Moines these past few days (we actually were in Madison, Wisconsin) surprised me as to how rude and inconsiderate drivers are becoming. The level of aggression seems to be increasing in intensity. And it’s not the truck drivers who are aggressive. It’s the guy’s thinking this is a NASCAR race.

  8. VCDaedalus says:
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    My experience on the road comes from driving different major metropolitan routes at varying times of the day. That means four interstates and the equivalent of two metro loops in a 50-mile radius.

    People who drive on the highway by constantly accelerating and then braking (because inevitably they come too close to the car ahead of them, or go too fast to merge smoothly) not only lose the time they think they’re making by going faster, but give themselves a less comfortable ride, more stress, more adrenaline and cortisol (because they rely on fear to moderate their brake reaction), and make the road more dangerous for all of us in the bargain.

    It’s the stupidest damn behavior you could ever see: cars constantly zooming and then braking on the interstate. Stupidest thing in the world, a thing of cack-brained morons–and it’s not the people obeying the speed limit who’re doing it either. It’s Mr. and Mrs. My Speed Is Always Safe, or perhaps young Master Zoombutt or Miss Like I Care.

    I’d like every parent to think about what the constant stab-braking motion does to a little infant’s skull contents–even in the car seat. I know I hate the way my stomach feels when I have to endure being a passenger with drivers like this.

    I use cruise control–like pilots do. My goal is to enter the highway, maintain speed, and never use my brakes until I’ve exited. That includes freeway-to-freeway on- and off-ramps. It’s like golf: the fewer times you hit the brakes, the better your score.

    Of course, this sort of piloting requires constant attention, both hands on the wheel, and an eye for traffic flow like a chess champion for the board. Who needs a fricking video game? This is real. Drive well or die, you know what I mean?

  9. Jim Walker says:
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    I also just drove about 3,000 miles of I-94, I-80 (including all of Iowa), I-76, and I-70 in a trip from Ann Arbor to Estes Park, CO and back (9/7/09-9/16/09). Much of the aggressive driving behavior correctly described by Steve Lombardi in Iowa is due to the improper posted speed limits and the lack of laws or enforcement for “Keep Right Except to Pass” rules for lane courtesy/discipline. The best areas were those posted at 75 mph where lane courtesy was better and “left lane bandits” causing aggressive driving were less common.

    As in my post of August 28th, the real secret to many of these issues of traffic safety is posted limits on main roads set at the 85th percentile speed of free flowing traffic under good conditions. On most rural freeways in the US, that would post limits of 75 to 85 mph (except in the high mountains where 65-70 limits are usually best).

    85th percentile posted speed limits have been known to be the best since at least 1941 that I can prove in writing (1941 National Safety Council Report on Speed).

    Then you need the enforcement resources previously wasted on enforcing artificially low posted speed limits that actually harm safety and smooth traffic flow to refocus on things like proper lane use – Keep Right Except to Pass – plus the other common aggressive behaviors noted by Steve Lombardi like tailgating, improper passing, poor merging, etc. Using this change in enforcement tactics would mean that the left lane(s) would be open most of the time for the faster cars, passing would be easier, and the slower cars would have a smooth ride in the right lane(s) – largely undisturbed by the faster cars. It is the secret to the unrestricted speeds on German Autobahns where 62 mph (100 kph) heavy trucks mix safely with 120 mph Porsches and Mercedes — with a fatality rate lower than US Interstates.

    The problem with this solution is that the 35+ years of misinformation and disinformation from NHTSA, the IIHS, and others in the so called “safety lobby” have convinced the public that just painting lower numbers on the speed limits signs is required for safety. That view is utterly false, but a huge percentage of the public believes it, so they lobby their legislators to do the wrong things that actually harm safety.


    Jim Walker
    JCW Consulting (automotive consulting)
    Member – National Motorists Association http://www.motorists.org
    2050 Camelot Road
    Ann Arbor, MI 48104