Does Speed Kill?

A better way to put this situation is that it’s not how fast you are going as much as how fast are you stopping.  The human body can only take so much deceleration before it ends up injured.  In an accident there are at least three collisions that occur.  The first is the vehicle (or as Newton would say – the object in motion) decelerating as it impacts another object.  The other is your body being slowed down by such things as belts, air bags, and portions of the vehicle’s interior.  Finally all the soft tissues inside your skin (and skull) also being subjected to rapid deceleration.  Just ask Richard Hammond, of Top Gear fame, who survived a rollover crash in a jet car traveling 288 miles per hour.

Today’s vehicles are designed with a sort of encapsulated frame designed to isolate the passenger area from most of the crushing effects of a collision.  Known as crumple zones they are areas of the vehicle that are intended to sacrifice their integrity so that as much energy as possible is expended by the time the passenger compartment is directly involved with a collision.  Front engines are designed to slide under the passenger compartment and fenders and trunks are designed to collapse all in the name of absorbing energy that would otherwise be transferred to the passenger compartment and the vehicle’s occupants.

Of course you can be traveling at great speed, lose it on a corner, spin off the road, slide across a grassy area, and come to a stop.  Again, the speed doesn’t kill unless you collide with something.

Walk into a wall and you will bruise your head.  Do the same on a skate board and I hope you are wearing a helmet.  Restrain your body in a car and hit a wall and you could find out what Dale Earnhardt did when his NASCAR ride hit the wall at one o’clock.  Your body will be restrained, but your head is not and will be compelled to keep going unless you have an air bag or HANS device to save you.

Avoid rollovers.  The national average is that a third of vehicle deaths are due to rollovers.  That is just the national average, in Montana it is twice that as indicated in the excerpt from the NHTSA’s report titled: An Analysis of Motor Vehicle Rollover Crashes and Injury Outcomes

“In 2004, for the United States as a whole, 31,693 passenger vehicle occupants were fatally injured in crashes of all types, 10,553 were fatally injured in rollovers, and 8,565 were fatally injured in single-vehicle rollovers. This means that 33% of passenger vehicle occupant fatalities were in vehicles that rolled over. State-by-State, this percentage ranged from 10% for the District of Columbia to 67% for Montana.

If you are going to be in a rollover it pays to be short and light.  Here is another conclusion from the same report:

“One finding of this section is that among fatally injured drivers, those who were restrained tended to weigh more, be taller, and have a higher BMI than those who were unrestrained. Another interesting finding is that drivers who weighed less, were taller, and had a lower BMI tended to be overrepresented in single-vehicle fatal rollovers. Thus, while heavier individuals received fewer benefits from seat belts, they might also have been at a lower risk of fatality given involvement in a single-vehicle rollover. On the other hand, this over representation of lighter, taller, and lower BMI drivers could be related to age and its relationship to risk-taking.”

Do I need to add that seat belt usage improved the odds?  Here is a quote from another NHTSA report entitled: Characteristics of Crash Injuries Among Young, Middle Age, and Older Drivers

There was a statistically significant reduction in injury severity in both rollover and non-rollover crashes to the driver when seat belts were used. Non-belted drivers were eight times more likely than belted drivers to sustain serious injury. The driver serious injury risk (odds) in vehicle rollover crashes is three times higher than that in vehicle non-rollover crashes.”

Pay attention to the emphasis on fatalities.  These figures don’t include the percentage of incapacitating injuries that occur at a higher rate.

As you may have noticed the weight of vehicles in each class has been rising over the years.  For example, you could have bought a Ford Fiesta in 1978 that weighed in at just over 1800 pounds while today your Ford Focus would weigh in at about 2600 pounds.  Some of this could be attributed to additional features and a bit more luxury, but the vast amount of extra pounds have been to design in crash worthiness into the vehicles. 

Do you need another example?  Noel provided a link to this news article from the Saratogian where rescue workers comment on how much more difficult it is becoming to extricate occupants from a vehicle that has been involved in a collision.  Where is used to take ten to fifteen minutes of use of hydraulic cutters, saws, and metal benders, it can now take twice as long.  The crews also have to be aware of just what they are cutting through and not set off airbags.  Hybrid cars introduce additional concerns of hidden power cables.  All these delays impact the “golden hour” or the period of time where critically injured people have the highest chance of survival if they can be extricated and moved to a hospital.

Don’t get me wrong, I like safety features.  I wouldn’t drive without using at least a three point safety belt.  I wouldn’t drive in an autocross or track day event without a helmet.  I am glad that car designs include crumple zones and reinforced passenger compartments.  Just keep in mind that there is no free lunch here.  What has been done to minimize your injury potential may impact just how quickly you can be rescued.

Does speed kill?  Stopping too fast (say a 40G impact) can definitely kill.  If we take it to its extreme we could insist that all vehicles travel a zero miles and hour and therefore eliminate all accidents.  Unfortunately we would also eliminate all the benefits of transportation of food, materials, people, etc.  There are risks in everything.  It is the circumstances that put you in that situation that can kill.  Doing things that keep us from focusing on the job of driving provide far more risk than the speed at which we travel.  Getting proper training on vehicle dynamics and handling limitations is not a bad idea either.

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11 Responses to Does Speed Kill?

  1. Jim's sister says:

    Seriously, where does one go to get “proper training on vehicle dynamics and handling limitations?” I don’t remember either of those concepts being discussed during my driver’s ed class back in 1964.

  2. jimsgarage says:

    Exactly. Driver’s Ed just focused on traffic laws and getting you to the point of being able to pass the “test”. They showed horror films of car crashes expecting it to get you to drive safely.

    If you want to get proper training ion vehicle dynamics and handling limitations your best bet is to invest in taking a training course as offered by Skip Barber or Bob Bondurant.

    This article by Autoweek is worth a look, too.

    If the budget isn’t there for a formal school try joining a local sports car club and trying your hand at autocross events. You will likely meet some nice folks and learn a lot. If you get tired of autocross and your budget allows there might be a road racing track that has HPDE (high performance driving education) days.

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  5. truthwalker says:

    I only partially agree with your idea that the weight is predominately from safety equipment. A good space frame chassis/body design would only weigh about 500 lbs fully dressed for a compact like the Focus. The weight comes not from engineering safety but engineering it invisibly. I would far rather have a full roll cage and 5 point harness in a aluminum racing seat than a front and side curtain airbags.

    Cars are not so much engineered to be safe as to get high crash scores. The thing that frustrates me the most about crash scores is that they only score crash survivability. I wish they had to have a combined score that scored crash survivability AND crash AVOIDANCE. I drove a Geo Metro for years (Which had a 1 of of 5 for safety). That car got out off troubles that a bigger car would have plowed right into.

  6. timboc says:

    An interesting article. In Britain we have a quaint class of road (or sidewalk) users known as pedestrains. We also have, on occasion, been known to cycle. I understand that in the US both are fewer in number. Reducing speed certainly reduces the number of pedestrain and cycle related injuries and fatalities. I guess from your petrol head viewpoint neither are worth discussing.
    5% world population, 25% world polution, keep it up you guys.

  7. jimsgarage says:

    Timboc –

    Unfortunately the US has placed a premium on the automobile as a mode of transportation. From time to time I myself am a pedestrian or even a bicyclist and come to realize rather quickly that the roadways are designed for the benefit of the automobiles and not the “others”. Even with painted crosswalks at intersections with lights ostensibly intended to help pedestrians cross, you must practically sprint the distance if you wish to make it to the other side before the light turns against you.

    Supposedly pedestrians have the legal right of way, but you wouldn’t know it from the behavior of most American drivers who treat them like a nuisance that is needlessly impeding their progress. The American landscape has been altered to facilitate the motor car at the expense of other modes of transportation. Parking lots abound, but it is a rare community that ensures there are plenty of trees and green plants to break up the expanses of tarmac. Once you have parked your vehicle you are left to your own devices as to how to walk to your destination without becoming fodder for some fender.

    As for 5% of the world population being responsible for 25% of the worlds pollution I don’t know if we have been surpassed by the newly developing countries or not. The bigger problem might just be that we have 6.5 billion people inhabiting a planet that can only comfortably support the needs and waste of 2.5 billion folks. Who wants to volunteer to help fix the problem?

    Thanks for your comments. They are appreciated.

  8. Booker says:

    Nice touch about the pollution, Jim. Timboc should go to the Olympics and take a deep breath, then a quick dip in the Yangtze. Those moths on the trees in the UK used to be white, too, until the glorious Industrial Revolution poured enough coal soot into the air to blacken all the trees. This forced the moths to evolve a different coloration (Black), or get eaten.

  9. mbryner says:

    I started driving sports cars and motorcycles around 1970 and was taught by my dad, a professional driver who also drove motorcycles and hot rods and trucks from before he was old enough to have a license. His advice was good then and even better now: assume everyone else on the road is stupid and not paying attention to anyone else. Try to be the smart one and you’ll live longer.

    I even had seat belts in my ’58 TR3 and started wearing full face helmets as soon as I could afford them. So even when I was stupid. at least I survived.

    I believe speed doesn’t kill, it just makes the crash harder to avoid and more spectacular.

    And pollution? I’ve had the soles of my shoes ruined by the polluted rain water on the streets of London and I’ve choked on the air in China ( and I haven’t seen anything that can compete with the wood/coal/exhaust fumes in a northern China winter). We in the US really need to clean up our act, and soon, but we aren’t the only polluters.

  10. truthwalker says:

    Ah, the old “US is 5% of the world population but makes 25% of the pollution” nag. It’s true. Of course, if the US made 25% of the worlds economy, that would mean they were breaking even with the pollution, but of course, the US doesn’t make 25% of the worlds products and services! It makes 32%.

  11. Noel says:

    It’s interesting how this discussion is shifting from speed and safety to environmental issues. Like it or not, the cars we love are detrimental to the environment, and that’s an issue we must acknowledge and address, individually, as nations and ultimately as a planet. Jim puts it well that we have 6.5 billion people on a world that can really only support about 2.5 to 3 billion.

    Unfortunately, in my opinion, it’s all going to get a lot worse before it gets better (if it does). I’m hoping we’ll see smaller, safer cars that get great mileage with much less pollution, but the reality is that is America, with its approach that “some is good more (and bigger) is better,” will continue leading the world off a cliff. Followed closely by China and all the developing nations who want the cars, houses and toys we’ve enjoyed for so long.

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