You may be right in many of your specifics, but I think that their
detail confuses the basic question here. The NHTSA study is not based
on arguments about physics, or even on crash tests. It is based or
real world data: it is based on then number of people who have in fact
died in SUVs as compared to the number of people who have died in
passenger cars of comparable or even less weight.
Statistical studies help make better predictions. Consider the
following:
Suppose a thousand people who were going to buy a SUV hear of the
NHTSA study and decide that SUVs are, pound for pound and dollar for
dollar, less safe than a passenger car. So half of them change their
decision and buy a mid-size or large passenger car at a price no
higher then the one they intended to pay for the SUV. The other half
stick with their decision and buy a SUV (because they have other
overriding concerns).
Prediction A: Three years down the road less people out of these
thousand will be killed in traffic accidents than if they had all
bought a SUV as originally intended.
Prediction B: Three years down the road more people out of the group
that decided to buy a SUV will be killed in traffic accidents than out
of the group that decided to buy a passenger car.
Don't you agree that the NHTSA study shows that both these predictions
are correct?
BTW, my motivation is not political at all. We are talking about
people risking death or injury; we should all insist that people be
better informed about their choices no matter where our political
convictions lie. People should know that, on average, SUVs are less
safe than cars.
"Robert A. Matern" <
[email protected]> wrote in message news:<
[email protected]>...
> This is just ridiculous... comparing apples & oranges isn't helpful.
>
> The advantage in a large vehicle is in vehicle to vehicle collisions; there
> is no advantage in single-vehicle accidents (i.e., rollovers). The large
> vehicle ALWAYS enjoys the advantage in any collision with a smaller vehicle.
> Attempts to deny that simple fact based on the laws of Physics using all
> kinds of clever statistical manipulations are simply absurd. Different
> vehicles enjoy advantages in different types of accidents based on their
> characteristics; wide-brush prejudicial generalizations don't help rational
> folk in the task of making informed decisions. This, and messages like it,
> are just political propaganda... plain & simple.
>
> Rollover:
> advantage: low center of gravity
> REASON: increases leverage required to roll (lever angle)
> winner: lower - heavier makes it better
> loser: higher - lighter makes it worse
> advantage: wide wheelbase
> REASON: increases leverage required to roll (lever length)
> winner: lower - heavier makes it better
> loser: narrow - lighter makes it worse
>
> Collision:
> advantage: high MASS
> REASON: more mass reduces accelerational forces after collision
> winner: heavier - good crash test performance makes it better
> loser: lighter - poor crash test performance makes it worse
>
> Spinout:
> advantage: long wheelbase
> REASON: increases leverage required to spin
> winner: long - heavier makes it better
> loser: short - lighter makes it worse
>
> Mixing the statistics for these VERY different types of accidents is poor
> statistics at best... and deceitful or even outright dishonest at worst.
> But these are the political times we live in...
>
> The comment about limiting size for everyone is socialist at best, communist
> at worst... and very authoritarian for sure! There's no reason that large
> vehicles can't be A LOT more economical... why not concentrate on that?
>
> The comment about limiting speeds for trucks, etc., is just absurd. Can you
> imagine the outcry from the truckers? We can't even get them to obey the
> speed limits now! Not to mention that while the standards for my vehicle's
> exhaust have become draconian, nothing at all has been done about truck and
> bus exhaust. Nor are there any CAFE standards for their fuel efficiency.
> If this was a real effort to increase safety & ecological concerns then
> TRUCKS & BUSES are the place to start!
>
> And, just to top it all off, do you really think you're safer hitting a
> large truck with your tiny car just because you made the truck drive slower?
> If so, THEN YOU DON'T UNDERSTAND THE PHYSICS AT ALL!
>
> And this is just the beginning... counting casualties in OTHER vehicles is
> just GOOFY... penalizing your choice because the other guy failed to make a
> similarly good choice is RIDICULOUS!
>
> Politically motivated propaganda isn't just bad science, it's USELESS as
> well.
>
> Bob
>
>
>
> "Dianelos Georgoudis" <[email protected]> wrote in message
> news:[email protected]...
> > Recently (October 14, 2003) the National Highway Traffic Safety
> > Administration (NHTSA) released a study about vehicle safety and
> > weight. See:
> >
> > http://www.nhtsa.dot.gov/cars/rules/regrev/evaluate/pdf/809662.pdf
> >
> > As expected, the NHTSA study did find that heavier vehicles are safer
> > for their occupants when they crash with a lighter vehicle. This is
> > well known, and many people buy SUVs thinking that their weight gives
> > them a safety advantage. Some publications stress this fact (for
> > example one by USA Today is titled "Lighter cars mean more deaths" so
> > many people who drive SUVs may feel reassured).
> >
> > In fact, as far as SUVs go, the NHTSA study could not have been more
> > unfavorable. Using real world statistics about tens of millions of
> > vehicles over several years they prove that the overall safety of SUVs
> > is worse than of lighter passenger cars. One of the reasons is that
> > SUVs have a much higher tendency to roll over. This means that many
> > people spend more to buy a SUV, spend more on gas, and also endanger
> > others, without much any advantage for themselves. The relevant
> > numbers are:
> >
> > Vehicle type Average weight Driver fatalities
> > (pounds) per billion miles
> >
> > Mid-size 4-door car 3,061 5.26
> > Large 4-door cars 3,596 3.30
> > Small 4-door SUVs 3,147 5.68
> > Mid-size 4-door SUVs 4,022 6.73
> > Large 4-door SUVs 5,141 3.79
> >
> > So it is more probable that you will be killed in a small or mid-size
> > SUV than in a mid-size car that weights less. Only large SUVs are
> > safer for their drivers than mid-size cars, but they are less safe
> > than large cars, even though large SUVs are 1,500 pounds heavier!
> >
> > These are amazing numbers. The prorated figures, which take into
> > account the fatalities in other vehicles involved, are, as expected,
> > even worse.
> >
> > The study does show that SUVs are safer than small and very small
> > cars, which have a disadvantage only because there are so many much
> > heavier vehicles around. Very few people who end up buying a SUV were
> > thinking of maybe buying a small or very small car, so this advantage
> > is irrelevant. Pound for pound SUVs are always less safe for their
> > passengers.
> >
> > Even when comparing SUVs only, more weight is not always better.
> > Significantly, small SUVs are safer for their drivers than mid-size
> > SUVs, even though the latter weight 900 pounds more. I suppose small
> > SUVs are more car-like and therefore avoid some of the safety
> > disadvantages of the SUV design.
> >
> > If you care about your personal safety then, clearly, the best
> > strategy is not to use a SUV but to use a mid-size or large passenger
> > car.
> >
> > Of course, the safest strategy for society would be to put an upper
> > limit to the weight of passenger cars: then we all would drive safer,
> > spend less money on cars, spend less on gas, protect others, protect
> > the environment, and be less dependent on unstable oil-producing
> > countries. Limiting the weight of vehicles is a
> > win-win-win-win-win-win proposition. Vehicles that have to be heavy
> > (such as trucks, heavy duty off-roaders, buses, etc) should have their
> > top speed electronically limited to low levels as to not endanger
> > other vehicles on the asphalt.
