"archer" <ns_archer1960@ns_hotmail.com> wrote in message
"]news:[email hidden]...
Quoted message said:In article
<[email hidden]>,
Quoted message said:[email hidden] says...
Quoted message said:Quoted message said:That's not true. Crash safety has to do with the
strength
Quoted message said:Quoted message said:of the passenger compartment, and how well that
structure is
Quoted message said:Quoted message said:designed to collapse and absorb energy. This is how
Indy
Quoted message said:Quoted message said:cars weighing only 1500 LB can crash into a wall
(infinite
Quoted message said:Quoted message said:mass) at 200 MPH, and the driver walk away. You don't
make
Quoted message said:But the car is destroyed and the wall is unhurt. That's
just an
Quoted message said:extension of what happens when a 7000lb SUV hits a 2000lb
sub-compact.
Quoted message said:The car is destroyed and the SUV is largely undamaged.
First, that's not true. The SUV *is not* undamaged. Often a side impact by a fairly light vehicle
will intrude deeply into the passenger compartment of an SUV.
Second, how the vehicles appear after the accident is immaterial. What counts is the condition of
the occupant. The force of an impact has to go somewhere. If it isn't absorbed by the vehicle, it
gets transmitted to the occupant. This became crystal clear back in the 1950s, when drivers of
Mercedes' 180D/220S were being injured and killed at an alarming rate. The problem was that the car
was built like a tank. It didn't dent, crush, or absorb any energy in collisions, instead
transmitting the forces directly to the driver. This deathtrap car was a revelation to the industry,
prompting a big change in automotive design.
Quoted message said:Of course if you compare them both hitting the wall or a tree, the occupant
of the car is
Quoted message said:probably more likely to survive than the SUV driver for
the reasons you
Quoted message said:mention.
The relevent issue is still how strong each vehicle is against its own weight, and how well it
absorbs energy. And if weight matters at all, physics dictates that speed matters more in terms
of kinetic energy. Going back to your high school physics, draw a vector diagram and you'll see
what I mean.
Take a couple of hypothetical (actually typical) examples.
One, a Honda Civic T-bones a big SUV. The Civic crushes back a couple of feet, absorbing the impact,
and the driver walks away unhurt. OTOH, the SUV isn't strong enough against its own weight to remain
rigid and be pushed sideways, like a normal car would. The Civic intrudes practically to the truck's
centerline, crushing its driver.
Two, how about a head-on collision between the same two vehicles. Again, the Civic's engine
compartment crushes but the passenger compartment remains intact, absorbing the impact and
protecting its driver. But the big SUV, bolstered by rigid frame rails, doesn't crush at all. It
seems hardly damaged, but the force of the impact is transmitted directly to the driver. He dies of
internal injuries where his seat belt practically cuts him in two.
These kinds of things are exactly what happens in the real world.
Automakers are starting to address the SUV safety issue, mostly because of fear of class action
lawsuits. They know these vehicles are less safe, and with so many of them out there now, they're
potentially a huge liability. Some of the newest, most expensive designs -- the BMW X5, for example
-- are as safe as anything else. But the average one is still a tarted-up version of a decades-old
truck design.
Matt O.