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IIHS Picks Safest Vehicles - READ ONLY

130 messages,  Last post on Sep 23, 2009 at 12:03 PM

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What is this discussion about? Car Safety

Messages Page 11 of 13

#101 of 130 Re: First hand experiences and thoughts? [backy] by jeffyscott

Nov 03, 2006 (7:32 am)

Replying to: backy (Nov 02, 2006 6:08 pm)
Then the weight of the vehicle plays a role, so the results couldn't be compared across weight classes--same as today.
 
I don't think that is true. You would be simulating a collision between the vehicle being tested and a second standard vehicle. This would make for a tougher test of small cars.

#102 of 130 Re: First hand experiences and thoughts? [jeffyscott] by backy

Nov 03, 2006 (7:49 am)

Replying to: jeffyscott (Nov 03, 2006 7:32 am)
I really don't want to debate the physics of this here, because it's off topic. When the car is moving, the weight of the vehicle plays a role in the severity of the impact. That is why the NHTSA and IIHS caution people not to compare cars in different weight classes on frontal tests, in which the car is moving. And I think it would be difficult to design a sled that represents a "standard vehicle" for a moving frontal impact test because cars differ so much in front-end configuration (engine position, frontal area), use of crumple zones, etc.
 
Maybe there is a discussion on the science of crash tests where we can continue this if you want to, so we can get back to the 2007 Sentra.

#103 of 130 Re: First hand experiences and thoughts? [backy] by jeffyscott

Nov 03, 2006 (8:42 am)

Replying to: backy (Nov 03, 2006 7:49 am)
I found something that would be close enough:
 
There is a discussion called: IIHS Picks Safest Vehicles
 
Can the host maybe move this there, so we can continue?

#104 of 130 done by pat

Nov 03, 2006 (9:01 am)

The preceding 15 or 16 posts have been moved from another discussion.

#105 of 130 Re: First hand experiences and thoughts? [jeffyscott] by backy

Nov 03, 2006 (9:16 am)

Replying to: jeffyscott (Nov 03, 2006 8:42 am)
OK, so here's an analogy: suppose there are two car-sized boxes. One weighs 10 pounds. The other weighs 4000 pounds. Both run head-on (maybe at an offset) into another box that weighs 3000 pounds, with each box traveling at 20 mph. Which box do you think would have the most damage? The box that weighs 10 pounds, or the box that weighs 4000 pounds? Or would they suffer the same amount of damage?
 
If you had a choice of being hit by the 10 pound box or the 4000 pound box, which would you choose?
 
These are extreme examples of course, but do you see that the weight of the car does factor into the test if the car is moving?

#106 of 130 Re: First hand experiences and thoughts? [backy] by jeffyscott

Nov 03, 2006 (9:48 am)

Replying to: backy (Nov 03, 2006 9:16 am)
Yes, of course the weight of the cars is a factor in a collision. This is a weakness of the current frontal tests. They adequately simulate a single vehicle crash or a crash with a similar weight vehicle.
 
If a "good" rated civic has a head-on crash with lower rated, but 1000 pound haevier car (eg Impala)...which will prove to be safer. I'm pretty sure it would be the Impala. Now what if the weight difference is only 500 pounds? Is an "acceptable" Fusion safer (based on frontal crash test results) than a "good" civic? I'd guess probably...but it is only a guess.
 
In a two vehicle accident the weight of both vehicles is a factor, because weight (actually mass ) is a factor in energy and momentum. So if a test has moving standard simulated vehicle crashing into a moving test vehicle, yes the weight of the test vehicle would be a factor...but this is just as it is in the real world.
 
IIHS managed to come up with a moving sled for side impacts, not sure why something similar would not be done frontal. Design something mimicing the front end of 3000 or 3500 pound car (and/or truck/suv) and crash it into the front end of a moving test vehicle.

#107 of 130 Re: First hand experiences and thoughts? [jeffyscott] by backy

Nov 03, 2006 (10:17 am)

Replying to: jeffyscott (Nov 03, 2006 9:48 am)
...yes the weight of the test vehicle would be a factor...but this is just as it is in the real world.
 
OK, then we are in agreement I think. If the IIHS were to implement a frontal test as you have suggested, where a moving car hits a moving barrier, then the tests could not be compared across weight classes. That was the original question we were discussing. The question was not whether the IIHS could design such a test and if it would be useful, but just whether the results could be compared across weight classes.

#108 of 130 Re: First hand experiences and thoughts? [backy] by jeffyscott

Nov 03, 2006 (12:45 pm)

Replying to: backy (Nov 03, 2006 10:17 am)
I don't see why you say it could not be compared across weight classes.
 
If they smashed a 3000 pound device into a Civic, the results would simulate what would happen in the real world if the civic were hit by a 3000 pound vehicle.
 
If they smashed the same 3000 pound device into an Impala, the results would be indicative of what would happen in the real world if the impala were hit by a 3000 pound vehicle.
 
Comparing them would tell you how one would do relative to other in a real world frontal collision with the same 3000 pound vehicle.

#109 of 130 Re: First hand experiences and thoughts? [jeffyscott] by backy

Nov 03, 2006 (12:52 pm)

Replying to: jeffyscott (Nov 03, 2006 12:45 pm)
Didn't you just agree that weight would be a factor if both the cars and the sled were moving??
 
We weren't talking about smashing a device into a car. I thought you had proposed taking a moving device and smashing it into a moving car.
 
I'm done on this topic.

#110 of 130 One last attempt... by jeffyscott

Nov 04, 2006 (6:10 am)

Replying to: backy (Nov 03, 2006 12:52 pm)
I thought you had proposed taking a moving device and smashing it into a moving car.
 
Yes, and this would mimic what would happen when a 3000 pound moving car smashes into the other moving (tested) car in the real world. Civics do not collide only with other Civics and Impalas with other Impalas in the real world.
 
What is wrong with the idea of a standardized test that mimics a 2 vehicle accident? The Civic owner is just as likely to collide with a 3000 pound vehicle as is the Impala owner.

Messages Page 11 of 13

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