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Thursday, April 14, 2005

NHTSA: Standardize the Interface

We need some more regulations. That's right, I am an automotive engineer, and I am calling for more regulations. Sometimes, regulation is necessary, to save lives. And since safety regulations apply equally to all manufacturers, they are not a competitive disadvantage.

At the SAE Congress, Dr. Joseph Kanianthra presented data (Detroit News article here) that showed the relative death rates of car passengers, when struck by a light truck or SUV.
For example, in 2001, there were 1,163 deaths when cars were struck in the side by other cars. There were 2,008 deaths when cars were struck by light trucks, NHTSA's latest research shows. (nearly double)

NHTSA and the OEMs need to collaborate, and come up with a set of interface standards between light trucks and cars. Then, those standards need to be made mandatory, and NHTSA would require tests designed to these standards. These would be similar to the new IIHS side impact test, which simulates the high bumper of an SUV hitting a vehicle in the side.

I am not a structural engineer, so I don't know exactly how the new standards would look like. The crash structures of light trucks may need to be lowered to better interface with cars, and the crash structures of cars would be raised.

For example, I might require that light trucks have a subframe in the front and rear, which would contact most car bumpers in the event of a front or rear crash, preventing over-run. This sub-frame could perhaps be removable, for the 3 Hummer H2 owners out there who actually want to take their behemoths off-roading.

I would also require cars to have a strong high mounted side impact beam, and side curtain airbags, to protect the passengers if a light truck hits them from the side.


B. ENG. said...

We've known this for quite a while.
(SAE Paper 980908. Feb 1998)

The research has already been conducted in this field and the primary factor that affects safety in impacts is the vertical relation between the frame height of the striking vehicle and the frame of the impacted vehicle.

Here is a study conducted from 1998-2000 by VW, Peugeot, DCX, and most of the other manufacturers with a large presence in Europe concerning vehicle collision compatibility:

Key findings wrt side impacts
1. An override of sills by the bullet vehicle is a disadvantage for the occupant of the struck vehicle.
2. The mass ratio is of minor influence.

These vehicles can be made much safer to others but people will need to give up the illusion that they use their vehicle for safari on the weekends. Since this constitutes 80% of the big 2.5 profit in US I do not think that we will see any progress in this regard.

The Auto Prophet said...

Actually, your first citation does seem to support a correlation between aggressivity and mass ratio...

The key thing here is will. NHTSA needs this done, and the OEMs need to come around.

The Angry Engineer said...

At some point, shouldn't we just mandate 10-point roll cages and full-face helmets for all vehicle occupants?

It'd be nice if we could see more concentration on improving driver habits, since I honestly thing we're past the point of diminishing returns when it comes to improving crash safety. A side impact is a T-bone, and it would seem that those are primarily a result of someone blowing through a traffic signal.

Seems to me that the structural engineering guys have done their job; now it's time for civil engineers to improve intersections and traffic signaling, and the ergonomic and human-factors guys need to determine how to minimize driver distraction.

That's my take on it. Given all of that, I'd welcome a bit more structure in upper door area of passenger cars. And while I think that frontal airbags aren't all that necessary with the use of proper restraints, side airbags sure seem to carry a lot of benefits.

I'd also appreciate it if people could select a vehicle in a socially-responsible manner. While some of us need a pickup with high bumpers, a lot of others could be commuting in something a lot closer to the ground. I've always thought that picking an SUV just for crash-safety reasons is another way of saying "f*ck you" to everyone else around you.

The Auto Prophet said...

I agree WRT the causes of side impact--it almost always means that someone didn't stop when they should have, like at a light.

I think that design changes to most SUVs could be done subtly, so that they still look "tough" and ride high, but don't pose as big of a danger. I personally don't know anyone who takes thier expensive late model SUV offroad--the guys I know who go rockcrawling use beat up old Jeeps and Toyotas.

The Angry Engineer said...

I agree with respect to lowing the bumpers of most SUVs - those things never leave the road. I'm just not sure how to legislate lower bumpers only on the Soccer-mom Specials.