Skip to comments.Heavier Vehicles Not Always Safer
Posted on 07/30/2002 7:58:36 AM PDT by cogitator
Heavier Vehicles Not Always Safer
ANN ARBOR, Michigan, July 29, 2002 (ENS) - More quality, not more weight, may make vehicles safer, say researchers from the University of Michigan and Lawrence Berkeley National Laboratory (LBNL).
The study counters car industry warnings that tighter emissions and fuel efficiency requirements would force the production of smaller, lighter - and less safe - vehicles.
Physicist Marc Ross and LBML scientist Tom Wenzel have released a report showing that vehicle quality is a better predictor of safety - both for the driver and for other drivers - than vehicle size and weight. Recent Senate hearings on Corporate Average Fuel Economy (CAFE) standards focused on the increased risk Americans would face if they had to give up their sport utility vehicles (SUVs) for vehicles that weigh less.
"We set out to see whether that risk is real, whether SUVs really are safer than cars. The answer, by and large, is no," Ross said.
The first major result Ross and Wenzel found is that SUVs are no safer for their drivers than cars. Popular midsize cars, minivans and import luxury cars have the safest records, while SUVs are about as risky as the average midsize or large car, and are no safer than many compact and subcompact models.
The researchers defined risk as the number of deaths per year per million vehicles.
Other studies have not considered combined risk, which looks at both risk to the driver of the model in question and risk to the drivers of all other vehicles involved in crashes with that model. The study found that, when measuring the combined risk, most cars are safer than SUVs, while pickup trucks are much less safe than all other types of vehicle.
"Clearly the characteristics of the drivers of certain types of vehicles also have a strong effect on their safety," Ross said. "However, it is not clear exactly what that effect is, and the age and sex of drivers do not fully explain these results."
Some of the safest subcompacts also have a high fraction of young male drivers. At the other extreme, elderly drivers dominate certain large cars but there is no clear pattern suggesting that those cars pose higher risk to drivers of other cars as a result.
To determine quality, Ross and Wenzel used quantifiable parameters such as new car price, used car price, Consumer Reports safety ratings, and country of origin.
"It is extremely difficult to determine the inherent safety of a vehicle type or model because it is too hard to separate the contribution of driver characteristics and behavior from the contribution of vehicle design. We can say, however, that quality is a much better predictor of safety than weight," Ross said.
"It turns out that relatively inexpensive light cars do tend to be unsafe, but more expensive light cars are much safer, and are as safe as heavier cars and SUV models," Ross explained. "In any event, the argument that lowering the weight of cars to achieve high fuel economy has resulted in excess deaths is unfounded. If designers pay careful attention to safety in vehicle design, smaller cars can be, and indeed have been, made as safe as larger ones."
Well, no s***. An SUV slamming into a Geo is going to cause a lot of hurt, and not to the SUV driver. But using the "combined risk" method here, the SUV gets docked for safety as much as the Geo. Brilliant.
This is like saying that guns are just as dangerous to the person pointing it as the person he is pointing it toward. This is Green crap.
As my kids would say, "Um, yeah, riiiiight."
What's not safe about this heavy truck?
If you forget to set the parking brake it might roll down your driveway and crush your house ...
Not to be too harsh about it, but I don't buy a Suburban to protect the other guy. I buy it and drive it to protect me and my family. Screw these people and their study.
Not really, I was just commenting on the absurdity of using combined risk as a valid indicator of safety. In addition to the roll factor, SUV and pickup owners are more likely to engage in riskier driving behaviors (off-roading, snow driving, etc.). HOWEVER, common sense (and hundreds of studies) leads me to believe that my personal person is a lot safer in a truck than in a Miata. That said, if you control for seat belt usage, air bag deployment, etc., I bet the safety differences are nominal. No company wants a deathmobile on the market.
OK, I have no beef with trying to use price as a predictor of quality, although I don't think one necessarly follow the other. But how is country of origin supposed to predict quality?? Are the weenies saying that a car made somewhere other than the US is automatically presumed to be better??
And what about using Consumer Reports safety ratings to predict quality?? If they find out these cars actually are safer, it just amounts to saying "Yeah, the cars that those other guys said are, um, safer." If they are trying to correlate to quality, why don't they use the repair ratings as a quality measure? This way, their thesis is "proven" by presuming it to be true in the study design.
Excellent point. That reminds me of an accident I was involved in. I was sitting stopped at a light in the rain in my '77 Plymouth, and was rear-ended by a Honda Civic, who was then rear-ended by a Toyota Genericus. The Toyota had major damage, the Honda was probably totalled, while I had a small scratch on my license plate. ;-)
The bigger the "m" (mass), the smaller the "a" (acceleration). The "a" is what kills.
Certainly, for a given mass, safety is strongly dependent upon design, but that doesn't change the fact that for a given design, heavier is safer.
I'm amazed you're still with us. I was hit from behind by a driver who "didn't see me" and hit full force at about 30mph. She exited her car through the windshield (obviously no seat-belt engaged, along with her brain.) I have permanent damage to my back & neck.
I now have been driving a Suburban for almost ten years. The next fool to rear-end me will be the only one hurt IMO.
Your accident illustrates one of the problems with vehicular safety that happens with vehicles of various sizes on the roads. The mass of the vehicle is one thing, and the height of the vehicle is another. The higher chassis of SUVs allows their frame to override the frame of smaller, lower cars, and "spear" the passenger compartment.
What's clear in all of this discussion is that the larger the disparity in size on the roads, the more likely that an "unbalanced" accident (i.e., large vehicle vs. small vehicle) will result in injuries and death to the passengers in the smaller vehicle. This study tells me that the most dangerous cars are going to be the lower-quality small cars; so one of the things that needs to be done is to raise the safety standards for those vehicles.
One of the arguments for higher mandated CAFE standards is that they would "compress" the vehicle size range, leading to an increase in overall safety. That isn't going to happen, so there will have to be advances in other areas. One potential advance would be side impact curtains (version of air bags), but that still won't help a passenger in a small car if the frame of a big car pushes into the passenger compartment. Clearly the most dangerous accidents now are side-impacts, so another facet of this would be to target dangerous intersections (easily determined by accident statistics) and modify them to reduce the chances of side impact collisions.
It's like reducing auto emissions pollution; 10% of the cars contribute 90% of the pollution, so vehicle testing programs for all cars are a big waste of money. Cameras that sample emissions and notify drivers of polluting cars that they are in violation are much more effective. Likewise, to improve vehicle safety, the main focus should probably shift from the vehicle to the intersections that are poorly designed, which leads to bad accidents. I expect that it's probably also a 10-90% situation, where about 10% of the intersections cause 90% or so of accidents with major injury or fatality.
I have seen two SUV's roll over WITHOUT AN IMPACT, while performing an emergency lane change. Any Hyundai Accent would have performed the maneuver safely.
A false sense of safety is not a good thing.
Discover had a piece about SUV safety that mentioned the increased rollover danger (higher center of gravity). It also noted studies showing that SUV drivers tend to drive faster -- increasing the rollover risk -- as they experience a reduction in their perceived speed because they are higher off the ground.
SUVs aren't for me, but I wouldn't tell someone else what to drive. But it's clear that SUVs require responsible and considerate drivers. I particularly worry about teenagers who are neither of those driving SUVs. (Many teens are responsible and considerate. Some are not. I worry about those that are not who are driving SUVs.)
That is what it is all about. My new Suburban has airbags for the driver and passenger and shoulder straps for all outside seat passengers. I would imagine an 18 wheeler would take a toll, but just about any passenger car is in a lose situation with it.
My new car is a Kia Sedona minivan. VERY fast and very stable with perhaps the best safety rating offered by Consumer Reports of any in its class. The warranty was the real kicker for me...that and the price.
But my heart belongs to the SUV.
When I can afford it (probably have to wait until I retire) I'll go to www.sportsmobile.com and have a custom DIESEL 4X4 VAN built to my specs--get a 15 yr mortgage on it and write it off my taxes as a second home, while travelling the USA with wife and Neufoundland dog. Check the site out (look for the 4x4 link) to see what I mean.
You people are missing something though, there are other ways to die other than car/SUV collisions. What matters is, what are your chances of death or serious injury, per year, in each type of car? One would naturally ASSUME that the SUV is far safer, for your reasons stated above, but there are other ways to get hurt, especially when drivers get a false sense of security due to ill concieved impressions of safety.
I dont know the stats, but since cars tend to roll over less often, break better, and maneuver better (thus being able to avoid accidents better), I'll bet its not what one might think.
I am not an anti-SUV zealot, heck, I think they have their uses, and I would be the first to oppose any kind of stupid gubmint regulations against them.