safety behind the wheel - bigger isn't necessarily better
 

The prevailing wisdom on this board appears to be that the bigger my car is, the safer I will be. Specifically, this seems to come up whenever someone mentions the Smart car.

Here's one interesting graph from a recent article in American Scientist. It shows risk to drivers and drivers of other vehicles, and the data comes from IHS accident statistics. Note e.g the relative safety of the BMW 3-series, Nissan Altima and Buick Century. Another interesting trio is the Durango, the Explorer and the Blazer.

http://www.americanscientist.org/Lib...03WenzelF4.jpg

Myself? I'll keep my European mid-size with more airbags than cupholders. :)

/ Johan

ps. The article goes into depth about how the results were produced and what conclusions can be made. Link to the source:

http://www.americanscientist.org/issues/feature/safer-vehicles-for-people-and-the-planet/1

Look at the Ford E series. That is wacked out 20-something delivery drivers.. Always good to steer clear..

Risk to drivers and risk to others - all American made..:(

People seem to like to have the potential ability to kill others with their car/SUV.

Makes them feel all powerful or something.

Top-selling cars? They're trucks
http://www.bankrate.com/brm/news/auto/car-guide-2007/20070801_top_selling_cars_a1.asp

wow, that is really surprising.

I'm baffled by how the North American compact cars (Escort, sunfire, cavalier, neon) fared so poorly... maybe rental cars would throw these numbers off?
http://forums.pelicanparts.com/uploa...1213720806.jpg

My first impression is that Eurpoean safety standards must be higher. This is based on the tighter distribution of European vehicles tending toward the lower left and the large number of domestic vehicles that are scattered around the outside of them.

well it looks like it confirms everyones bias

big cars/truck will cause the car they are hitting more damage.
mass and speed make a big difference, also where the point of impact

explorer's suck anyway you put it. blazer doesnt say if it is the smaller or full size version.
durango is probably the bigger version.

they probably got hit by all those big american SUV's

That graph provokes a lot of reactions - the article goes through some of the possible explanations as to why certain cars may be in different areas. What I find interesting is that similar cars, that are likely used in the same fashion and driven by the same type of drivers perform very differently in actual accidents.

• You're 50% more likely to die behind the wheel of a Corolla or Civic than a Jetta.
• You're twice as likely to die behind the wheel of a Grand Cherokee than a Lexus Rx300.

That's not intuitive, but it appears to be what the data is saying.

/ J

Now if they would just make a Hybrid 4WD Odyssey.

well there must be some genetic programming here...americans always equate bigger as better and safer. It is funny that people think a Smart is not safe because it is small

you get in your Smartcar, I will get in my buddy's 1/2 ton Chevy work truck, we crash them into each other and see who walks away.

If you are in 550 kilo telephone booth on wheels, and I hit you in a 2000 kilo body on frame truck, you are going to walk with a much worse limp than I, physics is a funny thing, and can be a bit of a bearcat. Ever see video of a train hitting something?

This is poorly presented info as it insinuates that an equal number of vehicles in an accident represents the total cross section sampled of each vehicle.

"Because we used actual crash statistics, the values we calculated reflect the risk of involvement in a crash and the speed at which it occurs, which hinge primarily on environmental factors and the behavior of the driver, as well as the risk of fatality once a serious crash has taken place, which depends on belt use, vehicle design and driver frailty. As such, our use of the word "risk" here is just shorthand for "risk as a car or truck is really driven."

So that's really sort of a stretch to graph this on a simple X-Y then isn't it.

Bigger=more mass=safer to the occupant and that's exactly why the Army doesn't make tanks out of mail jeeps.

obviously it depends on the circumstances of any accident...My brother has seen people die in what seems to be minor accidents...very low speed stuff..and yet has seen people walk away from huge wrecks....but he always says that suv's/trucks kill more people(both inside and out ) than small cars except when they hit trees.
He says it is the luck of the draw more than anything

That may be true in a controlled experiment, but in real-life driving I bet the 1/2 ton is far more likely to be in an accident than a Smart car.

Up here where I live, people are convinced they need a pickup or SUV to drive in the snow. Funny thing is when it's snowing, they are the first vehicles scattered along the median, shoulder and in the bushes... pointing backwards, on their sides... stunned drivers crying into their cellphones.

Pickups are even worse. Every now and then I borrow my FIL's pickup for some fiasco or another. That thing is terrible in the snow or rain.

I read a good summary somewhere a while ago:
SUVs are safer if you are going to be in a crash, but crappy if you don't want to be in a crash in the first place

Try this:
One guy gets in his Smart Car and have another get in the 1/2 ton pick-up. Both accelerate up to 60mph then have a semi truck pull out in front of them 120 ft away. Lets see which one gets out of that better assuming they both hit the brakes at the same time.

I just can't believe that there are people who would answer "B" to the following question:

2 cars get into a collision. Which car would you rather be in?

A. The Smart car
B. The 6,000 lb. car

Yes, without knowing any other facts, you could be worse off in the 6,000 lb car, depending on the circumstances. But to say that the chances of serious death or injury, in an accident between 2 vehicles where one outweighs the other by 2-3 times, are equal, or it's just "the luck of the draw," doesn't really work.

OK, I can play this game: 40 mph into an offset deformable barrier - European test procedures. I couldn't find any test results for large PUs, but here are a few examples. The 2007 Smart scored better than a 2005 Jeep Grand Cherokee, but worse than 2003 Saab 9-3.

1. 2007 Smart for two crash:
Front impact
The passenger cell remained stable during the impact. Structures in the dashboard presented a risk of injury to the knees and femurs of the driver and passenger.

Side impact
The dummy's head contacted the rubber window trim on the cant rail, leading to a high deceleration. However, the data recorded by the dummy suggested an adequate level of head protection. A side impact airbag to protect the chest and the head is available as an option but was not fitted to the test vehicle.
source:
http://www.euroncap.com/tests/smart_fortwo_2007/303.aspx

2. 2005 Jeep Grand Cherokee:

Front impact
Structures in the dashboard represented a potential hazard to the knees and femurs of the driver and passenger. Protection of the driver's chest was weak.

Side impact
Although the car was eligible, Daimler-Chrysler did not choose to sponsor a pole test.

source:
http://www.euroncap.com/tests/jeep_grand_cherokee_2005/239.aspx

3. 2003 Saab 9-3

Front impact
The knee impact area is particularly well planned, having a knee bolster that is designed to collapse when struck hard. But testers found that the steering column could transmit impact forces to the driver’s knees. The footwell was not deformed by the impact, posing few hazards to the driver’s feet and ankles. The front belts were fitted with load limiters and reel mounted pre-tensioners. Even so, the driver suffered a high-ish chest loading. The centre rear seat belt was of a three-point type, which provides much better protection than that of a lap-only belt.

Side impact
No points were lost for its side impact performance, including the pole test. The curtain airbag protected all occupants on the struck side. This deploys in glancing frontal impacts where occupants may be be partly ejected as the car rotates during impact.

source:
http://www.euroncap.com/tests/saab_9_3_2002/131.aspx

I think that's because pickups don't have to comply with the same safety standards as passenger vehicles. Please correct me if I am wrong on that, but that should give you an indication of how they might perform.

Do you think that if a manufacturer doesn't have to spend the money to meet a safety regulation that they'd go ahead and spend it out of the goodness of their hearts?

As a point of reference here are some of the same test for pickups trucks.

A 2008 Isuzu Rodeo/D-Max

Front impact
The passenger compartment became unstable in the frontal impact and the D-MAX did not achieve the minimum number of points in this test to get a three star rating, even though it scored enough points overall. Protection of the driver's head was rated as weak. The final star is struck through because dummy readings in the neck and chest indicated an unacceptably high risk of life-threatening injury. Structures in the dashboard presented a risk of injury to the knees and femurs of both the driver and passenger. Protection of the driver's lower legs was jeopardised by excessive upward movement of the brake pedal. Protection of the driver's feet was poor, owing to a ruptured footwell and pedal movement.

Side impact
A head-protecting airbag is not available on the D-MAX so a pole test was not performed.


http://www.euroncap.com/tests/isuzu_dmax_rodeo/316.aspx

A 2008 Nissan Navara - I've even put in the modified version which did well compared to the previous one.

Front impact
Nissan have modified the Navara to address some of the areas that caused greatest concern when the car was originally tested. The software that controls airbag firing has been revised and, in this test, the airbags deployed as intended. As a result, protection of the head and neck was good for both driver and passenger. However, the passenger compartment was again unstable which, combined with the chest compression measured by the dummy, led to protection of the driver's chest being rated as weak. Structures in the dashboard presented a risk of injury to the knees and femurs of both the driver and passenger. There was extensive deformation of the driver's footwell and the car was penalised because the lower chassis rail punched a hole in the toeboard. Dummy readings indicated weak protection of the driver 's lower legs and rearward movement of the pedals led to protection of the feet and ankles being rated as poor. Nissan have instigated a service campaign to upgrade D40 Navaras (from VSKCVND40U0016577) with the revised airbag software. Euro NCAP strongly encourages owners to have their vehicles upgraded if invited to do so by Nissan.

Side impact
The Navara scored maximum points in the side impact test. A head-protecting airbag is not standard equipment so a pole test was not performed

http://www.euroncap.com/tests/nissan_navara_2008_2/319.aspx

These did well in the side impact test but I wonder if that might be because the occupant is sitting higher than the impact device?

I understand why there may not be safety ratings for larger pick-up trucks. I'm not sure how the Euro NCAP decides what vehicles to test, but I don't think it's based on safety regulations, maybe by market size?

Here's a picture of what happened to a 2002 Mini Cooper and a 2002 F150 after hitting the same type of offset barrier:

http://www.bridger.us/pictures/mini_vs_f150.jpg
source: http://bridger.us/2002/12/16/CrashTestingMINICooperVsFordF150/

I think Ford has improved the F150 since.

/ J

M-1 Abrams are not subject to the same safety standards either. You think that gives you an indication of how they'd perform in a crash?

Nope.

Speculation isn't necessary since there are people who crash test cars for a living and the results are published. See the image I just posted for a comparison between the 2002 Mini Cooper and Ford F150.

/ J

That's a silly argument with all due respect. A main battle tank is pretty much a cost-no-object war machine. It's sole purpose is to destroy without being destroyed. I would guess that the manufacturer is not that worried about cutting cost to maximaize profit.

Now look at your average road going vehicle. Sure it's designed as transport, but it's purpose is to make $$ for the company that produces it - full stop. It's a money making machine. The comapny behind that will do whatever it can to penny pinch the vehicle for all they're worth and to push up the price on the other end to maximize profit.

I would imagine that a pasenger car wouldn't stand up too well to incoming fire.

You're on to something I think. I don't think you'd find that many full size pickups in Europe.

The real world test would have the smart car and 1/2 ton truck getting up to speed and then colliding into each other. I see a ton of vehicle collisions on the highway and in intersections. Simple physics dictate the bigger car will "win". My sister-in-law got rear ended waiting at a red light by a delivery truck. Most likely had she been in a smart or mini cooper she would not have survived. Pro's and con's in any direction.

So now all large vehicles perform to the same substandard as the poorly built F-150?

The same is true for a main battle tank. You think General Dynamics makes the M-1 to lose money? The truth is the M-1 could have all kinds of additional features and capabilities if money wasn't an issue. As it is now it is already an extremely expensive tank.

At any rate, my point was that just because something does not have to be tested against a certain criteria doesn't mean it wouldn't perform that criteria extremely well. I am sure an M-1 would absolutely own the various crash tests in use today even though not one seconds thought was ever put into doing such. ;)

In general, assuming equal construction and equally well thought out designs, the larger vehicle is always going to perform better- it's just physics.

Hit a smart car with the aforementioned F-150, and the smart car is going to react just like a baseball when struck by a bat. It may be intact, but it is still going to be the loser the the collision occurs. The F-150 is the bat- the SC is the ball.

My point exactly.

Size matters:

http://www.defenseindustrydaily.com/...rum_Ago_lg.jpg
hehe

I would like to see how the occupants of an M-1 look after hitting an immovable wall at 50 mph, compared to the occupants of a Mini Cooper (which has crash deformation zones and airbags).

Of course in a Mini vs Abrams collision the safe bet would be on the Abrams! :)

awwww..... :(

http://forums.pelicanparts.com/uploa...1213738576.gif

In the Apr 05 Thunder Run into Baghdad, M-1s were confronted with Highway dividers(like those on the NJ turnpike, the ones that taper out toward the base) 4 feet tall, double thick, linked end to end accross highway 8, blocking their path to the Baghdad airport.

The solution? The Abrams accelerated to max speed(about 45mph) and rammed/ jumped them until the dividers were reduced to rubble. No crewman were injured.

Imagine ramming a highway divider head on in a mini-cooper!!!

LOL! Story of my life. :-P

I posted this in another thread earlier.

MINI Cooper Struck by a Suburban both rammed into guardrail, MINI owner walks away Suburban driver carted off with 2 broken legs.

I'll take my chances with the MINI cooper, besides every time we have a road closing wreck on I95 down here, its an SUV rolled over in the median with passengers scattered everywhere.

http://www.northamericanmotoring.com/forums/showthread.php?t=16992&

Getting knocked into a guardrail is hardly the same as smashing head on into a concrete highway divider. ;)

Actually the worst car crash i ever had was a VW rabbit into a steel utility pole at about 40mph head on.

I walked away.

Quality of construction obviously has MUCH to do with it.

So that explains your posts here on PPOT. :)

Been staggering my way through life ever since my brother. :D

Yes, but I gave you a real world example of that happens when a MINI and Suburban get into t a typical traffic accident in an afternoon rush hour situation.

If you think that the guy in the Suburban would be in better shape than the guy in the MINI after having a head on collision with a concrete barrier go right ahead.

Physics tell me the 4,000 lb vehicle is going to bleed a lot more energy hitting that barrier than the 2700 MINI. My example above proves that point, both hit a guardrail at the same speed, MINI driver walks away without a scratch and the Suburban driver breaks both legs and smashes his face real good.

Again, I'll take my chances in a nimble little car that has proven it can take a beating and keep the driver safe.

The larger car has larger crumple zones to decelerate the vehicle more gradually.

I prefer medium sized cars myself. I feel they add the best of both worlds. Mass and maneuverability.

There are very few walls that would be considered "immovable" with an M1 strike at 50 mph.

I'm not in disagreement with you at all: I'm simply interested in separating fact from myth. I haven't found any objective data on what would happen if a Mini collided with a 1/2 ton truck, but if you want to take the simple physics route let's see where it will go.

If you assume that the Mini weighs half of the pick-up truck and they hit head-on each going 40 mph, conservation of momentum implies that the Mini will experience what amounts to a 47 mph crash into a solid object while the pick-up will experience the equivalent of a 33 mph crash.

Now looking at the total amount of energy that needs to be absorbed by each vehicle in the crash, the Mini has a 40% larger velocity change to cope with but since it only weighs half as much the energy absorbed is the same for both vehicles (actually 2% less for the Mini).

What remains is how well the deformations zones of each car are engineered. This is an area in which huge improvements have been made, and I think the major reason why weight alone is not sufficient to decide whether a car is safe or not.

/ Johan

You didn't read the crash tests for the pickup trucks did you?

exactly, they might perform great if you run them into the same bridge as a Suburban, they are lighter, less energy to dissipate. But if hit by the Suburban, the big vehicle is going to just crush the smaller one. I even bet it would cushion the deceleration of the larger vehicle as it used up the crumple zone of the Smartcar first.

I think the danger is more from the performance of the driver, than from the vehicle

This is the most important realization of the whole discussion. Although, basic physics might suggest which auto might absorb more energy, physics doesn't address the engineering of safe zones, graded crush (vs instantaneous or more rapid decelerations), or structural integrity. Large trucks, (and many truck based SUV's) suffer from structural issues ie old-style body-on-(ladder)- frame construction, which is very poor in absorbing energy in accidents, but cheap to make (GM and Ford were laughing all the way to the bank). In addition, the attention to wheel-footwell encroachment in the typical US truck (important for head on crashes) is lacking as demonstrated by numerous safety tests. What one needs to compare, is a unibody crumple engineered chassis in a heavier vehicle vs a smaller vehicle. Example, ML series vs Smart car. Then the ML will more likely come out the winner.