How do you know a collision between two light cars is better? (I’m not saying you’re wrong, just that it isn’t obviously true.)
For example, a car made ought of plywood would be lighter than a car made of steel, but it would also probably be much, much more dangerous. Of course there are other reasons why lighter cars are preferable ceteris paribus.
Materials that splinter rather than crumple would be problematic, but assuming we keep cars constructed basically as they are now, I would expect the collision between lighter cars to be better for basic F=MA reasons.
The results have a clear pattern: reducing a vehicle’s weight increases net risk in collisions with
substantially larger and stronger entities, reduces net risk in collisions with much smaller and more
vulnerable entities, and has little effect on net fatalities in collisions with vehicles of about the same
size (although nonfatal injuries increase).
It is a strongly written and interesting article which I suggest reading. It really illustrates a lot of irrationality in consumer car-purchasing decisions, though one particular example (the cupholders thing) has been chewed over here before and I disagree with the author of the article’s opinions on that one specific point. It also suggests at least some level of mystical thinking by the auto industry.
For those without the time, a short summary is provided:
It suggests that according to some statistics, the drivers of midsized cars are among the safest because the decreased ‘passive’ safety in driving smaller vehicles is compensated for by better ‘active’ safety in terms of better performance in accelerating, stopping, and especially turning to avoid problems—and that this second active safety effect is larger than the passive safety gains by switching . The safest of all is extremely large things like minivans because of details of their design and construction—being designed from the ground up for safety with e.g. crumple zones and so forth, but midsized cars are rather towards the safe end of things in terms of fatalities per millions of drivers. Finally, it suggests that the SUV is extremely unsafe but bought anyways for psychological reasons—people like to feel ‘big’ and ‘high up’ even if that is objectively safe. This works to the extent that at one time automakers made a back window smaller to make drivers feel like others couldn’t see in, and thus feel safer even though larger windows are objectively safer.
I know that I personally think it is less safe for me to be driving an SUV or truck compared to a smaller car; The giant mass feels great psychologically, but after driving a smaller car a lot, the larger ones I have driven feel too sluggish and slow to avoid things.
I would expect the collision between lighter cars to be better for basic F=MA reasons.
It may be that collision between lighter cars is better. If so the reasons are not ‘basic F=MA reasons”. In the basic collision model neither m nor a change. The relevant mass is the mass of the persons body and the acceleration is determined by the collision speed and the degree to which the cars crumple. The mass of the (identical) cars is irrelevant (for ‘basic’ purposes).
Again, there may be more complex reasons why more mass in the cars makes them more dangerous. For example if shrapnel is considered a relevant factor and 0.5% of the mass of the car creates shrapnel then lower mass becomes desirable all else being equal. (Cars designed with modern engineering standards should in theory eliminate most reasons why lighter could be better, basically by bringing the reality closer to the basic model and reducing the extent to which ‘chaotic moving car parts’ cause injury on top of the ‘human stops suddenly’ problem.)
I’m not sure why you think you’re corrected. Your quote seems to imply that larger cars for safety is defection because they increase safety for their occupants while reducing safety for people in smaller cars.
Yes, but if I’m reading this right, the payoff matrix is different from the PD. If two large vehicles collide, it’s about as bad as two small vehicles colliding. This means that if everyone drove a huge truck, safety would be improved overall (trees won’t get bigger to match, and no one cares about their safety). If all you care about is safety, the optimal situation is everyone in a large vehicle.
And the extra money for the car (larger and heavier tend to be more expensive) and the extra destruction of the environment (when aggregated across everyone who drives)
How do you know a collision between two light cars is better? (I’m not saying you’re wrong, just that it isn’t obviously true.)
For example, a car made ought of plywood would be lighter than a car made of steel, but it would also probably be much, much more dangerous. Of course there are other reasons why lighter cars are preferable ceteris paribus.
Materials that splinter rather than crumple would be problematic, but assuming we keep cars constructed basically as they are now, I would expect the collision between lighter cars to be better for basic F=MA reasons.
ETA: I stand corrected: See here on page 4:
I read a long time ago the following article about car safety:
Malcolm Gladwell’s article Big and Bad
It is a strongly written and interesting article which I suggest reading. It really illustrates a lot of irrationality in consumer car-purchasing decisions, though one particular example (the cupholders thing) has been chewed over here before and I disagree with the author of the article’s opinions on that one specific point. It also suggests at least some level of mystical thinking by the auto industry.
For those without the time, a short summary is provided:
It suggests that according to some statistics, the drivers of midsized cars are among the safest because the decreased ‘passive’ safety in driving smaller vehicles is compensated for by better ‘active’ safety in terms of better performance in accelerating, stopping, and especially turning to avoid problems—and that this second active safety effect is larger than the passive safety gains by switching . The safest of all is extremely large things like minivans because of details of their design and construction—being designed from the ground up for safety with e.g. crumple zones and so forth, but midsized cars are rather towards the safe end of things in terms of fatalities per millions of drivers. Finally, it suggests that the SUV is extremely unsafe but bought anyways for psychological reasons—people like to feel ‘big’ and ‘high up’ even if that is objectively safe. This works to the extent that at one time automakers made a back window smaller to make drivers feel like others couldn’t see in, and thus feel safer even though larger windows are objectively safer.
I know that I personally think it is less safe for me to be driving an SUV or truck compared to a smaller car; The giant mass feels great psychologically, but after driving a smaller car a lot, the larger ones I have driven feel too sluggish and slow to avoid things.
It may be that collision between lighter cars is better. If so the reasons are not ‘basic F=MA reasons”. In the basic collision model neither m nor a change. The relevant mass is the mass of the persons body and the acceleration is determined by the collision speed and the degree to which the cars crumple. The mass of the (identical) cars is irrelevant (for ‘basic’ purposes).
Again, there may be more complex reasons why more mass in the cars makes them more dangerous. For example if shrapnel is considered a relevant factor and 0.5% of the mass of the car creates shrapnel then lower mass becomes desirable all else being equal. (Cars designed with modern engineering standards should in theory eliminate most reasons why lighter could be better, basically by bringing the reality closer to the basic model and reducing the extent to which ‘chaotic moving car parts’ cause injury on top of the ‘human stops suddenly’ problem.)
I’m not sure why you think you’re corrected. Your quote seems to imply that larger cars for safety is defection because they increase safety for their occupants while reducing safety for people in smaller cars.
Yes, but if I’m reading this right, the payoff matrix is different from the PD. If two large vehicles collide, it’s about as bad as two small vehicles colliding. This means that if everyone drove a huge truck, safety would be improved overall (trees won’t get bigger to match, and no one cares about their safety). If all you care about is safety, the optimal situation is everyone in a large vehicle.
but you have to offset by QUALY’s you could have bought with the extra gas money.
And the extra money for the car (larger and heavier tend to be more expensive) and the extra destruction of the environment (when aggregated across everyone who drives)