f*l
发帖数: 742 | 1 Americans love big cars.?How much are they?costing the country?
Like Americans themselves, American cars are getting heavier and heavier
every year. Our new cars are?more efficient, with average fuel economy
climbing and carbon-dioxide emissions falling over the course of the past 30
years. But that is not because they are lighter. The average new car
weighed 3,221 pounds in 1987 but 4,009 pounds in 2010. Even small-size
sedans have packed on the pounds, thanks to more-powerful—if more-efficient
—engines, as well as features like nicer seats, more safety features, and
more legroom.
We pay a hidden cost for our fat cars. They may be sucking up less gas,
slowing the degradation of the environment and the warming of the planet.
But they have other "negative externalities" that do not figure into their
price tags or day-to-day costs as well—notably, more fatal traffic
accidents. The heavier the car, the safer it is for the driver and the more
dangerous it is for other vehicles and people on the road. You hardly need a
Ph.D. in physics to know that getting in a collision with a Hummer is going
to be very bad for the driver of a sedan, let alone a Smart Car, let alone
a bicycle. So how much are our fat cars costing us? And does it mean our
roads are less safe?
A working paper released this month by two economists from the
University of California, Berkeley,?Maximilian Auffhammer and Michael
Anderson, tackles the first question, attempting to put a price tag on the
fatalities associated with big cars. They studied accident data from eight
states, identifying the type and weight of vehicles involved in collisions
by their VIN numbers. The researchers confirm that the heavy cars kill.
Indeed, controlling "for own-vehicle weight, being hit by a vehicle that is
1,000 pounds heavier results in a 47 percent increase" in the probability of
a fatal accident. The chance is even higher if the heavy car is an SUV,
pickup truck, or minivan. (Taller vehicles tend to do outsize damage, too.)
The researchers then set out to calculate the value of the "external
risk" caused by our heftier vehicles. First, they considered a scenario in
which a driver chose between a car with the 1989 model-year average weight
of 3,000 pounds or the 2005 weight of 3,600 pounds. The heavier car
increased the expectation of fatalities by 0.00027 per car—27 deaths per
100,000 such vehicles. "Summing across all drivers," they write, "this
translates into a total external cost of $35 billion per year," using the
Department of Transportation's value of a statistical life of $5.8 million.
Judging against a baseline in which a driver chose the smallest available
car, such as a Smart Cars, the cost is $93 billion per year. The price tag
climbs beyond $150 billion per year if you include the cost of pedestrian
and motorcyclist deaths and figure in multi-car collisions.
Given the relationship between big cars and bad accidents, it might make
sense to make such cars more expensive to buy or drive. You could do this
with insurance premiums, or lawsuits. But the economists suggest a gas tax,
"because it is simple and because gasoline usage is positively related to
both miles driven and vehicle weight." They say it would take a 27-cent-per-
gallon gas tax to account for the $35 billion per year in extra costs from
heavier cars. (To account for the $150 billion in extra costs would require
a tax of more than $1 per gallon.)
But, surprisingly, none of this really means the roads are less safe.
Indeed, traffic deaths hit their?lowest-ever recorded level last year. In
part, that is because of cars' advanced safety features—steel cages, better
antilock brakes, improved air bags, stronger engines—and those tend to
weigh quite a bit. (Better emergency medicine, more stringent policing,
improved road quality, and the aging of the populace also figure in.) And
all things being equal, a heavier car is safer than a light one.
The problem is that American roads consist of a mix of heavier and
lighter cars, and the biggest danger is when they encounter each other. The
authors write that?relative?weight is what is most dangerous in crashes. The
recent vogue for lighter vehicles, driven in part by high gas prices and
changing fuel-economy standards, has raised worries about the chance of more
collision deaths. One study found that higher fuel-economy standards
imposed in the 1980s led to2,000 additional deaths per year. If Americans
suddenly start buying many more ultra-light cars, it is not hard to imagine
more deadly accidents as a result.
It's an unattractive choice. We can all buy heavier cars, all be a bit
safer, and all pay more for gas. Or some of us can buy heavier cars, pay
more for gas, and be safer while others buy lighter cars, pay less for gas,
and die more often on the road. As for the third option—we?all?buy lighter
cars, all pay less for gas, and all be safer—good luck trying to sell that
to America.
大意是：美国喜欢佬的车越来越大越来越重，然而代价是烧更多的燃料，对环境污
染更严重。较重的车对驾驶者来说致命的事故相对减少，但对较轻的车和行人却很致命
。所以，从以往的事故统计来看，最可怕的就是车重明显相差太大的事故。那么问题来
了，是大家都买较重的车获得更好的安全烧更多的油气，但给较轻的车造成更多的死亡
，还是大家都买较轻的车，皆大欢喜呢？ | x*********s
发帖数: 5554 | 2 写的挺符合常理的，虽然满篇都是推测。
heavier
30
efficient
,
【在 f*l 的大作中提到】
: Americans love big cars.?How much are they?costing the country?
: Like Americans themselves, American cars are getting heavier and heavier
: every year. Our new cars are?more efficient, with average fuel economy
: climbing and carbon-dioxide emissions falling over the course of the past 30
: years. But that is not because they are lighter. The average new car
: weighed 3,221 pounds in 1987 but 4,009 pounds in 2010. Even small-size
: sedans have packed on the pounds, thanks to more-powerful—if more-efficient
: —engines, as well as features like nicer seats, more safety features, and
: more legroom.
: We pay a hidden cost for our fat cars. They may be sucking up less gas,
| g*********y
发帖数: 500 | 3 这和禁枪异曲同工，要不都没枪。 有人有， 我就要有。 | y******e
发帖数: 1194 | | g*********y
发帖数: 500 | 5 撞墙是的， 因为反作用力＝ 作用力
【在 y******e 的大作中提到】
: 日拖拖们不是说越轻越安全么
| n*****e
发帖数: 79 | 6 撞墙轻重一样的
有吸能设计的撞墙稍好
撞墙是的， 因为反作用力＝ 作用力
【在 g*********y 的大作中提到】
: 撞墙是的， 因为反作用力＝ 作用力
| g*********y
发帖数: 500 | 7 动量＝MV 能量＝MVV
V一样， M越大， 动量和能量越大。
【在 n*****e 的大作中提到】
: 撞墙轻重一样的
: 有吸能设计的撞墙稍好
:
: 撞墙是的， 因为反作用力＝ 作用力
| j*****t
发帖数: 2225 | 8
轻重肯定不是一样的，结构强度应该是差不多的，但是比较重的车会相对溃缩多一些
。
【在 n*****e 的大作中提到】
: 撞墙轻重一样的
: 有吸能设计的撞墙稍好
:
: 撞墙是的， 因为反作用力＝ 作用力
| l*********u
发帖数: 19053 | 9 作者肯定是开小而轻的车 :)
heavier
30
efficient
,
【在 f*l 的大作中提到】
: Americans love big cars.?How much are they?costing the country?
: Like Americans themselves, American cars are getting heavier and heavier
: every year. Our new cars are?more efficient, with average fuel economy
: climbing and carbon-dioxide emissions falling over the course of the past 30
: years. But that is not because they are lighter. The average new car
: weighed 3,221 pounds in 1987 but 4,009 pounds in 2010. Even small-size
: sedans have packed on the pounds, thanks to more-powerful—if more-efficient
: —engines, as well as features like nicer seats, more safety features, and
: more legroom.
: We pay a hidden cost for our fat cars. They may be sucking up less gas,
| W***n
发帖数: 11530 | |
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