Thursday, November 18, 2010

On keeping people from dying

Over the past several years, the TSA has steadily increased the scrutiny that airline passengers face. There was the liquids thing, the ziploc thing, the shoes thing, the laptop thing, and now the backscatter/scrotum-mashing thing. The purported objective of all these things is to prevent terrorists from blowing up planes, which would result in passengers dying. Which would be bad.

However, as the burden of air travel increases, would-be passengers are likely to shift some of their air travel to other forms of transportation, such as driving. Megan McArdle and Stephen Bainbridge have already announced their intention to do so.

I drive about 15,000 miles a year. If I, and everyone like me, decided just once every 13 years that we'd rather drive 500 miles and back, instead of flying, we'd be driving 0.5% more than we do now. About 45,000 people die each year in the United States in motor vehicle accidents. Americans driving 0.5% more will kill about 200 more people each year in the US. That's as many deaths as a Boeing 757-200 being blown out of the sky every year. And 12,000 more people will be injured.

Flying is, by far, the safest means of transportation for covering a given distance. Making flying less attractive, relative to driving, has deadly consequences.

Is the TSA really trying to keep people from dying, or just push the blame outside their agency?

Update: Shortly after I wrote this post, Nate Silver covered the topic in both greater depth and breadth. (The nerve!) Here’s a particularly interesting excerpt:

Other passengers may substitute car travel for air travel. But this too has its consequences, since car travel is much more dangerous than air travel over all. According to the Cornell study, roughly 130 inconvenienced travelers died every three months as a result of additional traffic fatalities brought on by substituting ground transit for air transit. That’s the equivalent of four fully-loaded Boeing 737s crashing each year.

It’s nice to see that my back-of-the-blog estimates are in line with reality. Thanks, Sterl!

Here’s a related Fermi problem: How many people are aboard airline flights over the United States right now?

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