Public space

The NY Times recently wrote about a crash test demonstrating that if you crash a small car into a medium-sized car, occupants of the medium-sized car fare better. Duh. The article also uncritically quotes the president of the Insurance Institute for Highway Safety with the conclusion that “downsizing and down-weighting [cars to save fuel] is also associated with an increase in deaths on the highway.”

This conclusion is so dumb I barely know where to start, but here are just a few points:

• If no-one drove small cars, the benefits shown in this test for occupants of bigger cars would go away (since there would no longer be smaller cars for them to crash into).
• With the above point in mind, many people end up in an arms-race mindset, continually upsizing so their car is bigger than everyone else’s. Just look at people choosing S.U.V.s (a.k.a. “chelsea tractors”) for safety reasons. While socially detrimental, this mindset is individually rational, cf. tragedy of the commons.
• Such an arms-race mindset is detrimental because, as everyone inside cars upsizes, they do not gain any net benefit, but everyone outside of cars (pedestrians, cyclists) loses, and so does the environment.
• Additionally, based on this crash test we cannot even conclude that drivers in bigger cars are safer in the current environment, because it relies on the assumption that drivers of big and small cars are just as likely to get into a crash in the first place. There are at least two reasons why this assumption is probably wrong: risk compensation and physical constraints. Risk compensation implies that since the driver of the bigger car feels safer, he or she will drive ever-so-subtly less carefully, and hence get into more crashes. Physical limitations imply that the bigger car is harder to manoeuvre, and has a longer stopping distance, and will get into more crashes than the lighter, nimbler car. If you want to know more about this, I cannot recommend highly enough Malcolm Gladwell’s (now of “Blink” fame) 2004 New Yorker article “Big and Bad – How the S.U.V. ran over automotive safety”
• As a decision-making psychologist, it also galls me that the article presumes that people are motivated exclusively by narrow self-interest (“save fuel” vs. “increase own safety”). Hint: people do care about others, and some people consciously refuse to engage in an arms race of ever-upsizing cars precisely because they predict its futility and socially detrimental effect. (I’m not at all saying people are selfless altruists without limits. For example, nobody wants to be the only one in a tiny car surrounded by S.U.V.s. That is why some people support political legislation to punish or even prohibit driving S.U.V.s, or why they make an effort to ostracize S.U.V. drivers by condemnig or ridiculing their choice of vehicle).

For further reading, I really recommend John Adam’s Risk and Tom Vanderbilt’s Traffic.

This entry was posted on Monday, 27 April, 2009 at 14:24 by Marianne and is filed under Cars, Risk. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.