Misleading Scientific American Report On Traffic Cameras

from the not-always dept

Tom sent over a report saying that redlight cameras aren't just about making money for local police (and the companies who sell redlight cameras), but that one study in Barcelona found that the city saved a ton of money due to fewer accidents. Now, what I find interesting about this is that it seems to contradict nearly every other study we've seen on this subject. Study after study after study after study after study has shown no decrease in the number of accidents... and in many cases an increased number of accidents. So is there something that Barcelona did differently with its cameras that resulted in a decrease in accidents?

After digging in, it looks like some of this may just be bad reporting by Scientific American's Cynthia Graber. First, she focuses the article on red light cameras, but the actual study she discusses was for speed cameras. I'm surprised that Scientific American would mix up the two, since they're clearly different. Second, as some people pointed out in the comments to Graber's story, the study happened over a two year period during which unemployment in Barcelona shot up drastically, potentially leading to fewer cars on the road, especially during rush hour periods when accidents are most likely. In other words, while this might be some evidence in support of speed cameras, at best, it shows a correlation, and the causal factor may be something entirely different, such as the amount of cars on the road.

Filed Under: accidents, barcelona, redlight cameras, speed cameras, traffic cameras