I've heard anecdotal evidence that lifesize cardboard cut-outs of police officers in shops can deter shoplifting. Now Bangalore police are using the same method to deter traffic violators. "It is not a gimmick. Wherever we have put up these cut outs, violations have come down," Traffic Commissioner MA Saleem told the BBC.

Suzanne Paulson, UCLA professor of atmospheric and oceanic sciences, saw "Carmageddon" as an opportunity to make use of a "natural experiment." She and a colleague "measured pollutants in the air during the LA freeway shutdown last year, and have now released their findings.

Air quality near the normally busy highway improved by 83 percent that day last July, relative to comparable weekends. Elsewhere in West Los Angeles, the improvement was equally dramatic. Air quality improved by 75 percent on that side of the city and in Santa Monica, and by 25 percent throughout the entire region, as a measure of the drop in ultrafine particulate matter associated with tailpipe emissions.

"We saw what we expected: you take motor vehicles away, the air gets really, really clean," Paulson says, "which tells us that most of the pollution is from motor vehicles from one type or another in this area."

More: L.A.'s 'Carmageddon' Produced Dramatic, Instantaneous Air Quality Improvements (The Atlantic).

Another "Carmaggedon" just took place in LA. Wonder if there will be more science to come from this edition.

(Image: Dallas Traffic 10/19/11 1227pm, a Creative Commons Attribution Non-Commercial Share-Alike (2.0) image from nffcnnr's photostream)