New York City Mayor Michael Bloomberg has tackled some tough issues during his tenure, but now he’s seriously considering taking on the city’s traffic problem, according to Newsweek. If you’ve ever been to the Big Apple, you’ll realize this task is about as easy as riding in a subway car with 150 people in July — and not coming out with your suit smelling like onions.

What’s interesting is that his solution is not to build more roads, but rather, shut some of them down:

In general terms, traffic is caused by too much demand (from vehicles) meeting too little supply (roads). One solution is to increase supply by building more roads. But that’s expensive, and demand from drivers tends to quickly overwhelm the new supply; today engineers acknowledge that building new roads usually makes traffic worse. Instead, economists have suggested reducing demand by raising the costs of driving in congested areas. The best-known example is the "congestion pricing" plan London implemented in 2003. Drivers now pay about $11 a day to drive in the central city. According to one study, the program has reduced traffic by 16 percent.

In 2007 Bloomberg proposed a congestion-pricing plan for New York, but last year state legislators rejected it as an elitist move. In response, Bloomberg began tinkering with the city’s roads in ways that required no legislative blessing. He banned vehicles from Park Avenue for three Saturdays in August 2008. He closed two lanes of traffic on Broadway below 42nd Street. "Bloomberg is taking the position that as long as it’s within the two curbs, it’s [city] property and he can decide how to use it," says Sam Schwartz, the city’s former traffic commissioner.

These pilot projects fit in with a larger counterintuitive theory that’s gaining traction with urban-planning wonks: that closing roads can reduce congestion. During the 1990s, a British transit engineer named Stephen Atkins read about how San Francisco congestion decreased, rather than increased, after an earthquake knocked out a key freeway. He observed the same phenomenon in other cities that closed roads, too. "In a lot of places, the traffic was not just displaced—a lot of it disappeared," he says. In a 1998 study he commissioned, researchers studied 60 cases of road reductions and found that when roads were closed, drivers took steps to avoid the area. In economic terms, closing roads raises the perceived costs of the trip (because drivers anticipate hassles), reducing demand.

Hat tip to Chamber staffer Tony Spataro for the article.