Nancy Folbre: Traffic Jam Economics Sometimes, trying to get someplace faster, we end up slowing one another down. Traffic jams try our patience, waste our time and worsen the quality of our air. Urban congestion exemplifies the larger problem of effectively coordinating individual decisions to use largely unpriced goods like roads. Drivers are adept at anticipating delays and factoring them into decisions on whether and when to hit the road. But, absent tolls, they are not compelled to factor in the delays their driving imposes on others. One recent estimate puts the price of commuter delays alone at more than $100 billion in the United States in 2010, or nearly $750 for every commuter in the country. Some efforts to solve the problem, paradoxically, make it worse. For instance, a recent article in The American Economic Review by Gilles Duranton and Matthew Turner shows that road construction in the United States typically leads to a proportionate increase in utilization, leaving congestion unchanged. Build more roads and more cars will come. As a clever summary posted on Streetsblog.org (a fascinating platform for debates on urban transportation) waggishly puts it, "Roads cause traffic." Similarly, adding more taxis in an urban area can slow not just cabs but all traffic, making urban driving less efficient for everyone. A new plan to increase the number of cab medallions - and hence the number of taxis - in New York City has been greeted with enthusiasm. But the plan could backfire. The economist Charles Komanoff has developed a computer model that estimates the impact of the planned addition of about 2,000 taxicabs (all of them wheelchair accessible) to Manhattan streets. Cars in the central business district of Manhattan, already hampered by traffic, currently average about 9.5 miles per hour, a speed that many bicyclists can match. Cabs spend far more time than private cars cruising the streets. Mr. Komanoff estimates that adding one cab to the transportation mix is the equivalent of adding 40 private cars. His model predicts that a 15 percent increase in taxi traffic (equivalent to the planned increase in cab medallion sales) will cause travel speeds across all of Manhattan south of 60th Street from 6 a.m. to 6 p.m. on weekdays to fall by 12 percent. Called by Wired magazine "The Man Who Could Unsnarl Manhattan Traffic," Mr. Komanoff has long been developing his model of the city's transportation system. He makes a passionate and detailed case for a congestion pricing policy - essentially a toll to drive into congested areas - that would discourage auto trips to the city's central business district. Many economists favor the concept of congestion pricing (sometimes called road pricing) because it requires private users to pay for delays they impose on others. A clever animated version of the arguments in its favor is available online at Streetsblog.org. London, a city that resembles New York in many ways, introduced congestion pricing in 2003. The widely heralded results include a decrease in traffic, improvement in air quality and expansion of bus travel and biking. Two-thirds of Londoners express support for the policy, including members of the business community, who were initially nervous about its possible effects. Mayor Michael R. Bloomberg pushed hard in 2008 for New York City to put a congestion pricing plan into effect, but opposition was fierce from those living or working in other boroughs, and the state Legislature never came close to authorizing the plan. Mr. Komanoff asserts that this opposition could be overcome with a clear plan to use the revenues to expand and improve public transportation in the city. His proposal would impose a price of $8 to $10 on cars entering the central business district, with lower rates for nonpeak hours and weekends. Modern electronic toll collection systems make it easy to accomplish important details. Deliveries of food and other supplies to the area could be timed at nonpeak hours. Other policies, like reducing bridge tolls that do not help improve traffic flow, could help buffer the economic impact. Drivers would be allowed one free trip a month. More than $1 billion in projected annual revenues from this plan could significantly improve the bus, subway and bike-lane systems that many New Yorkers rely upon. The resulting changes could make it easier for residents of the boroughs and suburbs to get into and out of the central business district. Sometimes, paying money upfront saves everyone money in the end. Not to mention saving time, air and the energy we need to solve a variety of other environmental jams.