Don't Drive, He Said.(The Talk of the Town)(Michael Bloomberg)

Michael Bloomberg has always favored grand schemes. Last week, on Earth Day, the Mayor stood in the American Museum of Natural History's Hall of Ocean Life, beneath the blue whale, to lay out his vision for the city's future. In an expansive speech, Bloomberg described a New York that would, in 2030, be both "greater" and "greener," a city with nearly a million more residents, as well as cleaner water, new open space, and zippier transportation. This bigger, better metropolis would be a leader in combatting global warming; despite its increased population, the New York of the future would produce thirty per cent less CO2, resulting, as the Mayor put it, in "the most dramatic reduction in greenhouse gases ever achieved by any American city."

The printed version of Bloomberg's plan ran to a hundred and fifty-five full-color pages and contained a hundred and twenty-seven new initiatives. Just one of them--congestion pricing--got almost all the attention, much of it negative. The Mayor anticipated this--he referred to the pricing proposal as "the elephant in the room"--and his decision to include it anyway is perhaps the best reason to take the plan seriously.

The basic idea behind congestion pricing is simple: make motorists pay to use the busiest streets. Under the Mayor's proposal, an invisible line would be drawn around Manhattan from Eighty-sixth Street south to the Battery. Vehicles crossing this line on weekdays between 6 A.M. and 6 P.M. would be charged a fee--eight dollars for cars, twenty-one dollars for trucks. (Those travelling only within the congestion zone would pay half price, while taxis and livery cabs would be exempt.) The fees would be assessed electronically and could be paid either with a toll pass or over the phone or the Internet.

Driving crosstown for lunch is an easy, if maddening, way to appreciate the scheme's logic. The impression that one could walk--or at least trot--just as quickly is borne out by the numbers; according to data collected by the New York Metropolitan Transportation Council and analyzed by Bruce Schaller, a Brooklyn-based consultant, the average speed achieved by a vehicle travelling along Forty-second Street between the hours of 10 A.M. and 4 P.M. is 4.7 miles per hour. On Thirty-fourth Street approaching the entrance to the Queens Midtown Tunnel, the average speed drops to 2.5 miles per hour.

A few cities have tried congestion pricing, most notably Stockholm and London, and in most cases it has been a success. Stockholm imposed congestion pricing on a trial basis last year; the program worked so well that voters opted to reinstitute it. Since the London plan was introduced, in 2003, vehicle speeds in the city's central business district have increased by thirty-seven per cent and carbon-dioxide emissions from cars and trucks have dropped by fifteen per cent. The plan, which the newpapers initially derided as "Kengestion"--after its main supporter, London's mayor, Ken Livingstone--has grown increasingly popular; in 2004, Livingstone was easily reelected, and now nearly two-thirds of Londoners say that they back the ...