Watch out, Long Island commuters.If you're one of those daily workers who would rather roll into Manhattan in the tranquil comfort of your personal car than face the indignities of a fuming bus or a late commuter train or a screeching subway, you're on notice. The policy wonks know who you are, and they want you to repent.I'm talking about the level-headed urban visionaries at the Regional Plan Association, the tough-minded thinkers at the Partnership for New York City and a slew of other policy-makers. They know private cars are a major contributor to the chronic paralysis of Manhattan street traffic, and they've started to lean on the Bloomberg administration for a remedy.The idea everyone seems to love at the moment is the London plan. Were New York to steal this move from the Brits, it would charge motorists a flat fee - $7 perhaps - for the privilege of motoring into the most frantic parts of midtown at the busiest times of the day.The logic behind this idea is solid, I'm afraid.Every day, says a study prepared recently by Schaller Consulting for an organization known as Transportation Alternatives, 830,000 vehicles - mostly personal automobiles - inch into Manhattan's central business district (59th Street to the Battery), and this number will probably mount over time. Meanwhile, as the Schaller report delicately explains, cars "represent the least productive use of scarce public space."They clog the streets for buses, for delivery trucks, for taxis and even for pedestrians - as anyone who's ever tried to cross a gridlocked intersection can attest. Most of this car traffic is unnecessary, Schaller finds. Ninety percent of auto commuters live and work in areas where mass transit or other means of locomotion - remember walking? - are commonly used.Whenever the subject turns to Manhattan and traffic, you eventually hit a wall of basic math. Manhattan Island is only 23.7 square miles. It has a finite number of parking spaces and a finite number of bridges and tunnels. And right now the whole network is past its limit. The wonks are right: It's time for change.This might be a good time for Michael Bloomberg to exercise some of his famous independence. The mayor has flirted with bold traffic ideas before - only to jump back before he got burned. But, say his aides, Bloomberg is not considering the London idea "at this time."That's a pity.But I have a feeling this issue will come up again and again. And I have a feeling that New Yorkers will wind up paying a fee to cruise the streets of midtown in prime business hours.Traffic is the eternal New York problem. In his book on the world's great subway systems, Benson Bobrick found this quote from the New York Tribune a century and a half ago: "We can travel from New York halfway to Philadelphia in less time than the length of Broadway." On Park Row, Bobrick noted, the road rage of that time often caused stalled teamsters to lash each other with their whips.It's ultimately counterproductive to fight the wonks and impede progress - whether you're a suburbanite or an outer-borough resident. In the end, a rational New York City that lets goods, services and people flow will help keep the region's economy strong. All right, a rational New York is a mythical creature. Still, the better the city works, the better the region works.The answer is not to demand free access to midtown or to pitch a fit until the idea of congestion pricing dies. The answer is to accept what makes sense and to fight for a worthy cause in return. More parking slots at Long Island Rail Road stations would be one decent trade-off. Easier routes through the city for Long Islanders who want to get to New Jersey would be another.With a little policy wonkery and carefully applied street-level politics, who knows what miracles might be possible?