New York City's on-again, off-again attempts to adopt congestion pricing have left some feeling like they're caught in a kind of cosmic game of "red light, green light." Earlier this year, in a bid to reduce air pollution and traffic jams, the city announced plans to make drivers pay a premium—$8 for cars and $21 for trucks—to drive into Manhattan between 6 a.m. and 6 p.m.

The announcement sparked an outcry from trucking groups, which charged that the program would unfairly raise costs and would not appreciably reduce traffic congestion. So when the New York State Senate rejected New York City's proposal in mid-July, shippers and truckers breathed a sigh of relief.

But just two days later, the proposal got the green light again after some heavy-duty lobbying by Mayor Michael Bloomberg. By the end of the month, lawmakers had passed legislation authorizing the city to begin a pilot project and to form a commission to oversee it.

The pricing initiative still faces another hurdle, however. Once a specific plan is in place, it must be approved by the city council and then go to the state legislature for sign-off by March 2008.

What will happen to the estimated $500 million in annual fees the city expects to collect if the plan moves forward? Most of it will be earmarked for investment in public transportation, but critics like the American Trucking Associations charge that about half the money will go to pay for implementing the system.