There are powerful economic reasons for adopting Mayor Michael Bloomberg's congestion pricing policies. Thirty five years ago, I wrote a plan for the Lindsay administration that included tolls across the East and Harlem rivers. But to avoid the political heat of instituting tolls, our congressional leaders proposed to meet federal Clean Air Act's requirements to reduce auto use by making a serious commitment to capital financing for the Metropolitan Transportation Authority. However, the investment of $40 billion in transit has demonstrated that transit improvements alone do not sufficiently curb auto use.

Now, 35 years later, we finally have a mayor with the insight and guts to take on the "elephant in the room" -- our failure to charge drivers more than a fraction of the costs they impose by using their cars. Motorists who gripe about raising their cost to drive don't appear to realize that car and truck travel create huge public costs-lost productivity from congestion, traffic accident costs not covered by insurance, environmental damage, air and water pollution and noise.

This is not trivial. In the New York metropolitan area, the costs related to cars and trucks total more than $40 billion annually. Every time someone drives into Manhattan it costs the rest of us $30.

The addition of the million more residents and 750,000 more workers envisioned by plaNYC will increase car and truck use by 2 million trips a day in New York City and add millions of daily riders to our subway system. Accommodating this growth will take billions of dollars of investment. It will cost even more if we are to meet the mayor's goal of cutting carbon dioxide emissions by 30 percent.

At the same time, auto-centric mega-development like Gateway Center and Atlantic Yards in Brooklyn and the Bronx Terminal Market will further clog our roads and subways. New York can do better. The plan that I proposed 35 years ago recommended creating what we then called "urban activity centers." These were to be new communities within New York City where people could live, work, shop and play within walking distance without having to drive or even depending on transit. Cobble Hill in Brooklyn is such a community. Bloomberg's plaNYC overlooks this approach to real sustainability.

The other key to a successful plaNYC is congestion pricing. While the system the administration has proposed is unnecessarily complex and costly, those features are negotiable. What is important is that we finally have a mayor with the vision and persuasiveness to embolden timid elected officials to see the true equity of congestion pricing and give it a try. This took great courage.

Motorists cannot defend getting a free ride into Manhattan and imposing huge costs on everyone else, including other drivers stuck in traffic. Congestion pricing is the only fair way to level the playing field. It is also one of the few ways left to secure funding to expand and improve public transit.

Brian Ketcham is a traffic engineer who lives in Cobble Hill, Brooklyn.