A Tax on Driving into DC?

A few blogs have been buzzing about the possibility of a congestion tax in DC. New York City's Mayor Michael Bloomberg recently proposed a congestion tax as part of his Earth Day proposals to help green the city and cut down on traffic. DC's Mayor Adrian Fenty is a big fan of Bloomberg, and is reportedly thinking of something similar for DC. A similar congestion charge in London has already been successful in cutting traffic and reducing travel times.

Here are some basic arguments for and against a congestion tax:

PRO -- Reduce traffic at peak times, raise revenue for transportation needs, cut air pollutants (DC is a nonattainment area for ground-level ozone and fine particulates)

CON -- Fairness issues: The tax would hit low-income drivers the hardest, while high-income drivers would be able to enjoy the reduced traffic. And why only tax drivers in certain parts of the city? Workers don't control where their offices are located.

Arlington commuters who drive into DC for work would be hit hard by this tax. What do you think? Is it a good idea?