"For decades, congestion has been trapping more people in their cars. From 2000 to 2005 the annual delay per traveler in the Washington area rose by a whole workday, to second worst in the nation. At the same time, highway and transit modernization is seriously underfunded. The federal gas tax - the primary source of revenue - is not indexed to inflation and has not increased since 1993. And states are reluctant to raise their gas taxes. With more fuel-efficient vehicles, revenues fell even as vehicle miles rose.
A better solution that would address both the congestion and financing problem would be road-use pricing that varies with congestion. Drivers would directly pay for the costs they impose on others. These charges would vary with VMT, the level of congestion, and the type of vehicle. The Congressional Budget Office recently confirmed that such pricing would reduce congestion, result in shorter and more reliable travel times, and enable governments to make more efficient infrastructure investments.
Road-use pricing is not a new idea, but it is gaining popularity as congestion increases, funding decreases and technological advances make implementation easier. However, two strong arguments against road-use pricing must be addressed, especially if differential charges are high enough to reduce congestion significantly."