In another installment in what could become known as the “Science Proves the Obvious” category of DCist posts, a study released today finds that Washington metropolitan area suffers from the third-worst traffic woes in the nation — behind only San Francisco and Los Angeles.

The study, known as the Urban Mobility Study and conducted by the Texas Transportation Institute, found that Washingtonians spent, on average, 69 hours a year stuck in traffic (collectively adding up to 145.5 million hours), cost the economy $2.46 billion worth of lost productivity (the equivalent of a $577 tax per commuter), and that rush-hour now commands one-third of the day. Annual delays by hour in Washington area increased dramatically from 21 hours in 1982 to 69 hours in 2003.

Traffic congestion is a worsening problem nationwide, according to the study, which found that the 3.7 billion hours of travel delays cost the national economy $63.1 billion a year in lost productivity and 2.3 billion gallons of wasted fuel.

As for the solutions? Well, more and more well-managed roads and public transportation systems. As Washington-area commuters know, Metrorail is barely held together by spotty and inconsistent funding, and Loudoun County is the third-fastest growing county in the country.

Our prediction? More hours of traffic delays and more hours of lost productivity in the Washington area in years to come.

Is there a solution? Well, maybe. How about a $577 annual commuter tax, or $1.58 daily for each commuter driving to and from work?