The sputtering economy continues to put the brakes on Bay Area traffic congestion during commute hours.

For the third year in a row, congestion in the San Francisco-Oakland area is adding 50 hours a year to the average commuter’s drive, down from as high as 74 hours in 2006 and 2005, according to an annual report by the Texas Transportation Institute. As the recession hit, commuter delays took a dive in 2008, falling to 50 hours from 2007’s 71 hours.

Bill Eisele, a research engineer at the institute and a co-author of the latest report, said the researchers didn’t probe the causes behind the drop in commute delays but said it’s a “reasonable guess” that the recession and any improvements in the Bay Area’s transportation system take most of the credit.

Nationally among the large urban areas, the Bay Area was ranked seventh last year in commuter delays, down from the second-, third- and fourth-place rankings regularly recorded from 1983 to 2007. Washington, D.C., was rated worst last year with 74 hours of commute delay. Chicago ranked second with 71 hours and the Los Angeles area was third at 64 hours. San Diego ranked 15th with 38 hours, San Jose 19th with 37 hours and Sacramento 42nd with 25 hours.

In 1982, the earliest data reported by the institute, the San Francisco-Oakland area ranked fifth in the nation with an annual commute delay of only 20 hours!

The extra commuting time in the San Francisco-Oakland area cost the average commuter $1,019 a year in extra gas costs and the value of the extra time, the report said.

Data for the San Francisco-Oakland area included most of the cities around San Francisco Bay but didn’t extend into Sonoma County.

The report warned that the drop in commute delays is only temporary, noting once economic growth returns, the average commuter nationally can expected three more hours of delays by 2015 and seven hours by 2020.