SAN DIEGO -- The average San Diego driver lost 37 hours to traffic congestion in 2009, at a cost of $838, according to a study released Thursday.

Area drivers used an extra 31 gallons of gasoline because of traffic jams, according to the 2010 Urban Mobility Report from the Texas Transportation Institute at Texas A&M University.

San Diego ranked 18th among large U.S. urban areas for hours lost because of heavy traffic and extra gasoline use, and 20th for the financial impact, according to the report.

The hours lost by area drivers were down by four from 2008, but up four from 1999. In 1982, San Diegans wasted eight hours to congestion, according to the report.

Caltrans officials say a combination of local road projects and the economic downturn have created less congestion around San Diego County.

"Since the downturn in the economy, fewer people are driving and there is less congestion of the freeways," said Caltrans spokesman Ed Cartagena.

10News looked at traffic numbers at five local locations before and after the recession and found:

At the Interstate 5/805 merge, the number of vehicles travelling through there fell from 213,000 every day to 200,000

At the I-5 and State Route 78 merge, there was a drop in vehicles -- from 207,000 to 193,000

At 3 other locations -- I-5 and SR-54, I-8 and SR-125, I-15 and SR-78 -- there were similar, though slightly smaller, drops

Caltrans doesn't believe it will last, however.

"When [the] economy does bounce back, we're anticipating growth," said Cartagena.

When the economy does come back, experts said there are other numbers that point to some potential problems.

Local drivers now travel almost 14 highway miles a day -- about 4 miles more than drivers in Los Angeles County.

Ann Tartre, of research group Equinox Center, said couple that with a predicted population surge and, "We're going to have to change our pattern of transportation if we want to maintain our quality of life."

A regional transportation study that is likely to focus on improving public transportation is due out in about a month, 10News reported.

The worst areas for commuting by car were Chicago and the Washington, D.C., metropolitan area, where drivers wasted 70 hours per year in their vehicles.

The report stated that there was less congestion in recent years nationally because of the weak economy, but that increasing economic activity has led to greater traffic on roadways.