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After being replaced by Honolulu for a year, Los Angeles once again earned the title of the most congested metro area in the country. At 5 p.m. on a Friday in 2012, the average driver wasted more than 28 minutes in traffic, according to INRIX, a traffic information and services group that collects data for individual road segments.



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In its 2012 Traffic Scorecard, INRIX found that traffic at peak hours on Interstate 405 in Los Angeles moved at just 14 miles per hour, adding 26 minutes to what should be an eight-minute drive. Last year, the average American wasted 38 hours sitting in traffic; however, for those living the nation’s most congested cities, that number jumped to 42 hours.

Not surprisingly, population density contributes to traffic congestion. Of the 10 metro areas with the highest population density in 2010, six ranked among the nation’s 10 most congested.

INRIX produces a congestion score, which is a compilation of factors including population density, the average time spent commuting and the percentage of the population that drives to work.

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In terms of the longest average daily commute, New Yorkers captured that honor with an average of 34.9 minutes. Washington D.C. finished a close second at 34.5 minutes. However, the availability and use of public transportation pushed those cities down on the top 10 list.

The congestion index is a metric of how much longer it takes the average driver to travel during peak traffic hours than when traffic is clear. Los Angeles has a congestion index of 28.8, which means it takes 28.8 percent longer to make a trip during peak congestion hours than it does when there is no traffic.

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This year’s most congested cities (with their congestion index in parentheses):

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1. Los Angeles (28.8)

2. Honolulu (26)

3. San Francisco (23.5)

4. Austin, Texas (20.7)

5. New York City (19.9)

6. Bridgeport, Conn. (19.1)

7. San Jose, Calif. (17.6)

8. Seattle (17.6)

9. Washington D.C. (16.4)

10. Boston (14.7)

INRIX scale is supported by other surveys. Researchers at the Texas A&M Transportation Institute recently issued its Urban Mobility report and found similar results.

In the Texas A&M rankings, Washington, D.C. tops the list, followed by Los Angeles, San Francisco-Oakland, New York-Newark and Boston. The second five are Houston, Atlanta, Chicago, Philadelphia and Seattle. The Urban Mobility report provides a detailed illustration of traffic problems in a total of 498 U.S. urban areas.

Congestion is frustrating, but researchers have found that it is also expensive – to society and drivers.

“We all understand that trips take longer in rush hour, but for really important appointments, we have to allow increasingly more time to ensure an on-time arrival,” said Bill Eisele, a TTI researcher and report co-author. “As bad as traffic jams are, it’s even more frustrating that you can’t depend on traffic jams being consistent from day-to-day. This unreliable travel is costly for commuters and truck drivers moving goods.”

The 2012 report estimated of the additional carbon dioxide emission attributed to traffic congestion: 56 billion pounds – about 380 pounds per auto commuter.

Additionally, the amount of fuel wasted in congested traffic was 2.9 billion gallons – enough to fill the New Orleans Superdome four times. That’s the same as 2010, but short of the 3.2 billion gallons wasted in 2005.

The total financial cost of congestion in 2011 was $121 billion, up one billion dollars from the year before, or $818 per commuter. Of that, about $27 billion worth was wasted time and diesel fuel from trucks moving goods on the system.