5 Freeway in L.A. County is state’s most congested, Caltrans says

California has some of the most congested freeways in the nation, and about half of them are in Los Angeles County, according to a report by the California Department of Transportation.

Of the 21 freeways identified in the report, the 5 Freeway in L.A. County was ranked the most congested in the state.

In 2012, drivers spent 6.6 million extra hours -- time they wouldn’t spend driving if traffic were quicker -- going less than 35 mph on the 5 Freeway, according to Caltrans’ Mile Marker report.

Statewide, drivers spent an average of 328,000 extra hours a day in their vehicles in 2012, the most recent data available, up from 303,000 a day the year before. Officials say the increase may be related to the growing economy.

The numbers come from sensors that track vehicle counts and speeds on freeways. The data helped officials identify 21 freeways that have terrible gridlock.

Most of the troubled freeways are in Southern California, and about 10 are in Los Angeles County, according to the report.

The findings are probably not surprising to Angelenos, who face traffic jams on a daily basis.

Although drivers generally don’t know exactly how much extra time they have spent on the road during traffic jams, officials say the data helps identify freeways that need the greatest improvements.

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ruben.vives@latimes.com