A study released by the American Highway Users Alliance, a nonprofit group that lobbies for interstate highway investment, examined which routes in the United States are the most continuously crowded, 24 hours a day, rather than during peak periods. It turns out that eleven of the nation’s 30 worst bottlenecks are in Greater Los Angeles — a statistic that may not surprise the average Southern California commuter.

“These are corridors that are continually congested,” said Monali Shah, the director of intelligent transportation at Here Connected Driving, one of the companies that provided GPS speeds for the study.

Using traffic speed data for passenger and freight vehicles and average traffic volumes along major corridors, researchers ranked the bottlenecks based on average estimated delays daily.

The worst bottleneck in the country is in Chicago along the Kennedy Expressway, but the Los Angeles area managed to claim several top slots on the list with bottlenecks on stretches of the 405, 10, 110 & 110 Freeways, including the 405 Freeway between the 22 and 605 in Seal Beach (ranked No. 2 nationally) and the 10 Freeway between Santa Fe Avenue and Crenshaw Boulevard (ranked No. 3 nationally).

The study found that the eleven Los Angeles-based jams represent about 44 million hours of lost time, or about half of the daily total delays on the list of the 30 worst bottlenecks nationwide. As a result, Southern California commuters lose nearly $1.17 billion in lost time on the routes.

The findings, Shah said, can help inform local governments about when and how to invest in expanding freeway capacity. However Shah cautioned that, “There’s a limit to how much the road network can be expanded.” In those cases, she said, technology — including gauging real-time road conditions — will come into play.

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