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What widening the 405 in Orange County means for drivers — and congestion

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Google Earth view of the 405, 605 and 22 freeways.
Luke Dorny via Google Earth / flickr Creative Commons
Google Earth view of the 405, 605 and 22 freeways.

The expansion project broke ground Friday. Caltrans hopes added lanes will relieve congestion, but some experts question how much projects like this help traffic.

The latest upgrade project on the 405 freeway broke ground on Friday. At $1.9 billion, it will be the second most expensive highway project in state history.

The improvements are happening in Orange County, along a 16-mile stretch of highway from State Route 73 in Costa Mesa to Interstate 605 near the LA County line. One lane will be added in both directions and two existing carpool lanes will be converted to a toll system.

Ryan Chamberlain is the Caltrans Director for Orange County. He said Caltrans hopes commuters can have patience through the construction work, which is expected to last through 2023, because it will pay off in the long run. 

"Currently the 405 is the most heavily congested freeway in the nation, 370,000 daily vehicle trips on that corridor. And in 2040 or close to 2040, with this improvement, we're anticipating an hour and a half -  or more -  in travel time savings for most commuters," Chamberlin said.

However, as KPCC's transportation reporter, Meghan McCarty Carino, points out there is research that shows expansion projects do not help congestion. Although intuitively more road space seems like it should reduce traffic, McCarty Carino said it's not that simple.

"Traffic is really a function of two major variables, one is space and the other is demand... And when you expand the space it turns out that you almost always expand the demand, something call induced demand." 

Many people will quickly start driving on a freeway more often, after they hear about an expansion so drive times will likely remain the same, she said, but that does not mean the project is pointless. Simply moving more vehicles along a roadway at a time can be a good thing, McCarty Carino said.

"It can facilitate more socializing, more people taking trips, more people going to restaurants, more people going to jobs, more economic activity. In the case of this particular corridor of the 405 it's an important link for goods movement for the port."

She also explained  this project will add a toll lane, which is one of the only research-proven ways of reducing congestion.

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