405 Freeway shutdown prompts Orange County traffic warnings

After 10 months of preparations, demolition crews were putting bulldozers, cranes and other wrecking equipment in place Saturday afternoon in the final hours before a full-scale shutdown of a four-mile stretch of the 405 Freeway in Orange County.

On an average summer weekend day, more than 300,000 vehicles zoom (or lurch) down that section of the 405 between the 605 and 22 freeways.

At 9 p.m. on Saturday the 20-hour closure is scheduled to begin, forcing traffic onto the streets of Westminster and nearby neighborhoods. It is one of the biggest and longest closures of the 405 in Orange County since that section of the freeway was built in the 1960s, said Ted Nguyen, a spokesman for the Orange County Transportation Authority.

“There will be some inconvenience for those people who are caught up in the closure,” he said.

Authorities have urged motorists to avoid the area. They posted warnings of the closure on 120 flashing electronic signs in Orange, Los Angeles, San Bernardino, Riverside and San Diego counties, Nguyen said.

The purpose of the shutdown is to allow for the demolition of an obsolete 50-year-old bridge that connects the 405 and 22 freeways. It is part of a $277-million project to link carpool lanes of the 405, 22 and 605 freeways.

The southbound 405 will be closed between the 605 and 22 freeways. The northbound side will be closed at Valley View Street.

To discourage curious onlookers from aggravating anticipated traffic backups, authorities say they will post updated photos of the demolition on its blog and on Twitter (hashtag “bridgebash”).

“They’re going to get a lot of behind-the-scenes work,” Nguyen said of online demolition watchers. “They’re going to feel like they’re actually there without being there physically.”

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Twitter: @finneganlatimes

michael.finnegan@latimes.com