405 Freeway closures through Sepulveda Pass planned this weekend

What’s more complicated than Carmageddon and could seriously mess with the flow of Angelenos’ long Presidents’ Day weekend?

It’s Jamzilla. That’s the monster-evoking moniker that transportation officials have adopted for the 405 Freeway lane closures slated to begin late Friday, just in time for the post-Valentine’s-Day dinner rush.

For 80 hours — from about 10 p.m. Friday until 6 a.m. Tuesday — most or all lanes on the busy northbound side of the freeway will be closed.

The shutdowns through the Sepulveda Pass will allow workers to pave and re-stripe the highway where a carpool lane is being added.

Transportation and law enforcement officials are urging drivers to avoid traveling north through West Los Angeles and the Sepulveda Pass for the duration of the closures. During daytime hours, two northbound lanes will be open, but all five will be closed at night.

Jamzilla recalls the full-freeway weekend closures of 2011 and 2012, which gave workers time and space to demolish the Mulholland Bridge. The first of those closures gave rise to the apocalyptic term “Carmageddon,” which simultaneously reflected and overstated the north-south artery’s importance to the region. The Southland survived the loss of drive time relatively unscathed.

For Presidents’ Day weekend, “we wanted to come up with a term that would be like Carmageddon in its ability to influence the public,” said Dave Sotero, a spokesman for the Los Angeles County Metropolitan Transportation Authority, which is managing the $1.1-billion freeway-widening project.

This closure, he said, is similar to Carmageddon but affects only the northbound side. Three of five northbound lanes between Getty Center Drive and Ventura Boulevard will be closed during the day. They are the three lanes closest to the freeway median, where workers will be paving. The remaining two lanes, Sotero emphasized, will not be able to accommodate the usual 405 traffic, nor will Sepulveda Boulevard be able to handle spillover during the day.

Southbound lanes will be unaffected during the day, but one or two lanes will probably be closed at night, Sotero said.

“Sepulveda will be at full capacity during the entire 80-hour operation,” he said. “At night, when we do a full closure, it is the designated alternative. During the day, it could easily become congested and should be avoided. It cannot accommodate diverted freeway traffic. Motorists should divert to other freeways rather than take a chance on Sepulveda.”

Metro and the California Department of Transportation are advising motorists to scope out alternate routes and to monitor traffic conditions via Twitter, Facebook, news reports and Metro’s 405 project website.

The 405 typically carries about 300,000 vehicles a day. In a bid to ease its notorious congestion, Metro and Caltrans in 2009 began preliminary work on the final 10-mile leg of a carpool lane through the pass.

In addition to completing the northbound “high-occupancy vehicle” link between Orange County and the San Fernando Valley, the project called for building new on- and offramps, demolishing and rebuilding three bridges, and adding miles of retaining and sound walls.

Officials initially forecast completion of the carpool lane by spring 2013. The timeline was later nudged to December 2013, then to summer 2014.

Sotero said the project team picked Presidents’ Day weekend because it was the earliest three-day weekend that would enable Kiewit, the contractor, to complete the project this summer. Memorial Day weekend would have cut it too close. Sotero said Metro and Kiewit were doing what they could to accommodate Valentine’s Day celebrants. The full northbound closure will not happen until 1 a.m. Saturday, he said.

Monday is a federal holiday, and most government offices and schools will be closed.

Jamzilla differs from Carmageddon in another key regard: It is unlikely that motorists will be pleasantly surprised by an early finish to the operation, as they were during the bridge-demolition weekends. The paving work is more complex, is subject to more variables and will take more time, according to Metro officials.

Workers will be removing old pavement and putting in new. Each layer must be “cured” so the concrete can achieve its full strength. That requires temperatures between 50 and 100 degrees — and about eight hours of curing time. Some portions at the San Fernando Valley end will require three layers.

“We’re going to be working 24 hours a day … to get the job done,” said Krishniah Murthy, Metro’s executive director of transit project delivery.

The weather appears to be cooperating. “All the plans are in place to proceed,” Murthy said.

The key will be getting the word out to motorists.

Cori Solomon, president of the Brentwood Glen Assn., a homeowners group west of the 405, said the imminent closure so far has sparked less concern among residents than did Carmageddons I and II.

“I’m not getting any complaints,” she said. Either people have grown accustomed to occasional closures, she added, “or they know they can’t do anything about it.”

Still, people attending Saturday afternoon’s basketball game at UCLA or the Northern Trust Open golf tournament at the Riviera Country Club in Pacific Palisades should plan ahead.

“I can tell you it’s going to be horrible on the 10 [Freeway],” said Leslie Einstein, a Pacific Palisades resident. Einstein, a supporter of the Los Angeles Opera, will be heading downtown Sunday afternoon to help with a dinner for the cast of “Billy Budd.” She’s bracing herself. “I’ll allow plenty of time.”

Lest anyone think this marks the end of disruptive closures, think again. Still to come, Sotero said, will be a shutdown on the southbound side that could last as long as 55 hours.

martha.groves@latimes.com