LOS ANGELES -- The car-crazed City of Angels is on edge as the hours tick off until "Carmageddon" the shutdown of a notoriously clogged 10-mile stretch of one of the busiest highways in the United States, on one of the city's busiest summer weekends.
Will it bring traffic to a standstill like a scene out of a summer disaster movie? Or fail to come to pass, like other apocalypse predictions?
Everyone will find out soon enough as authorities prepare to close Interstate 405 - known to locals simply as "the 405" -- for 53 hours beginning Friday night. Around the afternoon rush hour, the city will activate its emergency operation center before highway officers begin blocking access to on- and off-ramps. Then they'll close freeway lanes one by one until they reach a full shutdown by midnight.
Non-emergency street maintenance and repair projects will come to a halt. Police, firefighters, paramedics and traffic engineers will be on standby to respond to any crisis that may arise.
For weeks, officials have issued grim warnings about the closure in the same tones reserved for floods and threatening wildfires.
To prepare the public for the closure, they flashed signs on freeways as far away as San Francisco reminding drivers over and over: Stay off the 405 July 16-17.
They recruited celebrities with large followings on Twitter, such as Ashton Kutcher and Kim Kardashian, to get the message out.
Other celebrities going that route, notes CBS News Correspondent Bill Whitaker: Tom Hanks and Adam Levine.
Hanks tweeted: "This weekend LA! Avoid Carmageddon." Levine told his Twitter followers: "I think I want to throw a tailgate party... Meet me at the 405."
Facebook agreed to direct some 6.6 million driving-age people in the greater Los Angeles area to the Metropolitan Transportation Authority's Facebook page detailing the latest traffic conditions this weekend.
Radio and TV airwaves have been filled with public service announcements about the coming closure.
"The hype and horror," Whitaker remarked, "are worthy of Hollywood."
Transportation experts said the publicity campaign seems to be working.
They now predict that, while there will likely be some backups on other freeways and on surface streets near the 405, the weekend shouldn't end in massive gridlock.
"It's going to be fine; people had a lot of warning," said Lisa Schweitzer, a professor of urban planning at the University of Southern California.
Experts compared the shutdown to other big planned events, such as the 1984 summer Olympics, Los Angeles Lakers championship parades and Michael Jackson's memorial service two years ago.
The disastrous traffic jams predicted for each of those events never materialized. People knew to stay off the road. In fact, city residents marveled that, during the two weeks of the Olympics, traffic was actually much lighter than usual.
"For the 1984 Olympics, by repeating how complex and difficult it's going to be, some people chose not to travel, to take public transit or go away for vacation," said Martin Wachs of the Rand Corp. think tank.
That could be the case again this weekend.
Not that some people aren't still worried, as closing that section of the 405 for such a long time is pretty much unprecedented.
Whitaker reports some people are stocking up on supplies and hunkering down for the weekend. He says some couples have postponed their weddings. Sporting events and even church services have also been scrapped.
Transportation officials say the closure is necessary to replace the 50-year-old Mulholland Bridge as part of a $1 billion project to widen a perpetually bottlenecked segment of the 405.
That stretch goes through the Sepulveda Pass, which connects the San Fernando Valley to Los Angeles' West Side.
They say a full closure is necessary to demolish one side of the span, and they picked this weekend to minimize impact to traffic on a workday. They expect another closure next year to replace the other half.
On a typical July weekend, about a half-million vehicles use that section to get to such major destinations as Los Angeles International Airport, UCLA, Beverly Hills and numerous popular beaches.
To discourage driving, the city is offering free rides on the subway and certain bus lines and adding more commuter train service. Hotels and restaurants are offering discounts.
Around town, some people are organizing neighborhood walks, bicycle rides and even "Carmageddon" parties.
The famed Santa Monica Pier, Whitaker points out, says people should stay home -- but if a Valley resident should make it to the beach, all rides are free.
Joann Killeen, who lives near the 405, is going to attend such a party Saturday at her next-door-neighbor's house.
"We're going in our garages and looking for old Scrabble boards and Monopoly games and we're going to bring potlucks and just be silly from about 5 o'clock until midnight," she said.