A stretch of Interstate 405 stood vacant over the weekend, so workers could demolish an overpass as part of a $1 billion project to widen the California freeway.

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os Angeles' so-called weekend of "Carmageddon" was impressive, but not for the reasons city officials had feared (and news producers had, perhaps, relished). The closure of a 10-mile stretch of Interstate 405 did not produce an apocalyptic snarl of traffic as predicted because Angelenos largely stayed off the area's freeways, creating surreal scenes of a traffic-free Los Angeles. Equally stunning, the freeway-closing bridge demolition was completed 17 hours ahead of schedule, allowing the 405 to reopen at about noon on Sunday. Why did the episode end in such a whimper? Here, four theories:

1. The government's PR blitz worked
"A lot is said about the fact that this is the car capital of the United States," said Los Angeles Mayor Antonio Villaraigosa. Now, "everybody has seen we can get out of our cars every once in a while and survive." No wonder, says Simone Wilson at LA Weekly, given that motorists were "so inundated by city officials' and the media's depiction of an apocalyptic traffic crisis (decidedly yellow journalism, but for a good cause) that they were scared to even look out the front door."

2. The whole thing was overhyped from the start
"Carmageddon turned out to be a marketing campaign that was much better than the movie," says Cynthia Littleton at Variety. And that's probably no accident in Tinseltown. Everyone is crowing about how smoothly everything went, but I wouldn't be surprised if city and state officials consciously "took a page from the studio-exec handbook of underpromising and overdelivering." That may come back to haunt them next June, when the second half of the bridge comes down and they try to sell "Son of Carmageddon," says sociologist Dennis Mileti, as quoted by the Los Angeles Times.

3. Angelenos turned to creative travel alternatives
The obvious reason Carmageddon turned into "Carmaheaven" is that Angelenos decided en masse to find other ways to get around. Instead of falling victim to "this government-created problem," says Tim Cavanaugh at Reason, they individually opted to take the train, subway, helicopter, bike, and cross-city flights. JetBlue's flight from Burbank to Long Beach was an especially "fanciful idea," says Tom Vanderbilt at Slate, but it was revealed as embarrassingly impractical when a group of cyclists beat the plane to Long Beach.

4. Twitter
Celebrities and Twitter helped the city hype Carmageddon. The LAPD bragged that more than 30 stars — including Lady Gaga, Tom Hanks, and Kim Kardashian — with more than 100 million followers between them obediently tweeted about the upcoming closure. I guess the goal was to "reach the folks who don't tune into television or radio news, or, apparently, use the internet for staying up-to-date," says Lindsay William-Ross at LAist. "So basically 15-year-olds without driver's licenses"?