LOS ANGELES — The warnings had been grim: a knot of traffic stretching from the Pacific Ocean to downtown Los Angeles. Motorists struggling to make it from West Los Angeles across the Sepulveda Pass into the San Fernando Valley. A display of gridlock that would drain even the most hardened Los Angeles commuter, all caused by the weekend closing of a 10-mile stretch of Interstate 405
Instead, people in Los Angeles woke up Saturday to something many had rarely, if ever, seen: empty streets. An afternoon aerial tour over Los Angeles in a Fire Department helicopter — lifting off from the roof of a downtown city skyscraper, over the Sepuldeva Pass and into the San Fernando Valley, and looping back by the Los Angeles Airport — left city officials gape-jawed at empty highways and streets in places where summer Saturdays normally mean hot and vexing crawls.
And while there was justifiable concern that things could go sour before Interstate 405 was opened again on Monday morning — city officials were warning of complacency, even as they celebrated what seemed to be another Y2K moment — it seemed like the crisis of “Carmageddon,” as it was called, might end up being averted, or at least exaggerated.
“We had hoped this would happen, that people would answer the call and stay out of their cars,” said Mayor Antonio R. Villaraigosa, after a 30-minute tour in which he pointed at normally jammed streets and highways and circled twice over the bridge whose demolition this weekend was the cause of the shutdown. “I don’t think I have ever seen so few cars on the road on a Saturday afternoon.”
But, he added: “We are not over the hump yet. We are not going to gloat.”
Yet there was abundant evidence that Los Angeles residents had responded to months of warnings to get out of town or stay at home.
The intersection of Sunset Boulevard and Interstate 405 was desolate early Saturday, save for a few bored-looking police officers, busy keeping skateboarders from sneaking onto the highway to take photos of themselves doing tricks. A trickle of people with cameras showed up — on foot or on bicycle — to get photographs of what might reasonably called, at least for this weekend, the Eighth Wonder of the World: Interstate 405 without a single vehicle on it. There were a handful of arrests for trespassing by joggers and bikers.
“Driving up here this morning, seeing all the traffic control guys directing the traffic and people giving them high-fives, it’s a different vibe in this city,” said Yee-Ping Cho, a graphic designer who lives in Culver City. “Just generally, it’s like driving on a holiday, which is great here.”
A few miles south, a Los Angeles city traffic officer, Albert Fua, stood at an intersection just west of Interstate 405 in Brentwood, one of 300 traffic officers who had been positioned in the area to direct traffic in case of gridlock. He had nothing to do. “I’m hoping it stays that way,” Officer Fua said.
At the crisis nerve center — the newly opened Emergency Operations Center, tucked into a nondescript two-story building just east of downtown Los Angeles — a group of 40 police and fire officials in black uniforms gathered under a wall of giant screens.
On one, the Channel 7 news showed sweeping images of empty highways.
The cause for all the alarm was the closing, for an estimated 53 hours, of a 10-mile stretch of the highway that runs through the heart of western Los Angeles, over the Santa Monica Mountains and into the San Fernando Valley. The weekend closing was necessary to allow for the demolition of half the bridge that carries Mulholland Drive over the highway (the other half will be torn down next year), part of a project to extend carpool lanes over the mountain pass.
As the mayor’s helicopter circled low over the bridge, the extent of the demolition was clear and city officials said they were hopeful that construction crews would be done before the goal of 5 a.m. Monday.
“This isn’t just some exercise — it’s part of a grander vision and a bigger plan to close the gap in a system of H.O.V. lanes that will connect us from Orange County to the San Fernando Valley,” Mr. Villaraigosa said, referring to high-occupancy-vehicle lanes.
An estimated 500,000 cars travel the Sepulveda Pass every weekend, and city officials have been sounding alarms for three months about the potential disruption, urging motorists to stay off the road. There was not even any evidence of gridlock on alternative roads that motorists were expected to use to get into the valley. A drive over Laurel Canyon on Saturday morning was swift and easy.
“It was pretty cool driving to work today,” said Jessie Baum, 22, who works in a salon in Studio City. “I saw six police cars and nobody else. I saw them doing work on the Sepulveda Pass, and it was cool.”
Indeed, the city offered something of a motorist’s paradise on this sunny day, with cars zipping up and down roads like Santa Monica Boulevard that are usually mired in traffic. Cyclists, an often beleaguered bunch here, suddenly ruled, taking advantage of the empty, and presumably safer, roads to get around. The hundreds of traffic cops positioned on street corners throughout the city mostly looked on silently, or languidly waved along what few cars appeared.
“This is a dream come true,” said Sophie Levine, 42, who lives near the hilltop intersection of Beverly Glen Boulevard and Mulholland Drive and came to watch the demolition of the bridge with her dogs and husband. “Forget Carmageddon.”
As the morning fog began lifting, people here seemed most inclined to remark on the emptiness of the streets, an unusual mental adjustment for car-dependent residents who on a normal weekend would think nothing about driving 45 minutes to Malibu or the farmers’ market in Santa Monica.
“It’s not often you have the city all engaged in talking about one singular thing — this is pretty unique,” said Juliet Mothershed, director of marketing for the Westfield Fashion Square, a mall in Sherman Oaks. Indeed, people gathered at an intersection near Interstate 405 just to gawk.
“I’ve been in L.A. since ’72, and I’ve never seen this freeway closed, never empty,” said Sun Lau, 59, of Westwood. “I took some pictures and sent them to all my friends.”
With the impetus to stay out of cars, people assembled where the action was — Interstate 405 — to observe what for many was something of a historic day. “It’s a happening,” said Jodi Gechtman, there with a group of family members. “We were looking for things to do on a Saturday.”
Suddenly, she gazed a short distance away. “Is that a food truck?” she asked.
And it was — feeding construction workers by the side of the road.