Los Angeles (CNN) -- The nation's second largest city is preparing for potential traffic paralysis with the closure this weekend of a major highway that passes through the mountains of Los Angeles.
Last year's closure of Interstate 405 -- described by local officials as "the nation's busiest freeway" -- was expected to be so apocalyptic that car-loving Los Angeles labeled the weekend shutdown "Carmageddon."
In fact, traffic flowed rather smoothly because many motorists stayed home, and the freeway through the Sepulveda Pass reopened ahead of schedule on that July 2011 weekend.
This year's construction effort is dubbed "Carmageddon II," and officials are concerned again about ultra-gridlock out of a fear that motorists may take to the roads this weekend out of excessive confidence and complacency.
Motorists should avoid driving this weekend in affected areas, local officials said.
"We don't want people to become complacent based on the success of last year's closure. Once again, it's vitally important that we all plan ahead, avoid the area, and eat, shop and play locally. Otherwise, there will be problems," said Michael Miles, the California Department of Transportation's director for Los Angeles and Ventura counties.
K.N. Murthy, Los Angeles County Metropolitan Transportation Authority's executive director of transit project delivery, said: "The risk factors that caused transportation, law enforcement and emergency response agencies heartburn during last year's I-405 freeway closure have not changed.
"I-405 is still the nation's busiest freeway," he said. "The closure is still in the geographically constrained Sepulveda Pass, where there are no immediate or effective alternate routes. That's why we still need the public's full and complete cooperation if this second closure operation is going to be as successful as the first."
A 10-mile section of Interstate 405 is scheduled to be closed from as early as 10 p.m. Friday (1 a.m. ET Saturday) until 5 a.m. (8 a.m. ET) Monday.
The 405, as it's locally called, cuts through the Santa Monica Mountains and connects suburban San Fernando Valley with Los Angeles International Airport and the well-to-do neighborhoods of west Los Angeles, such as Bel Air and Brentwood.
Specifically, the 405 will be closed between Interstate 10 and U.S. 101.
The highway construction project this weekend will complete a carpool lane system over the mountain pass to create a continuous carpool lane of almost 73 miles in each direction between Orange County and Los Angeles County's San Fernando Valley -- the longest in the world, officials said.
Highway reconstruction will continue until 2013, when the overall $1.34 billion project is scheduled for completion, officials said. Improvements include new bridges and ramps and building 18 miles of retaining and sound walls, officials said.