Caltrans crews will be adding a carpool lane on the northbound 405 between the 10 and the 101 freeways.
In the long run, the project is expected to reduce congestion, but for now, it only brings inconvenience. Ramp closures will begin at 7 p.m. Wednesday.
On almost any weekday, the 405 Freeway is a slow ride along the Sepulveda Pass. With crews prepping for the start of a major construction project, motorists are bracing for even longer commutes.
"It just will probably lengthen my daily commute to work by doubling it, so instead of taking 30 minutes, it will probably take me an hour to get from Mulholland to Beverly Hills," said Marie Fuerst of Encino.
Tim Matthews of Huntington Beach said he would no longer take the 405 Freeway when the project begins.
"Unfortunately, I'll have to go all the way around. I'll probably take the 710 to the 5 and cut down through downtown, which is probably going to be more congested there now," he said.
The $1 billion project will eventually add a 10-mile carpool lane on the northbound side of the 405 through the Sepulveda Pass. As part of the construction work, nearly two dozen on- and off-ramps will be realigned. Bridges at the Skirball Center, Sunset Boulevard and Mulholland Drive are set to be replaced, and several miles of sound walls will be built.
Crews will do a lot of the work at night for the next two months. The project will impact freeway traffic between the hours of 7 p.m. and 6 a.m., and will affect segments of both the northbound and southbound sides of the 405. Full freeway closures will occur only between the hours of midnight and 5 a.m.
Next month, concrete barriers will be placed on the shoulder of the freeway along the 10-mile stretch to keep the work zone isolated from traffic.
Some motorists said while the project will be inconvenient, they look forward to the long-awaited improvements.
"If all of us have to be a little bit bothered by it, or leave 15 minutes early, I mean, this is our life, for our children, for everything, so go for it," said Barbra Hellwig of Encino.
The project is due for completion by 2013, and the improvements are expected to shave about 20 minutes off the average commute.
