The bridge now has eight lanes and is 30 feet wider. Each direction has a turning lane, which should help alleviate traffic.
"I think it's great. It's going to help reduce the traffic a bit," said Brian Bellingham, who is one of 22,000 motorists who use the bridge daily.
The construction is part of the $1-billion 405 Freeway widening project.
"This is a great benefit to the people who live here and people who travel through here," said Los Angeles County Supervisor Zev Yaroslavsky. "This also signifies that we're reaching the home stretch of the 405 project. This was the first major bridge, the first major part of the 405 project, and by this time next year, this project should be done."
Meantime, Westside commuters are bracing for Carmageddon 2 this weekend when the 405 Freeway will be closed for 52 hours between the 10 and 101 freeways so crews can demolish the north half of the Mulholland Drive Bridge.
Officials are urging Southern California drivers to avoid the area on Saturday and Sunday. Last year's first edition of Caramgeddon went smoothly because most drivers stayed off the roads.
While the first Carmageddon ended early, officials are not expecting that to happen this time around. They say they have 30 percent more work to do. The bridge should reopen at 5 a.m. next Monday.
Metrolink is also doing what it can to make getting around easier. It's adding service between Chatsworth and Los Angeles this weekend to give you more options. The special Ventura County service will go from Chatsworth to Union Station and back, and include stops in Glendale, Burbank, Van Nuys and Northridge.