The lanes were expected to reopen by 5 a.m. on Tuesday, the California Highway Patrol said.
The closure was for a four-mile stretch between the 10 and 101 freeways, and it began around midnight.
Crews were working on the reconstruction of the Mulholland Bridge.
It’s part of an ongoing Caltrans improvement project along the busy freeway. For more information: http://www.metro.net/projects/I-405/.