LOS ANGELES (CBS) — More overnight closures are planned on the San Diego (405) Freeway through the Sepulveda Pass, as work continues on a $1.2 billion improvement project.

The southbound freeway will be closed from the Ventura (101) Freeway to Getty Center Drive from Friday night to Sunday morning.

Some freeway ramps in the area could begin closing as early as 7 p.m. Friday and Saturday, and some lanes could be blocked beginning at 10 p.m. All southbound lanes will be closed at midnight, but the closures should be lifted by 5 a.m.

The closures will impact the northbound lanes between Getty Center Drive and Ventura Boulevard on Monday and Tuesday nights. More southbound closures are planned on the nights of March 12 and 13.

Officials said Sepulveda Boulevard will remain open during the freeway closures and will be available as an alternate route.

The project will add carpool lanes to the freeway and make other improvements, including the reconstruction of major bridges over the 405 in the Sepulveda Pass. It is scheduled to be completed next year.