SAN DIEGO — The passenger and freight rail line between Oceanside and San Diego was expected to reopen Monday in time for the morning commute, according to the San Diego Association of Governments.

The corridor has been closed since just after midnight Saturday for improvements but is set to resume service at 5 a.m., according to SANDAG.

Several improvements were to be made, including work on the Mid-Coast Trolley project, extending the UC San Diego blue line trolley from the Santa Fe Depot in Downtown San Diego north toward UC San Diego.

RELATED: Rail lines from Oceanside to San Diego closed all weekend

Four rail services use the San Diego segment of the Los Angeles-San Diego-San Luis Obispo coastal rail corridor: North County Transit District, Metrolink, Amtrak and the BNSF freight line.

Crews working on the Mid-Coast Trolley project had planned to remove temporary support structures, build retaining walls, protect slopes and install fencing and cable railing, as well as sewer, water, and drainage pipes. The entire project is expected to be completed late next year.

Near the San Diego River Bridge, crews had planned to add nearly a mile of double track across the river to create a continuous 7-mile stretch of double track in the southernmost portion of the coastal rail corridor.