All four southbound lanes have been closed at the Alum Rock Avenue overcrossing since about 11 a.m. due to flooding, CHP Officer Peter Van Eckhardt said.
Van Eckhardt advised motorists to take southbound state Highway 87 or southbound Interstate Highway 880 instead.
He did not have an estimate as to when the highway would be reopened, but said Caltrans crews are working to control the flooding and gradually reopen the lanes.
