From the folks at CalTrans:
Maintenance Planned for Posey Tube
January 17 and January 18, 10 p.m. to 4:30 a.m.
Oakland/Alameda – Caltrans Maintenance will close the Posey Tube (eastbound State Route 260 from Alameda to Oakland) on Monday night, January 17, and Tuesday night, January 18, from 10 p.m. to 4:30 a.m. During these closures traffic will be detoured.
Detour for Bicyclists and Pedestrians
Bicyclists and Pedestrian traffic should detour to the nearest AC Transit bus stop. In Oakland, board at Broadway. In Alameda, board at Webster St. and Buena Vista Avenue.
Bicyclists may also detour via city streets. In Oakland, from the Harrison Street entrance to the Posey Tube: North on Harrison St., west on 8th St., south on Webster St., east on 2nd Street, south on Oak St., east on Embarcadero. Take Kennedy St. to 23rd Ave., and south on Park St. Bridge. In Alameda, bicyclists may follow routes suggested in the Alameda Bike Map from Constitution Way/Atlantic Avenue to the Park St. Bridge.
Caltrans thanks commuters for their patience during this necessary maintenance.