Zusha Elinson/The Bay Citizen

In the back: the tower. In the front: The winch that will pull the suspension cable into place.

BART will continue to provide overnight service through 6 a.m. Monday, despite the reopening of the Bay Bridge's westbound upper deck, but will not provide overnight service between 1 and 4 a.m. Tuesday.

Additional ferry service will also continue to be offered to Alameda, Oakland and Vallejo through Monday.

The Bay Bridge's westbound upper deck reopened on Sunday night, more than 24 hours ahead of schedule following a planned holiday weekend closure for demolition and construction work.

Motorists passing through the toll plaza are asked to drive carefully, since the merge will be different. While 20 lanes will still merge down to 5, they will curve slightly to the south, Caltrans spokesman Bart Ney said.

The bridge was not scheduled to reopen until Tuesday at 5 a.m., but Ney said unexpectedly good weather had allowed work to progress quickly.

"The next time we plan to close the Bay Bridge will be to open the new Bay Bridge, Labor Day weekend 2013," Ney said.

The bridge's upper deck was closed at 8 p.m. Friday to accommodate demolition and maintenance projects related to the construction of a new eastern span. Crews demolished sections of roadway to make way for an inclined section that will eventually carry eastbound traffic.

The closure pushed a surge of southbound traffic on to the Golden Gate Bridge. Unofficial numbers show that more than 67,600 vehicles drove south over the bridge on Saturday, up from 39,799 vehicles on the Saturday of Presidents Day in 2011, Golden Gate Transportation District spokeswoman Mary Currie said.