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

With all planned demolition and maintenance work completed, California Department of Transportation Officials removed cones from the bridge and approaches around 7 p.m. and the first vehicles crossed the bridge around 8 p.m.

Caltrans spokesman Bart Ney said Mother Nature played a role in the early opening.

"We had some great sun," Ney told reporters. "It was nothing we could have forecasted, but it allowed us to finish the work quickly."

The bridge was not scheduled to reopen until Tuesday at 5 a.m.

Caltrans officials cautioned motorists passing through the toll plaza 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.

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 the 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.