San Francisco, California (CNN) -- Repair work on the San Francisco-Oakland Bay Bridge will continue nonstop into the weekend and the bridge may reopen Monday, but officials were making no promises Friday.
"Commuters are going to need to check back with us over the weekend," said Bart Ney, a spokesman for the California Department of Transportation. "We're going to do everything we can to get the bridge open for the Monday morning commute, but safety is the priority for us right now."
Repair work has not stopped since it began Tuesday night when two steel rods and a steel crossbeam plummeted from the bridge, landing on the roadway and forcing the span's closure. The same section had been the site of repairs over Labor Day weekend, when crews fixed a crack.
On Friday, workers were grinding the areas where there was the potential for steel-on-steel connection, Ney said. "We want them to be very smooth."
The rods' alignment has not been completed to the point where workers could begin stressing them, he said.
Once that work is complete, a third-party group will look at how the system handles vibrations, he said, adding, "There is still a lot of work to be done."
Transportation officials had said Thursday night that repairs of the bridge, which carried about 280,000 vehicles per day, would be complete by late Friday morning, but Ney said contractors were still working on custom-fitting steel for the structure.
Crews worked Friday to replace four steel rods. One of those had failed and caused the problems, Dale Bonner, California's secretary of business, transportation and housing told reporters Thursday. Engineers also will make sure the rods are centered and will strengthen the welds to ensure stability, Bonner said.
Vibrations in the rods, affected by strong winds, caused the break, officials said.
In the wake of the bridge's closing, commuters flocked to the Bay Area's rail system.
On Thursday, Bay Area Rapid Transit (BART) said, the system carried the most passengers ever, breaking a record set the day before.
About 442,000 people took BART, 24 percent more than on an average Thursday, the agency said in a news release.