Traffic was moving smoothly Friday morning with no problems reported, officials said.
The project to rebuild the ramp whose steel girders gave way in the intense heat of an April 29 tanker truck fire is one of the quickest emergency repair jobs of a major freeway connector in the history of Caltrans, the state transportation department.
One of the first drivers through the reopened maze was Douglas Spalding, 46, of Oakland, a physics teacher at East Bay School for the Arts. He said he was headed home from Emeryville, heard the ramp was about to reopen and got in line.
He wasn't the first, but was in the first pack of cars that raced onto I-580. "They did an amazing job of putting it back together," he said. "We're all crazy to be driving; we shouldn't be burning all this gasoline. But everybody's happy about what they've done."
Caltrans workers at 8:40 p.m. removed the barriers keeping traffic off the rebuilt ramp, but not before some motorists endured confusion and delays.
First, traffic coming off the Bay Bridge was stopped to allow the removal of sign covers. Then, as traffic started to move, a variable message sign erroneously indicated the ramp already had opened.
Earlier, Caltrans officials took care to assure reporters that the new viaduct would be safe in the wake of an expert's questions about damage to restored columns holding the connector ramp aloft.
Caltrans mustered engineers and consultants to say no corners were cut on safety for the rebuilt freeway. They assured reporters that concrete piers roasted by the burning tanker truck were sound enough to hold the freeway in a "maximum possible earthquake."
"There has been no compromising in no way, shape or form in the way this project was put together in seismic safety," said Kevin Thompson, a Caltrans bridge engineer. "So I hope these issues are put to rest forever. There's no doubt in the confidence in the structural integrity of those members."
University of California civil engineering professor Abolhassan Astaneh says he's not buying Caltrans' assurances until the agency shows its analysis to the public.
"I will not drive over that bridge until Caltrans puts up the data that says it's safe in a magnitude 7.3 earthquake on the Hayward fault," he said.
Astaneh, an expert in steel bridges and earthquakes tapped by the National Science Foundation to investigate the collapse of the World Trade Center towers and now I-580, still questions the piers' soundness, especially in a large earthquake.
He said he observed damage in the same freeway piers from the Loma Prieta earthquake almost 19 years ago. Caltrans shored them up with concrete, some of which was cracked by the more than three-hour fuel tanker blaze.
After the April 29 freeway meltdown, Caltrans had consultants drill into the remaining freeway, its railings and some supporting piers.
Some piers appeared unaffected and were left alone. But in at least two piers, consulting engineers found heat-related cracks, one under the crash site on I-880 and at least one supporting I-580. Inside a deep bore hole near the top of the I-580 support pier, engineers found a wide crack that suggested the tanker fire roasted the I-580 supports at as much as 1,500 degrees. On consultants' recommendation, Caltrans removed and re-poured the top four feet of concrete just under the new I-580 section.
"The concrete that remains out there, I'm confident, is sound. Our tests show that it is sound," said Kent Sasaki, branch manager and consulting engineer for Wiss, Janney & Elstner's Emeryville office.
But Astaneh said he doubts engineers know because the next concrete sample was taken far below on the pier. He says Caltrans should have trashed the roasted piers and built new ones, at a cost he estimates between $250,000 and $350,000.
"Why does he decide four feet and not five?" Astaneh said. "I would have brought in the bulldozer. We're not pouring gold here, we're pouring concrete. Do you know what the cost is to people sitting in their cars not feeling safe?"
The project's conclusion was achieved more than a month ahead of Caltrans' deadline of June 27 because of carefully coordinated work by subcontractors who wouldn't even see each other on a normally paced construction job, explained Peter Strykers, Caltrans senior bridge engineer.
"This was set so that everyone was there," he said, explaining that even before one part of the job was completed, such as installing 12 steel girders fabricated in Arizona, another phase began, such as installing steel reinforcement bar in preparation for concrete pouring.
"That's costly, because you've got guys standing round waiting for things to get done," Strykers said.
Another key factor, he noted, was contractor C.C. Myers' ability to mobilize all the needed companies and material quickly. The company will earn a $5 million bonus for getting the work done so far ahead of deadline.
"Everybody dropped everything else they were doing and worked on this," Strykers said, who handed off his own work on several ongoing projects to work on the Maze reconstruction. "That's designers, fabricators and tradesmen."
Major traffic problems were also averted with an inexpensive program of public transit enhancements, such as more and longer BART trains and improved bus and ferry service, said Randy Rentschler, spokesman for the Metropolitan Transportation Commission.
Commuters also stepped up, thousands giving up their cars for much of May and riding transit.
"A small change in traffic, but a few more cars, can congest the whole freeway. That's why metering lights work," Rentschler said. "Also, the reverse is true. That shift had a significant effect on the performance of the roadway system."
Gov. Arnold Schwarzenegger plans to mark the ramp's reopening with Caltrans Director Will Kempton and Dale Bonner, secretary of business, transportation and housing, at an event at the maze at 10:45 a.m., well after the conclusion of rush hour. The event will be webcast live at http://www.gov.ca.gov.