SAN FRANCISCO — When traffic flows across the new stretch of the San Francisco-Oakland Bay Bridge for the first time this week, it will do so nearly a quarter-century after a deadly earthquake during the 1989 World Series collapsed two 50-foot sections of the old structure.
The 6.9-magnitude Loma Prieta quake hit just as millions tuned in to watch Game 3 of the ‘‘Bay Bridge World Series’’ between the Oakland Athletics and San Francisco Giants, killing 63 people and causing up to $10 billion in damage.
The Bay Bridge failure prompted one of the costliest public works projects in state history. The $6.4 billion project finally draws to a close after decades of political bickering, engineering challenges, and billions in cost overruns. The new bridge is scheduled to open by 5 a.m. Tuesday at the latest.
The delays magnified public safety concerns over the need for a permanent solution as the original, seismically unsafe bridge, which opened during President Franklin Roosevelt’s administration, was patched up and continued operating.
Highlighting the decades of complications, the scheduled opening of the new bridge was in jeopardy again this year after crews discovered dozens of defective rods used to anchor the roadway to important earthquake safety structures. The bridge will open with a temporary fix for the broken rods while the permanent repair, expected to be completed in December, is being installed.
Issues with the rods and myriad delays have left many commuters with a feeling of trepidation about the bridge, even though state officials say it is one of the safest in the world.
The self-anchored suspension bridge with a looming, single white tower was designed to endure 150 years and withstand the strongest earthquake estimated by seismologists to occur at the site over a 1,500-year period.
Steve Heminger, chairman of the Toll Bridge Program Oversight Committee, the project’s watchdog, said the span is orders of magnitude safer than the current crossing.
‘‘Some bridges in California have been built not to collapse in an earthquake, but they may be out of service,’’ Heminger said. ‘‘We couldn’t have that with the Bay Bridge, which is not only pivotal to the economy but also plays a critical role in helping us recover.’’
‘‘I’m not here to suggest that there weren’t construction challenges along the way, but they have been dealt with.’’
In the decades since the earthquake, the bridge replacement project overcame many hurdles.
An initial scientific recommendation following Loma Prieta called for retrofitting the current span, not replacing it. A National Science Foundation team that studied damage to the bridge said in 1992 that the current eastern portion should be retrofitted for an estimated cost of $230 million.
But in 1996, the California Department of Transportation’s Seismic Advisory Board disagreed with those findings, saying the cost of replacing the old bridge would be comparable with retrofitting it.
At that time, Caltrans proposed building a simple concrete causeway — an elevated freeway — at a cost comparable to a retrofit.
But Bay Area leaders blasted that design as too vanilla, saying the area deserved a span that would complement the grandeur of the Golden Gate.
The self-anchored, single tower design was accepted in 1998, and Caltrans estimated it would cost $1.5 billion.
However, the ambition of the project created technical challenges that were not factored into original cost estimates — hurdles that delayed construction by years. During the delays the price of steel increased, and unforeseen engineering challenges created a need for more workers.
Costs skyrocketed, lead-
ing former governor Arnold Schwarzenegger in 2004 to propose scrapping the single-tower design in favor of the cheaper raised freeway concept. But the foundations of the bridge’s tower were already laid, so in 2005 the project continued.
Critics of the bridge’s design along the way have questioned assertions that the span is quake safe, saying more work is needed to know if there are more defective bolts or rods, said Bob Bea, an emeritus engineering professor at the University of California, Berkeley.
‘‘I do not think there are significant concerns for the ‘safety’ of the bridge under normal daily loadings. However, I do think there are remaining significant unresolved concerns for the ‘durability’ . . . and ‘safety’ of the bridge,’’ Bea said.
The project’s problems also exposed a government public works system that is no longer equipped to handle such ambitious projects, said Richard Walker, an emeritus geography professor at the UC Berkeley who has studied a century of public works projects in the United States.
‘‘America doesn’t do big infrastructure projects that well anymore,’’ Walker said. ‘‘California used to be at the leading edge . . . they built the Bay and Golden Gate Bridge, still one of the beloved structures in the world.
‘‘In those days, there were far fewer regulations, which allowed builders to put together local steel and cement plants for these projects . . . assembling a whole team was easier.’’