In a fierce push to prove the new eastern section of the Bay Bridge will be safe for the 280,000 motorists who cross it every day, Caltrans is hosting an unprecedented live public webinar Friday morning to explain how it tested the span's foundations.
The agency is responding to assertions in a Sacramento Bee story that there was improper testing and possible structural weakness in the concrete within the support structure beneath the $6.4 billion signature suspension span.
"The Bay Bridge is about as high profile ... as a project gets in the state of California, and public confidence means a lot to us," said toll bridge program Manager Tony Anziano. "But foundation testing is a technically dense area that requires an explanation of underlying engineering concepts in order to understand why the (assertions in the Bee article) are wrong. The webinar is an opportunity for us to do that."
Chief state bridge engineer Brian Maroney said Caltrans conducted numerous tests of the concrete during practice mixes, as it was poured into the foundation and after it was installed, and is completely satisfied with its integrity.
Despite Caltrans' vigorous safety assurances, Senate Transportation Committee Chairman Mark DeSaulnier, D-Concord, said he will hold investigative hearings this summer and seek independent analysis of the bridge's structural integrity.
"We know the old bridge is unsafe," DeSaulnier said. "We owe it to the public to have hearings and attempt as best we can to answer the questions about the safety of the new bridge, which is why we are building it in the first place."
The concrete testing protocol debate comes as Caltrans moves into the home stretch of the most expensive and politically tortured public works project in the state's history.
Set to open in late 2013, it has been nearly a quarter-century since the deadly Loma Prieta earthquake shook loose a piece of the bridge deck and started the race to replace the aging span before another temblor strikes.
Contractors in the past two weeks began hanging the steel vertical support cables on what will be the longest single-tower, self-anchored suspension span in the world.
Strung across the sky like giant harp strings, the cables are among the most visual and structurally key elements of the 1,263-foot span -- they tie the main overhead cable to the bridge deck and help spread the weight loads.
Workers are also pouring concrete in the bridge segment that will link the suspension span to Yerba Buena Island. In addition, Caltrans is about to start work on the touchdown structure between the 1.2 mile skyway and Oakland, said bridge project spokesman Bart Ney.
The massive project has weathered dozens of controversies and numerous state administrations -- cost overruns, design fights, White House intervention and accusations of faulty welds that later proved false.
The most recent dispute centers around whether Caltrans properly tested the concrete in the foundation beneath the 525-foot suspension tower.
According to the Bee story published May 27, a bridge contractor failed to disclose the results of a 2007 test showing that a 19-foot section in the foundation had not hardened before it was tested. The article also cited other testing inconsistencies and data gaps that may raise questions about the bridge's safety.
Caltrans has demanded a retraction. In the Bee's story about the dispute earlier this week, the newspaper said the story is "fair and accurate."
Maroney said he will tackle the dispute head-on during Friday's webinar, a web-streamed presentation on the Internet.
But in a telephone preview of his comments, Maroney equated the foundation's literal strength to that of the fictional Captain America's shield.
"Once people know the truth about how this foundation was built, they will feel very good about it," Maroney said.
The tower's foundation consists of 13 individual pilings sunk up to 180 feet into bedrock beneath the water line and capped with a massive steel housing.
Each of the 8½-foot diameter pilings is encased in a 4-inch-thick steel sleeve, filled with concrete and packed with multiple 2¼-inch diameter steel reinforcement rods placed horizontally and vertically.
The key test cited in the Bee report was done by the contractor for its own purposes. Caltrans used a different type of test more appropriate for the type of concrete used in the foundations, Maroney said. It was a more viscous mix designed to flow more easily around the steel reinforcement rods and take longer to harden up, he explained.