BAY AREA QUAKE : Inspectors Had Rated Nimitz Sound : Safety: Regular checks had turned up cracks and chips in the concrete pillars, but a Caltrans aide says they did not contribute to the freeway’s collapse.
Regular state inspections of the section of the Nimitz Freeway that collapsed in Tuesday’s earthquake found the structure to be in sound condition, despite the presence of numerous cracks and chips in the concrete pillars supporting the elevated highway.
The reports show that some of the cracks exposed the steel inside the structure’s concrete casing, allowing water to seep through and rust the reinforcements.
But a top California Department of Transportation maintenance official said the items cited in 32 years of inspection reports released Thursday in no way contributed to the catastrophic collapse, which killed at least 18 people who were crushed in their cars when the roadway’s upper level fell onto the lanes below. The drivers and passengers in an undetermined number of other cars remain unaccounted for.
“Nothing I have seen in these reports either gave the writer of those reports or me any concern” that it would not withstand a quake of Tuesday’s magnitude, said Elvin Klein, branch chief of Caltrans’ structural maintenance office.
Klein said the cracks are typical of freeways everywhere. “It is not cause for alarm,” he said.
Jim Drago, a Caltrans spokesman, added: “The collapse of the freeway was in no way related to any of the normal wear and tear that was listed in these inspection reports over the course of the years and addressed.”
The annual inspections began in 1957, the year the eight-lane, double-decked freeway opened as a state-of-the-art facility near the Bay Bridge in Oakland. The reports detail everything from sagging of the freeway decks to bumpy roadways, from drainage problems to the presence of graffiti on the structure.
In 1957, the freeway was reported to be in “excellent condition throughout.” In 1960, an inspector found the Nimitz to be “in good structural condition.” Later reports itemize the cracks and other flaws but give no overall assessment of the freeway’s structural integrity.
Typically, the reports use technical language and it is unclear what conclusions can be drawn from the findings.
In 1959, for instance, an inspector found “vertical cracks” in a column near where the freeway collapsed Tuesday. “Water seeps through the column and has rusted the reinforcing,” the inspector wrote. No corrective action was recommended.
Three years later, Caltrans found “numerous diagonal tension cracks” in the exterior girders. “The size and number of cracks on the easterly side of the structure appear to have increased considerably during the past year,” the inspector wrote.
In 1966, an inspector said that the back wall of one of the bridge abutments was cracking and said it appeared that the “superstructure is transmitting higher than anticipated . . . forces on the abutment back wall.”
The Times asked several earthquake experts to evaluate the reports. One of them, Vitelmo Bertero, UC Berkeley professor of earthquake engineering, said the cracks inspectors found in reinforced concrete girders are “structural cracks.”
“I have been one of those who has called attention to these,” Bertero said, adding that he had sent his students to look at the cracks before the collapse. “I’ve been scared about these.”
But even though Bertero has long been concerned about the apparent cracking, after inspecting the collapsed structure, he said he is convinced that the cross-beam cracks were not the cause of the failure during the quake. “What failed are the columns,” he said.
An engineering professor at another California university, who asked not to be identified, agreed with Bertero’s assessment of the bridge inspection reports. He said that failure to do proper maintenance can cause structural problems. But, he said, “Nothing clearly points to that.” The description of structural cracking is more troublesome, he said, but may not prove to be relevant to the collapse.
A UC San Diego earthquake engineer said Thursday that the collapse of the top deck of the freeway was caused by failed joints that linked the roadway with reinforced columns. Nigel Priestly, a structural engineering professor, said there was “virtually no reinforcement” in the joints even though the design was “state of the art” for the 1950s.
It is not clear whether the inspection reports found maintenance problems related to the joints.
Meanwhile, Gov. George Deukmejian announced the formation of an independent commission to conduct an inquiry into the freeway collapse. He named Ian G. Buckle, deputy director of the National Center for Earthquake Engineering Research, to head the task force.
“I want answers to the pertinent architectural questions as soon as possible,” the governor said in a statement. “This independent team comprised by leading structural engineering experts from throughout the nation will give us these answers.”
Other members of the commission have not been named, but will include representatives from the National Transportation Safety Board, the Federal Highway Administration, research institutions and private corporations, the governor’s office said.
Buckle, in an opinion article published in The Times on Thursday, defended Caltrans’ record in upgrading the state’s freeways to prevent destruction in an earthquake. He said the department had followed a proper strategy of fixing the simplest problems first and saving the most difficult problems--such as the San Francisco-Oakland Bay Bridge and the Nimitz Freeway double-decking--for last.
“Now is not the time for knocking Caltrans,” Buckle wrote.
Despite Buckle’s statement, Deukmejian Press Secretary Kevin Brett said the governor was confident that the earthquake expert from Buffalo, N.Y., would conduct a thorough investigation of the freeway collapse.
“We believe he is going to be objective in his evaluation,” Brett said. “We are certain he is going to be critical where he needs to be critical. We want the facts, and those facts may not be pretty, because we don’t want to see this tragedy happen again.”
Times staff writers John Hurst, Paul Jacobs and Richard Paddock contributed to this story.