SAN FRANCISCO – The chief designer of the new, $6.4 billion eastern span of the San Francisco-Oakland Bay Bridge says more than 2,000 bolts and rods on the span that have been called into question are safe and can remain in place, a newspaper reported.
The bolts and rods came under scrutiny after 32 other bolts cracked when they were tightened last year, threatening to delay the span’s opening.
But bridge designer Marwan Nader told bridge oversight officials at a meeting Thursday that the other 2,200 bolts and rods on the span are likely to be more corrosion-resistant than the 32 that failed. Although they will need extra protection against corrosion, Nader said the bolts and rods do not need to be replaced, the San Francisco Chronicle reported (http://bit.ly/1o02lDa ).
Nader based his conclusion on tests state transportation officials began conducting last year after the 32 seismic safety bolts broke.
“As engineer of record, I conclude these rods in service are safe,” Nader, of T.Y. Lin International, the firm that designed the span, said.
A final decision about replacing the bolts is still pending. But Steve Heminger, chairman of the bridge oversight panel, said he was encouraged by Nader’s assessment.
“The testing results, if they are borne out, are very good news,” Heminger said.
The oversight panel earlier recommended that 700 bolts and rods be replaced, but Heminger said that will now need to be reassessed.
The 32 bolts that failed secure earthquake shock absorbers to the deck of the bridge. Tests found hydrogen had infected the bolts, which also were made of poor-quality steel, making them brittle. When tightened to high tension, the brittleness gave way, causing the cracks.
Bridge officials found a temporary solution that allowed the bridge to open as scheduled over Labor Day weekend.
Also Thursday, the bridge oversight panel awarded $3 million to deal with some other problems that have surfaced on the new span, including rust-stained white paint and misaligned steel rods.
The new span replaced one built in the 1930s, which was not considered earthquake-safe. The old span was damaged during the 1989 Loma Prieta earthquake.
Information from: San Francisco Chronicle, http://www.sfgate.com