OAKLAND -- Caltrans and private engineers deliberated three months in 2003 over the proper corrosion method to use on high-strength steel rods for the new Bay Bridge, a decision that led to the embarrassing failure of 32 rods a decade later.
Documents reveal a series of back-and-forth letters and emails on the subject among more than two dozen engineers and designers from Caltrans and the hired Bay Bridge team of at T.Y. Lin International and Moffatt & Nichol.
Ultimately, the team concluded that mimicking specifications used on bolts in the Richmond-San Rafael bridge retrofit in 2001 would reduce the risk of hydrogen embrittlement -- and possible failure -- for 2,306 galvanized fasteners for the new Bay Bridge.
"Email communications show that designers, engineers and metallurgists were aware of the risks of hydrogen embrittlement ... and that they took steps in manufacturing and testing that they believed would prevent it," Caltrans Director Malcolm Dougherty wrote in a cover letter to Senate Transportation Committee Chairman Mark DeSaulnier.
This proved inadequate, Dougherty has conceded.
The documents released this week come as Caltrans, Bay Area Toll Authority, the bridge contractor and the team of private engineering consultants hired to design the span are scrambling to determine whether a proposed $5 million to $10 million repair job can be finished in time to open the bridge on Sept. 3 as scheduled.
They must also settle unanswered questions about the long-term integrity of the other 2,210 high-strength steel fasteners used on the bridge that were fabricated in the Midwest under identical specifications.
The documents show that Bay Bridge engineers were well aware of the potential problems.
National standards caution engineers about galvanizing high-strength steel due to the increased risk of embrittlement, and Caltrans' own bridge design manual prohibits the practice on ordinary spans. Embrittlement is a well-known phenomenon where hydrogen atoms invade and weaken the metal's molecular structure, making the part susceptible to fracture.
The special modifications for the steel on the bridge specified that the manufacturer must sandblast the fasteners rather than submerge them in an acid bath -- called pickling -- before dipping them into molten zinc, the process for galvanizing.
It was the same process used for steel rods on the Richmond-San Rafael Bridge, although those bolts are under far less load than those that snapped on the Bay Bridge.
That process "does the trick for galvanizing high-strength rods," wrote Caltrans engineer Robert Kobal to his colleagues in April 2003.
Ten years later, that decision would prove costly in dollars, time and public confidence.
In early March, a third of the 96 high-strength threaded rods -- 3 inches in diameter and 17 to 24 feet long -- installed in key seismic stabilizers on the span snapped after contractors tightened them down.
The state's design and engineering team initially specified in mid-2002 the high-strength grade and type of steel for the bolts -- A354 BD -- to be used on the new eastern span. The faulty anchor rods are among 288 bolts used in shear keys and bearings in the main pier east of the suspension span tower. The other fasteners are found in the anchorage, tower, saddles and to secure the cable.
The agency's internal Structural Steel Committee raised the issue of adequate corrosion protection on the fasteners in January 2003, just as the state advertised for bidders to build the iconic self-anchored suspension span.
The engineers discussed their options in a construction meeting in Oakland, according to a memo dated Feb. 28.
The fasteners were "too long and too heavy" to be mechanically galvanized, which involves coating the products with zinc in a tumbler. Other types of coatings could also be used, although the documents show engineers worried these products may be less effective.
The American Society for Testing and Materials has long warned against hot-dip galvanizing high-strength steel, but if it is necessary, the organization recommends precautions including the elimination of pickling, and extra tests. The national standards do contain a disclaimer: "This standard does not purport to address all of the safety concerns ... It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations before use."
Despite the warning, the bridge team chose the riskier path.
The bridge team in late March requested Caltrans consider the changes, including recommendations from the state's corrosion engineer Rob Reis to add extra testing to detect embrittlement. The state agreed and incorporated the provisions into the self-anchored suspension contract in Addendum No. 3 on April 4, 2003.
The contract as advertised was allowed to lapse in 2004, however, when only one bidder responded with a price of $1.4 billion, nearly double Caltrans' estimate of $740 million.
Delays persisted while then Gov. Arnold Schwarzenegger unsuccessfully attempted to persuade legislators to dump the signature self-anchored span and replace it with an extension of the skyway.
Caltrans re-advertised the suspension span contract -- with identical high-strength steel specifications -- and awarded the $1.7 billion job to American Bridge Fluor Joint Venture in 2006.