WCA September 2013

Statue of Liberty Image from BigStockPhoto.com Photographer: Marty

Amy Rein Worth, the chairwoman of the Metropolitan Transportation Commission (MTC), one of the California organisations involved in the construction of the new eastern stretch of the San Francisco-Oakland Bay Bridge, has a double perspective. She is also the mayor of Orinda, a small (13-square-mile) city in the area whose residents are highly sensitive on questions of seismic safety. In June, Norimitsu Onishi, the San Francisco bureau chief for the New York Times , interviewed Ms Worth and others for a status report on the work in progress on the bridge, the replacement for a span which partly collapsed during the last major Bay-area earthquake. The reopening was set for Labor Day weekend in early September, the traditional end of summer in the US, until it was discovered that some high-strength steel bolts embedded in the roadway had failed. In March, when workers tightened the 17 to 24 foot-long bolts, 32 in a batch of 96 snapped. The discovery, Mr Onishi wrote, presented California with two equally unattractive options for the most expensive infrastructure project in the state’s history. Under the assumption that the next major quake could occur at any time, should the state delay the opening of the new bridge – which despite its imperfections is believed to be more seismically resistant than its 77-year-old predecessor? Or should opening day go off according to plan, leaving some issues to be resolved later? Transportation officials were wrestling with the decision when the Times article appeared. (“In California, Bolts May Hold Up a Bridge in More Ways Than One,” 15 th June). The Bay Bridge’s western section, a suspension bridge that runs from San Francisco to Yerba Buena Island in San Francisco Bay, was successfully strengthened after the Loma Prieta earthquake of 1989. But the eastern half, a cantilever design that runs from the island to Oakland, was deemed beyond retrofitting. The new bridge, with a foundation in bedrock, will be the world’s largest self-anchored suspension bridge, an unusual design that contributed to its high cost ($6.4 billion, at last count). Equipped with the latest anti-seismic technology, the bridge was designed to last 150 years by remaining intact in a major earthquake. That is why the failure of some of the bolts attaching shock-absorbing devices, called shear keys, to a concrete crossbeam under the roadway raised alarms. “Engineers blamed hydrogen-assisted cracking, in which atoms of hydrogen infiltrate steel and make it brittle,” wrote Mr Onishi. “But they have yet to determine its cause.” On a recent visit to the pier where the defective bolts were installed, the Times ’s man in San Francisco was shown some others that, despite having been tightened, had loose nuts. “You can see how the nuts pop up a little bit,” a Bay Bridge spokesman pointed out. “That’s what clued everybody in that there was a problem with those.”

Automotive Americans are snapping up new cars and trucks at a pace not seen since before the recession In yet another sign that the US economy is on track for growth, preliminary figures published 2 nd July indicate that June 2013 was the best month for vehicle sales since December 2007, with a rise of around eight per cent from June 2012. The auto pricing site TrueCar.com estimated that dealers this June sold at an annualised rate of 15.7 million units. The gains were almost across the board for the domestic industry. Among major auto makers only Volkswagen bucked the trend. For a third straight monthly decline in US sales, the German company reported a three per cent drop in June. Ford Motor Co led the sales growth in the month, reporting a 13 per cent increase for its Ford and Lincoln brands. General Motors reported a gain of six per cent; Chrysler Group, 8 per cent. Sales for Nissan Motor Co rose 13 per cent, giving the company its best June sales month ever in the United States. Toyota Motor Corp, the world’s largest car maker, reported a sales gain of 9.8 per cent. Possible contributing factors include rising demand for better fuel economy, the aging fleet on American roads, and auto loan rates which remained near historic lows in June. According to Bankrate.com the interest rate on a four-year new-car loan averaged 2.7 per cent. An “interesting wrinkle” noted by Slate auto blogger Matthew Yglesias is that the biggest sales surge was in full-sized trucks, perhaps a secondary consequence of the revival in residential construction and continuing oil-related work across the country. ❖ Other bright notes were sounded at the midpoint of the year. The Conference Board consumer confidence index, which had improved in May, increased again in June. And the Standard & Poor’s 500, a stock market index of the leading companies publicly traded in the US and an acknowledged bellwether of the national economy, hit a six-year high. Also on 2 nd July, it was reported that private employers stepped up hiring in June and that new applications for unemployment benefits had fallen for a second week, pointing to a steadily improving labour market picture. A fable updated for our time: 32 failed bolts on the eastern span of the San Francisco-Oakland Bay Bridge put a $6.4 billion project on hold “We are pushing for time against when the next earthquake will occur, and that’s why there’s urgency about this. At the same time, there’s a strong feeling from all of us involved that we want to get it right.” ‘For want of a nail’

59

www.read-wca.com

Wire & Cable ASIA – September/October 2013