Pages

July 05, 2011

World's longest bridge center has flaws

Shanghai Daily - Safey fears have been raised over the newly opened cross-sea bridge, the world's longest, that links Qingdao City in east China to the island of Huangdao.

There is concern that the tight schedule ahead of the official opening left important work undone or incomplete.

Several gaps were found in the crash barriers on the 42.5 kilometer Jiaozhou Bay Bridge, while bolts inserted to fasten the barriers were found to be loose or uncovered.



Slower bridge construction is not necessarily safer construction. There have been accidents and safety problems with the Bay Bridge retrofit which is taking a lot longer.

San Francisco Bay Bridge October 2009 Eyebar crack, repair failure and bridge closure

During the 2009 Labor Day weekend closure for a portion of the replacement, a major crack was found in an eyebar, significant enough to warrant bridge closure.

Working in parallel with the retrofit, California Department of Transportation (Caltrans), and its contractors and subcontractors, were able to design, engineer, fabricate, and install the pieces required to repair the bridge, delaying its planned opening by only 1½ hours. The repair was not inspected by the Federal Highway Administration, who relied on state inspection reports to ensure safety guidelines were met.

On October 27, 2009, during the evening commute, the steel crossbeam and two steel tie rods repaired over Labor Day weekend snapped off the Bay Bridge's eastern span and fell to the upper deck. The cause may have been due to metal-on-metal vibration from bridge traffic and wind gusts of up to 55 mph causing failure of one rod which broke off, which then led to the metal section crashing down. Three vehicles were either struck by or hit the fallen debris, though there were no injuries On November 1, Caltrans announced that the bridge would probably stay closed at least through the morning commute of Monday, November 2, after repairs performed during the weekend failed a stress test on Sunday. BART and the Golden Gate Ferry systems added supplemental service to accommodate the increased passenger load during the bridge closure. The bridge reopened to traffic on November 2, 2009.

The pieces which broke off on October 27 were a saddle, crossbars, and two tension rods. For additional details see the Eastern span replacement of the San Francisco-Oakland Bay Bridge article.

There were also safety problems and incidents with the S-curve on the Bay Bridge.

A lot of the major components for the bridge are being built in China and shipped to the United States for installation.

The new Bay Bridge, expected to open to traffic in 2013, will replace a structure that has never been quite the same since the 1989 Bay Area earthquake. At $7.2 billion, it will be one of the most expensive structures ever built. But California officials estimate that they will save at least $400 million by having so much of the work done in China.

Eventually, the California Department of Transportation decided to revamp the western span of the bridge (which connects San Francisco to Yerba Buena Island) and replace the 2.2-mile eastern span (which links Yerba Buena to Oakland).

On the eastern span, officials decided to build a suspension bridge with a complex design. The span will have a single, 525-foot tower, anchored to bedrock and supported by a single, enormous steel-wire cable that threads through the suspension bridge.

The selection of the state-owned Shanghai Zhenhua Heavy Industries Company was a surprise, though, because the company made port cranes and had no bridge building experience.

Zhenhua put 3,000 employees to work on the project: steel-cutters, welders, polishers and engineers. The company built the main bridge tower, which was shipped in mid-2009, and a total of 28 bridge decks — the massive triangular steel structures that will serve as the roadway platform.

Pan Zhongwang, a 55-year-old steel polisher, is a typical Zhenhua worker. He arrives at 7 a.m. and leaves at 11 p.m., often working seven days a week. He lives in a company dorm and earns about $12 a day.

“It used to be $9 a day, now it’s $12,” he said Wednesday morning, while polishing one of the decks for the new Bay Bridge. “Everything is getting more expensive. They should raise our pay.”


If you liked this article, please give it a quick review on ycombinator or StumbleUpon. Thanks
blog comments powered by Disqus