Bridge upkeep is a struggle nationwide, engineers say
on October 28, 2009
For many Oakland commuters, this week’s Bay Bridge failure provided yet another test of patience, a new entry in a list of daily driving woes that include traffic jams, rising tolls and fluctuating gas prices.
Yet for engineers across the nation, the breakdown provided yet another opportunity to discuss the state of the country’s system of roads and highways, in which bridge failures—whether due to age, natural disasters or accidents—have become a growing concern in recent years.
Part of that concern is due to high-profile incidents such as the failure of the Interstate 35W bridge collapse in Minneapolis in 2007 and the collapse of Oakland’s MacArthur Maze following a truck accident during the same year.
There’s no connection between those events and Tuesday’s trouble on the Bay Bridge, but scientists emphasized Wednesday that the public should still be aware of the need for improved bridge safety across the nation.
As the country’s bridges age—requiring an estimated $2.2 trillion in repairs over the next five years—funding shortfalls, increasing traffic flows and faulty materials are compromising efforts to improve them, said Norbert Delatte, a member of the American Society of Civil Engineers.
“Just as with an old car, sooner or later you start getting more and more problems and malfunctions,” said Delatte, a professor at Cleveland State University in Ohio, who studies structural failure on the association’s technical council on forensic engineering. “At some point, complete replacement is necessary.”
The ASCE, which monitors the integrity of the country’s infrastructure, has long been concerned over the soundness of bridges both in the Bay Area and in other parts of California, where 30 percent of bridges are considered structurally deficient or functionally obsolete.
In a 2009 report, the organization gave the country’s bridges a “C” grade, noting that most bridges in the United States were built to last only 50 years, and that the average age is 43 years. In a 2007 report, all local bridges including the Bay Bridge, which opened in 1936, also received a “C.”
The 2007 report said that “the shortfall in funding levels to sustain adequate maintenance, system efficiency, and strategic expansion, if allowed to continue, will place the local economy at risk and cost the public five times more in rehabilitation and reconstruction costs.”
But it’s not easy to finding ways to improve bridges during an economic downturn, said Lijuan “Dawn” Cheng, an assistant professor at the UC Davis School of Engineering who studies bridges and other transportation structures. Cheng said she was disturbed by Tuesday’s malfunction and the fact that scientists and public officials now face the challenge of rehabilitating bridges with limited resources.
“With these budget cuts all over the place, it is a concern with a lot of people at this point,” Cheng said by phone. “They have to prioritize the existing system and figure out what would be the best strategy.”
Engineers are concerned that fiscal constraints might push some local and regional governments to pursue cost-cutting measures that might compromise safety, said Emir Macari, a Cal State Sacramento professor who has studied structural failures such as the levee collapses that took place in New Orleans during Hurricane Katrina.
One example, Macari said, is the use of imported steel, which critics say is not subject to the same quality control as steel fabricated in the United States. Although federally funded bridge projects require the use of domestically fabricated steel, Macari said, state and local governments can forego that rule if they fund infrastructure projects independently. Many governments, though, continue to use U.S.-made steel, said William McEleney, the director of the National Steel Bridge Alliance.
In the case of the Bay Bridge, local reports have noted that 900 panels of the bridge’s new eastern span were fabricated overseas. Private sector engineers don’t see a connection between foreign steel and Tuesday’s failure—McEleney said there’s currently no concern that the portion that broke was made with imported steel.
However, the use of imported products in the future could pose a long-term threat to some bridges—and local economies.
“With thousands and thousands of people crossing every day, we cannot afford to have these mishaps,” said Macari. “In a bad economy, this just goes on to worsen the situation.”
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