Critical Infrastructure Repairs: Is there a silver lining?
Barry Le Patner’s book, “Too Big to Fall: America’s Failing Infrastructure and the Way Forward” and his website, Save Our Bridges addresses $60 billion in bridge repairs that are not just essential to link transportation via a sustainable infrastructure, they will protect human life
Infrastructure demands are often like one of those items that are slotted on a book’s back pages due to its lack of star-power appeal. Then a disaster happens, like the Aug. 1, 2007 collapse of the I-35W Bridge in Minneapolis, killing 13 people with 145 injured.
The demand to know what went wrong and why the problems weren’t corrected is fundamental to Barry Le Patner’s website, Save Our Bridges. Here information is provided by the Federal Highway Administration’s National Bridge inventory listing 7,980 bridges that could collapse at any time – exactly like the I35W bridge did.
Not that funding was not planned to prevent such disasters – some of it just got spent in the wrong places, LePlatner writes. “Since its inception, money collected as part of the federal gas tax has been used to build and repair the nation’s roadways. Unfortunately, not all of the tax revenue collected is utilized for the maintenance and care of our infrastructure. A large percentage of the funds are diverted to new construction projects and congressional earmarks. Too often, the less glamorous job of infrastructure maintenance and repair is neglected.”
Structurally Deficient: Federal guidelines define a bridge as “structurally deficient” if certain key components―the superstructure, the substructure, or the deck―is rated at 4 out of a possible 10. Deficient bridges require significant maintenance, rehabilitation or replacement. While not inherently unsafe, states must post limits for both speed and the number of vehicles permitted to travel across these bridges. In short, structurally deficient bridges no longer meet the original design standards for which they were designed and therefore, from an engineering standpoint, have already “failed.”
Fracture Critical: A “fracture critical” bridge is defined by the FHWA as a steel member in tension, or with a tension element, whose failure would probably cause a portion of or the entire bridge to collapse. Fracture critical bridges, of which there are a total of about 18,000 throughout the U.S., lack redundancy, which means that in the event of a steel member’s failure there is no path for the transfer of the weight being supported by that member to hold up the bridge. Therefore, failure occurs quickly, as reflected in the video that captured the collapse of the I-35W Bridge in Minnesota.
Each state, under federal mandate, is required to perform an annual fracture critical inspection on each bridge in its state inventory. (Fracture critical bridge designs were discontinued in the late 1970s.) Recognizing that fracture critical bridges are inherently lacking the structural capacity to prevent failure if even one structural element fails, the annual fracture critical inspection is intended to identify which of these bridges is increasing its “risk profile” if needed maintenance is not forthcoming. Thus, those fracture critical bridges that have, from continued lack of maintenance to maintain their structural integrity, been rated by state transportation agencies as “structurally deficient,” i.e., “poor” as a reflection of its condition rating, are at the highest level of risk since a failure of any element of such a bridge will trigger a failure mode and potential catastrophe for all located on or near such a bridge.
There is some positive news to this story. Save Our Bridges writes that other dangerous bridges have been identified and closed since the Minneapolis bridge tragedy. “As recently as September 8, 2011, inspectors closed the I-64 Sherman Minton Bridge carrying six lanes of traffic across the Ohio River between Louisville, Kentucky, and New Albany, Indiana.
In addition, the website provides a comprehensive map of all designated suspect bridges, allowing voters to contact member of Congress seeking remediation.
As terrifying as this news is involving the management of such an overwhelming issue in the direst of economies, pens LePlatner, there is some flickering of light, depending on one’s perspective:
“Repairing the top 2,000 bridges will cost $60 billion and employ 1.2 million construction workers. During the recent recession, the construction industry was one of the hardest hit sectors. Putting unemployed workers back to work will help stimulate the economy. Further ensuring that all of the fuel tax revenue is used for its intended purpose, and raising awareness among the public are crucial to solving our infrastructure problems.
“The difficult truth revealed by the Save Our Bridges Map is that the nation’s leaders can’t wait any longer to provide the needed funding to make our bridges safe. They must act now.”
Source: Save Our Bridges, Barry B. LePatner, Al Lewis The Wall Street Journal
Sustainable Cities Collective