The American Society of Civil Engineers says:
As of 2005, 156,335 of the nation's 595,363 bridges, or 26.3%, were structurally deficient or functionally obsolete, as compared to 34.6% of all bridges in 1992. However, despite this improvement, functionally obsolescent or structurally deficient bridges on the nation's transportation systems continue to constitute significant potential hazards which may jeopardize the safe, reliable and efficient operation of these.
To simply maintain the current condition of these bridges will require an annual $7.3 billion (2000 dollars) investment. To eliminate all bridge deficiencies will require $9.4 billion (2000 dollars) annually for a period of 20 years. Total bridge expenditure by all levels of government for capital outlays (including system preservation and system expansion) was at $8.8 billion in 2003. Additional funding beyond that level will therefore be needed to continue to reduce the backlog of structurally deficient bridges, and prevent more bridges from becoming structurally deficient.
To get you started looking at the condition of your state's bridges, try this Web site. It is part of the federal bridge-inventory list. You can find out which bridges in your state are structurally deficient, functionally obsolete or both. Minnesota has 1,500 bridges that fall into one or both of those categories. But some states have many more, including Texas, California, Kansas, Missouri, Oklahoma and Pennsylvania.
NICAR, the National Institute for Computer-Assisted Reporting, makes it easy for you to get very specific bridge-by-bridge data. For very little money, NICAR can supply you with bridge data through late last year.
The data includes fields showing the year the bridge was built, the number of lanes it has, and several key fields that can be used for an overall indication of a bridge's quality. There is also a field that indicates the intersection. This would include a bridge going over a body of water or intersecting another highway or roadway.
You may also want to ask questions about:
- How often inspectors do underwater inspections. Scouring is a tremendous problem for aging bridges. This occurs when water eats away at the underwater foundation of bridges. These inspections can be difficult to do in murky or fast-water rivers. They are also time-consuming and costly. A bridge can look great from above the water but be dangerous when you look down below. This is what Minneapolis underwater inspection reports look like [PDF], although I have not located the latest report for the specific bridge that collapsed yet.
- What political pressures come into play in your state when it comes to replacing bridges. Do the most needy bridges get the attention, or is it about whose district the bridges are in?
How Do They Build Super Bridges?
PBS has a wonderful site explaining how bridges are built. You can click on sections of the site to interact with different kinds of bridges.
A History of Bridge Collapses
1915: The Spokane Division Street Bridge in Washington collapsed.
1932: The Sligo Creek Bridge collapsed in Takoma Park, Md.
1940: The Tacoma Narrows Bridge collapse on Nov. 7 in Washington is among the more notable events in U.S. history. This is partly because of the extraordinary film taken of the so-called "galloping" bridge, which would sway from time to time.
1967: A West Virginia bridge called the "Silver Bridge" collapsed. Forty-six people died. Here is more background on that one.
1980: The Sunshine Skyway collapsed over Tampa Bay.
1981: The GAO found that federal dollars were not going to the bridges that needed repair the most.
1989: In Tennessee, the Hatchie River Bridge collapsed. This collapse resulted in the National Transportation Safety Board recommending that the feds modify the National Bridge Inspection Standards. The board recommended follow-up or diver inspections of bridges with underwater parts that are unable to be examined during a bridge inspection because the water is too deep or murky.
2003: A 100-foot section of the bridge over the Napa River in California collapsed.
Last night: WCCO's interview with a structural engineer explains how span bridges hold their weight and how investigators will begin to find out what happened. This engineer tells the Minneapolis station that the way the debris fell will tell investigators a lot. He also says this collapse will trigger a global investigation of the bridge safety system.
KSTP in Saint Paul, Minn.,
talked with a safety engineer about a 2006 inspection of the bridge that questioned the integrity of beams that run under the deck of the bridge.
This site is dedicated to historic bridge disasters.
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Editor's Note: Al's Morning Meeting is a compendium of ideas, edited story excerpts and other materials from a variety of Web sites, as well as original concepts and analysis. When the information comes directly from another source, it will be attributed and a link will be provided whenever possible. The column is fact-checked, but depends on the accuracy and integrity of the original sources cited. Errors and inaccuracies found will be corrected.
