Five years ago yesterday, the Interstate 35W bridge in Minneapolis collapsed into the Mississippi River, killing 13 people.

The National Transportation Safety Board later attributed the collapse to a design flaw more than 40 years before in plates used to connect the bridge's beams. The plates were half the thickness they should have been. The weight of some construction materials in the aging bridge was also found to be a factor.

What's most troubling about the bridge's collapse is that it is potentially not an isolated incident.  As the Alliance for American Manufacturing (AAM) reported last week in a new study by Gov. Tom Ridge (the first secretary of the U.S. Department of Homeland Security) and Col. Robert B. Stephan (a former Assistant Secretary for Homeland Security for Infrastructure Protection), a number of bridges, dams, and rail systems throughout the U.S. are in aging, decaying condition.  Simply put, the U.S. urgently needs to repair or replace many aging infrastructure systems.

Some worrying items from the report:

• More than 26% of the nation’s bridges are either structurally deficient or functionally obsolete.
• The number of “deficient” dams in the U.S. has risen to more than 4,000, including 1,819 high-hazard dams. Over the past six years, for every deficient, high hazard potential dam repaired, nearly two more were declared deficient. There are more than 85,000 dams in the U.S., and the average age is roughly 51 years.
• Leaking pipes for the nation’s drinking water lose an estimated 7 billion gallons of clean drinking water a day. Although Americans still enjoy some of the best tap water in the world, the costs of treating and delivering that water where it is needed continue to outpace the funds available to sustain the system.
• Of the 257 locks still in use on the nation’s inland waterways, 30 were built in the 1800s and another 92 are more than 60 years old. The average age of all federally owned or operated locks is nearly 60 years, well past their planned design life of 50 years.
• In 2009, the Association of State Dam Safety Officials (ASDSO) estimated that the cost to repair the nation’s dams totaled $50 billion and the needed investment to repair high hazard potential dams totaled $16 billion.
• A 2009 Report Card for America’s Infrastructure by the American Society of Civil Engineers estimated current overall U.S. infrastructure repair needs at $2.2 trillion.

A further concern is that the offshoring of critical manufacturing sectors and a reliance on foreign suppliers may leave the U.S. unprepared to deal with a potential catastrophe.  In their report, Ridge and Stephan conclude that the U.S. must revitalize its manufacturing capacity to reduce such vulnerability.

Click here to read the full report.

Photo by Flickr user edkohler, used following Creative Commons guidelines.