Are our bridges safe?

That's the question many are asking this morning following the tragic and horrific and as yet unexplained collapse of the I-35W bridge across the Mississippi River in downtown Minneapolis yesterday.

The USDOT Federal Highway Administration has a bridge inventory online. (Who knew there were so many bridges? -- it must be a massive undertaking just to inventory them, much less inspect them all every year.) One of their tables lists bridges in the US that have been classified as "structurally deficient" or "functionally obsolete."

According to the DOT, "Bridges are structurally deficient if they have been restricted to light vehicles, require immediate rehabilitation to remain open, or are closed. Bridges are functionally obsolete if they have deck geometry, load carrying capacity, clearance or approach roadway alignment that no longer meet the criteria for the system of which the bridge is a part." Designation is based on a scoring system covering several criteria.

Overall, 153,990 bridges (25.8%) of the nation's 596,842 bridges are either structurally deficient or functionally obsolete. 12.4% are rated as structurally deficient, and 13.4% are rated as functionally obsolete, according to the latest USDOT report.

Statistically, Southern states mirror almost exactly the overall national ratings, with 25.7% of its bridges rated as either structurally deficient or functionally obsolete. We have slightly lower percentage of structurally deficient bridges (11%) and a slightly higher percentage of functionally obsolete bridges (14.7%).

States with the highest percentage of structurally deficient or functionally obsolete bridges (and exceeding the overall Southern percentages) are:

• West Virginia (37.3%)
• Kentucky (31.5%)
• Louisiana (30.4%)
• North Carolina (28.7%)
• Alabama (27.1%)

The state with the lowest percentage of structurally deficient of functionally obsolete bridges is Florida, with 17.6%.

Mississippi has the highest percentage of structurally deficient bridges (18.7%), and West Virginia has the highest percentage of functionally obsolete bridges (21.8%).

These numbers are somewhat disturbing, and reflect ongoing neglect of our nation's infrastructure over the years. According to the American Society of Civil Engineers, it will cost $9.4 billion per year for the next twenty years to eliminate all bridge deficiencies, noting that "Long-term underinvestment is compounded by the lack of a federal transportation program." Ironically, we are able to find plenty of money to rebuild Iraq's infrastructure.

Here's the data for Southern states: