The average age of a bridge in the United States is 43 years old and almost 4 in 10 are over 50 years old. Part of Barack Obama’s 2013 infrastructure plan dealt with the bridge problem in the United States.
The Department of Transportation tracks structurally deficient and functionally obsolete bridges annually.
A structurally deficient bridge requires significant maintenance, repair or rehabilitation. It is not necessarily unsafe but may become so over time. A functionally obsolete bridge may be too narrow, may not have adequate shoulders or other design flaws. Official definitions can be found here.
In the infographic below, the condition of Indiana’s bridges is explored in detail as compared to the national standards.