President Obama noted in his State of the Union speech that there are 70,000 structurally deficient bridges in the country. Jon Stewart has some fun with that line, in this video.
For the record, USDOT has specific definitions for Structurally Deficient and the less serious Functionally Obsolete:
Structurally Deficient – A highway bridge is classified as structurally deficient if the deck, superstructure, substructure, or culvert is rated in “poor” condition. A bridge can also be classified as structurally deficient if its load carrying capacity is significantly below current design standards or if a waterway below frequently overtops the bridge during floods.
Functionally Obsolete – Highway bridges classified as functionally obsolete are NOT structurally deficient, but their design is outdated. They may have lower load carrying capacity, narrower shoulders or less clearance underneath than bridges built to the current standard.
Jump ahead to 2:15 for the bridges section.