According to the study, about 14% of bridges 20 feet or longer are structurally deficient, and another 14% of bridges 20 feet or longer are functionally obsolete.

TRIP noted that structurally deficient bridges are not necessarily unsafe, but are often posted to carry only lower weight vehicles. Bridges that are functionally obsolete no longer meet current highway design standards.

However, the number of bridges considered deficient declined 18% from 1992 to 2002, from 199,090 to 163,010, according to an Associated Press computer analysis of Federal Highway Administration data.

The Bush administration has proposed increasing highway and transit funding by 13% to $247 billion over the next six years.