The Interstate System serves as the backbone of transportation and commerce in the United States. Interstate route miles increased from 46,675 in 2000 to 46,747 in 2002. About 70.8 percent were in rural areas, 3.9 percent were in small urban areas, and 25.3 percent were in urbanized areas. In 2002 the Interstate System included 55,245 bridges, 27,316 rural bridges, and 27,929 urban bridges.
In 2002, Americans traveled approximately 282 billion vehicle miles on rural Interstates, 23 billion vehicle miles on small urban Interstates, and in excess of 389 billion vehicle miles on urban Interstates. Interstate vehicle miles traveled (VMT) grew at an average annual rate of approximately 3.1 percent between 1993 and 2002.
About 26.3 percent of all urban Interstate bridges were deficient in 2002, and 15.8 percent of all rural interstate bridges were deficient. In 2002, 97.8 percent of rural Interstate pavements met the standard for "Acceptable" ride quality, compared to 95.3 percent for Interstates in small urban areas and 91.7 for Interstates in urbanized areas.
To maintain the current level of user costs on urban Interstates, an average annual investment level of $10.96 billion would be required. For all Interstates, an average annual investment in bridge preservation of $2.13 billion would be required so that the bridge investment backlog would not increase above its current level.
The 2002 level of rural and urban Interstate bridge preservation investment would be adequate to address the economic backlog of bridge deficiencies if that level of investment could be sustained. However, 2002 appears to have been an unusually high year for rural Interstate capital spending, especially for rural bridges. On urban Interstates, significant increases in funding for preservation and expansion above current levels would be required to prevent both average physical conditions and operational performance from becoming degraded.