System Characteristics: Highways and Bridges
The mobility needs of the American people were served by a network of 4.0 million miles of public roads in 2004. About 75.1 percent of this mileage was located in rural areas (those with populations less than 5,000). While urban mileage constitutes only 24.9 percent of total mileage, these roads carried 64.1 percent of the 3.0 trillion vehicle miles traveled (VMT) in the United States in 2004. In 2004 there were 594,101 bridges over 6.1 meters (20 feet) in length; approximately 76.8 percent of these were in rural areas.
Rural local roads made up 51.3 percent of total mileage, but carried only 4.4 percent of total VMT. In contrast, urban Interstate highways made up only 0.4 percent of total mileage but carried 15.5 percent of total VMT.
| Functional System | Miles | Bridges | VMT |
|---|---|---|---|
| Rural Areas | |||
| Interstate | 0.8% | 4.7% | 9.0% |
| Other Principal Arterials | 2.4% | 6.1% | 8.1% |
| Minor Arterial | 3.4% | 6.8% | 5.7% |
| Major Collector | 10.5% | 15.8% | 6.7% |
| Minor Collector | 6.7% | 8.3% | 2.0% |
| Local | 51.3% | 35.1% | 4.4% |
| Subtotal Rural | 75.1% | 76.8% | 35.9% |
| Urban Areas | |||
| Interstate | 0.4% | 4.7% | 15.4% |
| Other Freeway & Expressway | 0.3% | 2.9% | 7.0% |
| Other Principal Arterials | 1.5% | 4.1% | 15.2% |
| Minor Arterial | 2.5% | 4.2% | 12.3% |
| Collector | 2.6% | 2.6% | 5.5% |
| Local | 17.7% | 4.7% | 8.6% |
| Subtotal Urban | 24.9% | 23.2% | 64.1% |
| Total | 100.0% | 100.0% | 100.0% |
Total highway mileage grew at an average annual rate of 0.2 percent between 1995 and 2004, while total VMT grew at an average annual rate of 2.5 percent. Rural road mileage has been declining since 1997, partly reflecting the reclassification of some Federal roads as nonpublic and the expansion of urban area boundaries as a result of the decennial Census.
Rural VMT grew at an average annual rate of 1.4 percent from 1995 to 2004, compared with an average annual increase of 1.8 percent in small urban areas (population 5,000 to 50,000) and 2.3 percent in urbanized areas. Rural VMT declined from 2002 to 2004 primarily as a result of boundary changes associated with the decennial Census; boundary changes also tend to inflate urban VMT growth.
In 2004, about 76.5 percent of highway miles were locally owned, States owned 20.4 percent, and 3.1 percent were owned by the Federal government.
In 2004, approximately 50.6 percent of bridges were locally owned, States owned 47.6 percent, 1.4 percent were owned by the Federal government, and 0.5 percent were either privately owned (including highway bridges owned by railroads) or had unknown or unclassified owners. Bridges are, on average, 40 years old with an average year of construction of 1964.
Based on surveys of 78 of the largest metropolitan areas, the deployment of intelligent transportation systems (ITS) has advanced steadily over time. Real-time data collection sensors have been deployed on more than one-third of the total freeway mileage in these areas, and on-call service patrols cover half of the freeway mileage.
Progress has also been made in the deployment of integrated ITS infrastructure. Among the 75 metropolitan areas tracked since 1997, the number with a "High" level of progress in the integrated deployment of ITS has risen from 11 to 30 in 2004, while the number of areas ranked "Low" has fallen from 39 to 12 (the remainder are ranked "Medium).