Our Nation's Highways: 2008
Figure 2-3. Interstate Annual Average Daily Traffic, 2006
The most widely used parameter of measuring traffic activity on a highway or highway segment is annual average daily traffic (AADT). AADT can also be used to assess how serious congestion is by comparing the highway’s capacity with AADT at peak times and directions. These calculations help transportation agencies decide whether highway infrastructure is adequate to the demand.
Data Source: U.S. Department of Transportation, Federal Highway Administration, Office of Highway Policy Information, Highway Performance Monitoring System.