Notes:

Information:

Road congestion is one of the major causes of travel time delay and negatively impacts transportation system reliability. In 2011 peak-period congestion resulted in traffic dropping below posted speed limits on 13,500 miles, or 6 percent, of the National Highway System. This congestion created stop-and-go conditions on an additional 8,700 miles of road.

Source:

U.S. Department of Transportation, Federal Highway Administration, Highway Performance Monitoring System and Freight Analysis Framework, version 3.4, 2013.