This indicator shows the percent centerline miles congested on Florida Interstate Highway System. A road is said to be congested at the level of service E (operating conditions at or near the capacity level) the level of service F (forced or breakdown flow). Percent miles congested are the number of centerline miles of roads that are congested during the peak hour, divided by the total number of centerline miles. A centerline mile refers to the length of road in miles. The Florida Intrastate Highway System consists of interstates, the Turnpike Enterprise, freeways, and other high speed, high volume roadways. The source for this indicator is the Florida Department of Transportation's Florida Highway Data Source Book.