The average travel speed for each segment is derived by summing: (1) the percent of volume at heavily congested (HC) speeds multiplied by the heavily congested speed; (2) the percent of volume at mildly congested (MC) speeds multiplied by the mildly congested speed; and (3) the percent of volume at uncongested (UC) speeds multiplied by the uncongested speed. Volumes within the three categories add up to 100%. The average travel speed for an area is calculated by summing the products of the segment average speeds and the segment VMTs and then dividing it by the total segment VMT.

Field-measured travel speed data, provided by HERE Technologies through Regional Integrated Transportation Information System (RITIS) at the University of Maryland’s Center for Advanced Transportation Technology (CATT Lab), is used for HC, MC and UC speeds. The field-measured travel speed data covers most of the State Highway System (SHS) and National Highway System (NHS) roadways. On roadways not covered by the field data, the average travel speed is calculated based on speeds estimated from speed-volume functions.

• Area Type
  • Urbanized Area: An area with a population of at least 50,000 people.
  • Non-Urbanized Area: An area with a population less than 50,000 people.
• Average Travel Speed: The speed at which motorists travel on a section of the roadway during a specific time period.
• Context Classification: A classification assigned to a roadway that broadly identifies the various built environments in Florida, based on existing or future land use characteristics, development patterns, and the roadway connectivity of an area. For more information about context class, please reference the methodology report.
• Facility Type
  • Arterials: Signalized roadways that primarily serve through traffic, with intersections spaced two miles or less apart.
  • Highways: High-speed roadways with signalized intersections spaced more than two miles apart.
  • Freeways: Multilane, divided highways with at least two lanes for exclusive use of traffic in each direction and full control of ingress and egress.
• Highway System: An integrated network of roads and highways for motor and non-motor transport. Multiple highway systems exist in Florida, with the following three maintained by the State of Florida with a little distinction:
  • National Highway System (NHS): Roads designated by Congress as nationally important for inter-regional travel, including roads designated as connectors to NHS intermodal facilities, which are part of the State Highway System, and other NHS facilities.
  • State Highway System (SHS): Roads under the jurisdiction of the State of Florida and maintained by the Florida Department of Transportation or a regional transportation commission; includes roads with Interstate, US, and SR numbers.
  • Strategic Intermodal System (SIS): A statewide network of high-priority transportation facilities, including the state's largest and most significant airports, spaceports, deepwater seaports, freight rail terminals, passenger rail and intercity bus terminals, rail corridors, waterways, and highways. The FDOT Source Book reports roadway SIS facilities on the SHS or the NHS.
• Reporting Periods
  • Peak Hour: 5:00 p.m. to 6:00 p.m. on a weekday. This hour is chosen to allow consistent comparisons among transportation modes. It may not be the hour of greatest travel for any given roadway, mode, or area. The majority of travel typically occurs during the PM peak hour resulting in more congestion in the PM peak than the AM peak.
  • Peak Period: 4:00 p.m. to 6:00 p.m. on a weekday in which travel is greatest. These peak period hours are chosen based on the hours of greatest travel in different area types.
• Segment: A portion of roadway defined by two boundary points.
• Vehicle Miles Traveled (VMT): Estimated amount of travel for all vehicles in a geographic region over a given period of time. It is calculated as the sum of the number of miles traveled by each vehicle.