The average speed vs. posted speed limit (PSL) measure is expressed as the ratio of average peak-hour speed against the PSL. The output depicts to what extent (expressed in percent of an hour) drivers were able to drive at PSLs during the peak hour.

The average peak-hour speed for an area is the average of all hourly roadway segment travel speeds during the peak hour captured by field-measured travel speed data or modeled through speed volume functions, weighted by the segment’s vehicle miles traveled (VMT). The field-measured travel speed data was provided by HERE Technologies through the Regional Integrated Transportation Information System (RITIS) at the University of Maryland’s Center for Advanced Transportation Technology Laboratory (CATT Lab). The field-measured travel speed data covers most of the State Highway System (SHS) and National Highway System (NHS) roadways. On roadways where the speed data does not cover the SHS or NHS, the average speed vs. posted speed is calculated based on speeds estimated from speed-volume functions.

• Area Type
  • Urban Area: An area with at least 2,000 housing units or at least 5,000 people.
  • Rural Area: An area with less than 2,000 housing units or less than 5,000 people.
• Average Speed vs Posted Speed Limit: Percent of the posted speed limit achieved by all vehicles during the peak hour.
• 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.
• 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 period of time. It is calculated as the sum of the number of miles traveled by each vehicle.