What is the purpose of a speed limit?
The primary purpose is to provide improved safety by reducing the probability and
severity of crashes. A speed limit sign notifies drivers of the maximum speed
that is considered acceptably safe for favorable weather and visibility. It is
intended to establish the standard in which normally cautious drivers can react
safely to driving problems encountered on the roadway. Properly set speed
limits provide more uniform flow of traffic and appropriately balance risk and
travel time, which results in the efficient use of the highway's capacity and
Who sets speed limits on the state highways?
The Florida Legislature authorized the Florida Department of Transportation to
establish speed limits on state highways up to the following maximums: 70 mph
on Interstates, 65 mph on a four-lane divided highway outside an urban area
(with a population of 5,000 or more), and 60 mph on other state highways.
Select the following links (These links open a new browser windows) for
information concerning the establishment of state speed limits, residential
speed limits, and school speed limits in the state of Florida. More information
can be found at The Florida Legislature's
Why are speed limits different in each state?
Federal legislation gives individual states the authority to establish their
own maximum speed limits. The Florida Legislature, as mentioned above,
establishes our maximum speed limits.
How are speed limits established?
It is common traffic engineering knowledge that about 85 percent of all drivers
travel at reasonably safe speeds for the various roadway conditions they
encounter, regardless of speed limit signs. This leaves 15 percent of drivers
who must be reminded of the maximum speed limit. This reminder must be coupled
with meaningful enforcement. Based on this knowledge, a traffic engineering
study is conducted to establish speed limits on the state highway. The
Department uses the "85th percentile" method of determining appropriate and
safe posted speed limits in conjunction with the maximum statute based speeds.
This method is based on extensive nationally accepted studies and observations.
By measuring the speed of hundreds of vehicles at various points along the
roadway, traffic engineers are able to use data to determine a reasonable and
safe maximum speed to post for all vehicles to travel.
What influences a driver's selected speed?
A driver's choice of speed is a balance between expedience and safety, and is
often a subconscious reaction to the environment. The vehicle speed chosen by a
driver may be influenced by, the presence of other vehicles, weather, road
conditions, road geometrics, and other factors such as:
- Time of Day Purpose of trip
- Ambient light
- Familiarity of driver with the road
- Condition of vehicle
- Urgency of trip
- Emotional condition of driver
- Driver skill
- Personality of driver
- Speed of other vehicles
- Drive late or on time
- Presence and/or history of enforcement
- Length of Trip
- Pavement wetness
- Type of vehicle
- Vehicle parking
- Lane width
- Traffic volume
- Adjacent land use and development
- Pavement roughness
- Shoulder width and condition
- Pavement type and condition
- Speed traveled for previous 5 or 10 miles
How do I get a speed limit reviewed on a State Highway?
If you feel there is a need to change a speed limit on a state highway, or you
have further questions regarding our determination of speed limits, please
contact the District Traffic Operations Engineer
at your local Florida Department of Transportation office.