HOW ARE SPEED LIMITS ESTABLISHED?

In Florida, speed limits are set by Florida Statutes, Chapter 316, which deals with the "State Uniform Traffic Control".

Florida Statutes, Chapter 316.187, authorizes the Florida Department of Transportation (FDOT) to set maximum and minimum speed limits for travel on the roadways under its authority as it deems safe and advisable, not to exceed 55 miles per hour, 65 mph on certain designated segments of interstate highways.

Florida Statutes, Chapter 316.189, presents the authority for establishment of municipal and County speed zones maintained by these agencies. This section indicates that the maximum speed on any Municipal or County maintained road is 30 mph. However, the Municipality or County may set speed zones altering such speeds, both as to maximum and minimum after investigation determines such a change is reasonable and in conformity with the criteria established by the FDOT.

Traffic engineers throughout the country use the normal driver's speed as a guide in setting speed limits since most drivers tend to regulate their own speed according to traffic, road and weather conditions.

For a speed limit to be effective, at least 85 percent of the drivers must voluntarily comply with the law. It is important to remember that the speed regulation informs the driver of the limits in which one can safely operate a vehicle under normal circumstances and within which the driver can be expected to react safely. Setting speed limits at appropriate levels will create a reasonable uniform flow of traffic, discourage violation of the law and help keep streets and highways safe.

The FDOT criteria for setting speed zones are presented in the publication entitled "Speed Zoning for Highways, Roads and Streets in Florida for Compliance with the Florida Statutes, Chapter 316." This publication indicates "The 85th percentile speed is the speed at or below which 85 percent of the observed free flow vehicles are traveling." It also states that a speed limit should not differ from the 85th percentile speed by more than 3 mph and it shall not be more that 8 mph less.

"It is common traffic engineering knowledge that most drivers (about 85%) travel at a reasonably safe speed for the various roadway conditions encountered regardless of speed limit signs, but it is for those drivers who don't that the practice of speed zoning does take place for the purpose of providing realistic speed restrictions to which meaningful enforcement can be applied."

"The vehicle speed chosen by a driver is influenced by many factors: The presence of other vehicles, weather, road conditions, road geometrics, adjacent land use, and other factors tabulated in this report. A driver's choice of speed is a balance between expediency and safety, and is often a subconscious reaction to environment."

"Motorists tend to pay little attention to speed regulations which they consider unreasonable unless there is an inordinate degree of enforcement."

"Unreasonably low speed limits are commonly violated by a majority of motorists, making enforcement difficult, with resultant operation speeds sometimes higher than would exist with proper, realistic speed limits."