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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation
FHWA Highway Safety Programs

Purpose & Scope

Despite the wide-spread acceptance and use of speed limits throughout the world, there has been no consensus among practitioners concerning the methods and techniques that should be used to select the most appropriate speed limit for a particular facility. Currently, it appears unlikely that consensus will be achieved in the near future. This leaves practitioners without definitive guidance on this important issue, and in search of information that may assist them. This report provides the information necessary for practitioners to make informed decisions concerning the method that is selected for setting speed limits in their jurisdiction.

This report presents the various procedures that highway agencies can and do use to set speed limits. It is an informational report and provides a broad overview of the different speed limit setting methods that are available, but makes no specific recommendations or suggestions.

Special situations, such as advisory, school zone, and work zone speeds are discussed. Speed limit enforcement and periodic reevaluation of speed limits are discussed briefly. The design speed for the roadway will not be discussed, except as it relates to the setting of speed limits. This is because design speed is a characteristic of the roadway that is essentially "built-in" to the road, and is not easily modified.

Technical terms are defined in Appendix A.