A Tool to Aid Practitioners in Determining Appropriate Speed Limit Recommendations
USLIMITS2 is a web-based tool designed to help practitioners set reasonable, safe, and consistent speed limits for specific segments of roads. The tool is applicable to all types of roads; however, it is not applicable to school zones or construction zones. USLIMITS2 is of particular benefit to local communities and agencies without ready access to engineers experienced in conducting speed studies for setting appropriate speed limits. For experienced engineers, USLIMITS2 can provide an objective second opinion and increase confidence in speed limit setting decisions.
USLIMITS2 was developed based on research through National Cooperative Highway Research Program (NCHRP) Project 3-67 and considers all major factors used by practitioners to make engineering judgment in determining an appropriate speed limit. This includes: operating speed (50th and 85th percentile), annual average daily traffic, roadway characteristics and geometric conditions, level of development in the area around the road, crash and injury rates, presence of on-street parking, and extent of ped/bike activity, as well as several others depending on the road type. These factors are further described in the User Guide, NCHRP 3-67 report, and Decision Rules documentation.
Disclaimer: The U.S. Government assumes no liability for the use of the information contained in this tool. This tool does not constitute a standard, specification, or regulation.
Before beginning a new project, it is recommended that you read through the User Guide and be prepared to enter the necessary data (e.g., 50th and 85th percentile speed, roadway characteristics, and crash history). If the segment you are studying is a new route, the system will not require this data, but it is recommended that the statutory speed be posted on new routes until such time that reliable data on operating speed, crashes, and other factors can be collected.
After entering all project information you will have the opportunity to save the recommendation report. You also can save the project file and upload it in the system at a later time to revise your project if needed.
To understand how USLIMITS2 arrived at the recommended speed limit, review the Decision Rules.
If you have any questions about USLIMITS2 or experience any technical difficulties while using this program, find any bugs, or have suggestions for improving USLIMITS2, please send an email to firstname.lastname@example.org.