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A Tool to Aid Practitioners in Determining Appropriate Speed Limit Recommendations

Two workers in hard hats changing a highway speed limit sign from 70 to 55 miles per hour.

USLIMITS is a web based tool designed to help practitioners set reasonable, safe, and consistent speed limits for specific segments of roads. USLIMITS is applicable to all types of roads ranging from rural local roads and residential streets to urban freeways.


User-friendly, logical, and objective, 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.



New Project

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, statutory speed limit, roadway characteristics, annual average daily traffic, and crash history).


To create a new project, click the new project link below. At the end of the process you will be asked to save a project file. The project file can be revised or updated later.


Create A New Project



Existing Projects

If you wish to revise or update an existing project, click the revise project link to upload your project file.


Revise Or Update An Existing Project



Additional Resources

NCHRP 3-67 Project Report - This 2006 report, Expert System for Recommending Speed Limits in Speed Zones, includes information on the research conducted to develop USLIMITS. Chapter 6 (specifically pages 50-55) provides brief overview of the logic flow and the decision rules that are used in the tool.


User Guide - This guide provides detailed information on the background and objective of the tool as well as fundamentals for using the USLIMTS2 web based tool.


Decision Rules - This resource includes decision rules flowcharts to aid in use of the USLIMITS2 web based tool.



Technical Support

If you experience any technical difficulties while using this program, or find any bugs, please send an email to help@uslimits.org.

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