Vehicle Speeds

4. Analyze and share results. Using the provided speed study worksheet or your own spreadsheet, evaluate and illustrate speeds before and after project installation. If no pre-installation data is available, compare postinstallation data to the street’s posted speed limit and/or speed thresholds that are safer, such as 25 mph. For easier data processing, communicate with your data collection provider to ensure data are tabulated and organized to suit your needs.

Data Considerations

• To improve data quality and reliability, collecting data over the course of several days is preferred over collecting only one day of data.

• For post-installation counts, allow adequate time (at least two weeks) after project installation for travel patterns to adjust.

• These metrics are meant to measure the impact of a project, not to establish speed limits. An engineering study to establish speed limits must follow MassDOT procedures.

Additional Resources

• NACTO’s guide, City Limits: Setting Safe Speed Limits on Urban Streets provides a comprehensive overview of applying a safe systems approach to speed management across contexts. For additional information on conducting evaluations, see pages 82-89.

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