The Speed Limit Setting and Signing Project aims to help reduce speed-related crashes as part of Vision Zero, the Boulder community’s goal to end severe crashes.

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Completion Date
2024

Project Overview

The project developed a consistent framework for setting and communicating city speed limits citywide to reduce speed-related crashes as part of Vision Zero, Boulder’s goal to end fatal and serious-injury crashes.

The project studied primarily arterial and collector roads, which are key roads that connect the city and often have higher speed limits.

The project began directly from the recommendations, goals and objectives of the Transportation Master Plan and the Vision Zero Action Plan, a plan with prioritized actions the city will take to end serious injury and fatal crashes on our streets.

Next Steps

Implementation of speed limit changes will begin with 13 different street segments in the summer of 2024. View a map of these street segments to learn more.

The project team will continue to work on validating and refining the results through engineering judgement and finalizing the implementation plan recommendations. We anticipate completing the evaluation changes by 2027 as part of the 2023-2027 Vision Zero Action Plan.

Project Background

This project considered local context, data, national best practices, peer agency reviews, and input from a stakeholder committee to identify the factors that should be considered. These inputs helped create an innovative point-based system that prioritized selected factors and assigned them to street segments.

Boulder community members have also identified speeding as one of the top traffic safety concerns on city streets, with speeding being an over-represented factor contributing to serious injury and fatal crashes. As part of our Vision Zero goals and efforts to reduce speeding-related crashes and improve safety for all roadway users, no speed limits will be increased as part of this current effort.

The project began in 2023 and the evaluation ended in 2024. Learn more using the tabs below.

Project approach; long description in caption.

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This is a text alternative to the image: The project’s methodology included 5 main steps. First, a review of best practices and peer agencies was conducted, which included USLIMITS 2, National Cooperative Highway Research Program (NCHRP), and Colorado Department of Transportation guidance, 6 peer cities, and 240 data collection locations. Then, through a review of methodology factors with stakeholders and a workshop on data availability and quality, 16 factors were selected for analysis out of 19 total and the selected factors were divided into tiers based on priority. Next, a point system was developed based on the priority of factors, where speed-related crashes and vulnerable user data were analyzed to quantify the need for lower speeds. Then, speed limit ranges and outputs were compared to street classification and surrounding land use. Finally, an implementation plan was developed based on the city’s capacity and programs.  

The project improved the consistency of and methodology behind citywide speed limit setting and signing by:

  • Developing a quantitative citywide approach and practice for speed limit implementation methodology.
  • Creating a methodology document and sharing with the community and stakeholders.

The project team interviewed peer agencies about their speed limit setting methodologies and conducted an extensive review of national best practices and tools related to speed limit setting. Using this information, along with input from a stakeholder committee, the team identified factors frequently considered in speed limit setting.

In partnership with a community stakeholder working group, Boulder staff reviewed and prioritized factors to be included in the methodology considering city values. The team used that information to develop a flowchart establishing the methodology's logic and key decision points. Supplemental traffic data was also collected. The methodology was tested and refined through an iterative process that considered the context and values of the city. Through this process, we reviewed city streets in the project, recommending new posted speed limits for some segments.

Can the recommendations change?

Speed limit setting is also based on context. For example, if there is significant change in the roadway characteristics, like with a major construction project, city staff could refine and reevaluate.

What about state-owned roads?

Colorado Department of Transportation (CDOT) owned roads are not included in the analysis. However, the proposed methodology reviewed and incorporated certain elements of the framework used by CDOT in setting speed limits

CDOT is currently working on its own speed limit setting methodology, which will be used to set speeds on state highways across the state. While Boulder doesn’t have authority to set speed limits on state highways, reviewing CDOT’s methodology provided the framework for the Boulder’s methodology and the opportunity to build on it.

What about residential roads?

This study did not include local residential streets as these streets have a 20 mph speed limit as part of a city effort completed in 2020.

View the Speed Limit Setting Methodology

A detailed overview about the evaluation and methodology is available in the report.

For a PDF alternative, view the web-accessible text version of the Framework.


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