Safety Before & After Studies

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The Vision Zero Action Plan states that we will review the efficacy of transportation safety mitigation measures by assessing conditions before and after implementation, which will inform future policies and implementation of such mitigation measures. This page summarizes the findings and next steps for before / after studies conducted on safety improvements, such as: 

  • Location-Based Before/After Studies - Assessment of crash rates before/after quick-build improvements or other hot spot improvements were installed at a location. 
  • Tool-Based Before/After Studies - Evaluation of the impact that an engineering tool has on safety across multiple locations. 
  • Pilot Safety Project Before/After Studies - Evaluation of the impact that a pilot safety project had on addressing the identified safety issue. 
  • Speed Management Before/After Studies - Assessment of before/after speeds along corridors with recent speed management treatments. 

View the sections below to learn more about past or ongoing before/after analysis for each of these categories.

Location-Based Before/After Studies


Tool-Based Before/After Studies

Coming soon!

Pilot Safety Project Before/After Studies

Whenever we install a pilot safety project, we identify performance metrics so we can study whether the project is successfully addressing safety concerns through either quantitative or qualitative measures. See below for examples of before/after performance tracking for completed Vision Zero safety pilot projects. For more information about each project, please visit the Safety Pilot Projects page. 

Speed Management Before/After Studies

Coming soon!