Meet the Data Science for the Public Good team for this project

  • Undergraduate Interns: Kyle Klemba and Pride Akana Techa ​
  • Graduate Mentor: Yuanyuan Wen
  • Faculty Advisors: Michael Cary, Yujuan Gao, and Le Wang

Project description

Across the United States, there has been a steady rise in pedestrian fatalities. California alone accounts for nearly 15% of the nation's traffic fatalities. ​In October 2023, the state passed Assembly Bill 413 (AB-413), commonly known as the "daylighting" law. The law prohibits parking, standing, or stopping within 20 feet of any marked or unmarked crosswalk (or 15 feet where a curb extension is present).​

This project asks two research questions: 

  1. Has the introduction of AB-413 improved pedestrian safety? 
  2. How does the effectiveness of AB 413 vary across cities?​

Our analysis suggests that AB 413 reduced pedestrian crashes statewide, particularly possible-injury and minor-injury crashes, although no significant changes were found for fatal or serious-injury crashes. The variation across cities highlights the importance of consistent local implementation and enforcement, suggesting that policymakers should strengthen enforcement guidance and support cities in effectively applying the statewide policy.

“What makes this project especially valuable is its focus on a real-world policy with a direct impact on public safety and people’s lives. The team’s work helps move the conversation beyond whether a policy exists to whether it is actually improving outcomes for communities, and how differences in local implementation may shape its effectiveness. These findings provide useful insights into how transportation safety policies work in practice, while laying a foundation for future analysis and lessons that may extend beyond California, including to Virginia.” - Le Wang, professor and David M. Kohl Chair
3 images of a male and female student presenting their research poster to a group.

Intern insights

Kyle: This summer, I worked on a research project assessing the effectiveness of California Assembly Bill 413, a policy aimed at reducing pedestrian-related traffic injuries and fatalities. I was excited to work on this project because, through collaboration with our stakeholder, California Walks, a local advocacy group dedicated to creating safe and walkable streets for all Californians, our work has the potential to influence future lifesaving policymaking.

Working alongside another intern, Pride, our objectives were first to assess how the law has been implemented throughout jurisdictions across the state and, second, to create a model that captures the law’s impact. While we worked on this project, we had a large network of graduate and faculty mentors to support and guide us. The most impactful part of the experience was the ability for our team to execute a research project from start to finish, and to do so while communicating with an external partner who is interested in using our work to create real change.

The challenge of safe roads has been ever-increasing in California, with a steady rise in pedestrian-related accidents. While the state has made attempts to combat this rise, there is minimal existing knowledge on the true success of these policies. We hope that looking at the impacts of previous policies, such as this one, is the first step toward more effective future policymaking and saving lives.

While I learned several technical skills during this internship, such as econometric methods like Regression Discontinuity in Time, more importantly, I learned soft skills of how to work in a research team and communicate findings with an external partner and general audience. An experience that I will remember from this project is conducting a spatial analysis of the crash data—something that I think is very interesting to visualize. This project solidified my understanding that data science can be used as a tool to create positive change.

Pride: Joining the Daylighting Project gave me a new perspective on how data science can improve people's lives. Our team examined California's Assembly Bill 413, a law designed to improve pedestrian safety by increasing visibility at intersections. Working with California Walks, our community stakeholder, made the project especially meaningful because our findings had the potential to inform future transportation policy and public safety decisions.

One of the most impactful parts of the experience was learning to evaluate whether a public policy was truly making a difference. Although I had no prior experience with causal inference methods, I gradually learned how to use them to separate the effects of the law from other factors that influence crashes. More importantly, I learned that meaningful research stems from asking the right questions and understanding the assumptions behind every analysis. This taught me that good data science is not about proving a hypothesis but about letting the data tell an honest story.

Apart from technical depth and analysis, this program helped nurture other important skills. Conducting literature reviews helped me understand existing research and identify important knowledge gaps, while frequent presentations enhanced my confidence and made communicating complex findings to both technical and non-technical audiences much more seamless. Above all, this experience showed me that curiosity, collaboration, and clear communication are just as essential as coding when using data science techniques to address real-world challenges.

Graduate mentor insights

Yuanyuan Wen

This summer, I had the opportunity to work as a graduate mentor with our fabulous interns, Pride and Kyle, on a project assessing the effects of California’s traffic safety policy, AB 413 (also known as “Daylighting”).

Watching them proactively solve problems and approach the project with genuine curiosity was incredibly inspiring and reminded me to bring the same spirit to my own research. We explored many different ways to examine whether the effects of AB 413 varied across jurisdictions. Although we did not find the exact patterns we had expected based on our theory, the process itself was a valuable reminder that research rarely unfolds exactly as planned and that unexpected findings can often lead to new questions and insights.

Beyond gaining mentoring experience, which I know will be important for my future career in academia, this experience also gave me a different perspective on my own research struggles. Seeing the research process from the mentor’s side helped me reflect on my own work, particularly how to stay curious, persistent, and open-minded when the results do not immediately align with our expectations.

I am grateful to Pride and Kyle for making this such a rewarding experience. I learned a lot from mentoring them, and I hope they also took away something valuable from our time working together.

What our stakeholders had to say about their experience

"I was really thrilled with the work that the students did, which reinforces the outcomes we already see in other parts of the world. I look forward to future opportunities to collaborate and partner with the program."

Kevin Shin, Co-Executive Director, California Walks

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