Author ORCID Identifier

https://orcid.org/0000-0001-8372-6269

Semester

Spring

Date of Graduation

2026

Document Type

Dissertation

Degree Type

PhD

College

Chambers College of Business and Economics

Department

Economics

Committee Chair

Brad Humphreys

Committee Co-Chair

Heather M. Stephens

Committee Member

Palak Suri

Committee Member

Daniel Grossman

Abstract

Urban environments are shaped by dynamic interactions between infrastructure development, policy interventions, and episodic demand shocks, all of which can generate unintended externalities in the form of motor vehicle collisions, injuries, and fatalities. This dissertation investigates the determinants of traffic safety in dense urban settings, with a particular focus on how different sources of urban activity affect collision risk and severity. Using New York City as a case study and leveraging high-resolution spatial and temporal data, I examine three distinct but interconnected mechanisms: construction activity, traffic safety policies, and large-scale events.

The first chapter analyzes the impact of urban development, measured through construction permit activity, on traffic safety outcomes between 2013 and 2018. Using census block-level data, the results show that construction sites increase the expected number of collisions, injuries, and fatalities, with particularly pronounced effects for cyclists and pedestrians. These disruptions translate into substantial social costs, highlighting the externalities associated with urban growth and redevelopment.

The second chapter evaluates the effectiveness of speed reduction policies, including slow zones, speed humps, and automated speed enforcement, using a spatial difference-in-differences framework with daily street-level data. The findings reveal heterogeneous effects across policy types: moderate interventions such as slow zones and speed humps reduce collisions and injuries, while stricter enforcement through automated speed cameras is associated with increases in collisions and spillover effects on nearby streets. A cost-benefit analysis indicates that moderate, infrastructure-based interventions are more cost-effective in improving traffic safety.

The third chapter exploits Major League Baseball games as predictable, high-frequency shocks to urban traffic demand to study short-run impacts on traffic safety. Using a dynamic difference-in-differences design, the analysis shows that games increase injury incidence during and shortly after events, particularly in areas surrounding stadiums and during peak commuting periods. These effects are localized and reflect interactions between congestion, infrastructure, and travel patterns.

The findings demonstrate that traffic safety in urban environments is highly sensitive to both persistent and transient sources of activity, and that policy effectiveness depends critically on spatial spillovers and behavioral responses. This dissertation contributes to the literature on urban economics and transportation by providing causal evidence on the external costs of development, the heterogeneous impacts of safety policies, and the role of demand shocks in shaping traffic risks. The results offer important implications for urban planning, infrastructure investment, and the design of targeted interventions to mitigate the social costs of urban mobility.

Download

Share

COinS