- Luke Catalano - M.S. Quantitative Economics & Finance, UC Santa Cruz
- Eleanor Stoever - B.S. Applied Mathematics, B.A. Environmental Studies & Economics, UC Santa Cruz
This paper explores the causal effect of New York City’s Lower Manhattan congestion pricing policy on traffic collisions in the district of Manhattan. The study utilizes a Difference-in-Differences (DiD) empirical approach to evaluate how the policy, implemented on January 5th, 2025, affected total weekly collision counts.
- Significant Reduction: We find a statistically significant decrease of approximately 20 total collisions per week in the treatment area.
- Impact Scale: This represents a 16.66% reduction from the average weekly collision count over the 10 weeks following implementation.
- Economic/Safety Implications: The study focuses on "reportable" collisions—those involving at least $1,000 in vehicle damage or personal injury.
The analysis compares two geographically similar areas that exhibited parallel collision trends prior to the policy:
- Treatment Group: Lower Manhattan (the "Congestion Relief Zone" below 60th Street / 40.7650° N).
- Control Group: Upper Manhattan (above 40.7650° N).
The study employs a linear regression model with robust heteroscedastic standard errors to account for non-constant variance over time:
- Validation: The "Parallel Trends" assumption was verified through visual trend plotting and a Treatment-Control Balance Table, confirming no statistically significant differences in pre-treatment characteristics such as time of day or injury severity.
The dataset is derived from the City of New York’s Motor Vehicle Collisions-Crashes database, maintained by the NYPD.
- Period: January 2023 – March 2025.
- Scope: 115 weeks of data, providing 230 total observations (treatment vs. control pairings).
- Variables: Includes collision coordinates (latitude/longitude), injury/death counts, and contributing factors.
Project formatted in LaTeX - November 2025