Three Essays in Applied Microeconomics

This dissertation consists of three chapters connected by a common theme: examining how environmental and transportation externalities influence public safety and human behavior. Using applied microeconomic methods, each chapter explores a distinct but related outcome—the impact of infrastructure failure (e.g., bridge collapse) on cognitive health, the effect of railway quiet zones on highway-rail crossing fatalities, and the impact of ridesharing services (Uber and Lyft) on crime. Each chapter poses a causal question and investigates the mechanisms through which these effects operate. In the first chapter, I investigate the impact of an infrastructure failure on statewide comprehensive exam test scores. The 2007 collapse of the I-35W Mississippi River Bridge in Minneapolis, Minnesota, led to a substantial disruption of the learning environment for students in affected communities. The collapse resulted in numerous fatalities and injuries; notably, a school bus carrying 63 students was on the bridge during the collapse, and traffic patterns were disrupted for a year. Leveraging the collapse as a natural experiment, I use two-way fixed effects (TWFE) and synthetic difference-in-differences methods to show that the disaster negatively affected student test scores in nearby schools. The results suggest that the trauma and traffic disruption associated with the collapse had lasting negative impacts on student achievement. My analysis also considers potential mechanisms, including changes in air quality, but finds that psychological stress appears to play a dominant role in explaining the observed decline in test scores. In the second chapter, I examine the trade-off between safety and noise mitigation by using a quasi-experimental research design to estimate the impact of quiet zone establishment on railway accidents and property values. Railway quiet zones substitute train horns for alternative safety measures at railway crossings to mitigate noise pollution. I find that quiet zones are associated with a 1.27 times higher annual accident rate at railway crossings, which significantly increase fatalities and injuries. To compare the costs of increased fatalities and injuries associated with quiet zones against their noise reduction benefits, I conduct a cost-benefit analysis using residential property sales data from Cook County, Illinois. Using a hedonic pricing model, I find that quiet zones raise the value of nearby homes by 11.07%, or or approximately $25,483 per property. This translates to aggregate benefits ranging from $1.27–$5.90 million per crossing and about $51.78 million at the neighborhood level. In contrast, estimated costs—including engineering, maintenance, and the value of additional fatalities and injuries—total roughly $1.8 million per crossing and $20 million at the neighborhood level. A welfare analysis suggests that the housing price capitalization of reduced noise pollution exceeds the safety costs. Comparing these figures, I conclude that in high-density areas like Cook County, quiet zones yield benefits that clearly outweigh their costs, but in lower-density settings with limited housing appreciation, they are unlikely to pass a cost-benefit test. The third chapter examines the impact of the introduction of ridesharing services like Uber and Lyft on crime rates across U.S. cities, leveraging a natural experiment created by their staggered rollout. Using a TWFE model, I find that the introduction of ridesharing services leads to a 4.7% reduction in violent crimes, a 5.5% decrease in property crimes, and a 10.4% drop in burglary rates. No significant effects are observed for larceny, motor vehicle theft, or arson. I also investigate the mechanisms through which Uber and Lyft reduce crime and find that their entry improves local labor market conditions—raising employment and reducing unemployment—particularly in cities with high baseline unemployment and for crimes driven by financial motives. This "gig economy effect” emerges as the primary channel behind the observed crime reductions. Secondary factors, such as demographic changes, shifts in alcohol consumption, alterations in transportation mode share, and broader quality-of-life improvements, appear to play more limited, complementary roles.

Date

2025-07-22

Resource Type

Text

Resource Subtype

Dissertation

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