Urban bus ridership, income, and extreme weather events

Climate change is projected to worsen weather extremes, such as heat waves and days of heavy precipitation, which could pose serious health and economic risks to U.S. cities. These extreme weather events could also affect urban mobility, since people who walk or bike may shift to public transit or avoid travel if they cannot afford a vehicle. To address these concerns, this study examines the effects of extreme weather events on bus ridership and the extent to which this relationship varies by income and destination. This study analyzes highly detailed micro-level bus data between 2012 and 2017 for a county in the Pacific Northwest using a negative binomial regression model. Results suggest modest reductions in bus ridership on very hot and cold days, as well as on days with heavy rainfall, with impacts differing between weekdays and weekends. Findings also show that bus ridership is more sensitive to extreme weather events in lower-income areas relative to the wealthiest neighborhoods, which may be partly driven by a large university student population who can ride the bus for free. Finally, results show that bus ridership around commercial areas and parks increases on very cold days and days with heavy precipitation, reinforcing the importance of public transit during these weather events. These results suggest extreme weather events affect urban mobility, with greater impacts in lower-income neighborhoods, parks and commercial areas. Transit agencies and policymakers should consider ways to increase accessibility and mobility during these weather events, especially for lower-income households.