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Weathering the ride: Associations of heat, smoke, precipitation, and ozone with bus ridership in Colorado
Priyanka deSouza1, Elizabeth Dzwonczyk2, Peter Ibsen3
1Department of Urban and Regional Planning, University of Colorado Denver, United States; CU Population Center, University of Colorado Boulder, United States.
Environmental Research
|July 2, 2026
Summary
Extreme cold and precipitation significantly reduce urban bus ridership, while heat has weaker effects. Transit resilience can be improved by considering weather impacts and infrastructure like shelters.
Area of Science:
- Environmental Science
- Urban Planning
- Transportation Science
Background:
- Urban travel behavior is increasingly influenced by weather and climate variability.
- Understanding the short-term impacts of weather on public transit is crucial for urban mobility.
Purpose of the Study:
- To analyze the short-term temporal dynamics and contextual modifiers of weather-transit relationships in urban bus ridership.
- To quantify the impact of different weather conditions on transit usage.
Main Methods:
- Analysis of system-wide hourly bus ridership data from Denver (June 2022-September 2023).
- Utilized fixed-effects negative binomial distributed lag nonlinear models (DLNM) for Universal Thermal Climate Index (UTCI), precipitation, ozone, and wildfire smoke.
- Stratified analyses examined heterogeneity by time, season, fare policy, and shelter availability.
Main Results:
- Cold thermal stress caused the largest ridership declines (-15.7% over 24 hours).
- Precipitation led to transient reductions (-8.4% to -9.8% within 3-6 hours).
- Heat impacts were context-dependent; ozone and wildfire smoke showed limited associations.
Conclusions:
- Short-term weather exposure, particularly cold and precipitation, has a stronger impact on transit ridership than air quality.
- Fare policies and shelter availability significantly modify weather-transit associations, offering strategies for enhancing transit resilience.
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