Disproportionate weather sensitivity in bus travel: Evidence from smart card data in the West Midlands, UK

Introduction As adverse weather events become more frequent, public transport users face increasing challenges to service reliability and inclusivity. This study examines how weather acts as a differential barrier to bus travel across five distinct passenger groups, aiming to provide evidence for weather-resilient and equitable transport policies. Methods We analyse six years (2016-2022) of smart card data from the West Midlands, UK, linked with hourly weather observations. A matched-pair approach is used to isolate short-term weather effects on bus ridership, with ridership disaggregated by passenger group. In addition to key meteorological variables such as precipitation and temperature, two thermal comfort indices - the Heat Index and the Actual Sensation Vote - are applied to capture perceived outdoor conditions. We quantify how these variables affect ridership among older adults, people with disabilities, children, students and long-term pass holders. Results Results reveal that adverse weather reduces bus ridership across all groups; however, the magnitude is highly uneven. Precipitation exerts the strongest and most consistent negative effect overall. Older adults and people with disabilities show the greatest sensitivity, with the sharpest ridership declines under both wet and adverse thermal conditions, while long-term pass holders are the least affected. These disparities suggest that differences in weather sensitivity stem from both physical vulnerability and differences in travel flexibility. Conclusions The study provides robust evidence that weather operates as a differential barrier to bus travel and demonstrates an uneven distribution of weather-induced mobility loss, especially among vulnerable groups. These findings highlight the need for targeted, weather-resilient transport strategies to address the specific sensitivities of these groups and to support inclusive and equitable mobility under increasing climate variability.