Connecting Transportation Scenarios and Extreme Heat Exposure in Urban Areas
Despite the connection between travel behavior and heat exposure, there is virtually no prior research that quantifies its extent or examines its implications for future transportation policy. We demonstrate an approach for measuring transportation-driven exposure to dangerously high outdoor temperatures using activity-based travel demand model output and high-resolution urban climate data from the San Francisco Bay Area in the United States. Disaggregate, simulated one-day travel patterns for all Bay Area residents were joined with 1-kilometer interpolated temperature data from DayMet that was validated against observations from in situ meteorological stations. Within a geographical information system framework, Individually Experienced Temperatures (IETs) were estimated for each of the 3.6 million trips made by walk, bike, or public transit during the simulated travel day in 2010. These individual exposure time series were then aggregated to population-wide measures of Extreme Heat Degree-Minutes. Disparities in heat exposure are evident across socioeconomic, racial, and geographical dimensions, and in some cases these contrasts are amplified under different future transportation plans. Opportunities to reduce public health risks and inequities associated with high temperatures may be possible with urban design and planning strategies that target the specific places and sub-populations where this integrative approach reveals extreme heat exposure to be most severe.