Extreme heat, intensified by urban heat islands and climate change, increasingly affects travelers, especially vulnerable populations such as older adults, people with disabilities, and those with chronic diseases. This dissertation develops a comprehensive system to evaluate cumulative heat exposure at the trip level, focusing on these vulnerable groups. By integrating computer vision-based sidewalk analysis for shade modeling, developing TransitSim and SidewalkSim for detailed transit trip trajectories, and applying meteorological data with thermal comfort indices, the study bridges the gap between micro-level physiological simulations and macro-level qualitative assessments. This approach addresses the dynamic nature of heat exposure during transit and walking trips, providing quantifiable and scalable analysis. The effectiveness of this system is demonstrated through two case studies. The first analyzes over 40,000 transit trips from the Atlanta Regional Commission’s Transit Onboard Survey to assess cumulative extreme temperature exposure and associated thermal risks, highlighting disparities across demographic groups and projecting trends under future climate scenarios. The second applies shortest path routing for hypothetical walk trips in Downtown Lawrenceville during an extreme heat event, offering insights into potential changes in travel behavior when individuals are informed about their thermal exposure. This research contributes to transportation resilience and urban thermal comfort by enhancing the theoretical understanding of cumulative health risks in travel decisions, integrating interdisciplinary analytical techniques, and providing open-source tools for planning agencies to assess and mitigate heat risks.
