To address the dearth of knowledge about person-based and trip-level exposure, we developed the Icarus model. Icarus uses mesoscale traffic model—activity-based model—to analyze the heat exposure of regions of interest at an individual level. The goal with Icarus was to design accurate, granular models of population and temperature behavior for a target region, which could be transformed into a heat exposure model by means of simulation and spatial-temporal joining. By combining and implementing the most robust software and data available, Icarus was able to capture person-based exposure with unparalleled detail. Here we describe the model methodology. We use the metropolitan region of Phoenix, Arizona, USA to carry out a case study using Icarus.

This study addresses the social and physical constraints and opportunities for South Mountain Village, particularly along the Rio Salado as it intersects with the proposed light rail extension on Central Avenue. The primary goals guiding this document are ecological restoration, social and physical connectivity, maintenance, management, development and future planning. This study discusses the history of the Rio Salado riparian area, analyses current riparian conditions, and provides context from similar cases both locally and nationally.

It has been demonstrated that access to recreational opportunities can improve the livelihood and reduce negative health effects for residents nearby. With this in mind, the physical connectivity of South Mountain residents is assessed to determine the degree of accessibility to recreational areas of the Rio Salado. This analysis will also be used to address areas in which residents do not have equitable access and will be used to guide recommendations to increase that access. Additionally, as growth occurs, existing social vulnerability concerns are addressed in regard to marginalized populations relying on the area’s ecological and grey infrastructure for refuge.

As the Rio Salado 2.0 Project and the Valley Metro South Central light rail extension begins construction and the opportunity to develop increases, residents and business owners are concerned that redevelopment will affect the integrity and connectivity of the area. This study outlines how these changes may affect stakeholders while keeping the area accessible and equitable for all. Evaluation of the sites and parcels surrounding the Rio Salado for future development while taking into account its rich history and needs of the community is important for the community and the City of Phoenix as a whole. This study incorporates concepts from the Rio Salado Beyond the Banks Area Plan and other existing plans and regulations for the area. This study aims to provide a roadmap for future development along the Rio Salado at South Mountain Village in a sustainable and equitable way.

Heat exposure for urban populations has become more prevalent as the temperature and duration of heat waves in cities increase. Occupational exposure to heat is a major concern for personal health, and excessive heat exposure can cause devastating outcomes. While occupational heat exposure studies have traditionally focused on environmental temperature, work intensity, and clothing, little is known about the daily exposure profile of workers, including their daily travel and working patterns. This study developed a novel measure of exposure and reprieve dynamics, the moving average hourly exposure (MAHE) to balance short-duration but high-exposure events and capture the inability to reprieve from exposure events. MAHE was assessed by combining an activity-based travel model (ABM) and the Occupational Requirement Survey to simulate urban workers' total daily heat exposure. The simulation considers daily travel, work schedules, and outdoor working frequency. The simulation was conducted for 1 million workers in Phoenix, Arizona, using Mean Radiant Temperature (MRT). The results show that 53% to 89% of workers in Phoenix's construction, agriculture, transportation, raw material extraction, and entertainment industries will likely experience MAHE over 38°C for at least an hour. These industries also have up to 34% of the laborers exposed to over 7 hours of continuous 38°C and above MAHE exposure. The location of the most intense heat exposure was identified near the downtown and central business districts, significantly different from the home locations of the workers in suburban and rural areas. Formulating the MAHE balances heat risk events with cooling benefits and aids in identifying individuals with prolonged high heat exposure.