California Air Resources Board

Development of a method and mapping tool for evaluating transportation access disparity and other social determinants of health among California neighborhoods

Transportation access is an important driver of health because it facilitates access to jobs, schools, health care, and healthy food and contributes to quality of life. Furthermore, access to clean transportation reduces the likelihood that outcomes of the transportation system—like air pollution—will negatively impact health. Access to clean transportation is one “social determinant of health,” alongside other factors related to the environmental, economic, and social conditions we experience in our daily lives. Thus, improving clean transportation access can result in health benefits.

This project developed a method and produced a statewide Transportation Disparities Mapping Tool that helps users better understand some of the patterns and consequences of disparities among neighborhoods related to transportation and other social determinants of health. The tool also sheds light on some of the potential causes of low rates of vehicle ownership, such as insurance premiums and borrowing costs. Based on multiple data sources, the tool includes over three dozen indicators that fall into five categories: transportation, accessibility, sociodemographics, housing, and health.

Results from analyzing the indicators from this tool found that lower income neighborhoods experience several challenges compared to higher income neighborhoods: greater barriers to vehicle ownership, disproportionately fewer clean vehicles and more “clunkers” (defined as vehicles aged 20 years and older), less access to private vehicles, and less access to infrastructure that supports active transportation. The other major finding is a significant diversity in transportation and accessibility characteristics among low-income neighborhoods (and higher income ones). For example, while most low-income neighborhoods are park poor, some are not, and not all low-income neighborhoods are identical in terms of their transportation challenges and opportunities. California’s complex and highly heterogeneous neighborhood system means that equity policy should go beyond a simple “one-size” approach to promoting equitable and just sustainable development.

The database and mapping tool can be used to develop more equitable transportation policies and plans by identifying the geographic specific transportation challenges and opportunities for neighborhoods. It will help inform CARB’s implementation of Senate Bill (SB) 375, SB 350, and SB 150 and will contribute to California’s commitment to ensure that all segments of society benefit from the state’s climate change agenda, including disadvantaged populations and neighborhoods.