The concept of Environmental Justice is about equal and fair access to a healthy environment, with the goal of protecting underrepresented and poorer communities from incurring disproportionate environmental impacts. The region of Southern California Association of Governments (SCAG) is vast and geographically distinct. Demographically, it is one of the most diverse regions in the country. The area is also quite economically diverse, and displays the extremes in household income.

Since SCAG is currently moving towards the use of activity-based travel demand model (ABM), the purpose of this study is to use SCAG ABM to analyze environmental justice, using data prepared for SCAG’s Regional Transportation Plan. SCAG ABM System that contains three major components can generate rich information to analyze environmental justice. The first component is a socioeconomic simulator that generates detailed socioeconomic and vehicle ownership characteristics for each synthetic person, including race, ethnicity, income, age, and gender. The second component, an activity-travel simulator, estimates each person's daily activity and travel patterns, including mode use, travel schedule, activity type, and travel location. After converting person trips to vehicle trips, an Equilibrium Assignment module will be used to create traffic flows on network.

In this study, we will use model output of SCAG ABM to develop methodology to calculate various accessibility and mobility indicators for different population groups. And then compare the results among different scenarios to analyze environmental justice. Accessibility indicators to be developed include accessibility to jobs, park/open spaces, and medical services. Mobility indicators will include travel distance and travel time. Both accessibility and mobility will be calculated by three major modes: auto, transit, and walk. Travel time by walk will be calculated to analyze the benefit of physical activity and public health. Population groups to be compared will include people by their race/ethnicity, age (elderly), and income. A sub-model will be developed to estimate person with mobility constraint.

Since little research has been done to validate the application of ABM on environmental justice analysis, it is expected that the contribution of this study is to prove the usefulness of the model on environmental justice analysis.