Tierra Bills

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Tierra S. Bills is an Assistant Professor of Public Policy and Civil and Environmental Engineering at the University of California, Los Angeles. She specializes in the evaluation of transportation planning and system outcomes, and travel demand modeling, with a special emphasis on transportation equity. Dr. Bills brings a unique and innovative perspective to the challenge of transportation inequity, aimed at impacting transportation science, practice, and quality of life for vulnerable communities. She has worked in the transportation equity domain since 2009 and her current work builds off this track record, including her master’s research, dissertation work, study and training as a Research Scientist at IBM Research, Michigan Society Fellowship research, and previous work as a former Assistant Professor at Wayne State University.

Dr. Bills has extensive training in travel demand modeling and is engaged in ongoing work on representation of transport vulnerable travelers, in household travel surveys. These travel surveys are traditionally used to estimate and validate travel demand models and this is a pathway to developing travel models capable of reflecting the needs and behaviors of disadvantaged travelers and fine-grain transportation equity outcomes. Dr. Bills also works to advance accessibility measurement for transportation project evaluation, and develops strategies for ranking alternative transportation plans using equity-based criteria. 

At UCLA, Dr. Bills directs the Transportation Equity Innovation (TrEI) Lab, and leads a team of graduate and undergraduate students in developing innovative, meaningful, and effective tools for assessing fairness in transportation infrastructure, systems, and policies.  Dr. Bills is also affiliated with the UCLA Institute of Transportation Studies, UCLA Bunche Center, and collaborates with students, faculty, and researchers across engineering, policy, planning and other disciplines. Her team’s work is published in a range of journals including Transport Policy, Transportation Research Part D, Transportation,  and Transportation Research Record. 

 

Selected Publications

Srisan, T., & Bills, T. (2024). A Case for Race and Space in Auto Ownership Modeling: a Los Angeles County study. Transport Policy. (Link)

Bills, T. S. (2022). Advancing the Practice of Regional Transportation Equity Analysis: a San Francisco Bay area case study. Transportation, 1-26. (Link)

Bills, T. S., Twumasi-Boakye, R., Broaddus, A., & Fishelson, J. (2022). Towards transit equity in Detroit: An assessment of microtransit and its impact on employment accessibility. Transportation Research Part D: Transport and Environment, 109, 103341. (Link)

Bills, T. S., & Carrel, A. L. (2021). Transit accessibility measurement considering behavioral adaptations to reliability. Transportation research record, 2675(5), 265-278. (Link)

Bills, T. S., & Walker, J. L. (2017). Looking beyond the mean for equity analysis: Examining distributional impacts of transportation improvements. Transport Policy, 54, 61-69. (Link)

Bills, T. S., Sall, E. A., & Walker, J. L. (2012). Activity-based travel models and transportation equity analysis: Research directions and exploration of model performance. Transportation research record, 2320(1), 18-27. (Link)

Hao Ding

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Hao Ding is a doctoral student in Urban Planning, focusing on urban design and transportation planning. His research interests include the equity and justice impacts of urban design regulations, the interaction between urban form and transportation, and transportation equity. His most recent works examine the effects of urban design and land use regulations on place identities in the Asian American ethnoburbs in Los Angeles, and the effects of conventional local transportation planning practices on housing production and affordability. He is also a Graduate Student Researcher at the Institute of Transportation studies, and has been involved in several research projects that study the past, present, and future of California’s land use and transportation systems, sexual harassment on public transit, homelessness in transit environments, and public transit during the Covid-19 pandemic.

Samuel Speroni

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Sam Speroni is a doctoral student in the UCLA Department of Urban Planning and a researcher with the UCLA Institute of Transportation Studies and UCLA Lewis Center for Regional Policy Studies.  He completed his master’s degree in Urban and Regional Planning, also at UCLA, in June 2020.  Sam is advised by Dr. Evelyn Blumenberg and Dr. Brian D. Taylor.

Sam’s primary research interest lies at the intersection of transportation, education, and new mobility, where he looks for ways to improve equitable access to educational opportunities for vulnerable and disadvantaged student populations.  His research extends to many other aspects of travel behavior and transportation systems, all with an emphasis on equity.  Sam’s recent applied planning research project analyzing high school students’ ridehail trips to school for HopSkipDrive (full report | policy brief) received the national Neville A. Parker Award for outstanding master’s capstone in transportation policy and planning from the Council of University Transportation Centers (CUTC).

Sam is a Future Leaders Development fellow of the Eno Center for Transportation in Washington, D.C., and in 2020 he was named the Pacific Southwest Region University Transportation Center (PSR UTC) outstanding student of the year.  He is also the recipient of the Dwight D. Eisenhower Transportation Graduate Fellowship (2019 and 2020) and the Intelligent Transportation Systems California / California Transportation Foundation joint graduate scholarship (2020).

Prior to UCLA, Sam was a high school English teacher and school administrator in Charlotte, North Carolina, through Teach for America.  Originally from New England, Sam grew up in Massachusetts and earned his bachelor’s degree in Urban Studies with honors from Brown University in 2011, where he was also captain of the varsity swimming & diving team.