On Friday, October 17, 2014, USC Price School of Public Policy PhD students Andy Hong, Eun Jin Shin, and Yuting Hou presented their ACSP transportation research to students, faculty, and practitioners at the University of Southern California as part of the METRANS Transportation Research Seminar Series. They will also present this research at the upcoming 54th Annual Conference of the Association of Collegiate Schools of Planning (ACSP) conference, Big Ideas, Global Impacts, to be held October 30 to November 2 in Philadelphia. –

“I have been looking forward to attending one of these seminars, and I found it very interesting how the audience gave comments, not only on the content, but on the presentation and visuals as well,” said USC Viterbi Master of Science in Civil and Environmental Engineering student, Nathan Ho.  “I learned presentation tips and got a taste of what public policy transportation research looks like.  I am very new to the transportation sector, but what interests me most about it is how relevant it is to our lives.  I am curious how transportation related decisions are made and problems are solved.”

Andy Hong began the event with his research, “Is public transit a new diet pill? The effects of new light rail transit on physical activity.”

Hong notes that moderate walking between home and transit stops can be a significant portion of daily physical activity. Yet, he cautions, we know little about the role of new public transit service in promoting physical activity at the neighborhood level. In an effort to identify this role, Hong conducted experimental research to examine the impact of the new Expo light rail line on physical activity levels of residents living close to ( with  ½ mile, treatment group) the new light rail station compared to the residents living farther away from (greater than ½ mile, control group) the station. “I was most interested to learn how public transit access could affect physical activity,” remarked attendee USC Price Doctoral student, Grace Nadel, who will use her degree to further her career in transit management after she graduates this spring

For Hong’s study, participants completed a travel diary, and carried a portable GPS tracking device and an accelerometer for 7 days before and after the opening of the new light rail system.  Using the 70 paired samples of individuals collected through the longitudinal survey Hong found a complex relationship between the Expo line and physical activity.  “Essentially, light rail use results in physical activity,” Hong discovered.  “Within the half mile area, people increased their walking activity significantly.  Increased use of bus and train led to increase in physical activity,” he added. 

Eun Jin Shin presented, “Exploring causal effects of living in an ethnic enclave on immigrants' commuting mode choices.”

Self-selection bias has become one of the primary issues in the literature on the relationship between the environment and travel behavior, Shin notes. However, she cautions, this self-selection issue has not been well-addressed in previous studies on the travel behavior of immigrants. Using the 2010-12 Caltrans Household travel survey, Shin’s study applies the propensity score matching method to examine the causal impact that living in an ethnic enclave has on immigrants' commuting mode choice.

“Hearing these presentations from my fellow PhD candidates is so helpful for me when I have to do this kind of presentation in the future,” said USC Price Public Policy and Management doctoral student Heejin Cho.  “The research ideas were very intriguing and the discussion about transportation and public policy, and even the public good, is so interesting,” she continued.

Shin separates internal-household carpools from external-household carpools to test whether living in an ethnic enclave where social capital abounds actually plays a role in increasing the probability of carpooling with non-Household members. By matching immigrants living in an ethnic enclave to similar immigrants living outside an enclave, Shin hoped to be able to identify the impact of ethnic enclaves. 

“The impacts of living in an ethnic enclave still remain statistically significant,” Shin discovered.  “However, the implications of living in an urban enclave differ from those of living in a suburban enclave.  My results imply that there is a social network effect in urban ethnic enclaves while it is not certain in the suburbs,” she added.  

Yuting Hou presented her research, “Traffic congestion, poly-centricity and intra-metropolitan firm location choices- A study of the Los Angeles region”

Hou’s study explores the economic impacts of traffic congestion on agglomeration through the lens of firms' location decisions. Using a discrete choice model and defining employment centers as the choice set, she explicitly examines whether traffic congestion is an important determinant of the location choices of new businesses among intra-urban agglomerations (i.e. employment centers) within the Los Angeles metropolitan area. 

“I found the diverse relationship between transportation access and firm or household location choice very interesting,” said USC Price Urban Planning and Development doctoral candidate Jung Ho Park, who plans to pursue a career in teaching and conducting research to contribute to solving urban challenges in South Korea.

Hou’s results show that regional congestion delays reduce the probability of employment centers being chosen by firms in most industrial sectors, while congestion delays inside centers do not reduce the agglomeration benefits of the centers until reaching a threshold. She also found that services and information sectors benefiting more from agglomeration are more likely to endure congestion delays within the centers.

“Congestion delays at the regional scale significantly affect the location decisions of firms among center,” Hou found.  “Policy implications are clear. Congestion mitigation policies aimed at improving metro wide access would be more cost effective than reducing congestion at a more localized scale. These policies would also have differential effects on different types of activities, depending on how these activities favor agglomeration.”

Andy Hong is a Ph.D. candidate in Urban Planning and Development at the USC Sol Price School of Public Policy.  Andy is working with his faculty advisor Marlon Boarnet on the Los Angeles Exposition Light Rail Line study investigating a before/after impact on travel changes and health-related factors among residents near the newly opened line. His doctoral research investigates health impacts of the transportation system, focusing on three emerging health issues: physical activity, air pollution exposure, and traffic safety.

Eun Jin Shin is a Ph.D. candidate at the USC Sol Price School of Public Policy, with an academic focus on urban spatial structure and transportation. She received her B.S. and M.S. degrees in Civil, Urban, and Geosystem Engineering from Seoul National University, and her Master’s degree in Urban Planning from the University of Washington, Seattle. Her advisor is Gen Giuliano, and her research focuses on the travel behavior of transportation-disadvantaged populations.

Yuting Hou is a Ph.D. candidate at the USC Price School of Public Policy. She is a research assistant at the METRANS Transportation Center and works with Professors Christian Redfearn and Genevieve Giuliano. Her research interests include evolution of metropolitan spatial structure, transportation and urban growth, land use and spatial analysis.