dissertation, thesis, or capstone

Alternative Fuel Adoption Behavior of Heavy-duty Vehicle Fleets

book/book chapter

Understanding and Modeling the Impacts of COVID-19 on Freight Trucking Activity

Abstract

Restrictions on travel and in-person commercial activities in many countries (e.g., the United States, China, European countries, etc.) due to the global outbreak and rapid spread of the coronavirus disease 2019 (COVID-19) have severely impacted the global supply chain and subsequently affected freight transportation and logistics. This chapter summarizes the findings from the analysis of truck axle and weight data from existing highway detector infrastructure to investigate the impacts of COVID-19 on freight trucking activity. Three aspects of COVID-19 truck impacts were explored: drayage, long and short-haul movements, and payload characteristics. This analysis revealed disparate impacts of this pandemic on freight trucking activity because of local and foreign policies, supply chain bottlenecks, and dynamic changes in consumer behavior. Due to the ongoing effects of COVID-19, it is not yet possible to distinguish between transient and long-term impacts on freight trucking activity. Nonetheless, a future expansion of the study area and the incorporation of other complementary data sources may provide further insights into the pandemic’s impacts on freight movement.

policy brief

Connected and Automated Vehicle Impacts in Southern California: Travel Behavior, Demand, and Transportation System Perspectives

Abstract

Connected and automated vehicle (CAV) technologies received extensive attention in the recent decade. CAVs are vehicles that can drive without a human driver (automated vehicle, or AV) and can communicate with other vehicles and infrastructures (connected vehicle, or CV). The technologies can benefit transportation systems in many aspects, including safety, economics, efficiency and convenience, and accessibility. While studies of CAV operations are accelerated by tons of data collected from on-road tests worldwide, the comprehensive impacts of CAVs on transportation systems are still unclear. These benefits might affect travel behavior fundamentally, which might induce more travel demand, while on the other hand, vehicle automation and connection would enhance roadway capacity. Ultimately, it’s essential to evaluate the CAV impacts on transportation systems in the context of significantly changing travel demand and supply. This study aims to answer the following questions: 1) how the deployment of CAVs impacts people’s travel behaviors in Southern California; 2) to what extent the changes in people’s travel behavior can affect the travel demand; 3) how well can the increased roadway capacity help alleviate the strain on the network with CAV deployment; and 4) will the CAV technologies contribute to the travel accessibility of underserved groups?

published journal article

Grocery shopping in California and COVID-19: Transportation, environmental justice, and policy implications

Abstract

To understand how COVID-19 changed grocery shopping and explore implications for transportation and environmental justice, we surveyed in May 2021 California members of KnowledgePanel®, the largest and oldest U.S. probability-based panel. We asked how frequently Californians grocery shopped before and during the pandemic, and how they may grocery shop afterward in-store, online with home delivery (“e-grocery”), or online with store/curbside pick-up (“click-and-pick”). We found that most Californians continued to grocery shop in-person during the pandemic, although less frequently than before. Many relied more on e-grocery (+8.9 %) and click-and-pick (+13.3 %), although older generations remained attached to in-store shopping. African American households grocery shopped in-store less than Whites pre-pandemic; post-pandemic, they may compensate with more e-grocery and click-and-pick. While higher levels of environmental injustice (based on CalEnviroScreen) were associated with less in-store shopping, we found no association with e-grocery or click-and-pick. Our results have implications for travel, food logistics, and parking management.

policy brief

Student Transportation Options Provided by California Community Colleges Often Limited to Parking Permits and Transit Passes

policy brief

Barrier Effects of Freeways for Pedestrian and Bicycle Travel

research report

Understanding Transportation Programs and Services at California Community Colleges

Abstract

High transportation costs and access barriers can make it difficult for community college students to manage employment, household responsibilities, and education, negatively affecting their academic success. Understanding the state of existing transportation services and programs at California community colleges is the first step to addressing these barriers. We inventoried the transportation services, programs, and costs at 115 of the 116 California community colleges as advertised on each campus’ website. We found that most community colleges offer some form of parking or public transit student subsidies but little else. Due to the state education code, parking costs were similar across campuses. In contrast, transit pass costs varied from $0 to more than $100 per semester. On average, students paid more for transit passes than for parking permits. Throughout the search process, information on the campus’ transportation programs and services was difficult to locate since each campus posted this information in different places on their websites. The findings suggest that more colleges should consider offering low-cost transit passes by assessing a transportation fee or enacting partnerships with other government entities. California community colleges may also want to consider expanding how they provide transportation support and better publicizing information on transportation and standardizing how information is provided. Overall, community colleges, with the support of the State, have opportunities to better support students’ transportation needs to ensure that transportation access is not a barrier to educational outcomes.

presentation

Kent Distinguished Lecture, University of Illinois Transportation Center, Nov 2022: "Data, modeling and emerging technologies on the road to sustainable freight transportation."

policy brief

Rural Electric Vehicle Carsharing is Improving Household Mobility and Reducing Reliance on Personal Vehicles

Abstract

Households in marginalized areas of rural California contend with difficult transportation challenges resulting from infrequent transit service, limited access to app-based rideshare services, and higher vehicle ownership costs associated with long travel distances. In 2014, researchers at the University of California, Davis partnered with the San Joaquin Valley Metropolitan Planning Organization to engage with stakeholders to understand the challenges facing rural residents and develop solutions for improving mobility while reducing greenhouse gas emissions. One outcome of this work was the creation of an electric vehicle (EV) carsharing service known as Míocar. Míocar launched in 2019 and now has 27 vehicles located in eight affordable housing complexes in Tulare and Kern counties. Míocar provides a transportation option that helps to improve the mobility of individuals and households in marginalized communities and reduce greenhouse gas emissions by decreasing reliance on conventional personal vehicles.

research report

Dividing Highways: Barrier Effects and Environmental Justice in California

Abstract

We examine the barrier effects of freeways in California. We analyze the association between freeways and three measures of nearby street connectivity: the composite Street Network Disconnectedness index (SNDi), circuity, and the distance between crossings – underpasses or bridges that enable people to cross the freeway. We also assess the quality of a sample of these crossings for pedestrians and cyclists. We find that barrier effects are most pronounced in communities of color. We also find that even where crossings exist, they are unpleasant or even hazardous for pedestrians and cyclists because of high-speed traffic on on- and off-ramps, and because large volumes of traffic are funneled through a small number of crossings rather than being distributed over a wider network.