published journal article

Cross-sectoral and multiscalar exposure assessment to advance climate adaptation policy: The case of future coastal flooding of California’s airports

Abstract

Climate adaptation is inevitable in managing the climate risk of infrastructure systems and has become an emerging topic in the past decade. Despite the growing need for collaborative and multi-agency efforts in climate change adaptation, however, current airport and transportation governance structures reinforce siloed approaches to manage climate risk. Here we combine a novel coastal flooding exposure assessment of California’s airports and a policy review to address the importance of collaborative climate adaptation by viewing airport infrastructures as interconnected systems across spatial scales and sectors. Our exposure assessment innovates by investigating the airport perimeter, its interconnected infrastructure (road access, ground-based navigation, and communications systems), and multimodal interregional transportation corridors. At the local scale, we find that substantial airport assets are exposed as early as 2020–2040, suggesting the urgency for near-term adaptation actions. Regarding the interconnected infrastructures, 23 unaccounted airports are identified at risk of disruption when compared with existing studies, including global hubs such as the Los Angeles International Airport. At the regional scale, we investigate how exposed airports transfer risk within the interregional multimodal transportation corridors, and we identify the critical airports within these corridors to be prioritized for adaptation. Finally, based on a policy review of more than 100 state legislature and planning documents, the implications of our results are discussed at the national and state levels. This study presents a new generation of infrastructure exposure assessment to climate-induced hazards, by addressing cross-sectoral and multiscalar dependencies that are currently overlooked by adaptation policies. We also argue that new modes of collaborative efforts are needed to achieve effective climate adaptation for interconnected infrastructures.

policy brief

Sustainable Transportation and Just Affordable Housing

Publication Date

October 13, 2022

Author(s)

Allie Padgett, Anne Yoon, Chhandara Pech, Jacob Wasserman, Paul Ong, Tiffany Green

Abstract

California’s intense affordable housing crisis has highlighted the fundamental linkage between land use, transportation, climate policy, and equity. Reducing greenhouse gas emissions, the main contributor to climate change, is a priority policy goal for the state of California, and cutting vehicle miles traveled (VMT) is a key mechanism for achieving this goal. In order to equitably achieve this reduction, it is critical that affordable housing options be situated in areas that facilitate less driving, through reliable access to public transit, walkability, and proximity to employment. These elements, among others, can combine to create more sustainable communities.In the face of rising housing prices, publicly subsidized affordable housing is crucial for low-income and other vulnerable Californians. This study analyzed geographic transportation, environmental, and racial and economic equity indicators alongside the spatial distributions of two affordable housing programs in 2012 and their change from 2012 to 2019:
• Housing Choice Vouchers (HCV), also known as “Section 8”: the nation’s major tenant-based rental support program, a portable voucher designed to cover the gap between 30% of a household’s income and the cost of rent in a market unit.
• Low-income Housing Tax Credit (LIHTC): the nation’s largest project-based affordable housing development program, a tax credit used to subsidize income-restricted, lower-rent housing units.

policy brief

Can Green Hydrogen Be a Cost Competitive Transportation Fuel by 2030?

Abstract

There is growing international interest in electrolytic hydrogen produced from renewable energy (often referred to as green hydrogen) as a potential zero-emission alternative to gasoline and diesel in a variety of on-road and off-road transportation applications. Currently, gasoline and diesel are priced around $4 per gallon at the pump and a gallon of either fuel is roughly the equivalent of one kilogram of hydrogen based on energy content. Although hydrogen vehicles are generally more efficient than those fueled by petroleum, transporting and dispensing hydrogen is more expensive than for conventional fuel, so hydrogen must reach a cost substantially below $4/kg, possibly as low as $2/kg, to be a cost competitive option. Is this achievable? In short, this depends on the extent to which green hydrogen markets scale up globally. Projections of future green hydrogen production costs are generally in the range of $2–$4/kg by 20301 ; however, some expect faster and deeper declines reaching as low as $1.5/kg by 20302 and even $1/kg by 2030 under ideal conditions.3 This brief examines the evidence in support of green hydrogen production achieving a cost at or below $2/kg starting from its current level of between $5 and $6/kg,4 and assesses the time point at which this cost benchmark could be achieved.

presentation

California’s Hydrogen Strategy - Where Do We Go From Here?

policy brief

Hydrogen Can Have a Much Lower Carbon Intensity than Fossil Fuels But This Largely Depends on How It Is Produced and Distributed

Publication Date

September 23, 2022

Author(s)

Alissa Kendall, Arpad Horvath, Lewis Fulton, Pablo Busch, Stephanie Collins, Timothy Lipman

Abstract

As interest in hydrogen as an energy carrier has increased, the various ways that hydrogen is made are being categorized as “green,” “blue,” “gray,” and other colors in relation to their environmental impact. While these categorizations are somewhat useful to indicate the environmental and climate change impacts of different production pathways, they are not especially useful for policy making or industry decisionmaking purposes because they are subjective. For example, most definitions of green pathways for hydrogen production only include electrolysis from renewable electricity sources; however, Figure 1 indicates additional production pathways with some of these having near-zero or even negative greenhouse gas (GHG) emissions as well as low or no other emissions of concern. To help clarify the role of hydrogen in decarbonizing California, this brief summarizes the latest scientific findings from recent and in-progress research across the University of California Institute of Transportation Studies (UC ITS) concerning the relative carbon intensity (CI) of hydrogen production pathways. It also briefly covers the availability of biomass and biogas in California that could be applied to the production of low-CI hydrogen.

presentation

Innovative Pilot: Universal Mobility Pilot

research report

Retrospective User Survey for a Rural Electric Vehicle Carsharing Pilot in California’s Central Valley

Abstract

Rural areas in California present unique transportation challenges associated with long travel distances, infrequent transit service, the cost of car ownership, and limited access to app-based rideshare services that are common to more populated urban centers. Researchers at the University of California, Davis, partnered with the eight San Joaquin Valley Metropolitan Planning Organizations to identify and support the development of innovative regional mobility pilot concepts, including an electric vehicle carsharing service known as Míocar. Míocar launched in August 2019 with roundtrip EV carsharing hubs in affordable housing complexes in the southern San Joaquin Valley. This study summarizes the data collected through a telephone survey with current Míocar users from January 2022 through March 2022. The survey asks users to reflect on their use of the service since they enrolled, and it builds upon past data collection efforts for this program by gathering detailed information on member characteristics, transportation needs and capabilities, and Míocar’s role as a transportation option for the users’ households. The results provide qualitative insights into members’ mobility challenges and considerations and the service’s impacts on user travel. Comparisons to existing carsharing programs suggest that Míocar is achieving similar impacts as other programs in some areas, such as reducing personal vehicle use, ownership, and associated greenhouse gas emissions. However, respondents emphasize its role in improving mobility within the rural region. The evaluation provides information for researchers to enhance future evaluations of rural carsharing, and findings may inform member recruitment, training, program design, and other efforts conducted by rural carsharing operators.

research report

The Spatial Dilemma of Sustainable Transportation and Just Affordable Housing: Part I, Housing Choice Vouchers

Publication Date

September 13, 2022

Author(s)

Allie Padgett, Anne Yoon, Chhandara Pech, Jacob Wasserman, Paul Ong, Tiffany Green

Abstract

This study examines the spatial distribution of tenant-based Housing Choice Voucher (Section 8) units to understand whether geographic patterns and trends are consistent with climate change and equity goals. The analysis compares the location of heavy commercial vehicle units in 2012 and net changes from 2012 to 2019 with a number of transportation, environmental, and racial and economic equity metrics. While the change in units from 2012 to 2019 shows promising trends for reducing vehicle miles traveled and increasing walkability and transit accessibility, there is a cost: higher exposure to pollution and a higher rate of vehicle collisions. heavy commercial vehicle units are further concentrated in disproportionately low-income neighborhoods and neighborhoods of color, with worsened access to economic opportunity. The findings reveal an inherent structural dilemma in whether the heavy commercial vehicle program is able to simultaneously achieve climate and equity goals.

published journal article

Equity Implications of Robo-Taxis on Job Accessibility: Avoiding the Ecological Fallacy with Agent-Based Models

Abstract

Robo-taxis or shared-use automated vehicle-enabled mobility-on-demand services (SAMSs) are now in operation in the US and China. By removing drivers’ labor costs, SAMSs promise to provide significantly lower-cost transportation than human-driven mobility-on-demand services. Under this assumption, prior research indicates SAMS can provide sizable employment accessibility benefits to workers. The current paper aims to analyze the distribution of SAMS accessibility benefits across segments of the population (i.e., perform an equity analysis) using an agent-based travel modeling approach. The study’s methodology (i) clusters workers by their socio-demographic and -economic characteristics using latent class analysis, (ii) estimates hierarchical work location and commute mode choice models for four worker segments, and (iii) obtains logsum-based monetary measures of accessibility for each worker in a synthetic population of Southern California. Using this information, we analyze the distributions of SAMS accessibility benefits across several population segmentations. We utilize box plots to visualize the distributional differences across population segments. Additionally, we use ANOVA and post-hoc Tukey’s Honestly Significant Difference tests to analyze the overall and inter-group statistical significance of the distributional differences, respectively. The results indicate that low-income, Black, and Hispanic workers receive larger SAMS accessibility benefits on average than high-income, White, and Asian workers. Additionally, workers in zero-car households benefit more from SAMSs than one- and multi-car households, particularly after conditioning on the transit accessibility of the worker’s residence. The study also aggregates the agents into their origin census tracts, classifies the census tracts based on agent socio-demographic attributes, and then analyzes the distribution of SAMS accessibility benefits across census tract designations (e.g., low median income tracts vs. high median income tracts). The study finds that if analysts were to make individual-level inferences based on the spatial analysis, the inferences would be inaccurate in the case of household income and age, thereby misinforming policymakers regarding who benefits more/less from SAMS.

research report

The Spatial Dilemma of Sustainable Transportation and Just Affordable Housing: Part II, Low-income Housing Tax Credits

Publication Date

September 1, 2022

Author(s)

Allie Padgett, Anne Yoon, Chhandara Pech, Jacob Wasserman, Paul Ong, Tiffany Green

Abstract

This study examines the spatial distribution of Low-income Housing Tax Credit (LIHTC) units to understand whether geographic patterns and trends are consistent with climate change and equity goals. The analysis compares the location of LIHTC units in 2012 and net changes from 2012 to 2019 with a number of transportation, environmental, and racial and economic equity metrics. Unit locations are, at best, somewhat more sustainable than the state overall, with slightly lower-skewing vehicle miles traveled and better walkability, though low transit accessibility. What environmental gains there were, though, come at the cost of higher exposure to pollution. LIHTC units are also concentrated in disproportionately low-income neighborhoods and neighborhoods of color, with worse access to economic opportunity. The findings reveal an inherent structural dilemma in whether the LIHTC program is able to simultaneously achieve climate and equity goals.