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Open Access Publications from the University of California
Dissertations by ITS researchers.
Cover page of Integrated and Data-Driven Transportation Infrastructure Management through Consideration of Life Cycle Costs and Environmental Impacts

Integrated and Data-Driven Transportation Infrastructure Management through Consideration of Life Cycle Costs and Environmental Impacts


The main goal of this dissertation was to develop frameworks, quantitative models, and databases needed to support data-driven, informed, and integrated decision-making in managing the vast transportation infrastructure in California. Such a management system was envisioned to consider both costs and environmental impacts of management decisions, based on full life cycles of the infrastructure, and using reliable, high quality data that well represent local conditions in terms of materials and energy sources, production technologies, design methods, construction practices, and other critical parameters.

This PhD research consisted of three parts: 1) development of a comprehensive life cycle inventory (LCI) database for implementation of life cycle assessment (LCA) methodology in transportation infrastructure management in California. 2) Evaluation of current and potential sustainability actions at the state and local government levels through the development of frameworks, models, and datasets needed for objective and accurate quantification of the impacts of management decisions. 3) Assessment of recycling practices available for pavements at their end of life to quantify changes in environmental impacts compared to conventional methods, considering the effects of recycling through the use stage.

Cover page of Exploring the Changing Faces of Housing Development and Demand in California: Millennials, Casitas, and Reducing VMT

Exploring the Changing Faces of Housing Development and Demand in California: Millennials, Casitas, and Reducing VMT


Changes are coming to housing development and demand in California. The state’s sprawling development patterns have come under increasing scrutiny as the state struggles to reduce its greenhouse gas emissions, abate a decades-long housing supply and affordability crisis, and meet the needs of the largest generation in American history – the millennials (Generation Y). In this dissertation, I explore three ways in which residential development and demand in California could change going forward.

In my first study (Chapter 2 of this dissertation), I investigate how an upcoming change in California’s project-level environmental review law (the California Environmental Quality Act or CEQA) could affect the approval process for urban development. The state recently mandated that local, regional, and state agencies must replace “level of service” (LOS) with vehicle miles traveled (VMT) as the primary measure – and basis for mitigation – of transportation impacts under CEQA by July 1, 2020. I use a historical counterfactual approach to assess how replacing LOS with VMT could have impacted the approval process for 153 land development projects over 16 years in the City of Los Angeles. I find that most projects could have qualified for at least some environmental review streamlining under the VMT-based framework recommended by the state, including over 75 percent of residential-containing projects. My results suggest that swapping LOS for VMT could reduce the environmental review burden for development in urban areas and provide some of the approval process streamlining necessary to increase housing production in California. And because the streamlined development would be in areas characterized by lower VMT per capita than the regional average, it would likely contribute to reducing VMT per capita in line with state targets. 

In my second study (Chapter 3 of this dissertation), I look at accessory dwelling units (ADUs). How much ADUs can help with California’s housing supply and affordability crises depends on the homeowners who do not yet own one – their willingness and ability to build an ADU will determine the ceiling for ADU construction. I use a survey of 502 single-family homeowners in the Sacramento metropolitan area to investigate homeowners’ willingness to consider building an ADU, and the motivations and barriers they face. I find that as many as 54.1% of Sacramento city single-family detached homeowners could either have an ADU or be open to creating one. Familiarity with ADUs has the strongest association with openness to building an ADU in my logistic regression model. And homeowners’ top-ranked motivation for creating an ADU is housing family or friends. Cost-related concerns ranked as the biggest obstacles to creating an ADU, followed by permitting and regulatory issues. My findings suggest that ADUs have significant potential to help California close its housing supply gap.

In my third study (Chapter 4 of this dissertation), I explore how millennials – people born between 1982 and 2000 – choose where to live. Surveys suggest that millennials have a stronger preference than previous generations for urban amenities. But studies also indicate that most millennials will eventually settle in a suburb. That raises big questions for urban planners and policymakers, as well as for the future of sustainable urbanism. If most millennials will end up suburbanizing, what happens to their erstwhile preferences for urban amenities? Do they seek out suburban neighborhoods with urban amenities? Do their preferences simply change with time and major life events? I use in-depth interviews of 20 households who recently purchased homes in the San Francisco Bay Area to explore how millennials choose where to live when they reach the life cycle stages typically associated with bigger homes in suburban areas. I find that life cycle effects emerged in different ways for the households I interviewed. As they partnered and began having or thinking about having children, most households suburbanized or planned to suburbanize in the future. The households still valued urban amenities, but they generally did not prioritize urban amenities when searching for their suburban homes, with one exception – proximity to commuter transit.

Cover page of Fuels and Fuel Technologies for Powering 21st Century Passenger and Freight Rail: Simulation-Based Case Studies in a U.S. Context

Fuels and Fuel Technologies for Powering 21st Century Passenger and Freight Rail: Simulation-Based Case Studies in a U.S. Context


The last century brought a shift in rail propulsion from the (typically) coal-powered steam engine to a combination of the diesel-electric locomotive and the electrified locomotive running under electrified overhead lines. While, no doubt, an advance over the earlier technology, the two incumbent technologies are not without their shortcomings.

In the current era, rapid technological developments and increased concerns about climate change have also spurred interest away from the internal combustion engine and the use of fossil fuels in various applications. These same technologies hold promise in a rail context, a mode of transportation that relies on a smaller number of more centralized operators.

With the tremendous investment of time, cost, and other resources that can go into a pilot experiment of a fuel technology and, often, related regulatory processes, it makes sense to determine the key candidates for such pilots. A major goal of this work is to help industry and government narrow down the key technologies, in terms of cost, viability, and environmental impacts, and simultaneously identify the challenges that may be encountered by a given technology that otherwise appears to hold significant promise. This study focuses on a U.S. context, and on the period between 2022 and 2038. Passenger and freight rail routes and systems were examined, each with different characteristics, via simulations of a single rail trip, A general environmental analysis was also performed on freight switcher locomotive activity.

The fuels examined included diesel, natural gas, Fischer-Tropsch diesel, hydrogen, and, in a passenger rail and switcher context, diesel and hydrogen powertrains paired with batteries to take in regenerative braking energy. The study finds cost reductions with both natural gas and (natural gas-derived) Fischer-Tropsch diesel, but with limited environmental benefits. Hydrogen via fuel cell has significant promise to reduce GHG and criteria pollutant emissions. That technology’s costs, both fuel and equipment, are highly uncertain; however, the study finds that, with lower bound projected costs, it could be competitive with diesel-electric costs; in the case of passenger rail, hybridization with batteries is also compelling. Hybridized hydrogen also was found to demonstrate a clear environmental benefit in switcher locomotive applications.

Cover page of Modeling Bioenergy Supply Chains: Feedstocks Pretreatment, Integrated System Design Under Uncertainty

Modeling Bioenergy Supply Chains: Feedstocks Pretreatment, Integrated System Design Under Uncertainty


Biofuels have been promoted by governmental policies for reducing fossil fuel dependency and greenhouse gas emissions, as well as facilitating regional economic growth. Comprehensive model analysis is needed to assess the economic and environmental impacts of developing bioenergy production systems. For cellulosic biofuel production and supply in particular, existing studies have not accounted for the inter-dependencies between multiple participating decision makers and simultaneously incorporated uncertainties and risks associated with the linked production systems.

This dissertation presents a methodology that incorporates uncertainty element to the existing integrated modeling framework specifically designed for advanced biofuel production systems using dedicated energy crops as feedstock resources. The goal of the framework is to support the bioenergy industry for infrastructure and supply chain development. The framework is flexible to adapt to different topological network structures and decision scopes based on the modeling requirements, such as on capturing the interactions between the agricultural production system and the multi-refinery bioenergy supply chain system with regards to land allocation and crop adoption patterns, which is critical for estimating feedstock supply potentials for the bioenergy industry. The methodology is also particularly designed to incorporate system uncertainties by using stochastic programming models to improve the resilience of the optimized system design.

The framework is used to construct model analyses in two case studies. The results of the California biomass supply model estimate that feedstock pretreatment via combined torrefaction and pelletization reduces delivered and transportation cost for long-distance biomass shipment by 5% and 15% respectively. The Pacific Northwest hardwood biofuels application integrates full-scaled supply chain infrastructure optimization with agricultural economic modeling and estimates that bio-jet fuels can be produced at costs between 4 to 5 dollars per gallon, and identifies areas suitable for simultaneously deploying a set of biorefineries using adopted poplar as the dedicated energy crop to produce biomass feedstocks. This application specifically incorporates system uncertainties in the crop market and provides an optimal system design solution with over 17% improvement in expected total profit compared to its corresponding deterministic model.

Cover page of Modeling Framework for Socially Inclusive Bikesharing Services

Modeling Framework for Socially Inclusive Bikesharing Services


Bikeshare programs are increasingly popular in the United States and they are an important part of sustainable transportation systems, offering a viable mode choice for many types of last-mile trips. This popularity means that an increasing number of people can enjoy the convenience of cycling and the associated physical health benefits without actually owning a bike (or having access to their own bikes). However, bikeshare systems have not captured high levels of ridership from disadvantaged populations. Many barriers exist that prohibit residents from disadvantaged communities from accessing bikeshare services. These barriers include absence of bikeshare stations within walking distances, lack of financial resources, cultural barriers, and/or unsafe cycling environments. Most of the current research on bikeshare programs focuses on societal benefits (e.g. reducing greenhouse gas emissions by replacing auto trips with bike trips) and bikeshare system management (e.g., bike repositioning between stations). There is some emerging research focused on equity issues in developing bikeshare. However, far less attention has been paid to bikeshare programs’ potential benefits for disadvantaged communities and virtually no quantitative research on how to design bikeshare systems to improve access for these populations. This dissertation work addresses three fundamental bikeshare equity problems. 

Cover page of Homeless Negotiations of Public Space in Two California Cities

Homeless Negotiations of Public Space in Two California Cities


People experiencing homelessness find movement in urban public space constrained. Scholars have attributed this lack of accessibility to the consequences of anti-homeless laws, social exclusions and economic factors. I draw from spatial and mobility theory to frame movement and transgression within the partitioned city. I accompanied homeless people on walking interviews to discuss their movements, transgressions, and public space they occupied. I also mapped people’s behavior in public space, comparing the movements of homeless people with the movements of people with homes. The results indicate homeless people negotiate urban space by walking, biking and riding the bus in a manner that maximizes their ability to manage relationships as they travel. Constraints in movement arise from the partitioning of the city, i.e. the division into public and private, making it difficult to both rest in public space and move in socially-acceptable manners. The findings suggest cities can improve homeless movement through setting limits on the automobile and removing limits (or partitions) on informal patterns of movement.

Cover page of Environmental and economic costs, benefits and uncertainties of vehicle electrification: a life cycle approach

Environmental and economic costs, benefits and uncertainties of vehicle electrification: a life cycle approach


Battery electric vehicles (BEVs) have been proposed as a pathway for reducing the environmental impacts of transportation systems. While BEVs are often referred to as zero-emission vehicles, production and operation consume resources and emit pollutants through the vehicle supply chain and generation of electricity for vehicle charging. Life cycle assessment is a standardized methodology for assessing the environmental impacts of product systems from a system-wide perspective; considering the total supply chain and the product life cycle from cradle-to-grave. However, conventional LCAs are often limited; based off static supply chain analysis, omitting system interactions or indirect effects, and insufficiently reflecting the underlying variability and uncertainty to support robust public policy decisions.

The objective of this dissertation is to develop and refine methods of assessing the life cycle environmental impacts and economic costs of electric vehicle technologies and policies. The chapters of this dissertation make contributions in advancing spatial and temporal dynamics in LCA modelling, integrating vehicle operations with evolutions in technology, background systems, and product development, and offers novel estimates of the costs and emissions abatement potential of light and heavy duty electric vehicles. As shown herein, a systems perspective is required to estimate the environmental benefits and costs of vehicle electrification strategies. Efforts to achieve pollution abatement through technology change must address risks of leakage, substitution, and unintended environmental consequences.

Cover page of Economic and Econometric Analyses of the World Petroleum Industry, Energy Subsidies, and Air Pollution

Economic and Econometric Analyses of the World Petroleum Industry, Energy Subsidies, and Air Pollution


The decisions made by petroleum producers in the world oil market are both dynamic and strategic, and are thus best modeled as a dynamic game. In the first chapter of my dissertation, I review the literature on the world oil market and discuss my research on econometric modeling of the world oil market as a dynamic game. My research on econometric modeling of the world oil market as a dynamic game research builds on the previous literature by combining three erstwhile separate dimensions of modeling the world oil market: dynamic optimization, game theory, and econometrics.

In the second chapter of my dissertation, I develop and estimate a structural econometric model of the dynamic game among petroleum-producing firms in the world petroleum market. My model incorporates the dynamic behavior and strategic interactions that arise as petroleum-producing firms make their investment, production, merger, and acquisition decisions. I allow firms that are at least partially state-owned to have objectives other than profit maximization alone. I use the structural econometric model to analyze the effects of changes in OPEC membership, a ban on mergers, the privatization of state-owned oil companies, and demand shocks on the petroleum industry. Although I do not assume or impose that OPEC producers collude to maximize joint profits, but instead infer the strategy and payoffs for OPEC firms from the data, I find that OPEC behaves in such a way that is consistent with its mission and also with cartel behavior. Results of counterfactual simulations also show that a ban on mergers would decrease average firm payoff for both OPEC and non-OPEC firms, and decrease consumer surplus.

Gasoline taxes have been touted by many economists as an efficient and relatively simple tool to address environmental concerns and other problems associated with gasoline consumption. Nevertheless, rather than removing subsidies and increasing gasoline taxes, many countries still subsidize gasoline, which may have the opposite effect of exacerbating air pollution and other problems associated with gasoline consumption. The Iranian government has heavily subsidized petroleum products since the early 1980s. As a result of these energy subsidies and artificially low national energy price, Iran is one of the most energy-intensive countries in the world. The Iranian government has recently taken a series of measures to reform and cut back on the energy subsidies. In the third chapter of my dissertation, I evaluate the effects of the Iranian subsidy reform on air quality using a regression discontinuity design. My results provide evidence across multiple different empirical specifications that the subsidy reform in Iran led to improvements in air quality. In particular, the first subsidy reform event, which increased gasoline prices and implemented a gasoline consumption quota; and the second subsidy reform event, which increased energy prices and decreased energy subsidies, both led to declines in concentrations of CO, O3, and NO2. In contrast, the fourth subsidy reform event, which increased fuel prices but removed the gasoline consumption quota, was less effective in reducing air pollution.

Cover page of Understanding the Role of Transportation in Meeting California’s Greenhouse Gas Emissions Reduction Target: A Focus on Technology Forcing Policies, Interactions with the Electric Sector and Mitigation Costs

Understanding the Role of Transportation in Meeting California’s Greenhouse Gas Emissions Reduction Target: A Focus on Technology Forcing Policies, Interactions with the Electric Sector and Mitigation Costs


The overarching goal of this dissertation is to learn about the future options and policies for a low carbon energy system and transportation sector. It consists of three chapters that build upon and extend the CATIMES framework, and address three key issues in energy/economic modeling. Cost-effectiveness is an imperative performance measure in the policy world to evaluate any potential technology/policy measures considered for adoption to meet the long-term reduction target. Currently, insufficient attention has been paid to individual technology options or policy measures and their relative cost-effectiveness in the results of CA-TIMES, e.g., how cost-effective are electric vehicles under different scenarios/policies. In the first chapter, the author addresses the shortcomings of conventional cost-effectiveness curves, which are widely used in the policy world. The obtained curves in this chapter show costeffectiveness of various technology and policy options considering system-wide behavioral, technological, and intertemporal interactions.

Cover page of Performance Assessment of Asphalt Mixes Containing Reclaimed Asphalt Pavement and Tire Rubber

Performance Assessment of Asphalt Mixes Containing Reclaimed Asphalt Pavement and Tire Rubber


The pavement community, including both agencies and industries, is moving toward more sustainable pavement designs and pavement network management. Increasing amounts of recycled materials, both reclaimed asphalt pavement (RAP) and recycled tire rubber, are expected to be used in new pavement construction projects in the future to reduce the use of virgin binder and aggregates. The main concern of using recycled materials in new asphalt pavement is the potential negative effect on the performance. Thus, the primary objective of this dissertation is to improve the current laboratory testing technologies and performance assessment approaches for characterizing the performance-related properties of asphalt mixes containing recycled materials and to improve understanding of how these properties affect the performance of asphalt pavements so that they can be designed and constructed better.