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Description
It has been identified in the literature that there exists a "spatial mismatch" between geographical concentrations of lower-income or minority people who have relatively lower rates of car ownership, lower skills or educational attainment and who mainly rely on public transit for their travel, and low-skilled jobs for which they

It has been identified in the literature that there exists a "spatial mismatch" between geographical concentrations of lower-income or minority people who have relatively lower rates of car ownership, lower skills or educational attainment and who mainly rely on public transit for their travel, and low-skilled jobs for which they more easily qualify. Given this situation, various types of transportation projects have been constructed to improve public transit services and, alongside other goals, improve the connection between low-skilled workers and jobs. As indicators of performance, measures of job accessibility are commonly used in to gauge how such improvements have facilitated job access. Following this approach, this study investigates the impact of the Phoenix Metro Light Rail on job accessibility for the transit users, by calculating job accessibility before and after the opening of the system. Moreover, it also investigates the demographic profile of those who have benefited from improvements in job accessibility----both by income and by ethnicity. Job accessibility is measured using the cumulative opportunity approach which quantifies the job accessibility within different travel time limits, such as 30 and 45 minutes. ArcGIS is used for data processing and results visualization. Results show that the Phoenix light rail has improved job accessibility of the traffic analysis zones that are along the light rail line and Hispanic and lower-income groups have benefited more than their counterparts.
ContributorsLiu, Liyuan (Author) / Golub, Aaron (Thesis advisor) / Wentz, Elizabeth (Committee member) / Kuby, Michael (Committee member) / Arizona State University (Publisher)
Created2014
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Description
Increasing concentrations of carbon dioxide in the atmosphere will inevitably lead to long-term changes in climate that can have serious consequences. Controlling anthropogenic emission of carbon dioxide into the atmosphere, however, represents a significant technological challenge. Various chemical approaches have been suggested, perhaps the most promising of these is based

Increasing concentrations of carbon dioxide in the atmosphere will inevitably lead to long-term changes in climate that can have serious consequences. Controlling anthropogenic emission of carbon dioxide into the atmosphere, however, represents a significant technological challenge. Various chemical approaches have been suggested, perhaps the most promising of these is based on electrochemical trapping of carbon dioxide using pyridine and derivatives. Optimization of this process requires a detailed understanding of the mechanisms of the reactions of reduced pyridines with carbon dioxide, which are not currently well known. This thesis describes a detailed mechanistic study of the nucleophilic and Bronsted basic properties of the radical anion of bipyridine as a model pyridine derivative, formed by one-electron reduction, with particular emphasis on the reactions with carbon dioxide. A time-resolved spectroscopic method was used to characterize the key intermediates and determine the kinetics of the reactions of the radical anion and its protonated radical form. Using a pulsed nanosecond laser, the bipyridine radical anion could be generated in-situ in less than 100 ns, which allows fast reactions to be monitored in real time. The bipyridine radical anion was found to be a very powerful one-electron donor, Bronsted base and nucleophile. It reacts by addition to the C=O bonds of ketones with a bimolecular rate constant around 1* 107 M-1 s-1. These are among the fastest nucleophilic additions that have been reported in literature. Temperature dependence studies demonstrate very low activation energies and large Arrhenius pre-exponential parameters, consistent with very high reactivity. The kinetics of E2 elimination, where the radical anion acts as a base, and SN2 substitution, where the radical anion acts as a nucleophile, are also characterized by large bimolecular rate constants in the range ca. 106 - 107 M-1 s-1. The pKa of the bipyridine radical anion was measured using a kinetic method and analysis of the data using a Marcus theory model for proton transfer. The bipyridine radical anion is found to have a pKa of 40±5 in DMSO. The reorganization energy for the proton transfer reaction was found to be 70±5 kJ/mol. The bipyridine radical anion was found to react very rapidly with carbon dioxide, with a bimolecular rate constant of 1* 108 M-1 s-1 and a small activation energy, whereas the protonated radical reacted with carbon dioxide with a rate constant that was too small to measure. The kinetic and thermodynamic data obtained in this work can be used to understand the mechanisms of the reactions of pyridines with carbon dioxide under reducing conditions.
ContributorsRanjan, Rajeev (Author) / Gould, Ian R (Thesis advisor) / Buttry, Daniel A (Thesis advisor) / Yarger, Jeff (Committee member) / Seo, Dong-Kyun (Committee member) / Arizona State University (Publisher)
Created2015
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Description
The development of microsimulation approaches to urban systems modeling has occurred largely in three parallel streams of research, namely, land use, travel demand and traffic assignment. However, there are important dependencies and inter-relationships between the model systems which need to be accounted to accurately and comprehensively model the urban system.

The development of microsimulation approaches to urban systems modeling has occurred largely in three parallel streams of research, namely, land use, travel demand and traffic assignment. However, there are important dependencies and inter-relationships between the model systems which need to be accounted to accurately and comprehensively model the urban system. Location choices affect household activity-travel behavior, household activity-travel behavior affects network level of service (performance), and network level of service, in turn, affects land use and activity-travel behavior. The development of conceptual designs and operational frameworks that represent such complex inter-relationships in a consistent fashion across behavioral units, geographical entities, and temporal scales has proven to be a formidable challenge. In this research, an integrated microsimulation modeling framework called SimTRAVEL (Simulator of Transport, Routes, Activities, Vehicles, Emissions, and Land) that integrates the component model systems in a behaviorally consistent fashion, is presented. The model system is designed such that the activity-travel behavior model and the dynamic traffic assignment model are able to communicate with one another along continuous time with a view to simulate emergent activity-travel patterns in response to dynamically changing network conditions. The dissertation describes the operational framework, presents the modeling methodologies, and offers an extensive discussion on the advantages that such a framework may provide for analyzing the impacts of severe network disruptions on activity-travel choices. A prototype of the model system is developed and implemented for a portion of the Greater Phoenix metropolitan area in Arizona to demonstrate the capabilities of the model system.
ContributorsKonduri, Karthik Charan (Author) / Pendyala, Ram M. (Thesis advisor) / Ahn, Soyoung (Committee member) / Kuby, Michael (Committee member) / Kaloush, Kamil (Committee member) / Arizona State University (Publisher)
Created2012
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Description
Bicycle sharing systems (BSS) operate on five continents, and they change quickly with technological innovations. The newest “dockless” systems eliminate both docks and stations, and have become popular in China since their launch in 2016. The rapid increase in dockless system use has exposed its drawbacks. Without the order imposed

Bicycle sharing systems (BSS) operate on five continents, and they change quickly with technological innovations. The newest “dockless” systems eliminate both docks and stations, and have become popular in China since their launch in 2016. The rapid increase in dockless system use has exposed its drawbacks. Without the order imposed by docks and stations, bike parking has become problematic. In the areas of densest use, the central business districts of large cities, dockless systems have resulted in chaotic piling of bikes and need for frequent rebalancing of bikes to other locations. In low-density zones, on the other hand, it may be difficult for customers to find a bike, and bikes may go unused for long periods. Using big data from the Mobike BSS in Beijing, I analyzed the relationship between building density and the efficiency of dockless BSS. Density is negatively correlated with bicycle idle time, and positively correlated with rebalancing. Understanding the effects of density on BSS efficiency can help BSS operators and municipalities improve the operating efficiency of BSS, increase regional cycling volume, and solve the bicycle rebalancing problem in dockless systems. It can also be useful to cities considering what kind of BSS to adopt.
ContributorsCui, Wencong (Author) / Kuby, Michael (Thesis advisor) / Salon, Deborah (Committee member) / Thigpen, Calvin (Committee member) / Arizona State University (Publisher)
Created2018
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Description
Carbon Capture and Storage (CCS) is a climate stabilization strategy that prevents CO2 emissions from entering the atmosphere. Despite its benefits, impactful CCS projects require large investments in infrastructure, which could deter governments from implementing this strategy. In this sense, the development of innovative tools to support large-scale cost-efficient CCS

Carbon Capture and Storage (CCS) is a climate stabilization strategy that prevents CO2 emissions from entering the atmosphere. Despite its benefits, impactful CCS projects require large investments in infrastructure, which could deter governments from implementing this strategy. In this sense, the development of innovative tools to support large-scale cost-efficient CCS deployment decisions is critical for climate change mitigation. This thesis proposes an improved mathematical formulation for the scalable infrastructure model for CCS (SimCCS), whose main objective is to design a minimum-cost pipe network to capture, transport, and store a target amount of CO2. Model decisions include source, reservoir, and pipe selection, as well as CO2 amounts to capture, store, and transport. By studying the SimCCS optimal solution and the subjacent network topology, new valid inequalities (VI) are proposed to strengthen the existing mathematical formulation. These constraints seek to improve the quality of the linear relaxation solutions in the branch and bound algorithm used to solve SimCCS. Each VI is explained with its intuitive description, mathematical structure and examples of resulting improvements. Further, all VIs are validated by assessing the impact of their elimination from the new formulation. The validated new formulation solves the 72-nodes Alberta problem up to 7 times faster than the original model. The upgraded model reduces the computation time required to solve SimCCS in 72% of randomly generated test instances, solving SimCCS up to 200 times faster. These formulations can be tested and then applied to enhance variants of the SimCCS and general fixed-charge network flow problems. Finally, an experience from testing a Benders decomposition approach for SimCCS is discussed and future scope of probable efficient solution-methods is outlined.
ContributorsLobo, Loy Joseph (Author) / Sefair, Jorge A (Thesis advisor) / Escobedo, Adolfo (Committee member) / Kuby, Michael (Committee member) / Middleton, Richard (Committee member) / Arizona State University (Publisher)
Created2017
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Description
Transportation network connectivity has been linked to positive urban outcomes, including increased rates of active transportation, reduced reliance on automobiles and other social and economic benefits. While many stakeholders in greenfield development processes have emphasized the positive benefits of connectivity and connectivity has increased in many U.S. metros in the

Transportation network connectivity has been linked to positive urban outcomes, including increased rates of active transportation, reduced reliance on automobiles and other social and economic benefits. While many stakeholders in greenfield development processes have emphasized the positive benefits of connectivity and connectivity has increased in many U.S. metros in the past two decades, many street networks remain fragmented and local connectivity remains far below that of historic patterns. This paper explores barriers to and influences on connectivity outcomes in new community construction in the Phoenix metropolitan area, employing mixed qualitative and quantitative methods. Interviews were conducted with members from various stakeholder groups in the subdivision development process. Case studies were developed with space syntax and network analysis measurements to illustrate the influence of variables and stakeholders on the planning process. Participants illustrated a complex political and economic reality surrounding the concept of connectivity, with site conditions and development market dynamics playing the clearest roles in shaping connectivity. The result is subdivisions are achieving moderate levels of connectivity and improving from historic patterns of dendricity but remain entrenched in planning paradigms built around self-contained sites and the policy and market limitations for robust connectivity beyond individual developments.
ContributorsSchumerth, Noah John (Author) / King, David A (Thesis advisor) / Kuby, Michael (Committee member) / Lindsay, Lucas (Committee member) / Arizona State University (Publisher)
Created2022
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Description
Since the mid-2000s, the domestic aviation industry has been influenced by new, rapidly growing ultra low-cost carriers (ULCCs) such as Allegiant Air, Spirit Airlines, and Frontier Airlines. These carriers augment the existing low-cost airline model by operating largely point-to-point routes with a minimum of passenger amenities. Existing literature, however, is

Since the mid-2000s, the domestic aviation industry has been influenced by new, rapidly growing ultra low-cost carriers (ULCCs) such as Allegiant Air, Spirit Airlines, and Frontier Airlines. These carriers augment the existing low-cost airline model by operating largely point-to-point routes with a minimum of passenger amenities. Existing literature, however, is limited for North American ULCCs, often lumping them together with mainstream low-cost carriers. The pattern of markets served by ULCCs is incongruous with the models of other airlines and requires further research to examine causal factors. This paper sought to establish conclusions about ULCCs and the relevant market factors used for airport choice decisions.The relationship between ULCC operations and airport choice factors was analyzed using three methods: a collection of 2019 flight data to establish existing conditions and statistics, two regression analyses to evaluate airport market variables, and three case studies examining distinct scenarios through qualitative interviews with airport managers. ULCC enplanement data was assembled for every domestic airport offering scheduled ULCC service in 2019. Independent variable data informed by previous research were collected for every Part 139 airport in the U.S. The first regression analysis estimated a OLS regression model to analyze the log of enplanements. The second model estimated a binary logistic equation for ULCC service as a 0-1 dependent variable. Case studies for Bellingham, Washington, Waco, Texas, and Lincoln, Nebraska were selected based on compelling airport factors and relevant ULCC experience. Results of the research methods confirm certain theories regarding ULCC airport choice, but left others unanswered. Maps of enplanements and market share revealed concentrations of ULCC operations on the East Coast. Each regression analysis showed a strong and positive relationship between population figures and the existence and quantity of ULCC operations. Tourism employment was only significantly related to enplanements. Other factors including distance and competition variables were significantly associated to ULCC service. Case studies revealed the importance of airport fees and costs in ULCC decision-making; factors that proved difficult to investigate quantitatively in this research. Further research may shed light on this complex and ever- changing subset of the domestic commercial aviation industry.
ContributorsTaplin, Drew (Author) / Kuby, Michael (Thesis advisor) / King, David (Committee member) / Salon, Deborah (Committee member) / Arizona State University (Publisher)
Created2021
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Description
Transportation infrastructure facilitates humans in moving themselves and material goods, and thereby supports the functioning of human society. Transportation planners, engineers, and decision makers in the 20th century largely excluded local stakeholders from planning processes; the resultant built environment has perpetuated inequity and social division. Transportation system planning has often

Transportation infrastructure facilitates humans in moving themselves and material goods, and thereby supports the functioning of human society. Transportation planners, engineers, and decision makers in the 20th century largely excluded local stakeholders from planning processes; the resultant built environment has perpetuated inequity and social division. Transportation system planning has often been conducted in specialized departments with little interdisciplinary collaboration. Integration of diverse perspectives and ontologies throughout transportation planning processes can produce robust, resilient, equitable, and sustainable transportation systems. Geodesign is a framework for planning the built environment that necessarily involves voices from multiple perspectives including local stakeholders, design professionals, geographic scientists, and information technology coordinators. Geodesign uses geographic information systems to create designs that reflect stakeholder needs, values, and priorities while addressing the study area’s geographic context. Geodesign has been used primarily for land use planning and has only addressed transportation planning concerns in relation to land use.This dissertation consists of an introduction, three projects that apply the geodesign framework to transportation planning and a concluding chapter. The introduction details the rationale for this research. The first project is a systematic review of geodesign projects that address transportation systems. The review seeks to identify epistemological alignment between the geodesign framework and participatory transportation planning. The results demonstrate that geodesign comports with transportation planners’ existing practices and uses of planning support systems. The combination of geodesign and transportation planning methods for stakeholder engagement could produce a synergistic framework for transportation infrastructure planning. The second project applies geodesign to locating refueling stations for hydrogen fuel cell vehicles around Hartford, Connecticut. Network designs generated by workshop participants were compared to networks generated by optimization models. The third project applies geodesign to locating sites for micromobility hubs in Tempe, Arizona, via short-form workshop series format. Participants considered the format conducive to collaborative public participatory design. These three projects demonstrate the suitability of the geodesign framework for node-based transportation facility planning via communicative rationality. The conclusion summarizes these three projects and highlights the reproducibility of the geodesign method for node-based transportation facility location planning in other study areas.
ContributorsLopez Jaramillo, Oscar (Author) / Kuby, Michael (Thesis advisor) / Wentz, Elizabeth (Committee member) / Ruddell, Darren (Committee member) / Arizona State University (Publisher)
Created2023
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Description
Walking and bicycling bring many merits to people, both physically and mentally.

However, not everyone has an opportunity to enjoy healthy and safe bicycling and

walking. Many studies suggested that access to healthy walking and bicycling is heavily

related to socio-economic status. Low income population and racial minorities have

poorer

Walking and bicycling bring many merits to people, both physically and mentally.

However, not everyone has an opportunity to enjoy healthy and safe bicycling and

walking. Many studies suggested that access to healthy walking and bicycling is heavily

related to socio-economic status. Low income population and racial minorities have

poorer transportation that results in less walking and bicycling, as well as less access to

public transportation. They are also under higher risks of being hit by vehicles while

walking and bicycling. This research quantifies the relationship between socioeconomic

factors and bicyclist and pedestrian involved traffic crash rates in order to establish an

understanding of how equitable access to safe bicycling and walking is in Phoenix. The

crash rates involving both bicyclists and pedestrians were categorized into two groups,

minor crashes and severe crashes. Then, the OLS model was used to analyze minor and

severe bicycle crash rates, and minor and severe pedestrian crash rates, respectively.

There are four main results, (1) The median income of an area is always negatively

related to the crash rates of bicyclists and pedestrians. The reason behind the negative

correlation is that there is a very small proportion of people choosing to walk or ride

bicycles as their commuting methods in the high-income areas. Consequently, there are

low crash rates of pedestrians and bicyclists. (2) The minor bicycle crash rates are more

related to socio-economic determinants than the severe crash rates. (3) A higher

population density reduces both the minor and the severe crash rates of bicyclists and

pedestrians in Phoenix. (4) A higher pedestrian commuting ratio does not reduce bicyclist

and pedestrian crash rates in Phoenix. The findings from this study can provide a

reference value for the government and other researchers and encourage better future

decisions from policy makers.
ContributorsWu, Feiyi (Author) / Nelson, Trisalyn (Thesis advisor) / Salon, Deborah (Committee member) / Kuby, Michael (Committee member) / Arizona State University (Publisher)
Created2020
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Description
With the acceleration of urbanization in many parts of the world, transportation challenges such as traffic congestion, increasing carbon emissions, and the “first/last-mile” connectivity problems for commuter travel have arisen. Transport experts and policymakers have proposed shared transportation, such as dockless e-scooters and bike-sharing programs, to solve some of these

With the acceleration of urbanization in many parts of the world, transportation challenges such as traffic congestion, increasing carbon emissions, and the “first/last-mile” connectivity problems for commuter travel have arisen. Transport experts and policymakers have proposed shared transportation, such as dockless e-scooters and bike-sharing programs, to solve some of these urban transportation issues. In cities with high population densities, multimodal mobility hubs designed to integrate shared and public transportation can be implemented to achieve faster public connections and thus increase access to public transport on both access and egress sides. However, haphazard drop-offs of these dockless vehicles have led to complaints from community members and motivated the need for neighborhood-level parking areas (NLPAs). Simultaneously, concerns about the equitable distribution of transportation infrastructure have been growing and have led to the Biden Administration announcing the Justice40 Initiative which requires 40% of certain federal investments to benefit disadvantaged communities. To plan a system of NLPAs to address not only the transportation shortcomings while elevating these recent equity goals, this thesis develops a multi-objective optimal facility location model that maximizes coverage of both residential areas and transit stations while including a novel constraint to satisfy the requirements of Justice40. The model is applied to the City of Tempe, Arizona, and uses GIS data and spatial analyses of the existing public transportation stops, estimates of transit station boardings, population by census block, and locations of disadvantaged communities to optimize NLPA location. The model generates Pareto optimal tradeoff curves for different numbers of NLPAs to find the non-dominated solutions for the coverage of population nodes and boardings. The analysis solves the multi-objective model with and without the equity constraint, showing the effect of considering equity in developing a multimodal hub system, especially for disadvantaged communities. The proposed model can provide a decision support tool for transport and public authorities to plan future investments and facilitate multimodal transport.
ContributorsQuan, Hejun (Author) / Kuby, Michael (Thesis advisor) / Frazier, Amy (Thesis advisor) / Tong, Daoqin (Committee member) / Arizona State University (Publisher)
Created2022