Doctoral Dissertations

Date of Award

8-2025

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Civil Engineering

Major Professor

Christopher Cherry

Committee Members

Candace Brakewood, Russell Zaretzki, Luke Jones

Abstract

This dissertation investigates the behavioral, environmental, and policy aspects of sustainable mobility solutions, specifically MaaS [Mobility-as-a-Service] and e-bikes [electric bicycles], to inform equitable and cost-effective strategies for reducing transportation-related carbon dioxide (CO2) emissions in the United States.

‎Chapter 2 examines the potential for MaaS subscription adoption among transit riders in Nashville, Tennessee, using a discrete choice experiment embedded in a stated-preference survey. Across all choice tasks, 65% of responses selected the opt-out option, indicating limited willingness to purchase MaaS bundles even when multiple options were presented. When selected, low-cost bundles were preferred, underscoring strong price sensitivity and weak demand for integrated multimodal access. Adoption was more likely among younger, lower-income riders and those using multi-ride passes, while higher-income individuals showed greater resistance to structured subscription models. These results highlight the need for MaaS designs that reflect the economic realities of transit-dependent users.

‎Chapter 3 analyzes mode substitution behavior among e-bike users, based on pooled data from the 2017 and 2023 national e-bike surveys. A multinomial logit model shows that e-bikes most commonly replace private vehicles and transit trips, especially for commuting and errands. Substitution patterns vary by income, trip purpose, and riding frequency, with middle-income and high-frequency users most likely to displace car travel. Over time, adoption has expanded beyond early adopters, indicating broader integration of e-bikes into daily travel behavior.

‎Chapter 4 evaluates the cost-effectiveness of flat e-bike purchase incentives in reducing CO₂ emissions. Simulations combining stated purchase probabilities and VMT substitution estimates reveal predictable emissions gains with increasing budget, with cost-effectiveness ranging from $600 to $830 per metric ton of lifetime CO₂ reduction. Middle-income respondents achieved the most significant displacement per dollar spent, and performance compares favorably with typical electric vehicle incentive programs.

Together, these chapters emphasize the importance of aligning decarbonization strategies with user behavior and economic context. While MaaS faces adoption challenges, e-bike incentives offer a more scalable and cost-efficient pathway for reducing transportation emissions. These findings support a pragmatic approach to mobility policy, grounded in behavioral evidence.

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