Transportation Commons^™

Functionality Risk Assessment And Risk-Based Management For Critical Infrastructure Systems, Anteneh Zewdu Deriba

Dissertations and Theses

Critical infrastructure systems such as transportation networks serve as the lifelines of modern society, supporting economic activity and ensuring access to critical services. Their disruption under extreme events can produce consequences extending far beyond physical damage to individual assets. In transportation networks for instance, failures of critical assets such as bridges and tunnels can reduce accessibility of communities, limit freight capabilities for commerce, and increase travel distance and travel time of road users. These consequences associated with the system functionality loss are tied not only to the physical vulnerability and failure of individual assets, but also to the system configuration …

Acceptance Of Shared Autonomous Vehicles: Exploring The Attitudes And Perspectives Of Older Adults, Sara Sohaee Urbina

Dissertations and Theses

The fast development of autonomous vehicle systems will create major changes in how people move around. Previous research shows that these technologies can benefit older people who struggle with mobility, safety and access to transportation. Shared Autonomous Vehicles (SAVs) enable older people to achieve self-reliance while obtaining essential services which enhance their quality of living. The successful deployment of SAVs requires users to accept this new technology which they must also be willing to use. This research study investigates which elements affect older adults to adopt SAVs by using an extended Technology Acceptance Model (TAM) framework.

The research design of …

Expanding Transmobilities: Understanding Genderdiverse And Transgender Travel Behavior Through An Art-Informed Methodology, Nicholas Michael Puczkowskyj

Dissertations and Theses

Transgender and genderdiverse people face discrimination and harassment in public when making trips in Portland, OR. People who identify as genderdiverse or transgender create unique travel behavior due to the influence of their internalized and expressed gender identity and through interactions in public. This dissertation examines how gender identity influences the travel behavior of genderdiverse and transgender people and how these experiences influence their subjective wellbeing when making trips in Portland, Oregon. Traditional one-on-one interviews were conducted in conjunction with allowing the interviewees to produce art as a non-verbal form of expression and communication of their experiences making trips in …

Evaluating The Impact Of Leading Pedestrian Intervals And Curb Extensions On Conflict Frequency And Severity, Sophia Semensky

Dissertations and Theses

Leading Pedestrian Intervals (LPIs) and curb extensions are commonly implemented countermeasures intended to improve pedestrian safety at signalized intersections. While LPIs have a well-established crash reduction record, fewer studies have evaluated their impacts using surrogate safety measures or examined how curb extensions interact with LPIs to influence pedestrian-vehicle conflicts. This thesis investigates the effects of LPIs and curb extensions on pedestrian safety using detailed conflict data collected at eleven signalized intersections in the Portland, Oregon metropolitan area.

Approximately 600 hours of video data were collected across four matched intersection pairs and three before–after sites. Pedestrian and vehicular volumes, turning speeds, …

An Integrated Multivariate Econometric Modeling Framework For Risky Driving Behavior Related Crashes: Evaluating Crash Risk And Severity Across Zones, Pabitra Kumar Roy

Dissertations and Theses

Rapid advancements in crash modeling have yet to fully integrate multiple behavior-driven crash types and their severity outcomes within a single, scalable framework, specially in a way that captures the sequential nature of these behaviors where one risky action may amplify another. This study proposed an integrated multivariate econometric framework to jointly model crash frequency and severity outcomes for three major behaviorally driven crash types: alcohol-related, distraction-related, and aggressive-driving-related crashes. Specifically, using Oregon's 2022 census block group-level crash data, we propose an Integrated Multivariate Negative Binomial – Generalized Ordered Probit Fractional Split (IMNB–GOPFS) model to analyze these dimensions simultaneously while …

Is Ride-Hailing A Potential Solution For Older Adults After Driving Cessation? The Role Of Objective And Perceived Accessibility, Minju Kim Song

Dissertations and Theses

Due to age-related physical and cognitive changes, older drivers have a greater risk of crashes and are restricted by age-dependent regulation. Nonetheless, many older adults in the United States maintain a car-dependent lifestyle and still prefer driving. When driving cessation or reduction becomes necessary, a primary concern is finding suitable alternative transportation modes. However, the availability of alternative transportation modes does not guarantee their actual use of these options.

As a relatively new transportation mode, ride-hailing services, such as Uber and Lyft, offer on-demand, door-to-door transportation and may be a feasible transportation solution for older adults who stop driving. While …

Geography Of Non-Daytime Work And Employer-Centered Transit Accessibility, Julia Mai Plotts

Dissertations and Theses

Non-daytime shift workers--including those on evening, night, rotating, and split shifts--face unique transportation challenges. Those who rely on public transit often contend with complicated commutes and longer wait times on public transit systems that have traditionally catered to the 9-to-5 workforce. Meanwhile, the non-daytime workforce is disproportionately composed of marginalized groups, including low-income workers, racial and ethnic minorities, and individuals with fewer education credentials. For many lower-income workers, car ownership does not present a viable alternative, as cost-of-ownership consumes a significant portion of their income. This makes access to nighttime public transit a critical equity concern. However, most transit accessibility …

Exploring Determinants Of Transit Recovery After The Covid-19 Pandemic, Udit Khandelwal

Dissertations and Theses

The COVID-19 pandemic significantly disrupted public transit systems across the US, resulting in substantial declines in ridership and revenue. At the same time, ridership has increased to different levels in cities. This thesis explores the determinants of transit recovery in American cities post-pandemic. It analyzes data from the National Transit Database (NTD) and employs a two-stage least squares (2SLS) regression model first laid out by Taylor et al. (2008) for data from 2000. Similar to the results of that paper, the thesis finds strong correlation between transit ridership and variables for transit supply and urban and demographic characteristics for 2019 …

The Central Role Of Perceived Safety In Connecting Crash Risk Factors And Walking Behavior, Kyu Ri Kim

Dissertations and Theses

Despite advanced policies, plans, and facilities, many pedestrians are still injured and killed in traffic crashes in the United States. To improve pedestrian safety and the walking environment, the relationship between surrounding crash risk factors and perceived safety that influence people's behavior needs to be studied. This study aims to examine pedestrian crash risk factors, the relationship between crash risk factors and perceived safety, measured as threatened experiences and safety attitudes, and the relationship between safety attitudes and walking behavior.

The analysis used data from three primary sources: (1) an original survey of 551 residents in 10 neighborhoods in Oregon …

A Survey Of North American Electric Bicycle Owners, Cameron Steven Bennett

Dissertations and Theses

Rapid recent growth in the popularity of electric bicycles (e-bikes) has captured the attention of transportation researchers and policymakers seeking safe, sustainable, and active alternatives to conventional transportation modes. This thesis presents an investigation of e-bike owners in North America, complementing previous efforts in 2013 and 2017, and suggests implications for North American transportation planning.

An online survey was distributed to e-bike owners in the United States and Canada through email outreach, purchase incentive programs, and social media. The survey included questions on the respondents’ demographics, e-bikes, purchase decisions, travel behavior, perceptions of e-bikes, crash experience, maintenance needs, and receipt …

A Gridded Co2 Emissions Inventory For Portland, Or, James E. Powell

Dissertations and Theses

Here we develop a new high resolution inventory of CO₂ emissions for the three Oregon counties which comprise the bulk of the City of Portland, Oregon, USA. Locally curated and long-running data collection efforts for on-road traffic activity and emission rates are used to model on-road emissions, and a new survey of the area's natural gas network informs the building energy model. The inventory estimates total emissions of CO₂ for each hour of the year 2018 in the on-road, residential, and commercial building sectors at 1 km² resolution. The onroad inventory compares to within 3% with an …

The Use And Influence Of Health Indicators In Municipal Transportation Plans, Kelly Christine Rodgers

Dissertations and Theses

Transportation is an important social determinant of health that shapes the places where people "live, learn, work, and play" to the extent that an individual's zip code better predicts their health than their genetic code. Researchers and practitioners have called for the use of health indicators in transportation as one way to integrate public health concerns into transportation. The underlying hope is that new organizational routines, such as measuring and tracking indicators, can translate policy goals into policy practice. However, it is unclear how indicators are used and what impact they have on policy--the creation or modification of policies and …

Transportation Mode Choice Behavior In The Era Of Autonomous Vehicles: The Application Of Discrete Choice Modeling And Machine Learning, Sangwan Lee

Dissertations and Theses

New mobility technologies, such as shared mobility services (e.g., car-sharing) and, more importantly, autonomous vehicles (AVs), continue to evolve. The supply-side advancement will likely disrupt and transform transportation mode choice behaviors, and create a new paradigm since they are emerging and becoming increasingly feasible alternatives to the existing modes of transportation. Accordingly, this dissertation employs discrete choice modeling (DCM) and machine learning (ML) using a U.S. nationwide stated choice experiment to understand how travelers adopt new transportation modes or continue to use conventional modes of transportation.

This dissertation consists of three papers. The first examines future market shares of each …

Adoption And Use Of E-Grocery Shopping In The Context Of The Covid-19 Pandemic: Implications For Transport Systems And Beyond, Gabriella Abou-Zeid

Dissertations and Theses

In 2020, the COVID-19 pandemic drastically impacted travel for in-person shopping, commute trips, global supply chains, and food business operations. Previously mundane tasks, like shopping for food and household items, became markedly different as new social distancing and mask guidelines were put in place to mitigate the spread of COVID-19. Concurrently, e-commerce sales in the U.S. skyrocketed. E-grocery pickup and delivery services saw unprecedented expansions. The adoption and use of e-grocery services have implications for equity and mobility, although the nature of the relationship of e-grocery to the latter is still unclear. Enhancing our understanding of the drivers of (and …

The Mode Less Traveled: Exploring Bicyclist Identity In Portland, Or, Christopher Johnson

Dissertations and Theses

This study explores bicyclist as a social identity in Portland, OR and a relatively under researched topic in the existing literature about transportation mode choice. The results indicate that bicyclists in Portland do have an understanding of what it means to be a bicyclist and particularly the normative behaviors associated with that social identity. Results also indicate that barriers to entry into this social group are quite low but the path to becoming someone who regularly chooses bicycling as a mode of transportation is not straightforward and is fraught with barriers that could easily discourage new group members. Bicyclists in …

Short-Term And Long-Term Effects Of New Light Rail Transit Service On Transit Ridership And Traffic Congestion At Two Geographical Levels, Huajie Yang

Dissertations and Theses

This dissertation quantitatively examines the effect of new Light Rail Transit (LRT) services on transit ridership and traffic congestion over time at two different geographical levels: at the corridor level, this study conducts case studies of two LRT lines in the Portland, Oregon region; at the regional level, this study uses a synthetic control method to construct a "synthetic" control Urbanized Area (UA) that closely approximates the counterfactual transit ridership and traffic congestion scenario in the absence of light rail project in three UAs across America. The results of the corridor-level study suggest that both LRT lines increased transit ridership …

Examining Bicycle And Motorized Vehicle Speeds And Their Relationships In The Context Of Urban Roadways, Jaclyn Sue Schaefer

Dissertations and Theses

This thesis presents a compilation of papers exploring passenger car and bicycle speeds through their interactions with each other and with urban roadway factors.

First, following a concern raised in part of the traffic literature that a large mode shift toward bicycling may cause travel time delays and potentially exacerbate congestion instead of alleviate it unless bicycle lanes are installed, an empirical study detailing how the presence of bicycles on urban roads without bicycle lanes may affect passenger car speeds is presented. Pneumatic tube data from six predominantly low speed, low volume roads in Portland, Oregon were utilized to identify …

Methodologies To Quantify Transit Performance Metrics At The System-Level Using High-Resolution Gps, Stop-Level, And Gtfs Archived Transit Data, Travis Bradley Glick

Dissertations and Theses

Performance metrics have typically focused at two main scales: a microscopic scale that focuses on specific locations, time-periods, and trips; and, a macroscopic scale that averages metrics over longer times, entire routes, and networks. When applied to entire transit systems, microscopic methodologies often have computational limitations while macroscopic methodologies ascribe artificial uniformity to non-uniform analysis areas. These limitations highlight the need for a middle approach.

This dissertation presents a mesoscopic analysis based around timepoint-segments, which are a novel application of an existing system for many transit agencies. For this research, routes are divided into a consecutive group of bus stops …

Comparing The Promise And Reality Of E-Scooters: A Critical Assessment Of Equity Improvements And Mode-Shift, Michael Glenn Mcqueen

Dissertations and Theses

In just three years, e-scooters have substantially disrupted and altered the urban mobility landscape. Throughout this period, they have been commonly touted as part of a larger micromobility solution that promises to erase equity barriers and solve the first-mile/last-mile problem. However, few studies in the nascent e-scooter literature have considered these claims. In this study, we surveyed students at Portland State University (n = 1,968) about the role that e-scooters, among other modes, played in meeting their general and university-related travel needs. We then estimated models that incorporated demographics, travel behavior, and latent attitudes distilled using exploratory factor analysis (EFA). …

"I Should Have Moved Somewhere Else": The Impacts Of Gentrification On Transportation And Social Support For Black Working-Poor Families In Portland, Oregon, Steven Anthony Howland

Dissertations and Theses

Portland has faced a mass displacement of Black households from the historically segregated area of Albina through various phases of urban renewal, urban deterioration, and gentrification. A substantial number of them have moved to East Portland, a suburban segment of the City of Portland that was unincorporated county land prior to the 1990's. As Black people have left Albina, the roots of Blackness there have eroded from the area as businesses and churches catering to them have also closed as a result of lost patrons.

In this study I interviewed 27 low-income working-age Black people with children with the sample …

The Impacts Of The Bicycle Network On Bicycling Activity: A Longitudinal Multi-City Approach, Wei Shi

Dissertations and Theses

Bicycling is a promising approach to improve health, environment, and economic development of urban places. Theoretically, a bicycle network's component goes beyond lanes and paths, and would generate greater impacts than the sum of its parts. However, most previous research focused on how individual types of bicycle-related infrastructure could promote bicycling. Few empirical studies investigated how bicycle networks impact bicycling activity. This project attempts to address this question. Specifically, how to properly measure bicycle networks, and what impacts bicycle networks have on bicycling activity, e.g. bike ridership and bike mode choice, across different cities and longitudinally.

To address the first …

Spatial Analysis Of Burglary And Robbery Crime Concentration Near Mass-Transit In Portland, Bryce Edward Barthuly

Dissertations and Theses

The relationship between mass-transit and the concentration of burglary and robbery crimes is inconsistent within the available literature in environmental criminology. A number of studies have provided evidence of crime concentration at and near mass transit locations where paths intersect, referred to as a node. These empirical studies bring in environmental criminology theory with the idea that crime is clustered, and the pattern of the concentrations is substantially influenced by how and why people travel and move in a city. It is suggested that public transit allows for a large proportion of the population to move around the community along …

Evaluating Project Assessment Techniques For High-Profile Transportation Projects Development And Delivery: Case Of State Departments Of Transportation (Dots) In The United States, Rafaa Ibrahim Khalifa

Dissertations and Theses

Time delays and cost overruns in construction projects are generally due to factors such as inappropriate planning, design errors, unexpected site conditions, inadvisable tools selection, change scope, weather conditions, lack of resources, and other project changes. Time delays and cost overruns are of concern to most project managers, owners, and governments. These elements of time and cost are two of the critical defects that impact the construction project delivery. These defects can lead to project failures and to various negative issues like increasing in disagreements among the project team, the contractor, suppliers, and the owner.

State Departments of Transportation (DOTs) …

The Influence Of Shared Mobility And Transportation Policies On Vehicle Ownership: Analysis Of Multifamily Residents In Portland, Oregon, Edgar Bertini Ruas

Dissertations and Theses

Since the beginning of the 21st Century, the world has seen the rapid development of the so-called "sharing economy" or collaborative consumption (Botsman, 2010). One of the first areas affected by the shared economy is vehicle ownership. With the emergence of several new providers of mobility services, such as Uber and car2go, there has been the promise of changes to the traditional way of owning and using a vehicle (Wong, Hensher, & Mulley, 2017). One potential consequence of shared mobility services is the reduction in vehicle ownership. At the same time, cities are trying to anticipate these changes by reducing …

Utilitarian Skateboarding: Insight Into An Emergent Mode Of Mobility, Michael Joseph Harpool

Dissertations and Theses

In recent years research and planning efforts to enhance the conditions and opportunities for active transportation modes have increased significantly; however, these efforts have primarily focused on pedestrians and bicyclists. Skateboarding and other alternative modes of mobility remain an untapped potential for healthy and sustainable travel. This research addresses numerous knowledge gaps in the literature on utilitarian skateboarding under the larger umbrella of active transportation. Analysis of online survey results and semi-structured interviews with skateboarders in Portland, OR provides insight into the motivations and barriers of traveling by skateboard and the demographics and perceptions of skateboard commuters. Like bicyclists and …

Recent Advances In Activity-Based Travel Demand Models For Greater Flexibility, Kihong Kim

Dissertations and Theses

Most existing activity-based travel demand models are implemented in a tour-based microsimulation framework. Due to the significant computational and data storage benefits, the demand microsimulation allows a greater amount of flexibility in terms of demographic market segmentation, temporal scale, and spatial resolution, and thus the models can represent a wider range of travel behavior aspects associated with various policies and scenarios. This dissertation proposes three innovative methodologies, one for each of the three key dimensions, to fulfill the greater level of details toward a more mature state of activity-based travel demand models.

Exploring The Determinants Of Vulnerable Road Users' Crash Severity In State Roads, Àlvaro Alfonso Caviedes Cómbita

Dissertations and Theses

Pedestrians and bicyclists are the most vulnerable road users and suffer the most severe consequences when crashes take place. An extensive literature is available for crash severity in terms of driver safety, but fewer studies have explored non-motorized users' crash severity. Furthermore, most research efforts have examined pedestrian and bicyclist crash severity in urban areas. This study focuses on state roads (mostly outside major urban areas) and aims to identify contributing risk factors of fatal and severe crashes involving pedestrians and bicyclists in state roads. Two ordinal regression models were developed (one for pedestrian and the other for bicyclist crashes) …

Utilizing High-Resolution Archived Transit Data To Study Before-And-After Travel-Speed And Travel-Time Conditions, Travis Bradley Glick

Dissertations and Theses

Travel times, operating speeds, and service reliability influence costs and service attractiveness. This paper outlines an approach to quantify how these metrics change after a modification of roadway design or transit routes using archived transit data. The Tri-County Metropolitan Transportation District of Oregon (TriMet), Portland's public transportation provider, archives automatic vehicle location (AVL) data for all buses as part of their bus dispatch system (BDS). This research combines three types of AVL data (stop event, stop disturbance, and high-resolution) to create a detailed account of transit behavior; this probe data gives insights into the behavior of transit as well as …

Assessing The Impact Of Land Use And Travel On Carbon Dioxide Emissions In Portland, Oregon, Zakari Mumuni

Dissertations and Theses

The negative consequences of sprawling metropolitan regions have attracted attention in both academia and in practice regarding how to better design settlements and alter travel behavior in a quest to curtail vehicle emissions. Studies that have attempted to understand the nexus between land use, travel and vehicle emissions have not been able to address the issue of self-selection in a satisfactory manner. Self-selection occurs when households choose their residential location based, in part, on expected travel behavior. This non-random experience makes the use of traditional regression frameworks that strongly rely on random sampling, unsuitable. This replication study's purpose was to …

"Are We Building Biking Solidarity": Gendered, Racial, And Spatial Barriers To Bicycling In Portland, Oregon, Kyla Jean Tompkins

Dissertations and Theses

Although Portland, Oregon is widely regarded as a "bike friendly" city, its bike equity remains in question. This thesis explores the barriers to biking that women and people of color face in Portland. This research uses feminist geography scholarship to understand how cycling spaces are unequal for marginalized cyclists. Using data from 28 in-depth, semi-structured interviews with infrequent and marginalized cyclists, I found that gender and race inequalities shape their barriers to biking. A hegemonic white, elite, and masculine bike culture controls the domination of cycling spaces. Women's gendered spatial inequalities are shaped by their childrearing demands, geography of fear, …