Transportation Commons^™

Spatiotemporal Dynamics Of Daily And Per Capita Vmt In California: A County-Level Analysis (2019–2023), Yong Lao, Bo Yang

Mineta Transportation Institute

Vehicle miles traveled (VMT) is a fundamental metric for assessing mobility trends and infrastructure needs. This study examines the spatial-temporal dynamics of daily VMT (DVMT) and per capita DVMT across California counties from 2019 to 2023, covering the pre-, mid-, and post-pandemic periods via GIS mapping and k-means clustering. To identify determinants of per capita DVMT, we compared traditional linear regression approaches (OLS, Ridge, LASSO, Elastic Net) with ensemble tree-based models. Specific results include: the ensemble models estimated using 2019–2022 data delivered substantially higher accuracy, achieving R² values exceeding 0.98; meanwhile, out-of-sample performance on 2023 data remained robust (R² ≈ …

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, …

Does What Happens In Vegas Increase Pedestrian Safety? A Longitudinal Study On The Effectiveness Of Pedestrian Bridges, Jalen Paulos, Joaquin Miguel Del Mundo, Brock Wentz, Janel Pietryga

Department of Orthopaedics Faculty Research

Urban populations continue to rise and the frequency that pedestrians are exposed to vehicular traffic continues to increase. The result is an increase in automobile versus pedestrian collisions. This study aims to determine the efficacy of pedestrian bridges in reducing the rates of automobile‒pedestrian collisions. Data for all automobile versus pedestrian collisions and injuries from July 1997 through December 2023 at four distinct intersections along Las Vegas Boulevard were retrieved from the Nevada Department of Transportation. These sites were chosen because of their historically high rates of automobile versus pedestrian incidents and the construction of pedestrian bridges at three of …

Causality-Aware Safety Testing For Autonomous Driving Systems, Wenbing Tang, Mingfei Cheng, Renzhi Wang, Yuan Zhou, Chengwei Liu, Yang Liu, Zuohua Ding

Research Collection School Of Computing and Information Systems

Simulation-based testing is essential for evaluating the safety of Autonomous Driving Systems (ADSs). Comprehensive evaluation requires testing across diverse scenarios that can trigger various types of violations under different conditions. While existing methods typically focus on individual diversity metrics, such as input scenarios, ADS-generated motion commands, and system violations, they often fail to capture the complex interrelationships among these elements. For instance, identical motion commands can produce different collision risks in varying scenes, and the same collision may result from different commands under different scenarios. This oversight leads to gaps in testing coverage, potentially missing critical issues in the ADS …

Weather Rescue At Sea: Recovering Historical Weather Observations From 19th Century British Naval Ships, Praveen Teleti, Ed Hawkins, Clive Wilkinson

Research Collection College of Integrative Studies

Ship logbooks represent a critical source of historical meteorological data, providing valuable observations of barometric pressure, air temperature, sea surface temperature, wind force and direction, and other variables. Substantial quantities of these records are unavailable to climate science as they have not yet been transcribed. We present ‘Weather Rescue at Sea’, a citizen-science project which transcribed millions of weather observations contained in 19th Century UK Royal Navy ship logbooks. We describe the logbook structure and weather observation-taking instructions and discuss significant challenges with the translation of handwritten text into accurate data due to errors arising from ambiguous handwriting, historical terminology, …

Evaluation Of Transportation Policy Effectiveness In The United States: Case Of Personal Electric Vehicles And Commercial Electronic Logging Devices, Hania Afzal

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Together, electric vehicle (EV) adoption and the electronic logging device (ELD) mandate illustrate two dimensions of transportation technology policy: the first driven largely by environmental and market-based incentives and the second by safety regulation and compliance requirements. Examining these cases side by side for the United States allows for a more comprehensive analysis of how technology adoption unfolds under different policy regimes, offering insights into the broader relationship between policy design, industry response, and public outcomes. The commercial motor vehicle (CMV) sector presents a different but equally important policy challenge in transportation technology adoption. Unlike consumer passenger vehicles, CMVs are …

Measuring Multimodal Equity In Resource-Challenged Mpos, Christopher Ferrell, David Reinke, John M. Eells

Mineta Transportation Institute

Ensuring transportation investments are equitable across different populations and travel modes is a priority for many agencies, yet existing tools often make these assessments difficult, especially for smaller and resource-constrained organizations. To address this gap, this report provides the findings of Phase II of our study on reviewing and developing transportation equity metrics. The Phase I project investigated transit equity metrics and provided recommendations on advancements in quantitative methods. Building on Phase I recommendations, this study investigates low-cost methods for comparing the equity between auto (roadway) and transit performance or investments for low resource transportation agencies. A literature review revealed …

What Holds High-Speed Rail Back: Lessons From Global Systems And California’S Experience, Deepak K. Sharma, Rajnish Lekhi, Scott Parr

Mineta Transportation Institute

This report examines benefits and challenges of integrating California High-Speed Rail (CHSR) with other rail systems and reviews California legislation impacting HSR’s contracting and financing alternatives. The research compares CHSR with high-speed rail systems around the world to identify similarities and differences in costs, speeds, ridership, and operating conditions. It also reviews Japan’s Land Readjustment Act as a model for value capture and land assembly and explores international experiences on rail integration, along with U.S. cases from the East Coast and Los Angeles. A review of California’s transportation legislation highlights how laws for highways and bridges differ from those for …

Equity Evaluation Of Residents’ Transit+Walk Accessibility To Sacramento Healthcare Facilities, Masoud Ghodrat Abadi, Ahoura Zandiatashbar, Aaron Pickett, Stephanie Nemet, Soheil Sharifi

Mineta Transportation Institute

Access to healthcare is a key component of public health equity, yet many U.S. communities remain dependent on private vehicles for medical travel. This study introduces an integrated framework, the Transit+Walk Score (TWS), to evaluate how effectively residents of Sacramento, California, can reach healthcare facilities via public transit and how safely, comfortably, and conveniently they can walk from transit stops to those facilities. The research aims to inform planners, transit agencies, and policy makers in designing equitable and multimodal transportation systems. The research team combined geospatial network modeling and field-based walkability audits to assess 123 healthcare facilities across Sacramento, with …

Cycling Past 50: A Closer Look Into The World Of Older Cyclists, Year 5 Survey, Carol Kachadoorian

Mineta Transportation Institute

This document reports on approximately 2,800 responses to a North American survey of older adults who cycle. The survey, open from March 2024 through February 2025, included questions that captured a person’s cycling over their life course, as well as their current cycling styles, habits, and preferences. Responses reflect the impact of various factors on an older adult’s cycling habits with respect to their ability and agility and their expectation to continue cycling. The survey asked about falls and near misses in the past year, coding fall descriptions into six categories and sorting them by the respondent’s gender and age. …

History Of The Interstate System In Indiana, Steven Wuertz

Purdue Road School

A brief history of the Interstate System in Indiana and across the Nation— 1956–2026: 70 years of the Interstate System

U.S. Arctic Sea Lines Of Communication (Sloc): The Imperative For A Maritime Complex And Corridor In The Bering Region, Samuel A. Krakower, Troy J. Bouffard

Joint Force Quarterly

This paper examines the current American capacity to defend its newfound Sea Lines of Communication in the North Pacific and Arctic Oceans. The history, and importance, of Sea Lines of Communication trace back to great naval strategists such as Rear Admiral Alfred Thayer Mahan and Sir Julian Corbett, and consistent protection of these maritime corridors in times of war and peace led to the success of the United States. As the Arctic Region emerges as a new theater of geopolitical importance, the United States finds itself significantly disadvantaged or "strategically handicapped” in terms of presence, capability, and proximity to defend …

Exploring The Effect Of Nanomodifiers On The Self-Healing Property Of Asphalt Binders, Debzani Mitra

Theses and Dissertations

This study aimed to investigate the influence of nanomodifiers on the self-healing of asphalt binder. Two base asphalt binders, PG 58-28, and PG 64-22 were modified with nanoalumina, nanoclay, and nanosilica at 1%, 3%, and 4% dosages by weight of binder. After performance grading and storage stability tests, Fourier Transform Infrared Spectroscopy (FTIR) assessed changes in unaged and short-term oxidized binders. Additionally, thermodynamic properties i.e., Surface Free Energy (SFE), of nanomodified binders were assessed via the sessile drop method. Finally, this study conducted healing characterization using the Modified Time Sweep and Linear Amplitude Sweep Healing tests. Moreover, this study looked …

Improving Public Transport Through Machine Learning Influence Flow Analysis (Mifa): Southern England Bus Case Study, Benjamin Lee, Wolfgang Garn, Masoud Fakhimi, Nick F. Ryman-Tubb

Research Collection School Of Accountancy

Public transport (PT) is crucial for enhancing the quality of life and enabling sustainable urban development. As part of the UK Transport Investment Strategy, increasing PT usage is critical to achieving efficient and sustainable mobility. This paper introduces Machine Learning Influence Flow Analysis (MIFA), a novel framework for identifying the key influencers of PT usage. Using survey data from bus passengers in Southern England, we evaluate machine learning models. Subsequently, MIFA uncovers that easy payments, e-ticketing, and mobile applications can substantially improve the PT service. MIFA’s implementation demonstrates that strength and importance lead to specific insights into how service characteristics …

Comprehensively Evaluating The Perception Systems Of Autonomous Vehicles Against Hazards, Xiaodong Zhang, Jie Bao, Jianlei Chi, Jun Sun, Zijiang Yang

Research Collection School Of Computing and Information Systems

Perception systems are vital for the safety of autonomous driving. In complex autonomous driving scenarios, autonomous vehicles must overcome various natural hazards, such as heavy rain or raindrops on the camera lens. Therefore, it is essential to conduct comprehensive testing of the perception systems in autonomous vehicles against these hazards, as demanded by the regulatory agencies of many countries for human drivers. Since there are many hazard scenarios, each of which has multiple configurable parameters, the challenges are (1) how do we systematically and adequately test an autonomous vehicle against these hazard scenarios, with measurable outcome; and (2) how do …

Removed: When Taxi Drivers Meet Dynamic Pricing: A Lesson From Singapore's Justgrab Program, Shih-Fen Cheng, Wen-Tai Hsu, Jing Li

Research Collection School Of Economics

This paper studies how dynamic pricing influences taxi drivers’ behaviors using a unique event, the inception of the JustGrab program in Singapore in 2017, which introduces dynamic pricing to some, but not all, taxi drivers. This is the first time in history that traditional taxi drivers have access to dynamic pricing. Using data covering the universe of taxi trips before and after the inception of JustGrab, we find that there is spatial reallocation that directs more taxi drivers to the previously less-served areas, that there is also a temporal reallocation that directs more taxi drivers to rush hours, as well …

Alternative Project Delivery Methods In California: The Path Forward, Ghada M. Gad, Maria Calahorra Jimenez, Chaimae Nacir, Ronald Shrestha

Mineta Transportation Institute

Alternative Project Delivery Methods (APDMs) are increasingly being recognized as effective alternatives to the traditional Design-Bid-Build (DBB) approach for transportation projects. As APDMs gain traction among California’s transportation agencies, understanding the legislative frameworks that enable their use and the characteristics of each method is critical. This study benchmarks the existing use of APDMs in California transportation agencies of varying types and sizes, while considering the characteristics (advantages and barriers/challenges to implementation) of each APDM and the authorizations enabling its implementation. Based on these findings, it also provides recommendations for key factors to consider in APDM selection and implementation. The study …

A Hydrogen Hub Blueprint For The California Supply Chain, Tyler Reeb, Barbara Taylor

Mineta Transportation Institute

As global climate targets tighten and state regulations accelerate, hydrogen technology presents a significant opportunity to help California supply chain and transportation stakeholders comply with state emissions mandates and global goals aimed to reduce the impacts of climate change. However, while fuel cell costs and infrastructure have received attention, workforce development remains overlooked. Hydrogen fuel cell electric vehicles (FCEVs) are especially promising for diesel-reliant sectors that are hard to decarbonize without negatively impacting operational efficiency. But scaling hydrogen vehicles and infrastructure in tandem with emerging consumer and industrial markets will not be easy. State and federal policies, often conflicting, further …

Understanding Mobility Limitations And Public Transportation Accessibility For People With Disabilities, Jada Meria Stringer

ETDs from 2020-2029

Mobility for people with disabilities (PWDs) depends on both the availability of transportation and public services and the accessibility of these systems. The presence of public transportation systems does not ensure usability. Vehicles, infrastructure, and the built environment must be designed to accommodate diverse physical, sensory, cognitive, and other needs. PWDs must also be able to navigate public buildings and surrounding spaces safely and comfortably. This thesis examines mobility limitations for PWDs in India and the United States, focusing on accessibility along the full mobility chain. A review of existing literature provides context on accessibility policies, design standards, and the …

Challenges In Alaskan Rural Pharmaceutical Delivery, Faith Ozer Green, Michael S. Jones

CAEPR Presentations

In remote Alaska, aviation supply chains are critical to maintaining timely flow of food and medicines to communities. We map these supply chains, and present preliminary findings from a pharmaceutical shipment data partnership with a state Tribal Health Organization. Mean and distributional shipment time are presented for communities on versus off the road system, and a multiyear regional map is presented outlining propensity for shipment times over one week. Ongoing work will incorporate multiple additional Tribal Health Organization datasets in a comprehensive econometric framework.