Below are abstracts presented at TRB by our incredible TRC team:
Lectern Session 2024: Equitable Access to Essential Places and Services
Title: Access to Early Voting and Ballot Drop Boxes in Atlanta, Georgia, During the 2020 General Election
TRC Faculty: Dana Rowangould
Abstract
Voting rights are fundamental to democracy and synonymous with citizenship. While most Americans over the age of 18 can vote, many barriers to voting exist that can prevent someone from casting a ballot in a given election. These include, among others, knowledge, motivation, childcare, time, and transportation. Historically, specific population groups have been explicitly denied the right to vote, including women, Black people, and non-property owners. Both the explicit discrimination of the past and the implicit effects of election administration decisions today combine to motivate the current work that seeks to understand how easily eligible voters in the Atlanta, GA metropolitan region—including Fulton and Dekalb Counties—can access early in-person and secure ballot drop box locations during the 2020 general election. Using spatial analysis, we find that if a voter has access to a car or a ride, there are few locations that would be burdensome from which to travel. But the vast majority of public transit trips across both counties would entail extremely burdensome trips—with travel times exceeding 10 times those of driving. The performance differences between public transit in Fulton and Dekalb counties are also substantial, with travel times in Dekalb county notably worse than those in Fulton. In all cases, eligible Black voters are likely to rely on public transit most heavily. The results have implications for election administration, equity analysis, and evaluating proposed changes in polling locations.
Title: Does Access to Voting Locations Affect the Choice to Vote?
TRC Faculty: Dana Rowangould
Abstract
Throughout US history, enfranchisement has been synonymous with citizenship. One potential means of increasing participation among populations that have been deliberately disenfranchised in the past is to make it easier for them to reach polling locations. However, recent evaluations of polling locations find that they are disproportionately harder to reach for people of color. The power (and potential abuse of power) posed by determining voting locations is underscored by the well-established effect of distance to polling locations on voter turnout. In this work, we address two open questions related to voting participation and access to polling locations. First, we extend previous studies by comparing five voting location accessibility metrics in terms of their relationship to voter turnout. Second, in light of concerns about disenfranchisement of non-white voters under the scaled back Voting Rights Act, we evaluate whether the effects of voting accessibility on participation varies by race. We evaluate these questions using voter data from the City of Atlanta, located in Fulton and Dekalb counties in Georgia, during the 2020 general election. Overall we find that accessibility has a modest but significant effect on voter participation regardless of the measure used, and that for the most part the accessibility measures that build in more realistic assumptions slightly outperform their simpler counterparts. We also find suggestive evidence that the effects of accessibility may vary depending on a voters’ race, pointing to the need for further investigation into the mechanisms behind the relationship between accessibility and voter participation.
Poster Session 2105: Emerging Research Topics in Transportation Economics and Finance
Title: Don’t Track Me: An Analysis of Public Opinions on Mileage-Based User Fees as an Alternative to the Gas Tax
TRC Faculty: Gregory Rowangould
UVM Graduate Student: Clare Nelson
Abstract
As states and the federal government begin seriously questioning the sustainability of the current transportation fuels excise tax, understanding public perception and acceptance of the alternatives is increasing pivotal for policymakers. We surveyed people in Vermont, New Hampshire, and Maine to gauge understanding of and support for a mileage-based user fee and a flat fee as potential replacements for current fuel taxes in each state using referendum style questions. The survey provided educational content regarding the current taxes and the common equity and privacy concerns associated with mileagebased user fees, in addition to respondent-specific cost estimations for current tax expenditure and hypothetical tax expenditure under each alternative using self-reported vehicle and travel information. Based on prior knowledge alone, most respondents new very little about how the current gas tax works and showed minimal support for a mileage-based user fee. After education, overall support for mileagebased user fees increased by 11%. Regression models were used to determine the variables having the largest impact on voting outcomes. Attitudes and beliefs about state government, the natural environment, personal freedoms, cars, and technology were highly significant predictors of voting preference, as were annual vehicle miles travelled, community type, and the estimated respondent-specific costs. Equity and privacy concerns became less significant with increasing education, suggesting that educational campaigns addressing these sensitive topics may be effective ways to garner future policy support. Overall, these models offer an avenue to predict future support for mileage-based user fees based on a wide array of variables.
Lectern Session 2221: Heat and Speed: Good Movies, But Not Good for Complete Street Users
Title: The Contribution of Roads and Other Paved Surfaces to Heat Microenvironments in Small Cities and Towns
TRC Faculty: Gregory Rowangould, Elizabeth Doran
TRC Graduate Students: Parker King, Brendan Lombard, Angus Nilgitsalanont, Ava Dwyer, Brittany Antonczak
Abstract
Extreme heat has been identified as the leading cause of weather-related deaths in the US and a serious public health threat that is projected to become increasingly problematic as the climate warms if adaptive actions are not taken. Compounded by the effects of climate change, the urban heat island (UHI) effect is an amplification of ambient temperatures produced by the heterogeneous properties of the built environment and can lead to disparities in extreme heat exposure across communities(1). This paper provides evidence that transportation infrastructure, comprising a significant portion of the built environment’s impervious surface area coverage, can heighten the existence and intensity of UHI’s within small and rural communities such as those found across the state of Vermont, USA. With data acquired from 11 days of mobile sampling across eight cities and towns, we use spatially corrected, sampled linear regression modeling to suggest that within a 100 m buffer of any given point, a 10% reduction of impervious surface area (ISA) could reduce canopy layer temperatures by 1°F. This finding has implications for transportation infrastructure design and regulation as well as local land use regulations and zoning across the urban-rural continuum. Additional research is required to confirm the robustness of these findings across geographic regions and climates and identify the role of any mitigating factors such as greenspace distribution or other built environment characteristics.
Poster Session 3041: Planning for Accessible Cities
Title: A Guidebook for Accessibility Measurement in Practice
TRC Faculty: Dana Rowangould
Abstract
This paper summarizes a larger guidebook on accessibility measurement. It introduces the concept of accessibility and provides guidance calculating and applying nine types of accessibility measures in different areas of transportation practice. Accessibility refers to the ease with which people can reach valued destinations and accessibility measures provide information about the links between people and opportunities. In contrast to traditional performance measures like level of service and congestion, accessibility captures the fundamental purpose of a transportation system—to link people to opportunities they value. Accessibility increases when many destinations are nearby, land uses are diverse, and multiple options are available to complete a trip. The guidebook’s information and methods can be used by agencies of different sizes, in different land-use contexts, serving different modes, and with varying levels of staff expertise, resources, and support. Its appendices contain many examples of accessibility analysis in practice and references to related resources including other guidance documents, software, and data sources. The guidebook is undergirded by a review of academic literature and transportation planning and programming documents gathered from all 50 state DOTs and approximately two dozen metropolitan planning organizations (MPOs) as well as interviews and a survey of transportation planning practitioners. The guidebook was also refined through piloting activities undertaken with transportation agencies around the country.
Title: Advancing Accessibility Measurement in Practice: Insights from Transportation Professionals
TRC Faculty: Dana Rowangould
Abstract
Transportation agencies are becoming increasingly interested in measuring accessibility, or the ease with which people reach desired destinations, in part because the concept of accessibility reflects the primary purpose of a transportation system—to connect people to the opportunities they value. Academic researchers have identified a wide range of accessibility measures that vary greatly in terms of their interpretability, data requirements, parameters, multimodalism, and relevance to different areas of transportation decision-making. At the same time, there has been a proliferation of new data and tools that provide opportunities to facilitate and improve accessibility measurement. Despite the promise of these measures, the landscape of accessibility measurement is vast and changing, which can be difficult for practitioners to navigate. In fact, the use of accessibility in practice is relatively limited, with a relatively small share of US transportation agencies using these measures. In this paper we draw from interviews and surveys of transportation professionals to determine how US transportation practitioners currently use accessibility measures, barriers to accessibility measurement, and opportunities to use accessibility measures moving forward. Our results point to a wide range of technical capacities and accessibility applications across agencies, a suite of considerations that influence whether and how accessibility measures are used, a desire among many practitioners to increase their use of accessibility, and barriers to doing so. We close with reflections on opportunities to expand and improve the use of accessibility measurement in practice to strengthen transportation decision making.
Lectern 3117: We Made It!: Time to Plan for Life After COVID-19
Title: Post-COVID Scenario Futures: A California Case Study
TRC Post-Doc: Sarah Grajdura
Abstract
The COVID-19 pandemic caused changes in how people spent their time and changes in how they traveled. Whether these changes will persist in the future, return to pre-COVID trends, or move in other directions is uncertain. This uncertainty creates an unprecedented challenge for transportation planners as they consider how best to meet sustainability and other goals in the coming years. Using California as a case study, we develop three future scenarios which aim to capture differing post-COVID travel regimes: COVID trends persist, return to pre-COVID trends, and urbanism returns. Using outputs from the state’s travel demand model, we implement a post-processing approach to modeling these scenarios at the transportation analysis zone (TAZ)-level using assumptions for five key modalities: telecommuting, eshopping, transportation network companies (TNC), public transit, and active travel. Our results indicate that policy makers should expect increases in trips and vehicle miles traveled (VMT), to varying degrees of intensity, across all three scenarios, though results differ with respect to patterns of mode use and trip purpose. The scenario analyses provide a valuable picture of possible transportation futures that can guide transportation planners as they shape future policies.
Lectern 3126: Advances in Stabilization Using Recycled Materials and Byproducts
Title: Investigating the Use of Xanthan Gum in Roadway Subbase Stabilization
TRC Faculty: Mandar Dewoolkar, Ehsan Ghazanfari
TRC Graduate Student: Ryan van der Heijden
Abstract
Treatment with additives is a commonly used technique for increasing strength and stabilization of soil for use in engineering applications. In roadway subbase applications, biopolymers are being explored as environmentally friendly alternatives to traditional stabilizers such as cement, calcium chloride, or asphalt emulsion. This study investigated the effect of the biopolymer Xanthan Gum on the strength, stiffness, and surface gas permeability of roadway subbase material. Two subbase materials were used in the study: a lab-created material and a reclaimed asphalt base material from an active roadway rehabilitation project. Scanning electron microscope imagery indicates that the Xanthan Gum coats soil particles and creates connections between them. Specimens were treated with different amounts of Xanthan Gum and subjected to different curing times. The results indicate that treatment of roadway subbase with Xanthan Gum substantially increases both the unconfined compressive strength and the elastic modulus after at least 14 days of curing. Surface gas permeability of the specimens was found to generally decrease with increased Xanthan Gum content. A strong relationship between the moisture content at time of testing and the unconfined compressive strength was observed. In general, the results of this study suggest that Xanthan Gum could be a suitable non-traditional stabilizer for roadway subbase materials.
Lectern 3207: Innovation in Accessible Transportation and Mobility
Title: Classifying Accessibility Measures and Dimensions
TRC Faculty: Dana Rowangould
Abstract
Accessibility measures that quantify the ease with which destinations can be reached have the potential to revolutionize transportation planning if they displace currently dominant mobility-focused measures. While accessibility embodies many strengths, understanding how and when to apply different measures is challenging. In this paper, we use a review of prior access-related work to organize the key dimensions or parameters that need to be defined to successfully measure the concept. We also identify six broad categories of existing measures and propose three others that address shortcomings with currently used approaches. The results will be useful for both academics and practitioners interested in applying access concepts and measures more widely.
Poster Session 3208: Critical Infrastructure Protection
Title: Evaluating Exposure to Extreme Heat Microenvironments from Transportation Infrastructure
TRC Faculty: Gregory Rowangould, Elizabeth Doran
TRC Graduate Student: Brittany Antonczak
Abstract
Extreme heat is widely recognized to be a major public health concern. The urban heat island effect exacerbates the local impacts of the climate change induced rise in temperatures and heat waves by creating micro-environments of excessively hot temperatures where people live. A significant portion of the built environment is made up of paved surfaces, a known driver behind the formation of extreme heat microenvironments within urbanized areas. Research suggests disproportionately higher extreme heat exposure for ethnic/racial minorities and individuals of lower socioeconomic status in the US and around the world. Previous research on social disparities in extreme heat exposure has predominately focused on major cities and it is unclear whether disparities exist in smaller cities and rural communities. This study presents a new population exposure-based analysis framework for evaluating disparities in the exposure to paved surfaces as a proxy for extreme heat that combines high-resolution land cover, parcel boundary, E911 site location, and sociodemographic data. Here we pilot the framework to better understand the distribution of exposure to paved surfaces across the urban-rural continuum of Vermont. This study provides evidence of widespread disproportionate exposure to the transportation infrastructure driving extreme heat microenvironments among sociodemographic groups. We find patterns of systematically higher exposure to paved surfaces for low-income neighborhoods and non-white populations in Vermont. Our findings have implications for mitigation and adaptation, as well as highlight the need for systemic solutions to the problem of widespread disproportionate heat exposure across the urban-rural continuum.
Poster Session 4060: Bicycling and Micromobility Research Omnibus Session
Title: Effect of E-Bike Use on Bicycle Infrastructure Preferences in Vermont
TRC Faculty: Gregory Rowangould
TRC Graduate Student: Stephen Montaño
Abstract
While a growing number of studies evaluate the potential for e-bikes to increase bicycle mode share and allow bicyclists to make longer trips, few studies have considered how e-bikes users' infrastructure preferences and needs may vary. We evaluate if e-bike users' infrastructure preferences, factors affecting route choice, and safety perceptions differ from those of conventional bicycle users. To evaluate these questions, we fielded a stated preference survey to current bicycle users in Chittenden County, Vermont, that asked conventional and e-bike users to identify the importance of various route characteristics, including the presence of different types of bicycle infrastructure and how safe they felt in different situations. For the most part, we find that both types of bicyclists have similar infrastructure preferences and safety concerns, but some differences were noted. Generally, e-bike users felt safer than conventional bicyclists in various contexts, with some differences being statistically significant but not very large. We also find that e-bike users' route choices are somewhat less affected by bicycle infrastructure than it is for conventional bicyclists. While e-bikes appear to have a slight effect on mitigating some safety concerns, by and large, our results suggest that both e-bike and conventional bicycle users share the same safety and infrastructure concerns and preferences. E-bikes do not reduce the need to improve conditions for bicycling on public roads.
Poster Session 4072: Current Research in Transportation Equity
Title: Who Lacks Cars and Where?: Rural–Non-Rural Disparities in Sociodemographic and Mobility Characteristics by Car Access in the United States
TRC Faculty: Dana Rowangould
TRC Graduate Student: Sierra Espeland
Abstract
Car access in dispersed rural areas is practically a necessity to get around. Yet about 4.5 million rural residents do not own a household car. Research on rural-nonrural mobility disparities is limited. This paper addresses the gaps in the literature by asking: (1) What is the scope and scale of rural car access? (2) Who does not own a car in rural areas and how people without a ready car get around? (3) What are consequences of not owning a household car in rural areas? In doing so, we applied a rural–nonrural classification and produced detailed cross-tabulations using descriptive statistics. The study results reveal stark rural–nonrural disparities in sociodemographic and transportation characteristics among zero-car households and residents. Compared to their nonrural counterparts, rural zero-car households earn 27.6 percent less ($16,000 vs. $22,100). Black or African Americans in rural areas are about 2.5 times more likely than the general rural population to be car-less, while this number decreases to 2 among their peers in nonrural areas. In rural areas, a larger proportion of zero-car residents bike or walk (19% vs. 17.1%), while the percentage of zero-car residents use public transit for work trips are significantly smaller: bus (4.9% vs. 21.6%) and subway or rail (0.18% vs. 26%), relative to their peers in nonrural areas. Collectively, the findings suggest rural zero-car households face significant mobility barriers and merit additional attention in research and practice and policy and funding interventions in improving rural mobility, accessibility, and equity.
Title: An Updated Census of the United States Near Roadway Population and Equity Analysis
TRC Faculty: Gregory Rowangould
TRC Graduate Student: Brittany Antonczak
Abstract
Ten years ago, we published a study that evaluated the size and makeup of the U.S. near roadway population. We found that 19% of the U.S. population lived within a proximity to high volume roadways where research suggests traffic emissions are elevated above urban background levels and the risk of negative health outcomes are increased. We also found that people of color and those with lower household incomes were overrepresented in the near roadway environment in almost every county in the U.S. Since our prior analysis, the evidence on a causal link between vehicle emissions exposure and a broad range of negative health outcomes has strengthened and studies continue to find elevated concentrations of traffic-related emissions along high-volume roadways. In this study, we present an updated analysis of the U.S. near roadway population using traffic data from 2018 and 2020 census data – a decadal update to our prior study – and refined equity analysis methods. We also break down exposure by light-, medium-, and heavy-duty vehicle traffic. We find that 24% of the U.S. population now lives near high volume roadways, a large share than 10 years ago. We also find that people of color and with lower household incomes are more likely to live closer to high-volume roadways or in an area with higher traffic density in majority (88%) of U.S. counties. While vehicle emission rates may have declined, the increasing size of the near roadway population and persistent inequities raise significant public health and environmental justice concerns.
Lectern Session 2123: Transitioning from Fuel Taxes to Mileage-Based User Fees
Title: A Data-Driven Analysis of Rural Equity and Cost Concerns for Mileage-Based User Fees in Vermont
TRC Faculty: Gregory Rowangould
TRC Graduate Student: Clare Nelson
Abstract
Examining substitutes to the current state and federal gasoline and diesel fuel excise taxes has become a pressing issue, exacerbated by the rise of high efficiency and alternative fuel vehicles threatening the revenue generating capacity of these taxes. A mileage-based user fee has been frequently proposed in the literature as an alternative which would offer greater benefits to rural and low-income populations than to urban and higher income populations. However, most prior analyses relied on small data sets. This study, for the first time, examined the impact of replacing the Vermont state fuels tax with a revenue-neutral mileage-based user fee using mileage and fuel economy data for over 300,000 registered passenger vehicles. We find that households would pay an additional $23 a year, with rural households and lowincome households seeing smaller price hikes than their urban and high-income counterparts. The impacts of a $180 flat fee replacing the Vermont state fuels tax was also examined due to state interest. Findings indicate a flat fee would result in much larger price fluctuations, with most households paying twice as much as they would under a mileage-based user fee. As Vermont looks towards a more sustainable future for transportation funding, a mileage-based user fee provides a more equitable outcome. The data-driven approach presented here directly questions public perceptions about inequitable cost differences. With horizontal and vertical equity concerns largely accounted for, there is political ground for further research into the implementation of a mileage-based user fee, including mileage collection technologies and administrative costs.
