National Center for Sustainable Transportation

While the United States has long supported basic needs of residents through social welfare programs, policies supporting affordable transportation for lower income individuals have been much more limited. Federal support for transportation includes subsidies to transit agencies and requirements to offer discounted fares to certain groups such as seniors and riders with disabilities, but income-qualified discounts are not required. This study explores opportunities for improving access to transportation affordable programs by gathering insights from existing income qualified transportation benefits. Researchers compare examples of these programs to design features of existing non-transportation benefits to characterize opportunities for increased coordination and standardization. Finally, as the U.S. has seen an increase in recent years of Universal Basic Mobility (UBM) pilots that provide flexible transportation funds, the study incorporates insights from UBM evaluations to understand how UBM design features may be useful to agencies who are pursuing transportation affordable discounts and subsidies. The results suggest that there is significant potential for income-qualified transportation program enrollment both for agencies that do not currently offer these benefits and for agencies that already offer them, and that inter-organizational coordination among stakeholders may be essential in implementing successful transportation affordable discounts or subsidies. Additionally, the structure of income-qualified transportation benefits may vary depending on agency resources. Finally, with transportation equity as growing priority for California and its transit agencies, program administrators may opt for programs with easy access and enrollment rather than those that create barriers to participation through strenuous application and verification procedures. 

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Extreme heat is the leading cause of weather-related mortality in the United States, and extreme heat events are projected to continue to increase in geographic extent, frequency, and severity in the United States as climate change progresses. Transportation infrastructure is a significant driver of the urban heat island (UHI) effect and exacerbating extreme heat events. Efforts to mitigate UHI impacts often focus on reflecting incoming solar radiation (i.e., increasing surface albedo) and providing shade (e.g., planting street trees). However, advanced and novel materials (ANM) for pavements that reduce heat storage, and green stormwater infrastructure (GSI) that promotes evaporative cooling, can provide additional heat mitigation pathways. Sidewalks facilitate non-motorized transportation, and are relatively low-risk, low-cost, and have simple structural requirements compared to other transportation infrastructure. Hence, sidewalks and adjacent planting strips can offer a logical test bed for new materials and designs. With the thermal comfort, safety, and efficiency of users in mind, environmentally responsible designs can also minimize energy embedded in construction materials and help maintain natural ecosystem processes. Although ANMs hold significant promise for heat mitigation, they have not yet achieved widespread implementation. This project systematically reviewed the growing literature related to theapplication of ANMs and GSI to reduce UHI effects and implemented a survey of urban planners and public works engineers to assess the current and planned use of these strategies and identify barriers to implementation. This report summarizes the emergent themes from the systematic literature review, survey results and policy recommendations for an anticipated reading audience of urban policy makers, planners, and practitioners. 

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Natural gas provides an alternative to petroleum-based fuels as an energy source that is being more widely adopted across multiple sectors in California. The viability of natural gas depends on its total life cycle emissions, specifically of those of methane. This paper addresses the possibility of and reason for fugitive emissions of methane from the transportation sector by surveying and quantifying methane plumes from compressed natural gas (CNG) and liquified natural gas (LNG) storage tanks at vehicle fueling facilities in the greater Los Angeles metropolitan area. This project used methane plume images provided by airborne imaging spectroscopy, collected by NASA’s AVIRIS-NG mission, to identify large methane point sources originating from CNG and LNG infrastructure. The periodic methane plume observations were converted into emission rates to provide an estimate for potential methane emissions from NG storage facilities across California. For the population of facilities that were analyzed, four had natural gas storage tanks with emission rates that are higher than the maximum rate specified by the tank manufacturers. The significant disparity between the expected emission rate and the actual emission rate can be explained by tank malfunction, as the number of observed plume events are far higher than what would be expected for a fully operational tank. If the tank malfunction rates found in the group that was analyzed were applied to the entire population of California CNG and LNG facilities, total emissions may be up to 1300 kg CH4 per hour, suggesting a need for leak monitoring and repair to prevent excessive methane emissions from this sector. 

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This project examines multi-hazard risks and the performance of emergency evacuation routes in California using spatial synthesis, mapping, modeling, and performance analysis techniques. It enhances evacuation planning by analyzing road networks under natural hazard scenarios. Key tasks included: 1. Collecting and organizing evacuation route data for 190 cities, revealing that only 23 had comprehensive GIS maps, highlighting gaps in current planning. 2. Assessing road network performance under various hazards for 450 cities, identifying high-risk areas, and classifying cities based on risk levels and concentration. 3. Analyzing evacuation routes during the 2018 Camp and Thomas fires, using mathematical modeling and Omniscape to assess bottlenecks and evacuation efficiency. 4. Evaluating evacuation route performance for different population segments and proposing improvements, including using public transit for future wildfire evacuations. The findings provide actionable insights for improving emergency evacuation strategies in the state. 

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The challenge of meeting transportation needs is heightened in rural contexts, where destinations are more dispersed and there are fewer transportation options. A growing body of literature has established that accessibility, or the ability to reach valued destinations, is critical to satisfying a person’s fundamental needs. Conversely, difficulty accessing destinations can result in travel burdens such as high transportation costs or unmet needs, adversely affecting well-being. This study evaluates differences in travel burdens and the factors that drive them in rural and urban contexts in the United States. Using the 2017 National Household Transportation Survey, the authors first evaluate differences in travel burdens across rural versus urban communities, including i) the magnitude of travel burdens, ii) who experiences travel burdens, and iii) the individual and environmental factors that are associated with travel burdens. This study finds that people living in rural areas are more likely to report burdensome travel costs and unmet travel needs compared to people living in nonrural areas, and these differences are exacerbated for people earning a low income and those without vehicle access. The authors also observe variation across rural contexts, pointing to the role that proximity to town centers plays for providing access for those without a vehicle. To better understand the relationship between unmet need and vehicle access, the authors conducted 59 semi structured interviews with two populations living in Vermont: i) people living in the largely rural Northeast Kingdom of Vermont, and ii) Latinx migrant workers living in Vermont. The qualitative interview results illustrate the transportation experiences, barriers, and adaptations of rural car-limited populations. Findings underscore the importance of vehicle access as a determinant of mobility for many people living in rural communities. The interview findings highlight barriers to mobility such as vehicle maintenance costs as well as the mobility that personal networks and limited public transportation provide for many people without a personal vehicle. The interview results also point to substantial variation in experiences and needs across rural populations, as Latinx migrant workers’ mobility was also related to English proficiency, proximity to an international border, and availability of a driver’s privilege card. As decision makers seek more sustainable rural transportation systems and a reduced reliance on vehicles, the findings from this study underscore the importance of addressing the needs of car-limited rural populations to ensure an equitable and just climate transition. 

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Reducing greenhouse gas emissions from transportation poses a significant challenge in the exurban fringe and rural communities. Populations living in these areas rely more heavily on personal vehicle travel than nonrural populations and are more likely to experience mobility challenges. One approach to curtailing these emissions is building more compact development or smart growth. However, nearly all research to date on travel and the built environment has focused on urban and suburban areas, leaving decision-makers in exurban and rural communities with little guidance for how to effectively reduce GHGs in their communities. To address this gap, travel behavior data from the Federal Highway Administration’s National Household Travel Survey is combined with detailed built environment data from the Environmental Protection Agency’s Smart Location Database to evaluate the relationships between personal and built environment factors and sustainable travel behaviors including vehicle miles traveled (VMT) and mode choice. The relationship between travel and the built environment is distinct in rural and urban areas. Notably, while in both urban and rural areas increased regional accessibility is associated with lower VMT, it is associated with increased motorized travel reliance and decreased utilitarian active travel in rural areas. Transportation planners and researchers should take note of the differing relationship of the built environment and travel between urban and rural areas. This research suggests that relationships between travel and the built environment observed in prior research conducted in urban areas may not hold in rural contexts. 

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This report outlines the technical development and application of the Total Cost of Ownership Spreadsheet Tool (TCOST), a Microsoft Excel-based calculator that simplifies and integrates the main functions, data, and outputs of pre-existing models (MOVES-Matrix and the GREET Model) and other external sources of economic data. The tool accommodates twenty-one user-input variables to produce comparative total cost of ownership figures for diesel and battery-electric trucks within any use case, broken down by cost type (capital, operation, and maintenance), both as a gross number and on a per-mile basis. The tool also provides a series of visualizations comparing cost breakdowns, breakeven points, and expected tailpipe and fuel-cycle emissions for both technologies. A hypothetical regional container drayage use-case example was developed using quantitative and qualitative data, to which TCOST was applied to demonstrate the application of the tool and its value to fleet managers and policymakers in its ability to model the cost effects of minor parameter adjustments or the multiplicative effects of simultaneous parameter adjustments quickly and easily. TCOST may be used to help inform the decision-making process for fleet vehicle acquisition and planning, helping decision makers to visualize a variety of future scenarios and map those scenarios onto their fleet operations to assess risks and make informed choices about the future technological makeup of their fleets. TCOST will help policymakers quickly model the cost impacts of potential policy levers from a business perspective. 

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California's Zero Emission Vehicle (ZEV) mandate targets all new Light Duty Vehicle (LDV) sales to be ZEVs by 2035. However, the current charging infrastructure is not well-developed in California, primarily serving households with home charging setups and leaving a noticeable gap in public charging facilities. This gap is seen as a significant barrier to Battery Electric Vehicle (BEV) adoption within California. This report explores driver charging behavior and their preference for public DC fast charging (DCFC), drawing on Stated Preference (SP) choice experiment data from a survey of 1,102 Plug-in Electric Vehicle (PEV) owners across California.

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Smaller and rural communities are often automobile dependent, a fact that has raised considerable concerns about the equity and effectiveness of market-based climate strategies including carbon taxes and carbon cap and trade schemes in rural states like Vermont. A lack of research and data describing how people in smaller and rural communities respond to changes in transportation costs is a critical gap to informing the design of market-based greenhouse gas mitigation policies and evaluating their potential outcomes. This report describes several related studies that focus on understanding the opportunities and constraints that people face in changing how they travel in small and rural communities in Vermont and also evaluates the equity implications of gas tax alternatives. The research is informed by data collected by the researcher team from interviews, surveys and unique administrative datasets. Findings show that urban, suburban, and rural households all made significant travel adjustments in response to higher gas prices. Urban households were more likely to substitute their mode of transportation or move, and rural households were more likely to adopt an electric vehicle (EV); however, most people in all community types were able to reduce the amount they travel by making fewer or shorter trips. Greater accessibility and more transit options were noted as barriers to change in all communities studied. Significant concerns about the feasibility of EVs were common and also shared across all communities. Overall, these findings suggest that market-based climate policies could be effective, even in smaller and rural communities. The authors also find that many people misunderstand how the gas tax is collected and what it funds, resulting in widely held beliefs that a mileage base fee alternative would be unfair, particularly to rural households. Using motor vehicle registration and inspection records, the researchers demonstrate that a mileage based user fee would be somewhat less regressive than the current gas tax and also less costly than the gas tax to rural households on average in Vermont. They also find that providing simple, factual, information about the gas tax and alternatives can significantly shift public support for gas tax alternatives in Northern New England. 

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The EVALUATE (Electric Vehicle Assessment and Leveraging of Unified models toward AbatemenT of Emissions) project (Phases I and II) develops a rigorous methodology involving a high-fidelity system of systems model (i.e., vehicle powertrain, EV charging profiles and grid dispatch datasets) for the purpose of forecasting the emissions outputs of a class of vehicles and use cases. Phase I findings explored urban trips by households that operate light duty vehicles (LDVs) for daily personal use. Phase II, presented here, focuses on a series of targeted case studies that extend prior work from LDVs operated by individuals to service-oriented vehicles operated by small and medium businesses. Vehicles used in the present study are representative of public service fleets including the following: pickup trucks, vans, Medium Duty (MD) delivery vehicles, and refuse trucks. In one of the study’s simulations for a MD use case where a specific marginal grid generating resource is identified on an hourly basis as the grid’s means of supplying a particular EV charging event, estimated CO2 emissions could be as much as 42% lower than a conventional gasoline vehicle, or as much as 24% higher than a conventional gasoline vehicle. This large variance is purely a function of when and how quickly the vehicle is recharged, and upstream grid factors. This study reveals key insights: (1) Higher temporal resolution is important to develop more accurate estimates of EV CO2 emissions. Along with this, EV charge management is imperative for all use cases, and has profound implications on infrastructure and emissions; (2) Hybrid Electric Vehicles (HEVs) often performed as well as EVs in contemporary simulations on the basis of emissions benefits, suggesting that consideration of an array of vehicle technologies is important; (3) There is a growing need to focus on higher rate EV charging applications (e.g., DCFC), and related implications on grid demands and energy storage, as proxied by large vehicle batteries; and (4) The trend toward increasing electrification of the transportation sector will continue in conjunction with electrification across other sectors (e.g., buildings, data centers, industry). As such, associated cross-sector planning and study of concomitant emissions must be considered in context of other grid trends. Primary contributions of this effort are the development of new methodologies, integration of sub-system models and independent data sources, and decision support tools that estimate the environmental impacts of vehicle electrification. The study’s methodologies and use cases can enhance understanding and scale-up in additional EV-grid applications, sectors and regions.

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