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¹ Parrish, R. G. 2016. “Environmental Scan of Existing Domains and Indicators to Inform Development of a New Measurement Framework for Assessing the Health and Vitality of Communities.” Conducted for the National Committee on Vital and Health Statistics, U.S. Department of Health and Human Services; World Health Organization (WHO). 2014. “Child Health and Development.” https://www.emro.who.int/child-health/research-and-evaluation/indicators/All-Pages.html. Accessed October 20, 2024; Hezri, A. A., and S. R. Dovers. 2006. “Sustainability Indicators, Policy and Governance: Issues for Ecological Economics.” Ecological Economics 60:86–99; Giles-Corti, B., A. V. Moudon, M. Lowe, D. Adlakha, E. Cerin, and G. Boeing. 2022. “Creating Healthy and Sustainable Cities: What Gets Measured, Gets Done.” The Lancet Global Health 10(6).

² Martens, K., J. Bastiaanssen, and K. Lucas. 2019. “2 - Measuring Transport Equity: Key Components, Framings and Metrics.” In Measuring Transport Equity, edited by K. Lucas, K. Martens, F. Di Ciommo, and A. Dupont-Kieffer (pp. 13–36). Amsterdam: Elsevier. https://doi.org/10.1016/B978-0-12-814818-1.00002-0; Pereira, R. H. M., and A. Karner. 2021. Transportation Equity. Amsterdam: Elsevier.

³ In the academic literature, transportation equity is often treated as synonymous with distributive justice in transportation; the term “justice” in this case refers to ideals of fairness rather than legalistic interpretations of right and wrong (as in the criminal justice system). This report uses the term “transportation equity” but refers to “justice” when it appears in referenced materials.

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⁴ Lewis, E. O., D. MacKenzie, and J. Kaminsky. 2021. “Exploring Equity: How Equity Norms Have Been Applied Implicitly and Explicitly in Transportation Research and Practice.” Transportation Research Interdisciplinary Perspectives 9(March):100332. https://doi.org/10.1016/j.trip.2021.100332.

distinguish between “horizontal” and “vertical” equity.⁵ Many have argued that providing sufficient access to all groups should be the primary goal of an equity-focused transportation system using a capabilities approach.⁶ This means understanding of someone’s access is mediated by understanding of the person’s individual characteristics, such as whether someone can use the transportation system as a function of, for example, disability, price relative to income, and freedom from harassment, among others, and how the interaction of the land use and transportation systems enable capability to reach desired destinations.⁷

Although transportation equity is principally concerned with the distribution of benefits and burdens, broader perspectives may be considered for achieving equity. For example, the concept of mobility justice refers to ways of ensuring that people have the freedom to live, move about, and exchange ideas. In academic literature, elements of mobility justice include distributive justice for access and basic capabilities as described earlier; deliberative justice to recognize individuals and invite them to deliberate and participate in decisions; procedural justice to guarantee meaningful participation in decision making, which includes access to information; restorative justice to acknowledge and repair past harms; and epistemic justice to acknowledge the role of individuals and communities in the production of knowledge and the value of their experiences as important data, including through compensation for their work in producing and sharing those data.⁸ From a practitioner perspective, mobility justice encompasses specific principles that, when followed, aim to reduce barriers to mobility and access. Such principles include acknowledging and repairing the historic harms imposed by planning, recognizing that identity influences vulnerability in the transportation system, valuing community input as proper data, and co-creating

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⁵ Litman, T. 2024. “Evaluating Transportation Equity: Guidance for Incorporating Distributional Impacts in Transport Planning.” Victoria Transport Policy Institute. https://www.vtpi.org/equity.pdf. Accessed October 20, 2024.

⁶ Golub, A., and K. Martens. 2014. “Using Principles of Justice to Assess the Modal Equity of Regional Transportation Plans.” Journal of Transport Geography 41:10–20; Pereira, R. H. M., T. Schwanen, and D. Banister. 2017. “Distributive Justice and Equity in Transportation.” Transport Reviews 37(2):170–191; Boisjoly, G., and A. M. El-Geneidy. 2017. “The Insider: A Planners’ Perspective on Accessibility.” Journal of Transport Geography 64:33–43; Martens, K. 2017. Transport Justice: Designing Fair Transportation Systems. New York: Routledge; Martens, K., and A. Golub. 2021. “A Fair Distribution of Accessibility: Interpreting Civil Rights Regulations for Regional Transportation Plans.” Journal of Planning Education and Research 41(4):425–444.

⁷ Pereira, R. H. M., T. Schwanen, and D. Banister. 2017. “Distributive Justice and Equity in Transportation.” Transport Reviews 37(2):170–191.

⁸ Sheller, M. 2018. Mobility Justice: The Politics of Movement in an Age of Extremes. Verso Books.

community processes for decision making, among others.⁹ Understanding how transportation investment decisions have produced inequities that persist in communities today (as an example, see Box 2-2 for the impact of the highway system on Atlanta, Georgia) is critical to producing a more equitable system in the future.¹⁰

Equity and Environmental Justice Analysis

Environmental justice analysis, long a part of transportation decision making, falls under the broader umbrella of equity analysis. Environmental justice analysis is rooted in Title VI of the Civil Rights Act of 1964, and the Executive Order on “Federal Actions to Address Environmental Justice in Minority Populations and Low-Income Populations,” signed in 1994. These laws and directives, together with related legislative acts and policies, propelled federal agencies to ensure nondiscrimination in funding and programming based on race, national origin, and income. Federal agencies were required to “collect, maintain, and analyze information assessing and comparing environmental and human health risks borne by populations identified by race, national origin, or income” and to “determine whether their programs, policies, and activities have disproportionately high and adverse human health or environmental effects on minority populations and low-income populations.”¹¹ The U.S. Department of Transportation (USDOT) issued its first environmental justice order in 1997 to implement the directives in the executive order, which has since been amended three times. The principles USDOT established included avoiding, minimizing, or mitigating disproportionately high and adverse health, environmental, social, and economic effects of transportation; ensuring fair and meaningful public participation; and preventing the denial of benefits to minority and low-income groups.¹² These principles tailored specifically toward environmental justice reflect an early approach to using equity in transportation planning and programming at the federal level. These same principles apply to those receiving federal funding or requiring federal approval for projects, such as public transit agencies implementing major service changes.

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⁹ For example, “Untokening 1.0—Principles of Mobility Justice.” November 11, 2017. http://www.untokening.org/updates/2017/11/11/untokening-10-principles-of-mobility-justice. Accessed October 20, 2024.

¹⁰ National Academies of Sciences, Engineering, and Medicine. 2024. Elevating Equity in Transportation Decision Making: Recommendations for Federal Competitive Grant Programs. Washington, DC: The National Academies Press. https://doi.org/10.17226/27439.

¹¹ Executive Order (E.O.) 12898. February 11, 1994. https://www.archives.gov/files/federal-register/executive-orders/pdf/12898.pdf. Accessed November 24, 2024.

¹² USDOT. n.d. “Environmental Justice Strategy.” https://www.transportation.gov/civil-rights/civil-rights-awareness-enforcement/environmental-justice-strategy. Accessed October 17, 2024.

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¹³ Federal Highway Administration, USDOT. “Environmental Review Toolkit, Guidance on Environmental Justice and NEPA.” https://www.environment.fhwa.dot.gov/env_topics/ej/guidance_ejustice-nepa.aspx. Accessed October 17, 2024.

¹⁴ Karner, A., and D. Niemeier. 2013. “Civil Rights Guidance and Equity Analysis Methods for Regional Transportation Plans: A Critical Review of Literature and Practice.” Journal of Transport Geography 33:126–134.

¹⁵ Karner, A., and A. Golub. 2015. “Comparison of Two Common Approaches to Public Transit Service Equity Evaluation” Transportation Research Record 2531(1):170–179. https://doi.org/10.3141/2531-20.

¹⁶ Karner, A., R. H. M. Pereira, and S. Farber. 2024. “Advances and Pitfalls in Measuring Transportation Equity.” Transportation, January. https://doi.org/10.1007/s11116-023-10460-7; Pereira, R. H. M., T. Schwanen, and D. Banister. 2017. “Distributive Justice and Equity in Transportation.” Transport Reviews 37(2):170–191. https://doi.org/10.1080/01441647.2016.1257660.

forward-looking perspective (“How will this intervention improve conditions?”) in contrast to a status quo perspective in the environmental justice approach (“Will this intervention produce disparate harms?”). Second, equity analysis includes more population groups than the narrower environmental justice analytical focus on people of color and low-income individuals and various dimensions in which an individual or community might be disadvantaged. These dimensions might include transportation insecurity, gender, disability, and immigrant status, and asset ownership such as car ownership and housing cost burden. Combinations of transportation disadvantage are also acknowledged.

More recent executive orders on racial equity and environmental justice strengthen the focus on data and metrics for transportation equity. In particular, the Executive Order on “Revitalizing Our Nation’s Commitment to Environmental Justice for All” requires the Office of Science and Technology Policy to develop a plan that includes recommendations for “disaggregating environmental risk, exposure, and health data by race, national origin, income, socioeconomic status, age, sex, disability, and other readily accessible and appropriate categories.”¹⁷ This requirement draws attention to data needs that support meaningful equity metrics.

CAUSAL CHAIN ANALYSIS AND TRANSPORTATION’S ROLE IN SOCIETAL OUTCOMES

Causal chain analysis is a way to better understand transportation’s role in compromising or improving outcomes for disadvantaged populations. In its most simple form, causal chain analysis produces a linear sequence of events such that event A causes event B which causes event C, where “cause” is established by logic or empirical evidence.¹⁸ In the field of public health, researchers use evidence-based logic models or pathway diagrams to connect policies and actions to outcomes. The analysis involves identifying and mapping out a series of intermediary steps or events that connect an initial cause (such as a risk factor) to its final effect (such as a health outcome).

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¹⁷ E.O. 14096. April 21, 2023. https://www.federalregister.gov/d/2023-08955/p-81.

¹⁸ Causal change and theory of change are closely related approaches. The theory of change examines how an intervention will lead to progressive change guided by theory (Rogers, P. 2014. Theory of Change, Methodological Briefs: Impact Evaluation 2. UNICEF Office of Research. https://www.entwicklung.at/fileadmin/user_upload/Dokumente/Evaluierung/Theory_of_Change/UNICEF_Theory_of_change.pdf). In many cases, the theory between transportation investments and societal outcomes is not well formed. A causal chain is a logic model allowing for descriptive relationships representing how interventions can lead to outcomes (Kneale, D., J. Thomas, M. Bangpan, H. Waddington, and D. Gough. 2018. “Causal Chain Analysis in Systematic Reviews of International Development Interventions.” CEDIL Inception Paper 4).

There are often intermediary variables that mediate the relationship between the initial exposure (or a base condition) and the final outcome. For example, smoking (initial exposure) leads to tar accumulation in the lungs (intermediary variable), which causes cellular mutations (another intermediary variable), which eventually leads to lung cancer (final outcome).

To connect transportation investments to long-term societal outcomes, each link in the causal chain that explains transportation’s role within domains such as employment or education is articulated. Causal chain analysis is particularly consistent with a safe system approach,¹⁹ which has been adopted by USDOT as the guiding framework for addressing roadway safety. Here, the intent is to identify comprehensive, holistic strategies for mitigating risks and improving safety outcomes in the transportation system. Consider the example of an intersection at which there have been many severe pedestrian–vehicle crashes. Under a safe system analysis, transportation safety planners and engineers may have identified this intersection, as well as other hotspots, using spatial data analysis. The societal (population-level) outcome is to lower the number of severe crashes, which could be expressed as a number or rate of crashes compared to a goal. A causal chain analysis would step backward from this metric to examine all the links leading to a reduction in severe crashes. The most proximate cause of the high number of crashes is likely to be related to a design characteristic of the intersection; for instance, a slip lane may encourage vehicles to turn through the intersection at a high rate of speed or objects like parked cars or trees may obstruct the view of drivers as they round the corner. Changing the configuration or improving daylighting at the intersection would eliminate, mitigate, or address the most immediate cause of the crashes.

However, the intersection’s design is not the root cause of the crashes. To use the language of epidemiology, stopping at this level of analysis would address the symptom but not the disease. One step back in a possible causal chain would look at what is generating the number of cars and pedestrians that travel through the intersection; in other words, the factors that contribute to a high level of risk exposure. For example, the intersection may be located near a car-oriented shopping development that is across the street from a senior living center. The analysis at this step might examine whether there are alternative modes available to the shopping center to reduce the number of vehicles passing through, whether driveways are encouraging unsafe movements near the intersection, and whether enough time is provided

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¹⁹ Elvik, R. 2003. “Assessing the Validity of Road Safety Evaluation Studies by Analysing Causal Chains.” Accident Analysis & Prevention 35(5):741–748; Shinar, D. 2019. “Crash Causes, Countermeasures, and Safety Policy Implications.” Accident Analysis & Prevention 125:224–231.

for older pedestrians to cross the street. Yet another step back in the chain might examine the broader conditions that contribute to patterns of vehicle and pedestrian movement. For example, land use and zoning policies may encourage a strict separation of residential locations from shopping districts and work locations, making travel by nondriving modes difficult or impossible. Solutions could involve zoning reform and incentives for mixed-used development, reducing the initial exposure of pedestrians to vehicles. Note that solutions at this stage are likely to involve land use planners, business owners, community development planners, and other professionals outside of the transportation sector.

In addition, the transportation outcome may not be the appropriate place to end the causal chain analysis to solve population-level outcomes. For example, if the survivorship rate of severe crashes is low, the analysis should move forward in the chain to examine postcrash care variables: emergency vehicle response times, hospital locations, medical staffing, and hospital capacity, among others. Addressing these issues would require collaboration with experts in other domains and may necessitate their own causal chain analyses to investigate solutions to deficiencies.

Not every transportation project will lead directly to improvements in individual or societal outcomes. Many times, transportation is just one (essential) piece of a larger group of elements that must be in place in the system: in other words, transportation improvements may be a necessary but not sufficient factor in improving individual or societal outcomes. Because policies across domains often function as an interdependent system, misalignment between domains can lead to inequitable outcomes, while policies that act together can make significant improvements in life circumstances.²⁰

OPERATIONALIZING TRANSPORTATION EQUITY METRICS

Indicators and metrics, as defined in the report, are the typology often used to operationalize evidence-based policies in public health.²¹ Using this

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²⁰ Robins, J. M. 1986. “A New Approach to Causal Inference in Mortality Studies with a Sustained Exposure Period—Application to Control of the Healthy Worker Survivor Effect.” Mathematical Modelling 7(9–12):1393–1512; Greenland, S., J. Pearl, and J. M. Robins. 1999. “Causal Diagrams for Epidemiologic Research.” Epidemiology 10(1):37–48.

²¹ Bell, S., and S. Morse. 2011. “An Analysis of the Factors Influencing the Use of Indicators in the European Union.” Local Environment 16(3):281–302; Sébastien, L., T. Bauler, and M. Lehtonen. 2014. “Can Indicators Bridge the Gap Between Science and Policy? An Exploration into the (Non) Use and (Non) Influence of Indicators in EU and UK Policy Making.” Nature and Culture 9(3):316–343; e.g., Giles-Corti, B., A. V. Moudon, M. Lowe, D. Adlakha, E. Cerin, and G. Boeing. 2022. “Creating Healthy and Sustainable Cities: What Gets Measured, Gets Done.” The Lancet Global Health 10(6):e919–e926.

typology, we can use causal chain analysis to connect transportation investments to long-term societal outcomes. Although societal outcomes are typically multicausal, identifying long-term outcomes and the causal chain back to transportation decision making is important for two reasons: (1) to select transportation indicators and metrics that have a meaningful relationship to long-term outcomes for individuals and communities, and (2) to align transportation investments with long-term societal outcomes that are equitable. For example, for the long-term outcome “economic security” and the intermediate outcome “employment,” the indicator “transit access” could be operationalized by the number of bus stops within half a mile or by the number of bus routes with frequent service. The transportation agency would have to decide which of these two metrics was the most meaningful to move toward equitable economic security.

Indicators can be categorized as inputs, outputs, and outcomes, as defined previously in Box 2-1. Outcome indicators measure the objective of the program or project, that is, the intended results. Outcome indicators are generally longer term and have multiple contributing factors. In causal chain analysis, transportation outcomes may be the final outcome from a transportation agency’s perspective; however, the transportation outcome may serve as an intermediate outcome on the causal chain toward an individual or societal outcome. For example, an increased share of trips via walking or biking may be the transportation agency’s long-term outcome, but it also represents an intermediate outcome along a causal chain of increasing physical activity (another intermediate outcome) toward a long-term societal outcome of improved physical health and reduced risk of chronic disease.

Output indicators measure a product or activity; a transportation example is miles of protected bicycle lanes. Output metrics are attractive to transportation agencies because they are within the agency’s sphere of control and are often easier to measure. However, on their own, output indicators do not signal if the agency is moving toward a desired outcome. For example, the miles of protected bicycle lanes built do not measure whether their use eventually leads to improved health outcomes or improved health outcomes for disadvantaged populations. The transportation agency should still consult research and evaluation results to connect the output (e.g., protected bicycle lanes) along a causal chain with the desired outcome (e.g., bicycle mode share). Even with a demonstrated connection, comparing progress of the output metric relative to the outcome metric enables the agency to assess whether a course correction is needed.

Input indicators measure the resources a transportation agency invests to produce outputs that work toward achieving an outcome; for example, funding for bicycle infrastructure is an input indicator. Coming earlier in the causal chain, inputs (e.g., investment levels) may not produce the desired

outputs or the expected outcomes. Evaluation of input and output metrics against the progress of outcome metrics informs decisions about appropriate levels of funding, resource efficiency, and whether projects or programs are appropriately scoped to meet goals and outcomes.

ACCESS TO DESTINATIONS

To address the statement of task’s charge to examine data, metrics, and analytic methods, related to addressing the challenges and barriers to access to housing, employment, health care, education, and essential services, the committee used an “accessibility” or “access to destinations” analytic framework. In this framework, access to destinations (or accessibility) is defined as the ease with which a person can reach valued destinations.²² An accessibility approach to transportation recognizes that the purpose of transportation is reaching—or accessing—employment, education, health care, and housing, which in turn enables progress toward a societal outcome such as improved health. Historically, transportation policy in the United States has focused on mobility solutions that speed up or reduce delay of vehicle travel as a way to address access to the places that people need to thrive.²³ As a public policy framework, access to destinations instead emphasizes meeting people’s access needs through a place-based decision-making framework that considers how people’s access needs can be met through a range of mobility improvements and changes in the proximity of relevant land uses (i.e., destinations).²⁴ Changes in land use, such as land development spurred by community or economic development policies, can also produce improvements in accessibility by locating destinations such as employment or health clinics nearer to residents.

Access to destinations is also a powerful framework for identifying and analyzing inequities in the current transportation system. Past and current patterns of transportation investments, residential segregation, neighborhood disinvestment, white flight, and suburbanization have, for certain communities, produced more extreme challenges and barriers to accessing the places that people need to thrive. By measuring the changes in access across geographies and by population, access to destinations represents one method to operationalize distributive justice in transportation.²⁵ For

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²² Handy, S. L., and D. A. Niemeier. 1997. “Measuring Accessibility: An Exploration of Issues and Alternatives.” Environment and Planning A 29(7):1175–1194.

²³ Handy, S. 2020. “Is Accessibility an Idea Whose Time Has Finally Come?” Transportation Research D: Transport and Environment 83:102319.

²⁴ Martens, K. 2015. “Accessibility and Potential Mobility as a Guide for Policy Action.” Transportation Research Record 2499(1):18–24.

²⁵ Pereira, R. H. M., T. Schwanen, and D. Banister. 2017. “Distributive Justice and Equity in Transportation.” Transport Reviews 37(2):170–191.

example, because access to destinations is critical to equitable community health outcomes, measuring changes in accessibility is an important way to evaluate transportation projects.²⁶

This section reviews the literature establishing the connection between transportation investments and disparities in people’s access to housing, employment, education, and health care and services. To the extent possible, this section also identifies the indicators used in the research literature to measure transportation’s contribution to societal outcomes in these domains. Table 2-1 illustrates transportation’s contribution to intermediate and long-term societal outcomes associated with access to housing and key destinations. This table is not intended to be comprehensive and does not identify the full causal chain for each issue.

Access to Housing

Historic and current land use and housing practices, such as redlining and housing discrimination, have produced neighborhoods segregated by race and income.²⁷ For people of color, one consequence of housing discrimination in its many forms is a lack of wealth-building opportunities, resulting in a persistent wealth gap between whites and other racial and ethnic groups.²⁸ Living in higher-poverty neighborhoods exposes residents

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²⁶ Northridge, M. E., and L. Freeman. 2011. “Urban Planning and Health Equity.” Journal of Urban Health: Bulletin of the New York Academy of Medicine 88(3):582–597. https://doi.org/10.1007/s11524-011-9558-5; Krapp, A., J. M. Barajas, and A. Wennink. 2021. “Equity-Oriented Criteria for Project Prioritization in Regional Transportation Planning.” Transportation Research Record 2675(9):182–195. https://doi.org/10.1177/03611981211001072.

²⁷ Hilovsky, K. L., and T. T. Williams. 2020. “Creating the Healthiest Nation: Health and Housing Equity.” https://www.apha.org/-/media/files/pdf/topics/equity/health_and_housing_equity.pdf. Accessed October 20, 2024; Dawkins, C. J. 2002. “Measuring the Spatial Pattern of Residential Segregation.” Urban Studies 41(4):833–851. https://doi.org/10.1080/0042098042000194133; Dawkins, C. 2006. “The Spatial Pattern of Black-White Segregation in US Metropolitan Areas: An Exploratory Analysis.” Urban Studies 43(11):1943–1969. https://doi.org/10.1080/00420980600897792; Menedian, S., S. Gamhir, and A. Gailes. 2021. “The Roots of Structural Racism: Twenty-First Century Residential Segregation in the United States.” https://www.councilforthehomeless.org/wp-content/uploads/2021/07/the_roots_of_structural_racism_report_and_appendix.pdf. Accessed October 20, 2024; Rothstein, R. 2017. The Color of Law: A Forgotten History of How Our Government Segregated America. Liveright Publishing; Dawkins, C. J. 2007. “Exploring Changes in Income Clustering and Centralization during the 1990s.” Journal of Planning Education and Research 26(4):404–414.

²⁸ Hilovsky, K. L., and T. T. Williams. 2020. “Creating the Healthiest Nation: Health and Housing Equity.” https://www.apha.org/-/media/files/pdf/topics/equity/health_and_housing_equity.pdf. Accessed October 20, 2024; Shapiro, T., T. Meschede, and S. Osoro. 2013. “The Roots of the Widening Racial Wealth Gap: Explaining the Black-White Economic Divide.” Research and Policy Brief. Institute on Assets and Social Policy, Brandeis University. https://heller.brandeis.edu/iere/pdfs/racial-wealth-equity/racial-wealth-gap/roots-widening-racial-wealth-gap.pdf. Accessed October 20, 2024.

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²⁹ Hess, C. 2020. “Residential Segregation by Race and Ethnicity and the Changing Geography of Neighborhood Poverty.” Spatial Demography 9:57–106. https://doi.org/10.1007/s40980-020-00066-3.

³⁰ Menedian, S., S. Gamhir, and A. Gailes. 2021. “The Roots of Structural Racism: Twenty-First Century Residential Segregation in the United States.” https://www.councilforthehomeless.org/wp-content/uploads/2021/07/the_roots_of_structural_racism_report_and_appendix.pdf. Accessed October 20, 2024.

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³¹ Jeon, J. S., C. Dawkins, and R. Pendall. 2018. “How Vehicle Access Enables Low-Income Households to Live in Better Neighborhoods.” Housing Policy Debate 28(6):920–939. https://doi.org/10.1080/10511482.2018.1494023.

³² Chetty, R., N. Hendren, and L. F. Katz. 2016. “The Effects of Exposure to Better Neighborhoods on Children: New Evidence from the Moving to Opportunity Experiment.” American Economic Review 106(4):855–902. https://doi.org/10.1257/aer.20150572.

³³ Dawkins, C. J., J. S. Jeon, and R. Pendall. 2015. “Vehicle Access and Exposure to Neighborhood Poverty: Evidence from the Moving to Opportunity Program.” Journal of Regional Science 55(5):687–707.

³⁴ Klein, N. J. 2024. “Subsidizing Car Ownership for Low-Income Individuals and Households.” Journal of Planning Education and Research 44(1):165–177. https://doi.org/10.1177/0739456X20950428.

³⁵ Renne, J. L., T. Tolford, S. Hamidi, and R. Ewing. 2016. “The Cost and Affordability Paradox of Transit-Oriented Development: A Comparison of Housing and Transportation Costs Across Transit-Oriented Development, Hybrid and Transit-Adjacent Development Station Typologies.” Housing Policy Debate 26(4–5):819–834. https://doi.org/10.1080/10511482.2016.1193038.

³⁶ Padeiro, M., A. Louro, and N. M. Da Costa. 2019. “Transit-Oriented Development and Gentrification: A Systematic Review.” Transport Reviews 39(6):733–754.

other protections for low-income renters in TODs may be effective tools to prevent residential displacement.³⁷

Access to Employment

Employment is critical to individual and community well-being.³⁸ In general, increased access to jobs by car or public transit improves the probability of employment.³⁹ Higher levels of job accessibility are associated with higher wages.⁴⁰ Residential segregation by race affects unemployment durations through racial differences in job accessibility.⁴¹ In one study, about half of employment rate disparities could be explained by job accessibility.⁴²

A meta-analysis of previous empirical research identified four categories of transportation indicators that are positively associated with employment outcomes: car ownership, public transport access, commute times, and job accessibility levels.⁴³ Because it is nearly impossible to complete daily activities in most places in the United States without a car, car access is a significant predictor of employment outcomes. Among low-income Americans, access to a car is associated with gaining and maintaining

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³⁷ Chapple, K., and A. Loukaitou-Sideris. 2019. Transit-Oriented Displacement or Community Dividends? Understanding the Effects of Smarter Growth on Communities. Urban and Industrial Environments. Cambridge, MA: MIT Press; Dawkins, C., and R. Moeckel. 2016. “Transit-Induced Gentrification: Who Will Stay, and Who Will Go?” Housing Policy Debate 26(4–5):801–818. https://doi.org/10.1080/10511482.2016.1138986.

³⁸ Badland, H., M. Davern, K. Villanueva, S. Mavoa, A. Milner, R. Roberts, and B. Giles-Corti. 2016. “Conceptualizing and Measuring Spatial Indicators of Employment Through a Livability Lens.” Social Indicators Research 127:565–675.

³⁹ Bastiaansen, J., D. Johnson, and K. Lucas. 2020. “Does Transport Help People to Gain Employment? A Systematic Review and Meta-Analysis of the Empirical Evidence.” Transport Reviews 40(5):607–628. https://doi.org/10.1080/01441647.2020.1747569.

⁴⁰ Chatman, D. G., and R. B. Noland. 2014. “Transit Service, Physical Agglomeration and Productivity in US Metropolitan Areas.” Urban Studies 51(5):917–937. https://doi.org/10.1177/0042098013494426.

⁴¹ Dawkins, C. J., Q. Shen, and T. W. Sanchez. 2005. “Race, Space, and Unemployment Duration.” Journal of Urban Economics 58(1):91–113.

⁴² Ihlanfeldt, K. R., and D. L. Sjoquist. 1998. “The Spatial Mismatch Hypothesis: A Review of Recent Studies and Their Implications for Welfare Reform.” Housing Policy Debate 9:849–892, cited in Bastiaansen, J., D. Johnson, and K. Lucas. 2020. “Does Transport Help People to Gain Employment? A Systematic Review and Meta-Analysis of the Empirical Evidence.” Transport Reviews 40(5):607–628. https://doi.org/10.1080/01441647.2020.1747569.

⁴³ Bastiaansen, J., D. Johnson, and K. Lucas. 2020. “Does Transport Help People to Gain Employment? A Systematic Review and Meta-Analysis of the Empirical Evidence.” Transport Reviews 40(5):607–628. https://doi.org/10.1080/01441647.2020.1747569.

employment and, in most studies, having a better paying job.⁴⁴ The income gains for households with car access have increased over time relative to those without, suggesting the growing importance of car access.⁴⁵ Many of these studies suggest a causal effect as well, with a metaregression showing that people who have access to a car are about 1.8 times more likely to be employed than those without car access.⁴⁶ Racial disparities in car access also predict racial disparities in unemployment.⁴⁷

High commute times are associated with decreased likelihood of individual employment among low-wage workers and low-educated women, whereas lower commute times are associated with increased likelihood of employment.⁴⁸ Although longer commute times clearly represent a transportation burden for low-income workers, there are two cautions associated with commute time indicators. First, commute time tends to rise with income as wealthier residents move to suburban areas⁴⁹ making it difficult to identify the burdens borne by low-income workers as compared to

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⁴⁴ Blumenberg, E., and G. Pierce. 2014. “A Driving Factor in Mobility? Transportation’s Role in Connecting Subsidized Housing and Employment Outcomes in the Moving to Opportunity (MTO) Program.” Journal of the American Planning Association 80(1):52–66. https://doi.org/10.1080/01944363.2014.935267; Gurley, T., and D. Bruce. 2005. “The Effects of Car Access on Employment Outcomes for Welfare Recipients.” Journal of Urban Economics 58(2):250–272. https://doi.org/10.1016/j.jue.2005.05.002; Hu, L. 2017. “Job Accessibility and Employment Outcomes: Which Income Groups Benefit the Most?” Transportation 44:1421–1443. https://doi.org/10.1007/s11116-016-9708-4; Raphael, S., and L. Rice. 2002. “Car Ownership, Employment, and Earnings.” Journal of Urban Economics 52(1):109–130. https://doi.org/10.1016/S0094-1190(02)00017-7; Sandoval, J. S. O., R. Cervero, and J. Landis. 2011. “The Transition from Welfare-to-Work: How Cars and Human Capital Facilitate Employment for Welfare Recipients.” Applied Geography 31(1):352–362. https://doi.org/10.1016/j.apgeog.2010.07.008; Smart, M. J., and N. J. Klein. 2020. “Disentangling the Role of Cars and Transit in Employment and Labor Earnings.” Transportation 47(3):1275–1309. https://doi.org/10.1007/s11116-018-9959-3.

⁴⁵ King, D. A., M. J. Smart, and M. Manville. 2022. “The Poverty of the Carless: Toward Universal Auto Access.” Journal of Planning Education and Research 42(3):464–481. https://doi.org/10.1177/0739456X18823252.

⁴⁶ Bastiaansen, J., D. Johnson, and K. Lucas. 2020. “Does Transport Help People to Gain Employment? A Systematic Review and Meta-Analysis of the Empirical Evidence.” Transport Reviews 40(5):607–628. https://doi.org/10.1080/01441647.2020.1747569.

⁴⁷ Covington, K. L. 2018. “Overcoming Spatial Mismatch: The Opportunities and Limits of Transit Mode in Addressing the Black-White Unemployment Gap.” City & Community 17(1):211–235. https://doi.org/10.1111/cico.12278.

⁴⁸ Bastiaansen, J., D. Johnson, and K. Lucas. 2020. “Does Transport Help People to Gain Employment? A Systematic Review and Meta-Analysis of the Empirical Evidence.” Transport Reviews 40(5):607–628. https://doi.org/10.1080/01441647.2020.1747569.

⁴⁹ Ihlanfeldt, K. R., and D. L. Sjoquist. 1998. “The Spatial Mismatch Hypothesis: A Review of Recent Studies and their Implications for Welfare Reform.” Housing Policy Debate 9:849–892, as cited in Bastiaansen, J., D. Johnson, and K. Lucas. 2020. “Does Transport Help People to Gain Employment? A Systematic Review and Meta-Analysis of the Empirical Evidence.” Transport Reviews 40(5):607–628. https://doi.org/10.1080/01441647.2020.1747569.

high-income workers. Second, commute time indicators are based on the travel patterns of employed individuals and therefore fail to capture those who are unemployed because of a lack of access to jobs.⁵⁰

Transit access also affects employment outcomes. The use of public transit is associated with lower rates of unemployment at the metropolitan area level.⁵¹ Better transit-based access to jobs is associated with gaining and maintaining employment among low-income households.⁵² Two natural experiments demonstrated that losing access to transit impacts employment outcomes. One study in Georgia found substantial increases in poverty and unemployment rates in neighborhoods affected by the closure of a local bus line.⁵³ The other, in New York City, found that the probability of being unemployed increased in neighborhoods that experienced an unexpected closure of a subway line, especially for those without access to a car.⁵⁴ Other research shows no effect of transit access on employment for people in poverty, but a positive effect on future earnings for people without cars (for all income levels), particularly in transit-rich areas.⁵⁵ Differences in employment based on transit job accessibility is larger in car-dominated metropolitan areas and for those who do not own a car.⁵⁶

Transportation can also play a role in providing greater access to employment through facilitating economic development: that is, transportation improvements can be used to attract employers to a neighborhood or community. The large and diverse body of research on the effect of transportation infrastructure on economic activity typically analyzes economic benefits at the regional level and tests hypotheses that posit that

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⁵⁰ Bastiaansen, J., D. Johnson, and K. Lucas. 2020. “Does Transport Help People to Gain Employment? A Systematic Review and Meta-Analysis of the Empirical Evidence.” Transport Reviews 40(5):607–628. https://doi.org/10.1080/01441647.2020.1747569.

⁵¹ Covington, K. L. 2018. “Overcoming Spatial Mismatch: The Opportunities and Limits of Transit Mode in Addressing the Black-White Unemployment Gap.” City & Community 17(1):211–235. https://doi.org/10.1111/cico.12278.

⁵² Kawabata, M. 2003. “Job Access and Employment Among Low-Skilled Autoless Workers in US Metropolitan Areas.” Environment and Planning A 35(9):1651–1668. https://doi.org/10.1068/a35209; Blumenberg, E., and G. Pierce. 2014. “A Driving Factor in Mobility? Transportation’s Role in Connecting Subsidized Housing and Employment Outcomes in the Moving to Opportunity (MTO) Program.” Journal of the American Planning Association 80(1):52–66. https://doi.org/10.1080/01944363.2014.935267.

⁵³ Li, F., and C. K. Wyczalkowski. 2023. “How Buses Alleviate Unemployment and Poverty: Lessons from a Natural Experiment in Clayton County, GA.” Urban Studies 60(13):2632–2650.

⁵⁴ Tyndall, J. 2017. “Waiting for the R Train: Public Transportation and Employment.” Urban Studies 54(2):520–537.

⁵⁵ Smart, M. J., and N. J. Klein. 2018. “Complicating the Story of Location Affordability.” Housing Policy Debate 28(3):393–410. https://doi.org/10.1080/10511482.2017.1371784.

⁵⁶ Bastiaansen, J., D. Johnson, and K. Lucas. 2020. “Does Transport Help People to Gain Employment? A Systematic Review and Meta-Analysis of the Empirical Evidence.” Transport Reviews 40(5):607–628. https://doi.org/10.1080/01441647.2020.1747569.

transportation investment provides economic benefit via reduced costs for firms, interregional labor mobility, or transport-induced economic development.^57,58 Generally, the research’s regional focus and the complex causal chain between economic activity and individual well-being makes it difficult to connect investment with individual or population-level outcomes, particularly for disadvantaged populations.⁵⁹ The disconnect between economic outputs and individual and community outcomes, sometimes described as “place prosperity” versus “people prosperity,” is also difficult to bridge in planning and transportation practice because practitioners primarily use place-based tools that may only indirectly benefit resident economic outcomes.⁶⁰

Access to Education

Transportation has a critical role in ensuring safe and reliable travel to school, a long-term education-related equity outcome. This section examines transportation’s role in providing access to K–12 education in two ways: (1) active travel (e.g., walking or biking) and (2) access to education and the “education debt” experienced by individuals and communities that results from systemic inequities that persist.⁶¹ Regarding the transportation field’s focus on active travel to school⁶² its attendant benefits include reducing traffic congestion, improving traffic safety, improving children’s

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⁵⁷ Elburz, Z., P. Nijkamp, and E. Pels. 2017. “Public Infrastructure and Regional Growth: Lessons from Meta-Analysis.” Journal of Transport Geography 58:1–8; Melo, P. C., D. J. Graham, and R. Brage-Ardao. 2013. “The Productivity of Transport Infrastructure Investment: A Meta-Analysis of Empirical Evidence.” Regional Science and Urban Economics 43(5):695–706. https://doi.org/10.1016/j.regsciurbeco.2013.05.002; Pokharel, R., L. Bertoli, and M. Brömmelstroet. 2023. “How Does Transportation Facilitate Regional Economic Development? A Heuristic Mapping of the Literature.” Transportation Research Interdisciplinary Perspectives 19:100817.

⁵⁸ Economies of agglomeration are represented by the dependence of a firm’s profit on the location of other firms, which can be a positive pull force (agglomeration economies) or a negative push force (spatial competition) (Combes, P.-P., and L. Gobillion. 2015. “Agglomeration Theory with Heterogenous Agents.” Chapter 4 in Handbook of Regional and Urban Economics. https://www.sciencedirect.com/topics/economics-econometrics-and-finance/agglomeration-effect. Accessed November 24, 2024.

⁵⁹ Pokharel, R., L. Bertoli, and M. Brömmelstroet. 2023. “How Does Transportation Facilitate Regional Economic Development? A Heuristic Mapping of the Literature.” Transportation Research Interdisciplinary Perspectives 19:100817.

⁶⁰ Schrock, G. 2014. “Connecting People and Place Prosperity: Workforce Development and Urban Planning in Scholarship and Practice.” Journal of Planning Literature 29(3):257–271. https://doi.org/10.1177/0885412214538834.

⁶¹ The committee did not take up the question of adult education.

⁶² Bierbaum, A. H., A. Karner, and J. M. Barajas. 2021. “Toward Mobility Justice: Linking Transportation and Education Equity in the Context of School Choice.” Journal of the American Planning Association 87(2):197–210.

physical activity levels,⁶³ increasing children’s independence,⁶⁴ and possibly improved academic performance.⁶⁵ Students from low-income families and students of color are more likely to walk or bicycle to school compared to white or higher-income students.⁶⁶ In practice, active travel to school is promoted through Safe Routes to School programs, pedestrian and safety-focused street designs, and encouraging school siting coordination between school districts and land use planning agencies.⁶⁷ Despite the effectiveness of active travel interventions, active travel to school programming has been limited in practice.⁶⁸

Active travel to school presumes attendance at a neighborhood school within walking and cycling distance. Neighborhood schools can be a stabilizing feature of the neighborhood, contributing to property values and community cohesion.⁶⁹ However, historic policies such as redlining have created disparate neighborhood conditions that continue to impact access

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⁶³ Community Preventive Services Task Force (CPSTF). 2018. “Physical Activity: Interventions to Increase Active Travel to School.” https://www.thecommunityguide.org/findings/physical-activity-interventions-increase-active-travel-school.html; Steiner, R. L., L. B. Crider, and M. Betancourt. 2006. “Safe Ways to School—the Role of Multimodal Planning.” Prepared for the Florida Department of Transportation Systems Planning Office. https://fdotwww.blob.core.windows.net/sitefinity/docs/default-source/research/reports/fdot-bd545-32-rpt.pdf. Accessed November 24, 2024.

⁶⁴ Steiner, R. L., L. B. Crider, and M. Betancourt. 2006. “Safe Ways to School—the Role of Multimodal Planning.” Prepared for the Florida Department of Transportation Systems Planning Office. https://fdotwww.blob.core.windows.net/sitefinity/docs/default-source/research/reports/fdot-bd545-32-rpt.pdf. Accessed November 24, 2024.

⁶⁵ Yeung, R., and P. Nguygen-Hoang. 2019. “It’s the Journey, Not the Destination: The Effect of School Travel Mode on Student Achievement.” Journal of Urbanism: International Research on Placemaking and Urban Sustainability 13(2):170–186; Walker, I., and T. Gamble. 2023. “Active Travel to School: A Longitudinal Millennium Cohort Study of Schooling Outcomes.” BMJ Open 13(3):e068388. https://doi.org/10.1136/bmjopen-2022-068388.

⁶⁶ McDonald, N. C. 2008. “Critical Factors for Active Transportation to School Among Low-Income and Minority Students: Evidence from the 2001 National Household Travel Survey.” American Journal of Preventive Medicine 34:341–344.

⁶⁷ Steiner, R. L., L. B. Crider, and M. Betancourt. 2006. “Safe Ways to School—the Role of Multimodal Planning.” Prepared for the Florida Department of Transportation Systems Planning Office. https://fdotwww.blob.core.windows.net/sitefinity/docs/default-source/research/reports/fdot-bd545-32-rpt.pdf. Accessed November 24, 2024.

⁶⁸ Jones, R. A., N. E. Blackburn, C. Wood, M. Byrne, F. Nassau, and M. Tully. 2019. “Interventions Promoting Active Transport to School in Children: A Systematic Review and Meta-Analysis.” Preventive Medicine 123:232–241.

⁶⁹ Alexander, M., and V. Massaro. 2020. “School Deserts: Visualizing the Death of the Neighborhood School.” Policy Futures in Education 18(6). https://doi.org/10.1177/1478210320951063.

to quality education today, including highly segregated schools.⁷⁰ Neighborhood schools are no longer the norm because of siting policies that prefer larger campuses and closure policies due to budget concerns and underperformance, among other reasons.⁷¹ Schools in segregated and/or high-poverty neighborhoods have higher suspension rates, fewer qualified teachers, higher rates of teacher turnover,⁷² and poor building conditions that inhibit learning.⁷³ Neighborhood schools can serve as community facilities, which can be important for high-poverty neighborhoods that otherwise lack access to community resources, such as libraries and community centers.⁷⁴ This is particularly true for “community schools” that offer integrated student supports, which have been shown to meet the needs of disadvantaged students in high-poverty schools and are associated with positive student outcomes, such as reduced absenteeism and improved academic outcomes.⁷⁵ It is also possible that community schools can catalyze community development, thereby benefiting the neighborhood as well as students.⁷⁶

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⁷⁰ Alexander, M., and V. Massaro. 2020. “School Deserts: Visualizing the Death of the Neighborhood School.” Policy Futures in Education 18(6). https://doi.org/10.1177/1478210320951063; Bierbaum, A. H., A. Karner, and J. M. Barajas. 2021. “Toward Mobility Justice: Linking Transportation and Education Equity in the Context of School Choice.” Journal of the American Planning Association 87(2):197–210. https://doi.org/10.1080/01944363.2020.1803104.

⁷¹ Alexander, M., and V. Massaro. 2020. “School Deserts: Visualizing the Death of the Neighborhood School.” Policy Futures in Education 18(6). https://doi.org/10.1177/1478210320951063.

⁷² Bierbaum, A. H., A. Karner, and J. M. Barajas. 2021. “Toward Mobility Justice: Linking Transportation and Education Equity in the Context of School Choice.” Journal of the American Planning Association 87(2):197–210. https://doi.org/10.1080/01944363.2020.1803104; Duncan, G., K. Magnuson, R. Murnane, and E. Votruba-Drzal. 2019. “Income Inequality and the Well-Being of American Families.” Family Relations 68(3):313–325. https://doi.org/10.1111/fare.12364; Levy, B. L. 2019. “Heterogeneous Impacts of Concentrated Poverty During Adolescence on College Outcomes.” Social Forces 98(1):147–182.

⁷³ Syeed, E. 2022. “The Space Beyond: A Blueprint of Radical Possibilities in School Design.” Educational Policy 36(4):769–795. https://doi.org/10.1177/08959048221087207.

⁷⁴ Louis Taylor, H., L. McGlynn, and D. G. Luter. 2014. “Public Schools as Neighborhood Anchor Institutions: The Choice Neighborhood Initiative in Buffalo, New York.” In Schools and Urban Revitalization: Rethinking Institutions and Community Development (1st edition). Edited by K. L. Patterson and R. M. Silverman. Philadelphia: Taylor & Francis Group; Syeed, E. 2022. “The Space Beyond: A Blueprint of Radical Possibilities in School Design.” Educational Policy 36(4):769–795. https://doi.org/10.1177/08959048221087207.

⁷⁵ Maier, A., J. Daniel, J. Oakes, and L. Lam. 2017. Community Schools as an Effective School Improvement Strategy: A Review of the Evidence. Learning Policy Institute and National Education Policy Center. https://files.eric.ed.gov/fulltext/ED606765.pdf. Accessed November 24, 2024.

⁷⁶ Butler, A., A. Bierbaum, and E. O’Keefe. 2022. “Leveraging Community Schools for Community Development: Lessons from Baltimore’s 21st Century School Buildings Program.” Urban Education 59(8):2458–2488. https://doi.org/10.1177/00420859221107615.

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⁷⁷ Ladson-Billings, G. 2006. “From the Achievement Gap to the Education Debt: Understanding Achievement in U.S. Schools.” Educational Research 35(7):3–12. http://doi.org/10.3102/0013189X035007003; Lee, I.-M., E. J. Shiroma, R. L. F. Lobelo, P. Puska, S. N. Blair, and P. T. Katzmarzyk. 2012. “Impact of Physical Inactivity on the World’s Major NonCommunicable Diseases.” Lancet 380:219–229.

⁷⁸ Bierbaum, A. H., A. Karner, and J. M. Barajas. 2021. “Toward Mobility Justice: Linking Transportation and Education Equity in the Context of School Choice.” Journal of the American Planning Association 87(2):197–210. https://doi.org/10.1080/01944363.2020.1803104.

⁷⁹ Bierbaum, A. H., A. Karner, and J. M. Barajas. 2021. “Toward Mobility Justice: Linking Transportation and Education Equity in the Context of School Choice.” Journal of the American Planning Association 87(2):197–210. https://doi.org/10.1080/01944363.2020.1803104; Duncan, G., K. Magnuson, R. Murnane, and E. Votruba-Drzal. 2019. “Income Inequality and the Well-Being of American Families.” Family Relations 68(3):313–325. https://doi.org/10.1111/fare.12364.

⁸⁰ Hopson, L. M., A. D. Lidbe, M. S. Jackson, E. Adanu, X. Li, P. Penmetsa, H. Y. Lee, A. Anderson, C. Obuya, and G. Abura-Meerdink. 2024. “Transportation to School and Academic Outcomes: A Systematic Review.” Educational Review 76(3):648–668. https://doi.org/10.1080/00131911.2022.2034748.

⁸¹ Stein, M. L., and J. A. Grigg. 2019. “Missing Bus, Missing School: Establishing the Relationship Between Public Transit Use and Student Absenteeism.” American Educational Research Journal 56(5):1834–1860. https://doi.org/10.3102/0002831219833917.

⁸² Ginsburg, A., P. Jordan, and H. Chang. 2014. “Absences Add Up: How School Attendance Influences Student Success.” Attendance Works. https://www.attendanceworks.org/wp-content/uploads/2017/05/Absenses-Add-Up_September-3rd-2014.pdf and https://www.attendanceworks.org/absences-add-up. Accessed October 24, 2024.

⁸³ Romero, M., and Y.-S. Lee. 2007. A National Portrait of Chronic Absenteeism in the Early Grades. National Center for Children in Poverty, Columbia University. https://www.attendanceworks.org/wp-content/uploads/2017/09/A-National-Portrait-of-Chronic-Absenteeism-in-the-Early-Grades-Oct-2007.pdf. Accessed October 24, 2024.

student access to these transit passes have had mixed impacts on school attendance and academic outcomes.⁸⁴

Access to Health Care and Services

Millions of Americans delay or miss medical care each year because of transportation issues.^85,86 Despite options for health care–related transportation, such as paratransit and Medicaid’s transportation benefit, nearly 2% of the population persistently reports a transportation barrier to health care.⁸⁷ Lack of access to a vehicle has been found to be a key barrier.⁸⁸ Fixed-route public transit may not align with the location of health care facilities or transit fares may too be expensive,⁸⁹ presenting a transportation barrier to those who depend on transit. Reliance on public transit predicts a lack of regular care.⁹⁰ Reduced-fare transit passes can help individuals with low

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⁸⁴ Bierbaum, A. H., A. Karner, and J. M. Barajas. 2021. “Toward Mobility Justice: Linking Transportation and Education Equity in the Context of School Choice.” Journal of the American Planning Association 87(2):197–210. https://doi.org/10.1080/01944363.2020.1803104.

⁸⁵ Wallace, R., P. Hughes-Cromwick, H. Mull, and S. Khasnabis. 2005. “Access to Health Care and Nonemergency Medical Transportation: Two Missing Links.” Transportation Research Record 1924(1):76–84; Wolfe, M. K., N. C. McDonald, and G. M. Holmes. 2020. “Transportation Barriers to Health Care in the United States: Findings from the National Health Interview Survey, 1997–2017.” American Journal of Public Health 110(6):815–822. https://doi.org/10.2105/AJPH.2020.305579.

⁸⁶ Transportation, a spatial factor in access to health care, affects the first two of the following five dimensions of health care access: availability, accessibility, affordability, acceptability, and accommodation (Penchansky, R., and J. W. Thomas. 1981. “The Concept of Access: Definition and Relationship to Consumer Satisfaction.” Medical Care 19(2):127–140. http://doi.org/10.1097/00005650-198102000-00001; Ye, H., and H. Kim. 2014. “Measuring Spatial Health Disparity Using a Network-Based Accessibility Index Method in a GIS Environment: A Case Study of Hillsborough County, Florida.” International Journal of Geospatial and Environmental Research 1(1):2. https://dc.uwm.edu/ijger/vol1/iss1/2. Accessed October 24, 2024).

⁸⁷ Wolfe, M. K., N. C. McDonald, and G. M. Holmes. 2020. “Transportation Barriers to Health Care in the United States: Findings from the National Health Interview Survey, 1997–2017.” American Journal of Public Health 110(6):815–822. https://doi.org/10.2105/AJPH.2020.305579.

⁸⁸ Syed, S. T., B. S. Gerber, and L. K. Sharp. 2013. “Traveling Towards Disease: Transportation Barriers to Health Care Access.” Journal of Community Health 38(5):976–993. https://doi.org/10.1007/s10900-013-9681-1.

⁸⁹ Rosenblum, J. L. 2020. Expanding Access to the City: How Public Transit Fare Policy Shapes Travel Decision Making and Behavior of Low-Income Riders. Doctoral dissertation, Massachusetts Institute of Technology. https://dspace.mit.edu/handle/1721.1/127617. Accessed October 24, 2024.

⁹⁰ Syed, S. T., B. S. Gerber, and L. K. Sharp. 2013. “Traveling Towards Disease: Transportation Barriers to Health Care Access.” Journal of Community Health 38(5):976–993. https://doi.org/10.1007/s10900-013-9681-1.

incomes reach medical appointments.⁹¹ Missing preventive care can lead to more costly health care visits⁹² and complicate health conditions, primarily by exacerbating health outcomes related to chronic disease.⁹³ Those with the highest burden of disease are also those with the greatest transportation barriers. They are more likely to be older, poorer, less educated, female, people of color, or people with disabilities.⁹⁴ Although the rates at which residents are able to access health care does not differ significantly between urban and rural populations,⁹⁵ rural residents must travel longer distances to access care and cite gasoline prices as a transportation barrier.⁹⁶

ENVIRONMENTAL JUSTICE AND PUBLIC HEALTH

The statement of task for this study asks the study committee to identify data, analytic methods, and metrics associated with environmental justice and public health concerns. The committee selected three areas to examine—exposure to traffic violence, exposure to air pollution, and disparities in health outcomes associated with a physical activity—while recognizing that transportation also affects other environmental justice and health outcomes. For example, a lack of street trees is one factor that

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⁹¹ Rosenblum, J. L., 2020. Expanding Access to the City: How Public Transit Fare Policy Shapes Travel Decision Making and Behavior of Low-Income Riders. Doctoral dissertation, Massachusetts Institute of Technology. https://dspace.mit.edu/handle/1721.1/127617.

⁹² Coster, J. E., J. K. Turner, D. Bradbury, and A. Cantrell. 2017. “Why Do People Choose Emergency and Urgent Care Services? A Rapid Review Utilizing a Systematic Literature Search and Narrative Synthesis.” Academic Emergency Medicine 24(9):1137–1149. https://doi.org/10.1111/acem.13220.

⁹³ Karter, A. J., M. M. Parker, and H. H. Moffet. 2004. “Missed Appointments and Poor Glycemic Control: An Opportunity to Identify High-Risk Diabetic Patients.” Medical Care 42(2):110–115; Salameh, E., S. Olsen, and D. Howard. 2012. “Nonattendance with Clinic Follow-Up Appointments: Diabetes as Exemplar.” Journal for Nurse Practitioners 8(10):797–803. https://doi.org/10.1016/j.nurpra.2012.09.017; Syed, S. T., B. S. Gerber, and L. K. Sharp. 2013. “Traveling Towards Disease: Transportation Barriers to Health Care Access.” Journal of Community Health 38(5):976–993. https://doi.org/10.1007/s10900-013-9681-1.

⁹⁴ Wallace, R., P. Hughes-Cromwick, H. Mull, and S. Khasnabis. 2005. “Access to Health Care and Nonemergency Medical Transportation: Two Missing Links.” Transportation Research Record 1924(1):76–84. https://doi.org/10.1177/0361198105192400110; Ng, A. E., D. Adjaye-Gbewonyo, and J. Dahlhamer. 2024. Lack of Reliable Transportation for Daily Living Among Adults: United States, 2022. National Center for Health Statistics, U.S. Centers for Disease Control and Prevention, NCHS Data Brief. No. 490. https://doi.org/10.15620/cdc:135611.

⁹⁵ Syed, S. T., B. S. Gerber, and L. K. Sharp. 2013. “Traveling Towards Disease: Transportation Barriers to Health Care Access.” Journal of Community Health 38(5):976–993. https://doi.org/10.1007/s10900-013-9681-1.

⁹⁶ Akinlotan, M., K. Primm, N. Khodakarami, J. Bolin, and A. O. Ferdinand. 2021. “Rural-Urban Variations in Travel Burdens for Care: Findings from the 2017 National Household Travel Survey.” Policy Brief. Southwest Rural Health Research Center. https://srhrc.tamhsc.edu. Accessed October 24, 2024.

contributes to the urban heat island effect, resulting in increased heat exposure that disproportionately impacts residents in formerly redlined areas.⁹⁷ Furthermore, climate change will exacerbate environmental justice issues that are already disproportionately borne by low-income communities and many communities of color. The exacerbation of environmental justice burdens created by climate change is not addressed here.

This section reviews the research literature establishing the connection between transportation investments and disparities in people’s experience of physical activity, traffic crashes, and air pollution. To the extent possible, this section also identifies the indicators used in the research literature to measure transportation’s contribution to societal outcomes in these domains. Table 2-2 illustrates transportation’s contributions to intermediate and long-term societal outcomes associated with these concerns. Table 2-2 is not intended to be comprehensive and does not identify the full causal chain for each issue.

Physical Activity and Associated Health Outcomes

Physical inactivity and sedentary behavior are risk factors for many kinds of chronic disease. Medical conditions associated with physical inactivity include type 2 diabetes, coronary heart disease, high blood pressure, high cholesterol, stroke, osteoporosis, breast cancer, colon cancer, and general premature mortality.⁹⁸ Sedentary behavior, including driving,⁹⁹ is a risk factor for cardiovascular disease¹⁰⁰ and many other chronic diseases.¹⁰¹

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⁹⁷ Hoffman, J. S., V. Shandas, and N. Pendleton. 2020. “The Effects of Historical Housing Policies on Resident Exposure to Intra-Urban Heat: A Study of 108 US Urban Areas.” Climate 8(1):12. https://doi.org/10.3390/cli8010012.

⁹⁸ Lee, I.-M., E. J. Shiroma, R. L. F. Lobelo, P. Puska, S. N. Blair, and P. T. Katzmarzyk. 2012. “Impact of Physical Inactivity on the World’s Major Non-Communicable Diseases.” Lancet 380:219–229; McTiernan, A., C. M. Friedenreich, and P. T. Katzmarzyk. 2019. “Physical Activity in Cancer Prevention and Survival: A Systematic Review.” Medicine & Science in Sports & Exercise 51(6):1252–1261.

⁹⁹ Sugiyama, T., K. Wijndaele, M. J. Koohsari, S. K. Tanamas, D. W. Dunstan, and N. Owen. 2016. “Adverse Associations of Car Time with Markers of Cardio-Metabolic Risk.” Preventive Medicine 83:26–30. https://doi.org/10.1016/j.ypmed.2015.11.029.

¹⁰⁰ Ford, E. S., and C. J. Caspersen. 2012. “Sedentary Behaviour and Cardiovascular Disease: A Review of Prospective Studies.” International Journal of Epidemiology 41(5):1338–1353. https://doi.org/10.1093/ije/dys078.

¹⁰¹ Patterson, R., E. McNamara, M. Tainio, T. Hérick de Sá, A. D. Smith, S. J. Sharp, P. Edwards, J. Woodcock, S. Brage, and K. Wijndaele. 2018. “Sedentary Behaviour and Risk of All-Cause, Cardiovascular and Cancer Mortality, and Incident Type 2 Diabetes: A Systematic Review and Dose Response Meta-Analysis.” European Journal of Epidemiology 33(9):811–829. https://doi.org/10.1007/s10654-018-0380-1.

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¹⁰² Ford, E. S., and C. J. Caspersen. 2012. “Sedentary Behaviour and Cardiovascular Disease: A Review of Prospective Studies.” International Journal of Epidemiology 41(5):1338–1353. https://doi.org/10.1093/ije/dys078.

¹⁰³ Raza, A., A. Pulakka, L. L. Magnusson Hanson, H. Westerlund, and J. I. Halonen. 2021. “Commuting Distance and Behavior-Related Health: A Longitudinal Study.” Preventive Medicine 150. https://doi.org/10.1016/j.ypmed.2021.106665.

¹⁰⁴ Sugiyama, T., K. Wijndaele, M. J. Koohsari, S. K. Tanamas, D. W. Dunstan, and N. Owen. 2016. “Adverse Associations of Car Time with Markers of Cardio-Metabolic Risk.” Preventive Medicine 83:26–30. https://doi.org/10.1016/j.ypmed.2015.11.029.

¹⁰⁵ Botchwey, N. D., R. Falkenstein, J. Levin, T. Fisher, and M. Trowbridge. 2015. “The Built Environment and Actual Causes of Death: Promoting an Ecological Approach to Planning and Public Health.” Journal of Planning Literature 3(3):261–281. https://doi.org/10.1177/0885412214561337.

¹⁰⁶ Ibid.

¹⁰⁷ U.S. Department of Health and Human Services. 2018. Physical Activity Guidelines for Americans (2nd edition). https://odphp.health.gov/sites/default/files/2019-09/Physical_Activity_Guidelines_2nd_edition.pdf.

¹⁰⁸ Crespo, C. J., E. Smit, R. E. Andersen, O. Carter-Pokras, and B. E. Ainsworth. 2000. “Race/Ethnicity, Social Class and Their Relation to Physical Inactivity During Leisure Time: Results from the Third National Health and Nutrition Examination Survey, 1988–1994.” American Journal of Preventive Medicine 18(1):46–53; Hawes, A. M., G. S. Smith, and E. McGinty. 2019. “Disentangling Race, Poverty, and Place in Disparities in Physical Activity.” International Journal of Environmental Research and Public Health 16(7):1193. http://doi.org/:10.3390/ijerph16071193; Lee, R. E, R. P. Joseph, L. T. Blackman Carr, S. M. Strayhorn, J. M. Faro, H. Lane, C. Monroe, D. Pekmezi, and J. Szeszulski. 2021. “Still Striding Toward Social Justice? Redirecting Physical Activity Research in a Post-COVID-19 World.” Translational Behavioral Medicine April:ibab026. https://doi.org/10.1093/tbm/ibab026.

life¹⁰⁹ and infrastructure for walking, bicycling, and transit are associated with increased physical activity.¹¹⁰

However, areas with concentrations of low-income and Black and Hispanic populations are more likely to have incomplete and unsafe pedestrian and bicycle infrastructure.¹¹¹ Interventions to improve active travel infrastructure may improve physical activity levels for low-income people and people of color, but whether and how new infrastructure improves health equity is not well understood.¹¹² Concerns about harassment, intrapersonal violence, or disproportionate policing are also barriers for women and people of color in undertaking active transportation.¹¹³

Transportation Safety and Personal Security

In the past decade, traffic-related deaths and fatalities have become a worsening crisis in the United States. More than 42,000 people were killed on U.S. roadways in 2021, which is a 27% increase in fatalities over the past

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¹⁰⁹ Office of the Surgeon General, U.S. Department of Health and Human Services. 2015. “Step It Up! The Surgeon General’s Call to Action to Promote Walking and Walkable Communities [Internet].” https://pubmed.ncbi.nlm.nih.gov/30860691.

¹¹⁰ Community Preventive Services Task Force (CPSTF). 2018. “Physical Activity: Interventions to Increase Active Travel to School.” https://www.thecommunityguide.org/findings/physical-activity-interventions-increase-active-travel-school.html. Accessed October 24, 2023.

¹¹¹ Ferenchak, N. N., and W. E. Marshall. 2020. “Is Bicycling Getting Safer? Bicycle Fatality Rates (1985–2017) Using Four Exposure Metrics.” Transportation Research Interdisciplinary Perspectives 8:100219; Thornton, C. M., T. L. Conway, K. L. Cain, K. A. Gavand, B. E. Saelens, L. D. Frank, C. M. Geremia, K. Glanz, A. C. King, and J. F. Sallis. 2016. “Disparities in Pedestrian Streetscape Environments by Income and Race/Ethnicity.” SSM-Population Health 2:206–216; Wang, Y., and M. A. Beydoun. 2007. “The Obesity Epidemic in the United States—Gender, Age, Socioeconomic, Racial/Ethnic, and Geographic Characteristics: A Systematic Review and Meta-Regression Analysis.” Epidemiologic Reviews 29:6–28.

¹¹² Hansmann, K. J., M. Grabow, and C. McAndrews. 2022. “Health Equity and Active Transportation: A Scoping Review of Active Transportation Interventions and Their Impacts on Health Equity.” Journal of Transport & Health 25(June):101346. https://doi.org/10.1016/j.jth.2022.101346; Lusk, A. C., A. Anastasio, N. Shaffer, J. Wu, and Y. Li. 2017. “Biking Practices and Preferences in a Lower Income, Primarily Minority Neighborhood: Learning What Residents Want.” Preventive Medicine Reports 7(September):232–238. https://doi.org/10.1016/j.pmedr.2017.01.006.

¹¹³ Barajas, J. M. 2021. “The Roots of Racialized Travel Behavior.” Advances in Transport Policy and Planning 8: 1–31; Payán, D. D., D. C. Sloane, J. Illum, and L. Blair Lewis. 2019. “Intrapersonal and Environmental Barriers to Physical Activity Among Blacks and Latinos.” Journal of Nutrition Education and Behavior 51(4):478–485; Roberts, J. D., S. Mandic, C. S. Fryer, M. L. Brachman, and R. Ray. 2019. “Between Privilege and Oppression: An Intersectional Analysis of Active Transportation Experiences Among Washington DC Area Youth.” International Journal of Environmental Research and Public Health 16(8):1313; Sethi, S., and J. Velez-Duque. 2021. Walk with Women: Gendered Perceptions of Safety in Urban Spaces. Boston: Leading Cities.

10 years.¹¹⁴ Urban traffic fatalities increased by 66% from 2013 to 2022.¹¹⁵ The increased amount of time people spend commuting, owing to decentralized development patterns, increases their exposure to traffic crashes.¹¹⁶ Suburban sprawl, which results in higher speeds on suburban streets, is also a risk factor for fatal traffic crashes.¹¹⁷ Higher levels of vehicle traffic and high-speed arterials can be found in Census tracts with concentrations of low-income populations and Black, Indigenous, and people of color.¹¹⁸ These populations are also disproportionately represented in traffic injuries and fatalities, and American Indians/Alaska Natives (AIs/ANs) have the highest traffic fatality rate of all racial and ethnic groups.¹¹⁹

Pedestrian deaths have increased significantly, with 2022 having the highest number of pedestrian deaths since 1981.¹²⁰ AI/AN, Black, and Hispanic populations are overrepresented in pedestrian deaths and injuries.¹²¹ Areas with lower incomes and higher poverty rates also have higher levels of pedestrian fatalities.¹²² In urban areas, pedestrian fatalities have increased 81% since 2013.¹²³ Multilane arterials are particularly danger-

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¹¹⁴ National Highway Traffic Safety Administration (NHTSA). 2023. “Traffic Safety Facts 2021 Data: Summary of Motor Vehicle Crashes.”

¹¹⁵ NHTSA. 2024. “Traffic Safety Facts: Overview of Motor Vehicle Traffic Crashes in 2022.”

¹¹⁶ Weir, M., J., Weintraub, E. Humphreys, E. Seto, and R. Bhatia. 2009. “An Area-Level Model of Vehicle Pedestrian Injury Collisions with Implications for Land Use and Transportation Planning.” Accident Analysis and Prevention 41(1):137–145.

¹¹⁷ Ewing, R., S. Hamidi, and J. B. Grace. 2016. “Urban Sprawl as a Risk Factor in Motor Vehicle Crashes.” Urban Studies 53(2):247–266.

¹¹⁸ Governor’s Highway Safety Association (GHSA). 2021. “An Analysis of Traffic Fatalities by Race and Ethnicity.” https://www.ghsa.org/sites/default/files/2021-06/An%20Analysis%20of%20Traffic%20Fatalities%20by%20Race%20and%20Ethnicity_0.pdf.

¹¹⁹ Marshall, W. E., and N. N. Ferenchak. 2017. “Assessing Equity and Urban/Rural Road Safety Disparities in the US.” Journal of Urbanism: International Research on Placemaking and Urban Sustainability 10(4):422–441. https://doi.org/10.1080/17549175.2017.1310748 ;NHTSA. 2023. “Traffic Safety Facts 2020 Data: Race and Ethnicity”; GHSA. 2021. “An Analysis of Traffic Fatalities by Race and Ethnicity.” https://www.ghsa.org/sites/default/files/2021-06/An%20Analysis%20of%20Traffic%20Fatalities%20by%20Race%20and%20Ethnicity_0.pdf. Accessed October 24, 2024.

¹²⁰ The most recent data presently available, GHSA. 2021. “An Analysis of Traffic Fatalities by Race and Ethnicity.” https://www.ghsa.org/sites/default/files/2021-06/An%20Analysis%20of%20Traffic%20Fatalities%20by%20Race%20and%20Ethnicity_0.pdf.

¹²¹ GHSA. 2021. “An Analysis of Traffic Fatalities by Race and Ethnicity.” https://www.ghsa.org/sites/default/files/2021-06/An%20Analysis%20of%20Traffic%20Fatalities%20by%20Race%20and%20Ethnicity_0.pdf. Accessed October 24, 2024; Roll, J., and N. McNeil. 2022. “Race and Income Disparities in Pedestrian Injuries: Factors Influencing Pedestrian Safety Inequity.” Transportation Research Part D: Transport and Environment 107(June):103294. https://doi.org/10.1016/j.trd.2022.103294.

¹²² Roll, J., and N. McNeil. 2022. “Race and Income Disparities in Pedestrian Injuries: Factors Influencing Pedestrian Safety Inequity.” Transportation Research Part D: Transport and Environment 107(June):103294.

¹²³ NHTSA. 2023. “Traffic Safety Facts 2021 Data: Pedestrians.”

ous; an analysis of fatal pedestrian crash hotspots found that they occurred on multilane roadways, with 70% requiring pedestrians to cross five or more lanes of traffic.¹²⁴ Traffic volumes, multilane streets, and shopping centers are associated with increased risk of pedestrian injury or death in low-income areas. However, they are not in more affluent areas where high-income individuals can avoid walking in dangerous environments to access essential destinations.¹²⁵ More pedestrian fatalities occur in the dark as compared to other times of day,¹²⁶ presenting an increased risk for pedestrians traveling at night, such as shift workers. Racial bias is another risk factor as people driving are less likely to yield to pedestrians of color.¹²⁷

Losing a family member from a crash can impact family mental health and well-being in the long term.¹²⁸ In addition to the mental and emotional stress, traffic fatalities can also mean a loss of a family wage earner or caregiver, which, among other stressors, can lead to residential relocation.¹²⁹ Serious injuries are also associated with psychological trauma and reduced quality of life for the victim,¹³⁰ potential loss of income for the household, increased health care costs, and increased burden of care by family members.¹³¹

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¹²⁴ Schneider, R., R. L. Sanders, F. R. Proulx, and H. Moayyed. 2021. “United States Fatal Pedestrian Crash Hot Spot Locations and Characteristics.” Journal of Transportation and Land Use 14:1–23.

¹²⁵ Dumbaugh, E., J. Stiles, D. Mitsova, and D. Saha. 2023. “The Most Vulnerable User: Examining the Role of Income, Race, and the Built Environment on Pedestrian Injuries and Deaths.” Transportation Research Record 2678(2).

¹²⁶ NHTSA. 2023. “Traffic Safety Facts 2021 Data: Pedestrians.”

¹²⁷ Coughenour, C., S. Clark, A. Singh, E. Claw, J. Abelar, and J. Huebner. 2017. “Examining Racial Bias as a Potential Factor in Pedestrian Crashes.” Accident Analysis & Prevention 98:96–100; Goddard, T., K. B. Kahn, and A. Adkins. 2014. “Racial Bias in Driver Yielding Behavior at Crosswalks.” https://doi.org/10.15760/trec.130.

¹²⁸ Attwood, C., A. Benkwitz, and M. Holland. 2023. “‘We Are the Forgotten Grievers’: Bereaved Family Members’ Experiences of Support and Mental Ill-Health Following a Road Traffic Collision.” Death Studies 47(9):1025–1032. https://doi.org/10.1080/07481187.2022.2160032.

¹²⁹ Huang, L. 2016. “Identifying Risk Factors for Household Burdens of Road Traffic Fatalities: Regression Results from a Cross-Sectional Survey in Taiwan.” BMC Public Health 16(1):1202. https://doi.org/10.1186/s12889-016-3813-3.

¹³⁰ Rissanen, R., H.-Y. Berg, and M. Hasselberg. 2017. “Quality of Life Following Road Traffic Injury: A Systematic Literature Review.” Accident Analysis & Prevention 108(November):308–320. https://doi.org/10.1016/j.aap.2017.09.013; Wang, C.-H., S.-L. Tsay, and A. E. Bond. 2005. “Post-Traumatic Stress Disorder, Depression, Anxiety and Quality of Life in Patients with Traffic-Related Injuries.” Journal of Advanced Nursing 52(1):22–30. https://doi.org/10.1111/j.1365-2648.2005.03560.x.

¹³¹ NHTSA. 2019. “The Economic and Societal Impact of Motor Vehicle Crashes, 2019 (Revised).” https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813403. Accessed October 24, 2024.

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¹³² Health Effects Institute (HEI). 2022. “Systematic Review and Meta-Analysis of Selected Health Effects of Long-Term Exposure to Traffic-Related Air Pollution.” HEI Special Report 23, Panel on the Health Effects of Long-Term Exposure to Traffic-Related Air Pollution, updated April 5, 2023. https://www.healtheffects.org/publication/systematic-review-and-meta-analysis-selected-health-effects-long-term-exposure-traffic.

¹³³ Asthma and Allergy Foundation of America. 2020. “2020 Asthma Disparities in America: A Roadmap to Reducing Burden on Racial and Ethnic Minorities.” https://www.aafa.org/wp-content/uploads/2022/08/asthma-disparities-in-america-burden-on-racial-ethnic-minorities.pdf. Accessed October 24, 2024.

¹³⁴ Commodore, S., P. L. Ferguson, B. Neelon, R. Newman, W. Grobman, A. Tita, J. Pearce, M. S. Bloom, E. Svendsen, J. Roberts, D. Skupski, A. Sciscione, K. Palomares, R. Miller, R. Wapner, J. E. Vena, and K. J. Hunt. 2021. “Reported Neighborhood Traffic and the Odds of Asthma/Asthma-Like Symptoms: A Cross-Sectional Analysis of a Multi-Racial Cohort of Children.” International Journal of Environmental Research and Public Health 18(1):243. https://doi.org/10.3390/ijerph18010243.

¹³⁵ Gray, S. C., S. E. Edwards, B. D. Schultz, and M. L. Miranda. 2014. “Assessing the Impact of Race, Social Factors and Air Pollution on Birth Outcomes: A Population-Based Study.” Environmental Health 13(1):4. https://doi.org/10.1186/1476-069X-13-4.

¹³⁶ Bekkar, B., S. Pacheco, R. Basu, and N. DeNicola. 2020. “Association of Air Pollution and Heat Exposure with Preterm Birth, Low Birth Weight, and Stillbirth in the US: A Systematic Review.” JAMA Network Open 3(6):e208243. https://doi.org/10.1001/jamanetworkopen.2020.8243.

¹³⁷ Tessum, C. W., J. S. Apte, A. L. Goodkind, N. Z. Muller, K. A. Mullins, D. A. Paolella, S. Polasky, N. P. Springer, S. K. Thakrar, J. D. Marshall, and J. D. Hill. 2019. “Inequity in Consumption of Goods and Services Adds to Racial–Ethnic Disparities in Air Pollution Exposure.” Proceedings of the National Academy of Sciences 116(13):6001–6006. https://doi.org/10.1073/pnas.1818859116.

areas are also disproportionately exposed to air pollution from traffic. High traffic volumes are a significant source of traffic-related air pollution and are a barrier to walking and cycling as well.¹³⁸ The number of people living near high-volume roads has increased to 24% from 19% in 2010. Nonwhite populations live in greater proximity to high-volume roads.¹³⁹ Differences in air pollution exposure between racial and ethnic minorities and whites are highest in the most segregated metropolitan areas.¹⁴⁰

Mental Health

Transportation affects health primarily through three pathways: exposures, social exclusion, and behavior.¹⁴¹ Exposure to traffic noise is not only associated with diseases such as cardiovascular disease and diabetes¹⁴² but also associated with a higher risk of dementia.¹⁴³ Depression has a socioeconomic gradient and appears related to environmental exposures, such as socioeconomic stressors and protective social ties.¹⁴⁴ Transportation can promote or prevent social interaction through public social spaces and walkability.¹⁴⁵ Accessible and affordable transportation reduces social

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¹³⁸ Rosenlieb, E. G., C. McAndrews, W. E. Marshall, and A. Troy. 2018. “Urban Development Patterns and Exposure to Hazardous and Protective Traffic Environments.” Journal of Transport Geography 66(January):125–134. https://doi.org/10.1016/j.jtrangeo.2017.11.014.

¹³⁹ Antonczak, B., T. M. Thompson, M. W. DePaola, and G. Rowangould. 2023. “2020 Near-Roadway Population Census, Traffic Exposure and Equity in the United States.” Transportation Research Part D: Transport and Environment 125(December):103965. https://doi.org/10.1016/j.trd.2023.103965.

¹⁴⁰ Woo, B., N. Kravitz-Wirtz, V. Sass, K. Crowder, S. Teixeira, and D. T. Takeuchi. 2019. “Residential Segregation and Racial/Ethnic Disparities in Ambient Air Pollution.” Race and Social Problems 11(1):60–67. https://doi.org/10.1007/s12552-018-9254-0.

¹⁴¹ Fan, Y., and P. Phua. 2020. The Health and Transportation Nexus: A Conceptual Framework for Collaborative and Equitable Planning. Prepared for Minnesota Department of Transportation, Office of Research & Innovation. https://cts-d8resmod-prd.oit.umn.edu/pdf/trs2201.pdf. Accessed November 24, 2024.

¹⁴² Frank, L. D., N. Iroz-Elardo, K. E. MacLeod, and A. Hong. 2019. “Pathways from Built Environment to Health: A Conceptual Framework Linking Behavior and Exposure-Based Impacts.” Journal of Transport & Health 12:319–335. https://doi.org/10.1016/j.jth.2018.11.008.

¹⁴³ Cantuaria, M. L., F. B. Waldorff, L. Wermuth, et al. 2021. “Residential Exposure to Transportation Noise in Denmark and Incidence of Dementia: National Cohort Study.” BMJ 374(1954). https://doi.org/10.1136/bmj.n1954.

¹⁴⁴ Blair, A., N. A. Ross, G. Gariepy, and N. Schmitz. 2014. “How Do Neighborhoods Affect Depression Outcomes? A Realist Review and a Call for the Examination of Causal Pathways.” Social Psychiatry and Psychiatric Epidemiology 49(6):873–887. https://doi.org/10.1007/s00127-013-0810-z.

¹⁴⁵ Frank, L. D., N. Iroz-Elardo, K. E. MacLeod, and A. Hong. 2019. “Pathways from Built Environment to Health: A Conceptual Framework Linking Behavior and Exposure-Based Impacts.” Journal of Transport & Health 12:319–335. https://doi.org/10.1016/j.jth.2018.11.008.

isolation and social exclusion.¹⁴⁶ Social exclusion is a multidimensional concept that encompasses the physical, geographic, or cost barriers to destinations such as employment as well as barriers to social opportunities.¹⁴⁷ In addition, social exclusion addresses an individual’s ability to participate in transportation decision making.¹⁴⁸ In terms of behavior, physical activity in transportation may be protective against adverse mental health outcomes, with research suggesting a moderate benefit for well-being, particularly for walking, bicycling, and transit trips.¹⁴⁹ In a study that employed structural equation modeling, walkable neighborhoods were directly linked to happiness in individuals aged 36–45 and indirectly linked to happiness for older adults.¹⁵⁰

CHAPTER SUMMARY

Transportation equity is best understood in the context of transportation’s role in desired outcomes within a larger societal system. A growing body of research shows that access to housing, employment, education, and health care and health services are affected by transportation, particularly for disadvantaged populations. Research on environmental justice and public health establishes connections between transportation and physical activity and associated health outcomes, transportation safety and personal security, and exposure to air pollution and health effects. As illustrated in the chapter, the research base supports the development of more insightful and useful metrics and tools for assessing equity impacts of transportation.

Causal chain analysis, a logic model approach that is used in health and safety research, as well as in other fields, could help to identify root causes and multiple contributors to an identified need or desired outcome. This type of analysis enables seeing beyond proximate causes, which can

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¹⁴⁶ Frank, L. D., N. Iroz-Elardo, K. E. MacLeod, and A. Hong. 2019. “Pathways from Built Environment to Health: A Conceptual Framework Linking Behavior and Exposure-Based Impacts.” Journal of Transport & Health 12:319–335. https://doi.org/10.1016/j.jth.2018.11.008.

¹⁴⁷ Lucas, K. 2012. “Transport and Social Exclusion: Where Are We Now?” Transport Policy 20:105–113.

¹⁴⁸ Fan, Y., and P. Phua. 2020. The Health and Transportation Nexus: A Conceptual Framework for Collaborative and Equitable Planning. Prepared for Minnesota Department of Transportation, Office of Research & Innovation. https://cts-d8resmod-prd.oit.umn.edu/pdf/trs2201.pdf. Accessed November 24, 2024.

¹⁴⁹ Scrivano, L., A. Tessari, S. M. Marcora, and D. N. Manners. 2023. “Active Mobility and Mental Health: A Scoping Review Towards a Healthier World.” Cambridge Prisms: Global Mental Health 11:e1. https://doi.org/10.1017/gmh.2023.74.

¹⁵⁰ Leyden, K. M., M. J. Hogan, L. D’Arcy, B. Bunting, and S. Bierema. 2023. “Walkable Neighborhoods: Linkages Between Place, Health, and Happiness in Younger and Older Adults.” Journal of the American Planning Association 90(1):101–114. https://doi.org/10.1080/01944363.2022.2123382.

mislead about the best ways to intervene. Analyzing deeper causal pathways can reveal other causes of a problem or need for which innovative solutions can be identified from the varied perspectives of urban planners, engineers, and community members. Tables 2-1 and 2-2 illustrate links in the causal chain between transportation actions and long-term outcomes. As such, they offer a starting point for agencies to develop their own set of indicators and metrics for their communities. The characteristics that make a useful indicator are discussed in Chapter 3. An even deeper understanding of the causal connections between transportation and desired outcomes through research would further inform the selection of indicators and metrics for planning and prioritization of transportation investments for people’s well-being.

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