Land use, transport, and population health: estimating the health benefits of compact cities.

Using a health impact assessment framework, we estimated the population health effects arising from alternative land-use and transport policy initiatives in six cities. Land-use changes were modelled to reflect a compact city in which land-use density and diversity were increased and distances to public transport were reduced to produce low motorised mobility, namely a modal shift from private motor vehicles to walking, cycling, and public transport. The modelled compact city scenario resulted in health gains for all cities (for diabetes, cardiovascular disease, and respiratory disease) with overall health gains of 420-826 disability-adjusted life-years (DALYs) per 100 000 population. However, for moderate to highly motorised cities, such as Melbourne, London, and Boston, the compact city scenario predicted a small increase in road trauma for cyclists and pedestrians (health loss of between 34 and 41 DALYs per 100 000 population). The findings suggest that government policies need to actively pursue land-use elements-particularly a focus towards compact cities-that support a modal shift away from private motor vehicles towards walking, cycling, and low-emission public transport. At the same time, these policies need to ensure the provision of safe walking and cycling infrastructure. The findings highlight the opportunities for policy makers to positively influence the overall health of city populations.

Urban sprawl, obesity, and cancer mortality in the United States: cross-sectional analysis and methodological challenges.

BACKGROUND: Urban sprawl has the potential to influence cancer mortality via direct and indirect effects on obesity, access to health services, physical activity, transportation choices and other correlates of sprawl and urbanization. METHODS: This paper presents a cross-sectional analysis of associations between urban sprawl and cancer mortality in urban and suburban counties of the United States. This ecological analysis was designed to examine whether urban sprawl is associated with total and obesity-related cancer mortality and to what extent these associations differed in different regions of the US. A major focus of our analyses was to adequately account for spatial heterogeneity in mortality. Therefore, we fit a series of regression models, stratified by gender, successively testing for the presence of spatial heterogeneity. Our resulting models included county level variables related to race, smoking, obesity, access to health services, insurance status, socioeconomic position, and broad geographic region as well as a measure of urban sprawl and several interactions. Our most complex models also included random effects to account for any county-level spatial autocorrelation that remained unexplained by these variables. RESULTS: Total cancer mortality rates were higher in less sprawling areas and contrary to our initial hypothesis; this was also true of obesity related cancers in six of seven U.S. regions (census divisions) where there were statistically significant associations between the sprawl index and mortality. We also found significant interactions (p < 0.05) between region and urban sprawl for total and obesity related cancer mortality in both sexes. Thus, the association between urban sprawl and cancer mortality differs in different regions of the US. CONCLUSIONS: Despite higher levels of obesity in more sprawling counties in the US, mortality from obesity related cancer was not greater in such counties. Identification of disparities in cancer mortality within and between geographic regions is an ongoing public health challenge and an opportunity for further analytical work identifying potential causes of these disparities. Future analyses of urban sprawl and health outcomes should consider exploring regional and international variation in associations between sprawl and health.

Urban sprawl, physical activity, and body mass index: Nurses' Health Study and Nurses' Health Study II.

OBJECTIVES: We evaluated the association between the county sprawl index, a measure of residential density and street accessibility, and physical activity and body mass index (BMI). METHODS: We conducted a multilevel cross-sectional analysis in a sample of Nurses' Health Study participants living throughout the United States in 2000 to 2001 (n = 136 592). RESULTS: In analyses adjusted for age, smoking status, race, and husband's education, a 1-SD (25.7) increase in the county sprawl index (indicating a denser, more compact county) was associated with a 0.13 kilograms per meters squared (95% confidence interval [CI] = -0.18, -0.07) lower BMI and 0.41 (95% CI = 0.17, 0.65) more metabolic equivalent (MET) hours per week of total physical activity, 0.26 (95% CI = 0.19, 0.33) more MET hours per week of walking, and 0.47 (95% CI = 0.34, 0.59) more MET hours per week of walking, bicycling, jogging, and running. We detected potential effect modification for age, previous disease status, husband's education level (a proxy for socioeconomic status), and race. CONCLUSIONS: Our results suggest that living in a dense, compact county may be conducive to higher levels of physical activity and lower BMI in women.

Evaluating the safety effects of bicycle lanes in New York City.

OBJECTIVES: We evaluated the effects of on-street bicycle lanes installed prior to 2007 on different categories of crashes (total crashes, bicyclist crashes, pedestrian crashes, multiple-vehicle crashes, and injurious or fatal crashes) occurring on roadway segments and at intersections in New York City. METHODS: We used generalized estimating equation methodology to compare changes in police-reported crashes in a treatment group and a comparison group before and after installation of bicycle lanes. Our study approach allowed us to control confounding factors, such as built environment characteristics, that cannot typically be controlled when a comparison group is used. RESULTS: Installation of bicycle lanes did not lead to an increase in crashes, despite the probable increase in the number of bicyclists. The most likely explanations for the lack of increase in crashes are reduced vehicular speeds and fewer conflicts between vehicles and bicyclists after installation of these lanes. CONCLUSIONS: Our results indicate that characteristics of the built environment have a direct impact on crashes and that they should thus be controlled in studies evaluating traffic countermeasures such as bicycle lanes. To prevent crashes at intersections, we recommend installation of "bike boxes" and markings that indicate the path of bicycle lanes across intersections.

Longitudinal analyses of the relationship between development density and the COVID-19 morbidity and mortality rates: Early evidence from 1,165 metropolitan counties in the United States.

This longitudinal study aims to investigative the impacts of development density on the spread and mortality rates of COVID-19 in metropolitan counties in the United States. Multilevel Linear Modeling (MLM) is employed to model the infection rate and the mortality rate of COVID-19, accounting for the hierarchical (two-level) and longitudinal structure of the data. This study finds that large metropolitan size (measured in terms of population) leads to significantly higher COVID-19 infection rates and higher mortality rates. After controlling for metropolitan size and other confounding variables, county density leads to significantly lower infection rates and lower death rates. These findings recommend that urban planners and health professionals continue to advocate for compact development and continue to oppose urban sprawl for this and many other reasons documented in the literature, including the positive relationship between compact development and fitness and general health.

Not Parking Lots but Parks: A Joint Association of Parks and Transit Stations with Travel Behavior.

Urban design literature says that public open space in a station area could promote walking and other types of physical activity, enhance place attractiveness, and increase property values. In the context of station areas, however, there is a lack of empirical studies on the relationship between the presence of parks and sustainable travel behavior, which is one of the primary goals of transit-oriented developments (TODs). This study examined the impact of park provision on transit users' mode choice in three U.S. regions: Atlanta (GA), Boston (MA), and Portland (OR). This study utilized multilevel multinomial logistic regression to account for hierarchical data structures-trips nested within station areas-and multiple travel modes-automobiles, transit, and walking. After controlling for the built environment and trip attributes, this study showed that when there was a park, people were more likely to walk or take transit to access or egress a transit station. A transit station having a park nearby may provide a more pleasant first-mile/last-mile travel experience. This paper demonstrated that station areas need to incorporate more public space, an overlooked element in current TOD plans.

Associations between Urban Sprawl and Life Expectancy in the United States.

In recent years, the United States has had a relatively poor performance with respect to life expectancy compared to the other developed nations. Urban sprawl is one of the potential causes of the high rate of mortality in the United States. This study investigated cross-sectional associations between sprawl and life expectancy for metropolitan counties in the United States in 2010. In this study, the measure of life expectancy in 2010 came from a recently released dataset of life expectancies by county. This study modeled average life expectancy with a structural equation model that included five mediators: annual vehicle miles traveled (VMT) per household, average body mass index, crime rate, and air quality index as mediators of sprawl, as well as percentage of smokers as a mediator of socioeconomic status. After controlling for sociodemographic characteristics, this study found that life expectancy was significantly higher in compact counties than in sprawling counties. Compactness affects mortality directly, but the causal mechanism is unclear. For example, it may be that sprawling areas have higher traffic speeds and longer emergency response times, lower quality and less accessible health care facilities, or less availability of healthy foods. Compactness affects mortality indirectly through vehicle miles traveled, which is a contributor to traffic fatalities, and through body mass index, which is a contributor to many chronic diseases. This study identified significant direct and indirect associations between urban sprawl and life expectancy. These findings support further research and practice aimed at identifying and implementing changes to urban planning designed to support health and healthy behaviors.

Obesity and the built environment at different urban scales: examining the literature.

The majority of people now live in an urban (or suburban) environment. The built (material) environment, its vehicular and pedestrian infrastructure, buildings, and public realm places, are the places used for working, living, and recreating. The environment currently favors and facilitates motorized vehicles generally, and private automobiles especially. The prioritization given to vehicles reduces opportunities for other, more active modes of travel such as walking and bicycling. Though the built environment cannot be said to directly affect human obesity, the built environment clearly has a relationship to obesity as a consequence of physical activity. Most concerning is that rates of obesity have risen as cars have become increasingly privileged, leading to places that favor driving over walking or bicycling. This review examines current empirical literature on the environment and obesity at 3 key urban scales: macro, meso, and micro. Other key issues examined include longitudinal studies and self-selection bias. Evidence for a relationship between urban and suburban environments and obesity is found in the literature, but the lack of longitudinal research and research controlling for self-selection bias remains underrepresented.

Relationship between urban sprawl and weight of United States youth.

BACKGROUND: Among United States youth there is an obesity epidemic with potential life-long health implications. To date, relationships between the built environment and body mass index (BMI) have not been evaluated for youth, and have not been evaluated longitudinally. OBJECTIVES: To determine if urban sprawl is associated with BMI for U.S. youth. METHODS: Using data from the 1997 National Longitudinal Survey of Youth (NLSY97), both cross-sectional and longitudinal analyses were conducted. Hierarchical modeling was used to relate characteristics of individuals, households, and places to BMI. Individual and household data were extracted from the NLSY97. The independent variable of interest was the county sprawl index, which was derived with principal components analyses from census and other data. RESULTS: In a cross-sectional analysis, the likelihood of U.S. adolescents (aged 12-17 years) being overweight or at risk of overweight (> or =85th percentile relative to the Centers for Disease Control growth charts) was associated with county sprawl (p=0.022). In another cross-sectional analysis, after controlling for sociodemographic and behavioral covariates, the likelihood of young adults (aged 18-23 years) being obese was also associated with county sprawl (p=0.048). By contrast, in longitudinal analyses, BMI growth curves for individual youth over the 7 years of NLSY97, and BMI changes for individual youth who moved between counties, were not related to county sprawl (although coefficient signs were as expected). CONCLUSIONS: Cross-sectional analyses suggest that urban form is associated with being overweight among U.S. youth. The strength of these relationships proved comparable to those previously reported for adults. Longitudinal analyses show no such relationship. It is unclear why these approaches give different results, but sample sizes, latent effects, and confounders may contribute.

Researchers and policymakers: travelers in parallel universes.

Public policy, in the form of laws, guidelines, and regulations, has a profound effect on our daily lives and health status. Reasons for a lack of consistent and systematic translation of public health research into public policy is examined, including differences in decision-making processes, poor timing, ambiguous findings, the need to balance objectivity and advocacy, personal demands of the process, information overload, lack of relevant data, and the mismatch of randomized thinking with nonrandom problems. Next, several actions are suggested that should help bridge the chasm between science and policy, such as greater involvement in the process, better understanding of political decision making, building of effective teams, and development of political champions. Scientists are obligated not only to discover new knowledge but also to ensure that discoveries are applied to improve health.

Indicators of activity-friendly communities: an evidence-based consensus process.

BACKGROUND: Regular physical activity, even at modest intensities, is associated with many health benefits. Most Americans, however, do not engage in the recommended levels. As practitioners seek ways to increase population rates of physical activity, interventions and advocacy efforts are being targeted to the community level. Yet, advocates, community leaders, and researchers lack the tools needed to assess local barriers to and opportunities for more active, healthy lifestyles. Investigators used a systematic review process to identify key indicators of activity-friendly communities that can assess and improve opportunities for regular physical activity. METHODS: Investigators conducted a comprehensive literature review of both peer-reviewed literature and fugitive information (e.g., reports and websites) to generate an initial list of indicators for review (n=230). The review included a three-tiered, modified Delphi consensus-development process that incorporated input of international, national, state, and local researchers and practitioners from academic institutions, federal and state government agencies, nonprofit organizations, and funding agencies in public health, transportation, urban planning, parks and recreation, and public policy. RESULTS: Ten promising indicators of activity-friendly communities were identified: land use environment, access to exercise facilities, transportation environment, aesthetics, travel patterns, social environment, land use economics, transportation economics, institutional and organizational policies, and promotion. CONCLUSIONS: Collaborative, multidisciplinary approaches are underway to test, refine, and expand this initial list of indicators and to develop measures that communities, community leaders, and policymakers can use to design more activity-friendly community environments.

Left-turn phase: permissive, protected, or both? A quasi-experimental design in New York City.

The practice of left-turn phasing selection (permissive, protected-only, or both) varies from one locality to another. The literature evidence on this issue is equally mixed and insufficient. In this study, we evaluate the safety impacts of changing left-turn signal phasing from permissive to protected/permissive or protected-only at 68 intersections in New York City using a rigorous quasi-experimental design accompanied with regression modeling. Changes in police reported crashes including total crashes, multiple-vehicle crashes, left-turn crashes, pedestrian crashes and bicyclist crashes were compared between before period and after period for the treatment group and comparison group by means of negative binomial regression using a Generalized Estimating Equations (GEE) technique. Confounding factors such as the built environment characteristics that were not controlled in comparison group selection are accounted for by this approach. The results show that the change of permissive left-turn signal phasing to protected/permissive or protected-only signal phasing does not result in a significant reduction in intersection crashes. Though the protected-only signal phasing does reduce the left-turn crashes and pedestrian crashes, this reduction was offset by a possible increase in over-taking crashes. These results suggest that left-turn phasing should not be treated as a universal solution that is always better than the permissive control for left-turn vehicles. The selection and implementation of left-turn signal phasing needs to be done carefully, considering potential trade-offs between safety and delay, and many other factors such as geometry, traffic flows and operations.

How the built environment affects physical activity: views from urban planning.

The link between the built environment and human behavior has long been of interest to the field of urban planning, but direct assessments of the links between the built environment and physical activity as it influences personal health are still rare in the field. Yet the concepts, theories, and methods used by urban planners provide a foundation for an emerging body of research on the relationship between the built environment and physical activity. Recent research efforts in urban planning have focused on the idea that land use and design policies can be used to increase transit use as well as walking and bicycling. The development of appropriate measures for the built environment and for travel behavior is an essential element of this research. The link between the built environment and travel behavior is then made using theoretical frameworks borrowed from economics, and in particular, the concept of travel as a derived demand. The available evidence lends itself to the argument that a combination of urban design, land use patterns, and transportation systems that promotes walking and bicycling will help create active, healthier, and more livable communities. To provide more conclusive evidence, however, researchers must address the following issues: An alternative to the derived-demand framework must be developed for walking, measures of the built environment must be refined, and more-complete data on walking must be developed. In addition, detailed data on the built environment must be spatially matched to detailed data on travel behavior.

Relationship between urban sprawl and physical activity, obesity, and morbidity.

PURPOSE: To determine the relationship between urban sprawl, health, and health-related behaviors. DESIGN: Cross-sectional analysis using hierarchical modeling to relate characteristics of individuals and places to levels of physical activity, obesity, body mass index (BMI), hypertension, diabetes, and coronary heart disease. SETTING: U.S. counties (448) and metropolitan areas (83). SUBJECTS: Adults (n = 206,992) from pooled 1998, 1999, and 2000 Behavioral Risk Factor Surveillance System (BRFSS). MEASURES: Sprawl indices, derived with principal components analysis from census and other data, served as independent variables. Self-reported behavior and health status from BRFSS served as dependent variables. RESULTS: After controlling for demographic and behavioral covariates, the county sprawl index had small but significant associations with minutes walked (p = .004), obesity (p < .001), BMI (p = .005), and hypertension (p = .018). Residents of sprawling counties were likely to walk less during leisure time, weigh more, and have greater prevalence of hypertension than residents of compact counties. At the metropolitan level, sprawl was similarly associated with minutes walked (p = .04) but not with the other variables. CONCLUSION: This ecologic study reveals that urban form could be significantly associated with some forms of physical activity and some health outcomes. More research is needed to refine measures of urban form, improve measures of physical activity, and control for other individual and environmental influences on physical activity, obesity, and related health outcomes.

Relationship between urban sprawl and physical activity, obesity, and morbidity - update and refinement.

AIMS: This study aims to model multiple health outcomes and behaviors in terms of the updated, refined, and validated county compactness/sprawl measures. METHODS: Multiple health outcomes and behaviors are modeled using multi-level analysis. RESULTS: After controlling for observed confounding influences, both original and new compactness measures are negatively related to BMI, obesity, heart disease, high blood pressure, and diabetes. Indices are not significantly related to physical activity, perhaps because physical activity is not defined broadly to include active travel to work, shopping, and other destinations. CONCLUSIONS: Developing urban and suburban areas in a more compact manner may have some salutary effect on obesity and chronic disease trends.

Safety countermeasures and crash reduction in New York City--Experience and lessons learned.

Traffic fatalities and injuries constitute a major global public health problem and the United States has fallen behind other developed countries in traffic safety. Yet, New York City stands out as a traffic safety model in the nation with its low fatality rate and its significant reductions in various types of crashes. This study develops a safety framework that considers three principal axes that affect crashes: why, who, and where. While "why" concerns exposure, conflict, and speed, "who" and "where" consider the unique characteristics of the road users and the surrounding built environment. Grounded in this safety framework, the effectiveness of 13 safety countermeasures and street designs installed in New York City between 1990 and 2008 are evaluated using a two group pretest-posttest design. The potential regression-to-the-mean problem is addressed by applying the ANCOVA regression approach. The results show that signal related countermeasures that are designed to reduce conflicts: split phase timing, signal installations, all pedestrian phase, and increasing pedestrian crossing time, reduce crashes. Traffic calming measures, including road diets, are also found to have significant safety benefits. Countermeasures that are designed to alert drivers' cognitive attention, such as high visibility crosswalks and posted speed limit reduction signs, appear to have a lesser effect. The various safety countermeasures implemented in New York City considered all three important dimensions in the safety framework: why, who, and where. The study suggests these strategies are likely to contribute to the large reductions in crashes in New York City. We also demonstrate that a rigorous quasi-experimental design can be readily deployed in transportation safety evaluation studies.

The association between community physical activity settings and youth physical activity, obesity, and body mass index.

BACKGROUND: This study examined the association between the level of physical activity (PA) friendliness of the built environment and adolescent PA and body mass index using a national sample of youth and data collected from the communities where they reside. METHODS: Data on height, weight, and PA were taken from annual nationally representative cross-sectional Monitoring the Future surveys of 8th and 10th graders in schools, from 2001 through 2003. Measures of safety, outdoor and commercial PA settings, and urban sprawl were constructed using data collected from the communities in which the students reside. Multilevel models were run and controlled for youth and community demographic and socioeconomic characteristics. RESULTS: Increased levels of physical disorder were associated with decreased PA and higher weight. A greater number of commercial PA facilities was associated with increased PA. More compact communities were associated with lower weight and less sports participation. CONCLUSIONS: It is important to explore these associations to help guide future development patterns and land use policies to create more active neighborhoods.

The built environment and physical activity levels: the Harvard Alumni Health Study.

BACKGROUND: Physical activity is associated with better health, but many individuals are insufficiently active. Modifying the built environment may be an approach capable of influencing population-wide levels of physical activity, but few data exist from longitudinal studies that can minimize bias from active people choosing activity-friendly neighborhoods. PURPOSE: This study aims to examine cross-sectional and longitudinal associations between the built environment and physical activity on a large scale. METHODS: This study examined cross-sectional associations between urban sprawl (mapping addresses to corresponding counties) and physical activity (self-reported) among men throughout the U.S. in 1993 and in 1988, and longitudinal associations between changes in exposure to urban sprawl for movers and physical activity, 1988-1993. Included were 4997 men (mean age, 70 years) in the 1993 cross-sectional study; 4918 men in the 1988 cross-sectional study; and 3448 men in the longitudinal study, 1988-1993. Data were collected prospectively in 1988 and 1993, and analyses were performed in 2007-2008. RESULTS: In cross-sectional analyses, less sprawl was significantly associated with more walking OR, comparing least with most sprawling areas, for meeting physical activity recommendations by walking=1.38 [95% CI=1.09, 1.76] in 1993 and 1.53 [1.19, 1.96] in 1988). Less sprawl also was associated with lower prevalence of overweight (corresponding OR=0.79 [0.64, 0.98] in 1993 and 0.81 [0.66, 1.00] in 1988). However, longitudinal analyses assessing change did not show that decreasing sprawl was associated with increased physical activity or decreased BMI. CONCLUSIONS: These findings suggest that the cross-sectional results may reflect self-selection, rather than indicating that the built environment--as measured by urban sprawl--increases physical activity. However, the longitudinal findings were limited by small numbers of men changing residence and associated sprawl levels.

Creating and validating GIS measures of urban design for health research.

Studies relating urban design to health have been impeded by the unfeasibility of conducting field observations across large areas and the lack of validated objective measures of urban design. This study describes measures for five dimensions of urban design - imageability, enclosure, human scale, transparency, and complexity - created using public geographic information systems (GIS) data from the US Census and city and state government. GIS measures were validated for a sample of 588 New York City block faces using a well-documented field observation protocol. Correlations between GIS and observed measures ranged from 0.28 to 0.89. Results show valid urban design measures can be constructed from digital sources.