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54% of counties in Mecklenburg county live in neighborhoods who’s center is more than 1 mile from a greenway entrance

Accessible Greenways: Theory vs. Reality

A multi-method analysis was conducted to assess greenway accessibility and its relationship to population health outcomes in Charlotte. Accessibility was quantified using a floating catchment area (FCA) model, generating a supply-to-demand ratio based on greenway area and population within a one-mile threshold. The analysis revealed a highly skewed distribution, with most tracts exhibiting no measurable access and higher values concentrated near core corridors. The results and limitations of the study sparked a hypothesis that proximity to green space may be dependent on sidewalk connectivity and other built environment features in order to impact health.

Accessible Greenways: Theory vs. Reality

54% of counties in Mecklenburg county live in neighborhoods who’s center is more than 1 mile from a greenway entrance

Reflections on Methodology

The study’s limitations became the question.

Each diagram below traces a gap in the original model — and the reasoning that drove a more rigorous second analysis.

Centroid Limitation A major limitation with this study is the use of geodesic centroids to measure proximity of a neighborhood to a greenway. Reality shows that a population weighted centroid will often be farther or closer to the service. In this case, a tract that falls inside the catchment area likely would not have if population weighted centroids been used.

Euclidean Buffer vs. Walkshed While Euclidean buffers serve as a good starting point, the weaknesses compared to using walksheds is apparent. Measuring distance to a service “as the crow flies” likely overstated the greenway accessibility of many neighborhoods. Note: this diagram is somewhat exaggerated to illustrate the constraint of Euclidean buffers.

In this case, the entire census tract is given the same greenway accessibility ratio even though it is divided by a major highway with few crossing points. If walksheds and sidewalk coverage were considered, it would likely represent the dynamic between greenways and residents better.

Part 2: Infrastructure as Intervention

The findings of the initial greenway accessibility research prompted a hypothesis: Greater park access is associated with lower obesity prevalence after accounting for neighborhood demographic and accessibility factors, particularly sidewalks. Thus, a secondary statistical analysis examines associations between accessibility and obesity prevalence, exploring the idea that limited proximity to parks and greenways may be linked to adverse health outcomes. These findings underscore the importance of integrating spatial accessibility metrics into public health and planning frameworks.

Project team: Mann Patel, Jackson Plemmons, Sydney Stine, Erik Darden

Part 2: Infrastructure as Intervention

Project team: Mann Patel, Jackson Plemmons, Sydney Stine, Erik Darden

Negative binomial regression residuals map

Spatial Distribution of Negative Binomial Regression Model Residuals White tracts indicate near-perfect predictions. The lack of autocorrelation indicates the model is not systemically skewing predictions. In lieu of sub-tract level population data, this model uses percent coverage per tract by parks and greenways to calculate supply, helping resolve inaccuracies from geodesic centroids.

Analysis Upgrade: Walksheds Swapping Euclidean point-to-point measurements strengthens the validity of the findings. Although there is still room for improvement — park/greenway quality, sidewalk quality, crime rate, noise pollution, and nonlinear thresholds were not accounted for.

Our direct model identifies socioeconomic status (income and race) as the primary drivers of obesity. While “Zero Vehicle Access” and “Park Proximity” trend in the expected directions, their impact is statistically secondary to systemic economic factors.

Key Insight: Further mediation analysis revealed that park access becomes a significant protective factor only when modeled through the pathway of safe pedestrian (sidewalk) infrastructure.