The evolution of urban sprawl: evidence of spatial heterogeneity and increasing land fragmentation.
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We investigate the dynamics and spatial distribution of land use fragmentation in a rapidly urbanizing region of the United States to test key propositions regarding the evolution of sprawl. Using selected pattern metrics and data from 1973 and 2000 for the state of Maryland, we find significant increases in developed and undeveloped land fragmentation but substantial spatial heterogeneity as well. Estimated fragmentation gradients that describe mean fragmentation as a function of distance from urban centers confirm the hypotheses that fragmentation rises and falls with distance and that the point of maximum fragmentation shifted outward over time. However, rather than outward increases in sprawl balanced by development infill, we find substantial and significant increases in mean fragmentation values along the entire urban-rural gradient. These findings are in contrast to the results of Burchfield et al. [Burchfield M, Overman HG, Puga D, Turner MA (2006) Q J Econ 121:587-633], who conclude that the extent of sprawl remained roughly unchanged in the Unites States between 1976 and 1992. As demonstrated here, both the data and pattern measure used in their study are systematically biased against recording low-density residential development, the very land use that we find is most strongly associated with fragmentation. Other results demonstrate the association between exurban growth and increasing fragmentation and the systematic variation of fragmentation with nonurban factors. In particular, proximity to the Chesapeake Bay is negatively associated with fragmentation, suggesting that an attraction effect associated with this natural amenity has concentrated development. (+info)
Built environment, adiposity, and physical activity in adults aged 50-75.
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Investment in safe routes to school projects: public health benefits for the larger community.
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INTRODUCTION: The Safe Routes to School (SRTS) program is designed to encourage active and safe transportation for children to school. This report examines the potential broader impact of these programs on communities within 0.5 mile (0.8 km) of schools. METHODS: We used a geographic information system to generate estimates of the land area within 0.5 mile of public schools in 4 U.S. Census-defined categories: 37 large urban areas, 428 small urban areas, 1088 metropolitan counties (counties in metropolitan statistical areas excluding the urban areas), and 2048 nonmetropolitan counties. We estimated population at the county level or at the U.S. Census-defined urban-area level using data from the 2000 U.S. Census. RESULTS: In large urban areas, 39.0% of the land area was within 0.5 mile of a public school, and in small urban areas, 26.5% of the land area was within 0.5 mile of a public school. An estimated 65.5 million people in urban areas could benefit from SRTS projects. In nonurban areas, 1% or less of land is within 0.5 mile of a public school. CONCLUSION: Results suggest that SRTS projects in urban areas can improve the walking and bicycling environment for adults as well as for children, the target users. Investment in SRTS can contribute to increased physical activity among children and adults. (+info)
Built environment correlates of walking: a review.
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