Problem, research strategy, and findings: The impact of density on emerging highly contagious infectious diseases has rarely been studied. In theory, dense areas lead to more face-to-face interaction among residents, which makes them potential hotspots for the rapid spread of pandemics. On the other hand, dense areas may have better access to health care facilities and greater implementation of social distancing policies and practices. The current COVID-19 pandemic is a perfect case study to investigate these relationships. Our study uses structural equation modeling to account for both direct and indirect impacts of density on the COVID-19 infection and mortality rates for 913 U.S. metropolitan counties, controlling for key confounding factors. We find metropolitan population to be one of the most significant predictors of infection rates; larger metropolitan areas have higher infection and higher mortality rates. We also find that after controlling for metropolitan population, county density is not significantly related to the infection rate, possibly due to more adherence to social distancing guidelines. However, counties with higher densities have significantly lower virus-related mortality rates than do counties with lower densities, possibly due to superior health care systems. Takeaway for practice: These findings suggest that connectivity matters more than density in the spread of the COVID-19 pandemic. Large metropolitan areas with a higher number of counties tightly linked together through economic, social, and commuting relationships are the most vulnerable to the pandemic outbreaks. They are more likely to exchange tourists and businesspeople within themselves and with other parts, thus increasing the risk of cross-border infections. Our study concludes with a key recommendation that planners continue to advocate dense development for a host of reasons, including lower death rates due to infectious diseases like COVID-19.

The article reaches two conclusions counter to accepted transportation engineering theory. First, the traffic environments of dense urban areas appear to be safer than the lower-volume environments of the suburbs. The reason is that many fewer miles are driven on a per capita basis, and the driving that is done is at lower speeds that are less likely to produce fatal crashes. Second, at least in dense urban areas, less-“forgiving” design treatments—such as narrow lanes, traffic-calming measures, and street trees close to the roadway—appear to enhance a roadway's safety performance when compared to more conventional roadway designs. The reason for this apparent anomaly may be that less-forgiving designs provide drivers with clear information on safe and appropriate operating speeds.

In 1997, the Journal of the American Planning Association published a pair of point–counterpoint articles now listed by the American Planning Association as “classics” in the urban planning literature. In the first article, “Are Compact Cities Desirable?” Gordon and Richardson argued in favor of urban sprawl as a benign response to consumer preferences. In the counterpoint article, “Is Los Angeles-Style Sprawl Desirable?” Ewing argued for compact cities as an alternative to sprawl. It is time to reprise the debate. This article summarizes the literature on urban sprawl characteristics and measurements, causes, impacts, and remedies since the original debate.

This study aims to model multiple health outcomes and behaviors in terms of the updated, refined, and validated county compactness/sprawl measures. Multiple health outcomes and behaviors are modeled using multi-level analysis. 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. Developing urban and suburban areas in a more compact manner may have some salutary effect on obesity and chronic disease trends.

By measuring twenty streetscape features and numerous other variables for 588 blocks in New York City, we were able to identify variables that explain pedestrian traffic volumes. We found significant positive correlations between three out of twenty streetscape features with pedestrian counts after controlling for density and other built environmental variables. The significant streetscape features are the proportion of windows on the street, the proportion of active street frontage, and the number of pieces of street furniture. This study provides guidance for streetscape projects that aim to create walkable streets and pedestrian-friendly environments.

(2017). “Does Compact Development Make People Drive Less?” The Answer Is Yes. Journal of the American Planning Association: Vol. 83, No. 1, pp. 19-25.