Good news on sprawl: It doesn't increase heart disease

Bad news: Traffic fatalities, cost of living, upward mobility, body mass index, obesity, physical activity, life expectancy, high blood pressure, diabetes.

That's the summary of Smart Growth America's Measuring Sprawl 2014, as reported by researcher Todd Litman in an article called "New Research on Smart Growth Benefits" on Planetizen. 

Litman's summary table is impressive:

"Measuring Sprawl rated 221 metropolitan areas and 994 counties in the U.S. according to four primary factors: density (people and jobs per square mile), mix(whether neighborhoods had a mix of homes, jobs and services), centricity (the strength of activity centers and downtowns) and roadway connectivity (the density of connections in the roadway network). Based on this information it assigned a Sprawl Index score to each area," Litman reports.

Least sprawling metro areas

New York and San Francisco topped all metro areas studied in least sprawl, and that's probably no surprise. But there are some unexpected metros near the top, including Miami-Dade County. 

Most sprawling

Here's a list of the most sprawling metro areas:

Litman explains these findings in more detail: 

Combined housing and transportation costs

The portion of household income spent on housing is greater, but the portion of income spent on transportation is lower, in smart growth communities. Each 10% increase in an index score was associated with a 1.1% increase in housing costs and a 3.5% decrease in transportation costs relative to income. Since transportation costs decline faster than housing costs rise, this results in a net decline in combined housing and transportation costs. This is consistent with Housing and Transportation (H+T) Affordability Index analyses.

Safety

Smart growth communities tend to have more traffic crashes (due to increased traffic density, that is, more vehicles per lane-mile, which increases the possibility of a crash), but they are less severe (because they occur at lower speeds). For every 10% increase in an index score, fatal crashes decrease by almost 15%.

Health

Smart growth community residents tend to live longer. For every doubling in the index score, life expectancy increases by about four percent. For the average American with a life expectancy of 78 years, this translates into a three-year difference in life expectancy between sprawled versus smart growth communities. This reflects significantly lower rates of traffic fatalities, obesity, high blood pressure and diabetes in smart growth communities, although these are somewhat offset by slightly higher air pollution exposure and murder risk.

Obesity and diabetes are higher in sprawl, and physical activity lower, the report notes. Upward mobility is also lower in sprawl. On the positive side, if you spend a lot of time in sprawl, it is associated with fewer traffic accidents (although the accidents that do occur are of greater severity), the report finds. And finally, sprawl does not increase heart disease. 

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