(http://www.pbs.org/wnet/need-to-know/files/2010/10/Transportation-Desk-Badge.gif) An emerging school of thought among urban planners suggests (http://www.who.int/mediacentre/news/releases/2010/urban_health_20100407/en/index.html) that our decisions about infrastructure have a direct impact on our health. For example, Americans spend an average of 46 minutes a day commuting (http://www.gallup.com/poll/28504/workers-average-commute-roundtrip-minutes-typical-day.aspx) to and from work by car. The Centers for Disease Control and Prevention (http://www.cdc.gov/) have concluded that replacing a quarter of that time with moderate exercise -- i.e. walking instead of driving -- can reduce the risks (http://www.cdc.gov/physicalactivity/everyone/health/index.html) of cardiovascular disease, type 2 diabetes and even some cancers. But too many American communities don't give residents the option to do anything but drive, according to Amanda Thompson (http://placeshakers.wordpress.com/2010/11/16/a-municipal-planners-call-to-arms-and-legs-hearts-and-lungs/). She's Director of Planning (http://www.decaturga.com/cgs_citysvcs_dev.aspx) for the City of Decatur, Ga. (http://www.decaturga.com/), and she's trying to do something about the problem by making it easier for residents of the city to walk and ride their bikes. It isn't an easy change to make, she says, but she thinks that once Americans understand the benefits, they'll clamor for a built environment that's also a healthier environment. (This podcast is done in conjunction with Blueprint America (http://www.pbs.org/wnet/blueprintamerica/), PBS's infrastructure reporting project.) Related: For high-speed rail, a tale of two governors (http://www.pbs.org/wnet/need-to-know/video/video-for-high-speed-rail-a-tale-of-two-governors/6436/)