The same technology used to study social networks is now equipped to analyze how the spatial layout of cities affects growth and change. And to offer a sigh of relief to cash-strapped cities and urban planners, it's free. The Urban Network Analysis, developed by MIT, uses mathematical network analysis methods to give policymakers a detailed, visual look at how decisions would shape nearly every aspect of urban development, including where jobs could land and where street traffic would be highest. The tool measures the "reach, gravity, betweenness, closeness, and straightness" to urban elements like public transit. Unlike other similar tools, UNA allows users to assign characteristics to individual buildings to get unique, more accurate results. The tool is an open-source plug-in for the ArcGIS mapping system and can be downloaded here.