The power of data to visually explain cities is magnified when you put a pair of maps side-by-side. Cities across the world don't speak the same language. But comparative maps, like the ones above, can. This is the premise behind a new project unveiled this week at the Esri user conference, an online Urban Observatory that aspires to be a "live museum with a data pulse" about cities all over the planet.
The interactive tool, designed by geospatial firm Esri, the film company @radical.media, and TED creator Richard Saul Wurman, is built around an extensive comparative mapping tool that so far includes 16 cities. Click through to the platform, and you can toggle between them, pulling up navigable maps on population density, road congestion, and land use, among other data points (beware, though, that some of the cities are currently not shown at the same scale).
That series shows open space in three global cities, as defined by developed or natural areas within town that are available for public use. Los Angeles has a smattering of small local parks and plazas; Rio has whole stretches of town with no open space at all. These next two maps show land in New York and Tokyo that's dedicated to commercial use:
And a similar map of the two cities showing their industrial land use:
Another set of maps, drawn from the Lincoln Institute's Atlas of Urban Expansion, illustrates areas which have more recently been developed, between 1990-2000. Here, it's clear that most of Chicago's growth has come at its western perimeter (also, that Milan is tiny):
The promise of such comparative mapping tools – and they're growing in number – is obviously limited by the available data. As long as cities, and whole countries, measure poverty or count crime incidents differently, it will be tough to plot answers on a map in a way that enables cities to learn from each other. This is a start, though. And as urban planners already know, you can always compare street grids. The top maps of Los Angeles and Paris do just that, while factoring in the posted speed limits on local roads.