It's been estimated that 50 percent of the world's population now lives in cities, with another two billion expected to move to already overcrowded urban areas in the next twenty years. The pressures of rapid urbanization often mean that careful urban planning is difficult, and may be completely overlooked in ad-hoc situations like slums.
In the hopes of helping urban planners and designers make better decisions in the face of such constraints, researchers at MIT's City Form Research Group have launched the Urban Network Analysis (UNA) toolbox, an open-source software that uses mathematical network analysis to describe spatial patterns of cities. Often used to study social networks like Facebook, network analysis methods can also be used to better examine urban issues like accessibility, spatial patterns, urban growth and change. According to Science Daily, the UNA toolbox is the first of its kind to be freely available to city planners. It comes as an open-source plugin for the ArcGIS mapping software, and allows users to "compute five types of graph analysis measures on spatial networks: Reach; Gravity; Betweenness; Closeness; and Straightness."
For example, the "Reach" measure describes how particular destinations -- say, like jobs or transit -- can be reached within a given walking radius from each building along a particular street. Measures like these give city planners and policy makers a better idea of how a city's spatial layout affects the way people inhabit and use it, and what infrastructure or services may be needed in any given area to make it more accessible or livable.
Science Daily describes how the UNA toolbox's abilities can make future urban planning more accurately reflect reality:
The tools incorporate three important features that make network analysis particularly suited for urban street networks. First, they account for geometry and distances in the input networks, distinguishing shorter links from longer links as part of the analysis computations.
Second, unlike previous software tools that operate with two network elements (nodes and edges), the UNA tools include a third network element -- buildings -- which are used as the spatial units of analysis for all measures. Two neighboring buildings on the same street segments can therefore obtain different accessibility results.
And third, the UNA tools optionally allow buildings to be weighted according to their particular characteristics -- more voluminous, more populated, or otherwise more important buildings can be specified to have a proportionately stronger effect on the analysis outcomes, yielding more accurate and reliable results to any of the specified measures.
The Urban Network Analysis (UNA) toolbox can be downloaded here (plus a video tutorial).
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