The City Form Lab has released a state-of-the-art toolbox for urban network analysis. As the first of its kind, the Centrality Tools this ArcGIS toolbox can be used to compute five types of graph analysis measures on spatial networks: Reach; Gravity; Betweenness; Closeness; and Straightness. Redundancy Redundancy Tools additionally calculate the Redundancy Index, Redundant Paths, and the Wayfinding Index.
The tools incorporate three important features that make them particularly suited for spatial analysis on urban street networks. First, they can account for both geometry and topology in the input networks, using either metric distance (e.g. Meters) or topological distance (e.g. Turns) as impedance factors in the analysis. 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 tools are aimed at urban designers, architects, planners, geographers, and spatial analysts who are interested in studying the spatial configurations of cities, and their related social, economic, and environmental processes. The toolbox is built for easy scaling - it is equally suited for small-scale, detailed network analysis of dense urban areas as it is for sparser large-scale regional networks. The toolbox requires ArcGIS 10 software with an ArcGIS Network Analyst Extension.
Credits: Andres Sevtsuk, Michael Mekonnen, Raul Kalvo.