MEASURING THE CONFIGURATION OF STREET NETWORKS : the Spatial profiles of 118 urban areas in the 12 most populated metropolitan regions in the US 002

In this paper we report an analysis of 118 urban areas sampled from the 12 largest metropolitan regions in the US. We deal with familiar measures of block size, street density, intersection density and distance between intersections. We also introduce two new variables, Reach and Directional Distance. Reach is the aggregate street length that can be accessed from the midpoint of each road segment subject to a limitation of distance. Directional distance is the average number of direction changes needed in order to access all the spaces within reach. We provide parametric definitions of these variables and implement their computation using new software which runs on standard GIS representations of street center lines. Building Large Comparative Data Bases of Street Configuration to Assist Urban Design and Planning If we were able to analyze the existing GIS representations of street networks, a comparative study in the structure of connectivity of cities could be accelerated. To allow this, new software, “Spatialist_lines” (available soon to the research community), was developed in the morphology lab at the Georgia Institute of Technology to compute some familiar and some new spatial variables from the GIS representations of street center-lines readily available from ESRI. Our purpose, in this paper, is to report the preliminary work from an analysis of a sample of urban areas in the US. Our work is in progress, and this paper should be read as a partial report, likely to be augmented by the time it is presented at the 6 International Symposium on Space Syntax in Istanbul. Our research was partly motivated by questions raised during the work on the Atlanta Beltline, a project aimed at creating a 35.4 kilometer transit loop, with trails and parks, around the 19 century city core and at offering opportunities for connecting Atlanta’s neighborhoods currently divided by the railway. The Georgia Institute