Spatial Accessibility & Network Analysis

The concept of evaluating and analyzing spatial accessibility and networks could be considered the quintessential use of GIS- the program is, after all, a powerful tool for spatial analysis, and accessibility to various networks of travel (streets, sidewalks, railways, etc.) is a very intuitive GIS task in some respects.  

The scenario above involves the closing of the Cypress Creek Campus of Austin Community College, in Travis County, Texas.  The yellow crosses are the other ACC campuses, with the map on the left including Cypress Creek.  The concentric polygons surrounding the campus locations represent the amount of time one might spend driving to that location from that distance, in increments of 5 minutes.  The overlap areas of the drive-time areas is immediately evident, and visual comparison of the two scenarios reveals the fact that a portion of the north-west part of Travis County will no longer be within a 15-minute drive of an ACC campus with the closure of Cypress Creek.  Models like this are useful for analysis of spatial access, as they take into account factors such as road accessibility (one-way restrictions, dead ends, etc.), speed limits, and even historic traffic patterns can be used as a model parameter.  If one were required to assess the impact of closing a college campus, like the above scenario, ArcGIS would be an invaluable asset for analyzing the situation.