Abstract

Evaluating the Impact of CCTV: Developing and Analyzing Realistic Viewsheds
Track: Law Enforcement and Criminal Justice
Authors: Elizabeth Groff

The use of Closed Circuit Television (CCTV) cameras is growing even without solid evidence of their crime reduction value. Unlike traditional approaches that rely on arbitrarily-selected buffer distances, this research constructs individual GIS polygons for each camera which reflect the influence of vegetation and other obstacles on the distance the camera can see. Because cameras were installed in close proximity (with a couple of blocks of one another) they often had overlapping viewsheds. In order to accurately model the total area within a viewshed, we developed a geoprocessing model which summarized the weekly area within a viewshed. Using these improved viewsheds we found cameras reduced burglary significantly and produced decreases in violent crime and vehicle theft. The presentation will discuss challenges in the creation of the viewsheds and the geoprocessing model used in the evaluation to assist other cities who are interested in evaluating their CCTV camera installations.