Assessing the Efficacy of Crime Prevention through Environmental Design: Creating Busy Streets By Making Them Safer

Introduction. Crime prevention through environmental design (CPTED) is an approach to crime reduction which recognizes the important influence of the urban built environment on human behavior. These interventions alter the physical environments of neighborhoods in ways that are meant to dissuade criminal behavior and reduce opportunities for crime. CPTED interventions are designed around four key principles: surveillance, access control, maintenance, and territoriality. Example intervention activities include adding lighting or fencing around empty lots, mowing or landscaping lawns, and fixing broken windows. With all CPTED activities, the goal is to increase the perception that spaces are owned, cared for, and monitored. Since the 1970s, evaluations of CPTED have demonstrated that these interventions are effective in reducing crime; however, there is still only sparse evidence of these positive effects. Previous studies have been limited by the fact that they did not examine the effects of the intervention spatially, they only evaluated one type of CPTED intervention, or they had only a short window of time over which the effects of the intervention were observed. In this study we examined five high-crime sites in Flint, Michigan which received intensive and diverse CPTED intervention activities beginning in 2012, in order to evaluate the efficacy of CPTED in reducing crime. Our approach makes use of innovative spatial and statistical methods in order to address some of the limitations that other studies of CPTED interventions have encountered.

Methods. With crime incident data provided by the Michigan State Police, we examine the declines in crime rates between 2012 and 2017 within 100 meter buffer areas of five intervention sites. We then compare these to the trends in crime rates throughout the rest of Flint using longitudinal mixed effects modelling.

Results. We find that yearly crime rates are declining across the city, but at a greater rate in CPTED intervention areas. CPTED intervention activities are a significant predictor of this decline, even when controlling for initial crime rate, estimated population, neighborhood disadvantage, and random effects associated with neighborhood/geography.

Conclusion. Our findings suggest that CPTED is an effective strategy for crime reduction. More research is needed to determine specific mechanisms of action for CPTED interventions, for example, which CPTED strategies provide the greatest reductions in crime, and how far out the effects of localized intervention activities radiate from intervention sites. We will discuss existing CPTED interventions and how community resources may be leveraged to reduce crime via environmental change.