Summary: Above simply mapping crime risks, we may want to look at potential causes of a risk surface. Many of these causes will be associated with the built environment or the demographics of an area of victimisation. Risk Terrain Modelling (RTM) is a method that uses GIS techniques to explore the relationship between crime and the spatial features that influence it, such as parks, houses, bars, public transport hubs, etc. RTM can help to identify the features that are most strongly associated with a given type of crime, and then produce estimates of the impact that re-configuring these features will have on crime rates.
This page provides information about Risk Terrain Modelling in crime analysis. The methods and associated software used have been developed by the Rutgers Centre on Public Security. The RTM website has many links to books and manuals that introduce the technique. In particular, the the main Risk Terrain Modelling Manual (right) can be downloaded for free. Also, you can watch a video of Prof. Leslie Kennedy, director of the Centre, discussing the technique in a seminar presented at the School of Geography, University of Leeds.
The principle behind Risk Terrain Modelling is that crime risk is, in part, associated with geography. Particular spatial factors will act to increase or decrease crime risk in the surrounding area. However, the relationship between risk factors and crime is non-trivial. Rather than one particular feature being associated with a linear increase or decrease in risk, it is more likely that different configurations of risk factors will determine overall risk. To quote the authors:
"Drawing from an example in meteorology, individual factors that are incorporated into weather forecasting do not necessarily produce rain, thunder storms or hurricanes by themselves. It is only when they intersect in space and time that they have the greatest potential to yield a particular outcome, e.g. a storm. Other times, only one or a few factors may be required to interact in the same geography and at certain times for a particular event to occur." (Caplan and Kennedy, 2010).
These pages will introduce the software and guide you through the steps to create a risk terrain model. This is not a substitute for excellent resources provided by the RTM authors; instead it provides a short, practical introduction.
The practical has been divided into two parts:
Caplan, J.M., Kennedy, L.W., 2010. Risk Terrain Modelling Manual. Rutgers Centre on Public Security, Newark, NJ.