Description

In this study by Sarit Weisburd, performed using data collected from geographic locators attached to police vehicles in Dallas, Texas over a one year period, researchers estimated the effect of policing on accident outcomes. They used a multi spell duration model with explanatory variables to differentiate between the immediate effect of police presence and the long-term effect of policing on expectations of future police presence. In order to address concerns of simultaneity bias, the study controlled for location speci…fic effects and measure the effect of “random patrol” created when police vehicles pass through an area en route to or returning from a call at another location. Estimates suggest that at least two days of high intensity stationary police presence at a given time interval and location can reduce that area’s accident rate by almost 40 percent during the following week. It was also noted that the presence of a stationary police vehicle can immediately reduce the accident rate by at least 9 percent, while the presence of moving police vehicles can produce the opposite effect. Mobility Managers may infer from these results that well-publicized Automated Traffic Management devices, such as red light cameras and speed detection monitors may help deter violations and reduce accident rates.