Traffic Safety Effects of Automated Speed Enforcement (ASE)

Abstract

Automated speed enforcement (ASE) and red-light cameras (RLC) reduce most types of car crashes. The categories of crashes include fatal, injury, and property damage only (PDO). ASE and red-light cameras are most commonly used in some countries in Europe, Asia, and North America. This research focuses on cities in the United States as a case study to collect the data; more specifically, focuses on several cities. The cities studied for ASE and red-light cameras implementation include the District of Columbia, D.C., Chicago, and Denver. This research studies and examines the spillover effects, either positive or negative, of the treated sites with automated speed enforcement. Spillover effects are the areas affected surrounding the ASE cameras or the speed cameras' effect on traffic in the area immediately surrounding the ASE sites just outside the camera enforcement sites. The research examines and studies the spillover effects; if positive, how much is the reduction in crashes compared to treated and nontreated sites. Furthermore, what can be done further to improve the safety and efficacy of the ASE sites. If the effects are harmful, how much does the percentage of crashes increase in the surrounding areas. The study provides countermeasures to mitigate the severity and reduce the overall occurrence of crashes. Additionally, the research examines and approximates the length of the spillover effects, including the time and distance that the effects last. The research indicates a high effectiveness rate of red-light cameras at close proximities, with efficacy gradually decreasing as the distance from the camera increases. Specifically, within proximity to the red-light camera locations, the effectiveness is consistently high across various urban settings, including Denver, Washington D.C., and Chicago. This trend is evident as the intervention significantly reduces crashes near the cameras. However, as the distance from these cameras extends, there is a noticeable decline in their impact on driver behavior and crash reduction. This pattern underscores the importance of strategic placement and density of red-light cameras in urban traffic management to maximize their deterrent effect. The findings suggest that while red-light cameras are highly effective in immediate vicinities, additional measures may be necessary to sustain traffic safety improvements over broader areas. These results are critical for urban planners and policymakers aiming to optimize road safety interventions and resource allocation. The behavioral modifications induced by the cameras are most potent in their immediate vicinity but gradually wane as drivers move further away. For example, within a smaller radius, the reduction in crashes is substantial, reflecting the direct influence of the cameras. Beyond this range, however, the deterrent effect starts to diminish, indicating that drivers may revert to less cautious driving behaviors as they perceive themselves out of the camera's surveillance range. Additionally, integrating red-light cameras with other traffic calming measures and public awareness campaigns could help sustain the positive effects over larger areas and longer durations. These findings are particularly relevant for urban planners and policymakers aiming to enhance road safety. They emphasize the importance of not only installing red-light cameras but also considering their optimal placement and the potential need for complementary measures. By understanding the spatial dynamics of camera effectiveness, cities can better allocate resources and design interventions that maximize safety benefits, ultimately contributing to the reduction of traffic-related injuries and fatalities.