Automated enforcement of traffic signals : a literature review

This document presents the results of an extensive review of available documents regarding automated enforcement of traffic signal compliance. The literature regarding the operation and impacts of systems that automatically enforce driver compliance with the red phase of traffic signals is extensive. However, reviewing the available documents for independent analyses of these systems yields very few examples. Efforts to assess the safety impacts of these systems by independent evaluators (not connected to the agencies or vendors operating the programs) have been made in Australia, the United Kingdom, and, to a lesser extent Howard County, Maryland. Each of these studies, as well as the remainder of the sources reviewed during this effort, indicate a significant reduction in the number of drivers running the red light. Crash reduction results are mixed and generally inconclusive. An early Australian study indicated significant reduction in crashes several years after the initiation of the program in Melbourne, Australia, while a follow-up study several years later found no significant reduction in collisions due to the system. Two studies in Scotland indicate significant benefits from the cameras. A graduate student project assessing the system in Howard County, Maryland also indicated positive impacts of that system on crashes and violations. The remainder of the literature consists primarily of statistics reported by the operating agencies and press reports of camera program results. Following an overview, the next section of this report describes the operational arrangements surrounding camera programs in the United States, including typical contracting arrangements and the fines and penalties associated with the programs. The third section of the document describes the reported impacts of the systems on violations and collisions, including a more detailed discussion of the few independent analyses of red light camera programs. Next, this report briefly summarizes the results of several public opinion surveys described in the literature. Section 5 lists several research projects regarding red light cameras known to be underway. The body of the report concludes with several recommendations for further research into the impacts of red light cameras. An annotated bibliography of the sources collected in this review follows the body of the report.