Implementing Red Light Camera Programs

Abstract

Red light camera (RLC) systems are believed to decrease the right-angle crashes that they are targeting but to have the undesirable side effect of increasing rear-end crashes. This belief was confirmed in a before–after study of 132 RLC installations in seven U.S. jurisdictions, as reported in a companion paper. In that research, the extent to which the increase in rear-end crashes negates the benefits for right-angle crashes was unclear, given the perceptions of severity differences in the two crash types. This paper reports on an examination of the changes in crash costs, based on a consideration of rear-end and right-angle unit crash costs for various severity levels, to establish the aggregate effects of the RLC programs evaluated. Part of the project derived the required unit costs by using information from national U.S. databases. The overall results show a modest to moderate economic benefit of between $28,000 and $50,000 per treated site year, depending on assumptions made. The ability to aggregate economic costs across crash types and severity created the opportunity to try to isolate program implementation factors and intersection characteristics that would favor the installation of RLC systems by using the aggregate economic benefit at each RLC site as the outcome variable. This investigation found, for example, that the greatest economic benefits are associated with the highest total entering annual average daily traffic, the largest ratios of right-angle to rear-end crashes, and the presence of protected left-turn phases.