This study evaluates the safety effectiveness of physical right-in-right-out (RIRO) operations compared with full turning movements at stop-controlled intersections. Geometric, traffic, and crash data from California were obtained for urban, three-legged, stop-controlled intersections with full movement and RIRO operations, as well as the downstream four-legged, stop-controlled or signalized intersections with full movement. A cross-sectional analysis provided estimates of the effects of turning movement restrictions while controlling for other differences between sites with RIRO and full movement. The aggregate results indicate reductions in total, all intersection-related, and fatal and injury intersection-related crashes at intersections with RIRO operations compared with full movement, with estimated crash modification factors of 0.55, 0.32, and 0.20, respectively. The reductions are statistically significant at the 95% confidence level for all crash types. Based on the disaggregate results, it does not appear that RIRO operations have different effects for different levels of traffic, design speed, or number of lanes. The analysis also examined the potential for crash migration from intersections where RIRO is implemented to the downstream intersection when determining the net benefits. The results indicate potential crash increases at downstream intersections, but many of the increases are not statistically significant at the 90% confidence level. Although the safety benefit-cost analysis suggests the strategy can be cost effective in reducing crashes at stop-controlled intersections, there is a need to analyze potential costs and benefits on a case-by-case basis with site-specific values.
There are more opportunities to improve safety across a highway network than funds available to implement projects. As such, safety program managers are challenged with selecting projects and allocating resources to maximize the program’s return on investment. The hotspot and systemic approaches are two complementary approaches to safety management. A common question is how to allocate funding between these two approaches to achieve the maximum return on investment, considering the objectives and relative risks of each. This paper presents a framework to consider tradeoffs of allocating funding between hotspot and systemic projects as well as when to apply each approach. The framework is based on average project costs, average project effectiveness, and average crash costs. To demonstrate the framework, this paper presents average values based on six countermeasures that represent the hotspot approach and six countermeasures that represent the systemic approach. In general, this paper uses higher-cost and higher-effectiveness projects to represent the hotspot approach and lower-cost and lower-effectiveness projects to represent the systemic approach. Based on the sample of countermeasures and data included in this paper, the average cost-effectiveness of systemic countermeasures is greater than the average cost-effectiveness of hotspot countermeasures. Although systemic countermeasures tend to be more cost-effective than hotspot countermeasures on average, there is a need to balance these two approaches. The framework could also apply to other situations, such as allocating funding between other safety programs (e.g., roadway departure and intersection safety programs) or prioritizing among project alternatives within a program (e.g., roundabouts, signals, or signing).
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