Turner-Fairbank Highway Research Center

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Safety Evaluation of Turning Movement Restrictions at Stop-Controlled Intersections

Product Type

Research Report


Thanh Le, Frank Gross, Tim Harmon, and Kimberly Eccles




The Development of Crash Modification Factors program conducted a safety evaluation of turning movement restrictions at stop-controlled intersections for the Evaluation of Low Cost Safety Improvements Pooled Fund Study. This study evaluated the safety effects of converting full movement, stop-controlled intersections to right-in-right-out (RIRO) operation using physical barriers, as measured by the change in crash frequency. The project team obtained geometric, traffic, and crash data for urban, three-legged, full movement and RIRO stop-controlled intersections, as well as the downstream four-legged, stop-controlled or signalized intersection with full movement in California. The team used a cross-sectional analysis to estimate the effects of turning movement restrictions while controlling for other differences between sites with RIRO and full movement. Aggregate results indicated reductions for all crash types analyzed (i.e., total, all intersection-related, and fatal and injury intersection-related) for stop-controlled intersections with RIRO compared to full movement. Reductions were statistically significant at the 95-percent confidence level for all crash types. Crash modification factors for total, all intersection-related, and fatal and injury intersection-related crashes were 0.55, 0.32, and 0.20, respectively. Based on the disaggregate results, RIRO intersections do not appear to have differing effects for different levels of traffic, design speed, or number of lanes. Potential for crash migration in determining net benefits needs to be considered. Results indicated potential increases at downstream intersections, but many increases are not statistically significant even at the 90-percent confidence level. While the economic analysis suggests the strategy can be cost-effective in reducing crashes at a hypothetical stop-controlled intersection, potential costs and benefits with site-specific values need to be analyzed on a case-by-case basis.

Link To Research Report

Safety Evaluation of Turning Movement Restrictions at Stop-Controlled Intersections


Turning movement restrictions
safety improvements
safety evaluations

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