Whether conversion and weather matter to roundabout safety. (September 2018)

• Record Type: Journal Article
• Authors: Zhao, Yue; Andrey, Jean; Deadman, Peter
• Is Part Of: Journal of safety research. Volume 66(2018)
• Page Start: 151
• Page End: 159
• Publication Date: 2018-09
• Subjects: Roundabouts -- Safety -- Conversion -- Inclement weather -- Rainfall; Industrial safety -- Periodicals; Accidents -- Prevention -- Periodicals; Safety -- Periodicals; Accidents, Occupational -- Periodicals; Sécurité du travail -- Périodiques; Accidents -- Prévention -- Périodiques; Accidents -- Prevention; Industrial safety; Periodicals; 363.1
• DOI: 10.1016/j.jsr.2018.07.001
• Languages: English
• ISSNs: 0022-4375

Abstract

Abstract: Introduction: Roundabouts, as a form of intersection traffic control, are being constructed increasingly because of their promise to improve both efficiency and safety. However, roundabout performance varies from one context to another; and information on their performance during inclement weather is limited. Methods: To evaluate the safety effects of converting signal-controlled intersections to modern roundabouts in a region that historically was unfamiliar with this type of traffic control, an empirical Bayes approach was used to analyze. Second, to examine the potential effects of rainfall on roundabout safety, a matched-pair approach was used to compare risk estimates of collision occurrence at roundabouts and signalized intersections under inclement weather conditions. Results: Roundabout installation is shown as an effective safety intervention for serious collisions since conversion from signalized intersections to roundabouts translates into an overall 20% reduction in the occurrence of injury/fatal collisions. However, roundabouts witnessed more property-damage collisions than what would have been expected had the conversion not occurred. With respect to weather, there is no evidence of a statistically significant increase in crashes on days with rainfall relative to good weather conditions for roundabouts, whereas there is evidence of such an increase in crash risk estimated to be 4% to 22% for signalized intersections. Conclusions: While injury collisions are consistently found to be lower at intersections that have been converted from signalized intersections to roundabouts, the same is not always that case for property-damage collisions, suggesting that drivers need time to adjust. In terms of weather, the evidence in this paper shows that roundabouts show less sensitivity to rainy conditions than signalized intersections. Practical applications: The trade-offs between design, operation, and safety should be considered carefully when planning a new roundabout. More research is required on the specific problems users experience with roundabouts and the effectiveness of public education programs. Highlights: Roundabout installation is effective at reducing serious collisions. Roundabouts witnessed more property-damage collisions than expected. There is no evidence of increased collisions at roundabouts on days with rainfall.