Evaluating Safety Impact of Roundabouts: A Systematic Review and Meta-Analysis

Evaluating Safety Impact of Roundabouts: A Systematic Review and Meta-Analysis

Roundabouts are increasingly being adopted as safer alternatives to unsignalised intersections, and their safety performance has been evaluated in numerous studies. However, despite the growing body of research, analytical methods for accurately estimating the actual safety outcomes of roundabouts remain underdeveloped. This study aims to establish a theoretical foundation by conducting a systematic literature review and meta-analysis to quantify the overall effect of converting traditional intersections into roundabouts based on crash severity.
A systematic review provides a clearly stated, reliable, and up-to-date summary of reported safety effects. This study utilized four major databases—ScienceDirect, Scopus, the Transportation Research Board, and Google Scholar—to identify relevant articles. Keywords such as “fatal crashes,” “serious injuries,” “property damage only,” and “roundabouts” were employed to guide the search. Articles were shortlisted using defined inclusion and exclusion criteria, with only studies published after 2000 considered for analysis. The final selection comprised 107 studies. Metadata extracted from these studies included publication year, study location, and key research themes. The highest number of publications (14) appeared in 2021. Country-wise analysis shows that the United States, Italy, and Canada contributed the most to the literature. A keyword co-occurrence analysis revealed dominant themes such as “road safety,” “roundabout,” “roads and streets,” “accident prevention,” “transportation safety,” and “motor transportation,” confirming the study’s thematic alignment.
Furthermore, the meta-analysis utilized reported safety effectiveness as the primary estimator, with many studies employing before-and-after comparisons to derive their conclusions. At this stage, the study presents a methodological framework for evaluating the safety impacts of converting conventional intersections into roundabouts. The incorporation of quality assessment within this framework will ensure that the findings are credible and high-quality with evidence. These insights provide valuable guidance for road designers and transportation policymakers seeking to improve traffic safety through informed infrastructure decisions.