Study Details

Study Title: Road safety effects of roundabouts: A meta-analysis

Authors: Elvik, R.

Publication Date: 2017

Abstract: This paper presents a meta-analysis of the road safety effects of converting junctions to roundabouts. 44 studies containing a total of 154 estimates of effect were included. Based on a meta-regression analysis, converting junctions to roundabouts is associated with a reduction of fatal accidents of about 65% and a reduction of injury accidents of about 40%. The mean effect on property-damage-only accidents is ambiguous. Summary estimates of effect are robust for fatal and injury accidents, but vary depending on the model of meta-analysis and the treatment of outlying data points for property-damage-only accidents.A trim-and-fill analysis suggests a weak tendency for publication bias, with modest influence on summary estimates of effect. It is concluded that roundabouts are very effective in reducing traffic fatalities.

Study Citation: Elvik, R. "Road safety effects of roundabouts: A meta-analysis." Accident Analysis and Prevention, Vol. 99, (2017) pp. 364-371.

Study Report: Download the Study Report Document

Comments: Although the authors developed CMFs using fixed-effects, random-effects, and regression meta-analyses, the Clearinghouse only included the results from the regression meta-analyses, since the authors focus on that result in the abstract. Also, the Clearinghouse includes the fatal CMF and injury CMF from Table 4, but not the PDO CMF since the authors express the opinion that the PDO CMFs are not reliable.


CMFs Associated With This Study

Category: Intersection geometry

Countermeasure: Convert intersection to roundabout

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.28 72 5 Stars All K Not specified Not specified
0.56 44 5 Stars All A,B,C Not specified Not specified