A conditional analysis for relating the number of accidents at four-approach traffic circles to the geometric and flow characteristics of the circles is presented. The conditional analysis takes into account the association among the observations taken at the four approaches within a traffic circle. It also allows for the inherent differences in safety among different circles. The main advantage of the conditional approach is one can use it to estimate the effects of geometric and flow variables without having to specify a distribution to represent the variability between circles. The conditional method is applied to a study of traffic circles in amman, jordan. This paper appears in transportation research record no. 1327, Visibility, rail-highway grade crossings, and highway improvement evaluation 1991
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