Investigation and Modeling of Road Traffic Accidents at Five-Legged Roundabouts in Addis Ababa City

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Addis Ababa University


In present time, road traffic accident is becoming among the most threatening concerns that prominently hamper the social, economic, and environmental conditions in Ethiopia and Africa at large. So far, previous crash prediction models at roundabout intersections have focused predominantly on the customary three-legged and four-legged roundabout types. This study however aimed at investigating and modeling road traffic Accidents/crashes at five-legged roundabouts in Addis Ababa City, Ethiopia. To this effect, the study collected necessary quantitative and qualitative data from both primary and secondary data sources. The data were analyzed through descriptive and inferential statistical approaches. APMs were developed using the Poisson and Negative Binomial Regression Models for the Severe-crashes (personal injuries & fatal crashes), and property damages only (non-injury) crashes, respectively. Accordingly, the study revealed that the peak hour vehicle volume entering the roundabout through the major road, ratio of diameter of the inscribed circle to diameter of the central island, and entry half road way width have positive associations with the frequency and occurrences of RTAs –particularly the PDO crashes at roundabouts. Furthermore, the study finally forwarded that reducing the entry half road width on the minor leg; constructing and maintaining bypass/detour roads; implementing advanced traffic management schemes; and decreasing the circulatory roadway width were important points that should be taken in to considerations so as to decrease crashes by decreasing the peak hour flows and optimizing the circulatory road way width to increase diameter of the central island. It has to be noted that special care should be required to consider flow parameters such as level of service and capacity situations.



Road Traffic Accidents, Roundabouts, Poisson, Negative Binomial, Accident Predictive Models, Addis Ababa