Safety Performance Appraisal at Roundabouts: Case Study of Salalah City in Oman

Although, roundabouts have proved significant in improving safety, capacity, and environmental performance, they have shown an increasing crash rate in Oman over the years. This article aims to evaluate the safety performance of the roundabouts in Oman through the development of crash-prediction models to examine the relationship between the geometric, traffic flow variables, and crash frequency and severity. These models can determine which variables are the best indicators for safety performance. GLM technique with Poisson or negative binomial regression (NBR) was carried out to develop these models. Two types of models were developed separately: the flow-based models including only exposure functions, and the full models containing exposure functions and other significant geometry and traffic variables. The result shows that the 85th percentile speed, number of lanes at specific approach, entry angle, and circulating width were the most significant variables. It was found that reducing the 85th percentile speed reduces the total and injuries crashes, however increasing the number of lanes in each approach and adding right-turn bypass lane may be the most effective methods to reduce the rear-end accidents.


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  • Accession Number: 01632390
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 18 2017 11:53AM