Inrecent years modern roundabouts are becoming more popular to use over other typesof intersections, because of their ability in enhancing intersection capacity and safety (Qu et al., 2014) (Agyeman, Abeka andAsiedu Boamah, 2015), in addition roundabouts reduce total delay when it iscompared with signalized intersection (Oketch, Delsey andRobertson, 2004) especially when the traffic volume is low (Sofia, Al-Haddad andAl-Haydari, 2012)Evaluation of intersections performance is the keyparameter in selection and designing of new intersection type or assessment ofexisting one. Intersection performance is measure by it is overall capacity anddelay.
Roundabout performance is measured by it is capacityand delay as well as the degree ofsaturation and queue length G1 (Qiao et al., 2002) (Che Puan, Muhamad Norand Peay Sien, 2015). Many studies focus on estimating roundabout capacity,delay have less attention. the existing delay models are either for signalizedintersection or stop sign intersection, roundabout have less attention (Behbahani et al., 2016).
Delay model can be developed by one of the followingapproaches, analytical approach, empirical approach, or simulation approach. Thesimulation approach has an advantage over two other type, it is more flexibleand realistic in describing the behavior of drivers and vehiclesMeasuring delay in the field is very complicated,costly and time-consuming, thus micro simulation present best approach toestimate delay G2 (Caliendo, 2014) (Qiao et al., 2002).Drivers tend tobehave differently some driver are patient they stop before entering the roundabout,but some drivers do not stop unless there are vehicles on the circulatingroadway; they would expect to travel at 40 to 50 km/h. these differences influencecapacity tremendously and this demonstrate that why approaches cannot betransferred from country to country without modification and calibration. ArahanTeknik (Jalan) 11-87 is the Malaysian guide for designing of at grade intersections.The guide using weaving approach to design roundabout entry capacity, but thereis no model for estimating roundabout delayInserted: theInserted: –