In an advantage over two other type, it is

recent years modern roundabouts are becoming more popular to use over other types
of intersections, because of their ability in enhancing intersection capacity and safety (Qu et al., 2014) (Agyeman, Abeka and
Asiedu Boamah, 2015), in addition roundabouts reduce total delay when it is
compared with signalized intersection (Oketch, Delsey and
Robertson, 2004) especially 
when the traffic volume is low (Sofia, Al-Haddad and
Al-Haydari, 2012)

Evaluation of intersections performance is the key
parameter in selection and designing of new intersection type or assessment of
existing one. Intersection performance is measure by it is overall capacity and

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Roundabout performance is measured by it is capacity
and  delay as well as the degree of
saturation and queue length G1 (Qiao et al., 2002) (Che Puan, Muhamad Nor
and Peay Sien, 2015). Many studies focus on estimating roundabout capacity,
delay have less attention. the existing delay models are either for signalized
intersection or stop sign intersection, roundabout have less attention (Behbahani et al., 2016).

Delay model can be developed by one of the following
approaches, analytical approach, empirical approach, or simulation approach. The
simulation approach has an advantage over two other type, it is more flexible
and realistic in describing the behavior of drivers and vehicles

Measuring delay in the field is very complicated,
costly and time-consuming, thus micro simulation present best approach to
estimate delay G2 (Caliendo, 2014) (Qiao et al., 2002).

Drivers tend to
behave differently some driver are patient they stop before entering the roundabout,
but some drivers do not stop unless there are vehicles on the circulating
roadway; they would expect to travel at 40 to 50 km/h. these differences influence
capacity tremendously and this demonstrate that why approaches cannot be
transferred from country to country without modification and calibration. Arahan
Teknik (Jalan) 11-87 is the Malaysian guide for designing of at grade intersections.
The guide using weaving approach to design roundabout entry capacity, but there
is no model for estimating roundabout delay

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