CONTRIBUTION TO THE U-TURN DESIGN AT MEDIAN OPENINGS IN IRAQ: Al-NAJAF CITY AS A CASE STUDY

Field observations indicate that left turning vehicles at U-turn sections lead to a significantly bottleneck (congestion) both origin and destination (opposing) roads. The bottlenecks have been observed in several U-turns such as Kufa –Najaf sections, Najaf –Karbala sections. It was found turn flow from leads high congestion on Therefore, field improvements done by the traffic policemen who create temporary barrier plastic signs order protect through opposing direction. This study introduces new design for trafficto increase level of performance. has tested using simulation model. developed model (S-Paramics) calibrated data collected Al-Najaf city. Then, validation implemented another set data. Finally, adopted test U-turn. gives higher capacity than current design.