Improving the Capacity and Level of Service at the Sixth Circle in Jordan by Using Traffic Signals and Roundabout Metering Approach

Ibrahim Khliefat1, *, Mohammed Naser2, Fadi Alhomaidat3, Shadi Hanandeh1
1 Department of Civil Engineering, Faculty of Engineering, AL-Balqa Applied University, Salt, Jordan
2 Department of Civil Engineering, School of Engineering, The University of Jordan, Amman, Jordan
3 Department of Civil Engineering, Faculty of Engineering, Al-Hussein Bin Talal University, Ma’an, Jordan

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Creative Commons License
© 2021 Khliefat et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Civil Engineering, Faculty of Engineering, AL-Balqa Applied University, Salt, Jordan; Tel: +8210-3146-9262; E-mail:


Background and Objective:

This study aims to improve the capacity and level of service at the sixth circle in Jordan by using traffic signals and a roundabout metering approach.


VISSIM software and C++ program were used to improve the capacity and level of service. The site area (Sixth circle) was located near Crown Plaza and the Jordan Gate Towers project, which causes congestion due to heavy traffic flow. Therefore, this paper assesses the traffic in the sixth circle and presents the possible solutions to reduce the daily traffic flow for the users of this circle.


Four signals were placed at the roundabout in the second scenario, which was connected to each other with different cycle lengths. 90-second cycle length gives D value of the level of service. The third scenario was placed adaptive signals on the roundabout, which connects traffic signals with ground detectors placed at a certain distance before the signal and based on the queue length of the flow cars that pass the detector.


The adaptive signals worked on the opening and closing and were designed according to the language simulation and the adoption of the language C++. The first two signals were opened considering the Swefieh road with the reference of King Faisal for a period of 45 seconds. It was then closed for 45 seconds to open the signal from the next street from the fifth circle with Zahran street.

Keywords: Adaptive signals, Interface, Level of service, Roundabout metering, Traffic flow, VISSIM software.