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. Methods: 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. Results: 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. Conclusion: 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.

The growing number of vehicles in Jordan has contributed to traffic congestion, particularly at roundabouts. Roundabouts deflect high volumes of traffic flow. To improve the performance of roundabouts, it is necessary to consider the impact of all components on traffic conditions, especially delay, queue length, and level of service (LOS), to reduce congestion and enhance efficiency and sustainability, etc. This study aims to (a) identify the optimal queue detector locations on all approaches at two selected roundabouts in Amman, Jordan, using micro-simulation (VISSIM) supported by programming (Python) software, and (b) validate the simulated models with the best LOS. Traffic and geometric data of roundabouts (Prince Faisal Bin al-Hussein, fifth; and Prince Rashid Bin Hassan, sixth roundabouts) were used for simulation purposes. The queue detector (across 15 distinct scenarios at various distances) and standard (base scenario, 50 m from the stop line) locations were assessed for optimal placement. The model validation was made based on all scenarios including signalized and non-signalized roundabouts. The best-case scenario for queue detector location was determined based on the highway capacity manual (HCM) criteria for measurement of effectiveness (MOE) at roundabouts. The optimal location was measured based on the duration of traffic delay (seconds), average queue length (m), and LOS. The optimal queue detector’s location was observed to be 97 m from the roundabout stop line. It can reduce the traffic delay (or speed up the traffic flow) by 85.25%. The average queue length can be reduced up to 76.76%. The LOS F status on the selected roundabouts can be improved to LOS D. Overall, the application of adaptive signal and queue detectors in appropriate locations at all roundabout approaches is crucial to improve imbalanced traffic flow while reducing delays.

The possibility of using white cement dust and iron filings as fillers to modify asphalt mix properties was investigated. Numerous aggregate tests were conducted, including sieve analysis, specific gravity, absorption, and abrasion tests. Several bitumen tests were also conducted, including penetration, softening point, ductility, flash point, and specific gravity tests. Marshall properties were used to evaluate the physical performance of the mixtures. The construction of pavements with iron filings in hot asphalt mixtures is not recommended, but white cement dust powder or limestone powder can be beneficial. A 5% content was observed to be the best white cement dust content. There is no clear relationship between air voids and the percentages of white cement dust and iron filings, as the curve fluctuates. The use of white cement dust as a filler always exhibits better results; therefore, using white cement dust widely is recommended over using iron filings.

Introduction: Continuous flow interventions were first introduced as an alternative to improve traffic operations in the intersections with severe congestion caused by heavy left-turn movements. Objective: This study quantified the effect of modifying the intersection angles of Double Continuous Flow Intersections (DCFI) on their operational characteristics. Mainly, the effects of changing the intersection angle between the different approaches of the main intersection and the angle of the minor cross-over intersections were investigated. Methods: VISSIM software simulation models were used for modifying several design features related to the DCFI and the operational performance was compared between the different simulation scenarios. Results and Discussion: Changes to the cross-over intersection angle increase the safety levels by providing better channelization of traffic movements on the minor intersections of the DCFI and reduce the intersection footprint to be used at high-density urban locations. Increasing the cross-over intersection angle and changing the layout geometry have adverse effects on the capacity of the conventional DCFI. This is mainly because of the added curvature in the intersection approaches which reduces the vehicle speeds, therefore reducing the overall capacity of the modified intersection when compared to the conventional DCFI. However, the total footprint for the intersection is reduced for the modified layout geometry, which improves the capacity of the DCFI. Conclusion: The study has explored the effects of modifying the DCFI intersection angles to fit the limited space in major urban areas on the capacity and performance of the intersection. It showed that DCFI designs could be applied in areas with limited space availability and skewed intersection angles.