DOI: 10.5176/2301-394X_ACE18.56
Authors: Nael Muwaffaq Alsaleh and Lina Izzat Shbeeb
Abstract:
In Jordan, we are looking for an innovative and cost-efficient solutions for the poorly functioning at-grade roundabouts; considering the required bulk cost for grade separation or intersections signalization. Thus, the study aims to evaluate the compatibility of applying new at grade traffic separation techniques with the field traffic conditions. Namely both Turbo roundabout and Flower roundabout are introduced to the Jordanian driving conditions and whether the conventional roundabouts can be upgraded to one of the new introduced roundabouts forms. The study also, aims to evaluate the performance measures of the studied areas including safety, capacity, queue length, delay, and level of service, then enforce the decision over the best replacement approach under certain traffic and geometric conditions. In order to do so, two major factors are taken into consideration while selecting appropriate samples to perform the study; flexibility on land use to implement Turbo roundabout without affecting sidewalks or private properties, and representation of several traffic conditions. Roundabouts that were found to satisfy both conditions are: Al-Thaqafa roundabout, Al-Durra roundabout, and Al-Eyadat roundabout in one of the Jordanian’s cities. The current functionality of the selected roundabouts was evaluated, while the new concepts were introduced and simulated for the sake functionality evaluation. The simulation was chosen due to the constraints of having a pilot constructed roundabout to evaluate the change based on the field measures. Thus, three roundabouts were analyzed before and after being redesigned using VISSIM software under peak traffic conditions to obtain the actual capacity, queue length, delay, and level of service values under the current design. The results of this study indicate that Turbo roundabouts offer the highest capacities, lowest delays and best level of services compared to Flower and conventional roundabout forms, while conventional roundabouts form have the lowest capacities, the highest delays and worst level of services. In addition, Flower roundabouts might offer higher safety levels than Turbo and conventional roundabout forms taking into consideration the reduction in the total number of conflict points from 32 on the two-lane conventional roundabout to 8 on Flower roundabout and 30 on Turbo roundabout.
Keywords: component; Turbo Roundabout; Flower Roundabout; Conventional Roundabout; Safety; VISSIM; Microsimulation.
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