turbo roundabout usage in lieu of conventional roundabouts for the jordanian traffic conditions

The main objective of this study is to check the possibility of upgrading at-grade roundabouts to turbo roundabouts considering the jordanian driving conditions. it is also to check how such upgrade is going to affect performance measures of the studied areas including safety, capacity, queue length, delay, and level of service (los). thus, three roundabouts were selected and analyzed using sidra software under off-peak, morning peak and evening peak traffic conditions to obtain the actual capacity, queue length, delay, and los values under the current design. then two designs were applied for each roundabout according to dutch design guideline manual using torus software by changing inner radius and opening width. the generated designs were analyzed using vissim software under the original traffic conditions, to evaluate the effect of introducing turbo roundabout system as a replacement to the conventional roundabout system. the results of this study indicate that turbo roundabouts offer higher capacities, less delays and better los compared to existing intersections. in addition, introducing turbo roundabouts might offer higher safety levels than conventional roundabouts; as conflict points were reduced from 32 on two-lane conventional roundabouts to only 12 on the proposed turbo roundabouts. consequently, reconstruction of intersections was warranted.