Conventional roundabouts have been prevalent worldwide since the emergence of modern roundabouts in 1966. An innovative design of multilane roundabouts known as turbo roundabouts, however, has been recently introduced as an alternative to conventional multilane roundabouts. Due to several reasons, there has been no general consensus on the operational performance of turbo roundabouts throughout the world. Nationwide, turbo roundabouts have yet to be part of roadway systems, but there is an ongoing project expected to be finished in early 2020. Therefore, this dissertation aims to evaluate the operational performance of a widespread variant of turbo roundabouts, namely basic turbo roundabouts, as compared with conventional double-lane roundabouts located across the State of Florida. Field data from three existing double-lane roundabouts was recently collected. A microsimulation analytical tool, namely VISSIM 11.00-02, was employed to develop base and alternative models. Operational performance measures of effectiveness included throughput volume, control delay, and maximum queue lengths. In addition, trajectory files automatically generated by VISSIM for vehicular traffic conflicts were considered using Surrogate Safety Assessment Model (SSAM3). Results indicated that basic turbo roundabouts with entry speed conforming to the Dutch standards of turbo roundabouts, namely 25 mph, provided slightly less capacity, quite comparable throughput volume for v/c ratios less than 0.70, fluctuating delay results, significantly lower traffic conflicts, and, for the most part, significantly shorter queue lengths.
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Doctor of Philosophy (Ph.D.)
College of Engineering and Computer Science
Civil, Environmental, and Construction Engineering
Length of Campus-only Access
Doctoral Dissertation (Campus-only Access)
Elhassy, Zuhair, "Basic Turbo Roundabouts as an Alternative to Conventional Double-lane Roundabouts: Operational Performance Evaluation" (2019). Electronic Theses and Dissertations, 2004-2019. 6868.