Turbo-roundabouts vs Roundabouts Performance Level

Abstract

In this paper the performance level of basic turbo-roundabouts and double-lane roundabouts are compared. Cowan’s M3\ud headway distribution was chosen to take into account bunched vehicles moving along each circulating lane; the Hagring\ud model was adopted to evaluate entry capacity both at turbo-roundabout and at double-lane roundabout.\ud The comparative analysis was performed evaluating operational performances in terms of delay suffered by users entering the\ud intersection.\ud Results of the analyses show that efficiency of basic turbo-roundabouts highly depend on traffic situations and can be\ud significant when major road captures most of the traffic deman

Methodological Frontier in Operational Analysis for Roundabouts: A Review

“…However, the critical headway and the follow-up headway being stochastically distributed cannot be considered as constant values, but each of them should be represented by a distribution of a set of values. Moreover, when capacity models based on the gap acceptance theory are used, analyst should specify the probability distribution of headways between vehicles in each major stream (Giuffrè et al, 2012a).…”

“…This is why Cowan's M3 headway distribution explicitly accounts for the number of bunched vehicles through the proportion of free vehicles expressed by the ϕ parameter. Some bunching models to estimate ϕ formulated by several authors have been collected by Giuffrè et al (2012a) and Akçelik (2007).…”

“…For instance, Giuffrè et al (2012a) used this model to compare performances of turbo roundabouts and double-lane roundabouts; so they specified the model in relation to values of the conflicting traffic flow (moving on the inner circulating lane Q c,i and/or the outer circulating lane Q c,e ), and τ c , τ f , and Δ values and obtained: …”

Traffic Efficiency Evaluation of Elliptical Roundabout Compared with Modern and Turbo Roundabouts Considering Traffic Signal Control

“…In urban context, turbo roundabouts showed good performance considering simultaneous presence of pedestrians and vehicles [19,20]. Giuffrè et al [21] found that the performance of turbo roundabouts highly depended on traffic situations. Turbo roundabouts performed better on major roads with higher demands.…”

Flower Roundabouts And Double-Lane Roundabouts: A Comparative Performance Analysis

“…When major-stream vehicles are moving very close together, minor-stream vehicles can enter the intersection when the gap after the last vehicle of the platoon meets or exceeds the critical gap (Tanner [20]). In the case of turbo roundabouts, where different entering modes are coexisting, application of capacity models assuming the same arrival headway distribution for each circulating stream has to be preferred (see Giuffrè, Granà, S. Marino [21]). …”