Search results for "Turbo-roundabout"

Analysis of Kinematic Parameters and Driver Behavior at Turbo Roundabouts

2018

This study focuses on both vehicle kinematic parameters (speed and acceleration) and behavior parameters (critical interval and follow-up time) of drivers at turbo-roundabouts. Empirical evaluations of such parameters can be helpful in calibrating traffic microsimulation models or assigning behavior parameters to closed-form capacity models in turbo-roundabouts (gap-acceptance capacity models) and are also related to evaluation of vehicles pollutant emissions. The research was based on traffic process observed in the first turbo-roundabout implemented in the city of Maribor in Slovenia. In 2016 a great number of traffic samples were taken with high-frame-rate video recordings [>50 frames pe…

Calibration of microscopic traffic simulation models for evaluating operation and safety performance at roundabouts

Turbo-roundabouts vs Roundabouts Performance Level

2012

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

Microsimulation-based passenger car equivalents for heavy vehicles driving turbo-roundabouts

2016

Due to its geometric design, turbo-roundabouts impose greatest constraints to the vehicular trajectories; by consequence, one can expect a more unfavourable impact of heavy vehicles on the traffic conditions than on other types of roundabouts. The present paper addresses the question of how to estimate Passenger Car Equivalents (PCEs) for heavy vehicles driving turbo-roundabouts. The microsimulation approach used revealed as a useful tool for evaluating the variation of quality of traffic in presence of mixed fleets (different percentages of heavy vehicles). Based on the output of multiple runs of several scenarios simulation, capacity functions for each entry lane of the turbo-roundabout w…

Recent Evolutions of Roundabouts: Methodological Issues and Practical Concerns.

2013

The aim of the research is to provide a choice criterion between innovative roundabouts (turbo-roundabouts and flower-roundabouts) and double-lane roundabouts by evaluating convenience in terms of performances, when traffic demand is known. For this purpose, comparisons of operational performances at innovative roundabouts with regard to those at traditional roundabouts were developed. We started from consistent assumptions regarding the arrival process of major streams and used capacity models founded on gap-acceptance theory. Having in mind a bunched exponential headways distribution, we proposed adaptations of the Hagring model for estimating entry capacity at intersections under examina…

Comparing Performances of Turbo-roundabouts and Double-lane Roundabouts

2012

Starting from assumptions regarding the arrival process of circulating streams and according to models based on the gap-acceptance theory, the paper is aimed at comparing operational performances between basic turbo-roundabouts and double-lane roundabouts. The paper proposes applications of the Hagring model for entry capacity estimations at double-lane roundabouts and turbo-roundabouts, these latter, in particular, featured by movements with only one or two conflicting traffic streams. This model allows to use, in fact, a bunched exponential distribution to quantify the distribution of major vehicle headways; it also considers specific values different by each lane for behavioural paramete…

EVALUATING CAPACITY AND EFFICIENCY OF TURBO-ROUNDABOUTS.

2009

Recent evolution of roundabout design has been directed towards the so-called turbo-roundabout, with the aim of ensuring better safety conditions than those afforded by traditional schemes. The few turbo-roundabout installations so far implemented have not allowed sufficient research in order to analyze operational conditions and capacity models validated by field observations. In any case the theoretical approach to the functional study of turbo-roundabouts undoubtedly involves more complex aspects compared to typical roundabouts because of the paths of entering streams (constrained to get onto physically separated lanes), the “turbine” configuration of the circulatory carriageway, as well…

Passenger Car Equivalent for Heavy Vehicles Crossing Turbo-roundabouts

2016

Abstract Turbo-roundabouts represent an innovative scheme of modern roundabouts which provides a spiraling traffic flow and requires drivers to choose their direction before entering the intersection, since raised lane separators mark the lanes on the ring. The configuration of the turbo-roundabout makes that patterns of conflict at entries with one and two conflicting traffic streams can coexist. This paper presents research efforts aimed at measuring quantitatively the effect of heavy vehicles on operational conditions of a turbo-roundabout. The study starts from the initial belief that the greatest constraints to the vehicular trajectories imposed by the turbo-roundabout necessarily impl…

Safety evaluation of turbo roundabout with and without internal traffic separations considering autonomous vehicles operation

The paper presents a microsimulation approach for assessing the safety performance of turbo-roundabouts where Cooperative Autonomous Vehicles “CAVs” have been mixed with conventional vehicles “CVs”. Based on the analysis of vehicle trajectories from VISSIM and subsequent analysis of traffic conflicts through the Surrogate Safety Assessment Model (SSAM), the research aims to evaluate the safety benefits of turbo-roundabouts where the lanes are physically separated by raised curbs compared to roundabouts without curbs. The paper shall also lead to describe the methodological path followed to build VISSIM models of turboroundabout with and without raised curbs, to calibrate the simulation mode…

Safety Evaluation of Turbo-Roundabouts with and without Internal Traffic Separations Considering Autonomous Vehicles Operation

2021

The paper presents a microsimulation approach for assessing the safety performance of turbo-roundabouts where Cooperative Autonomous Vehicles “CAVs” have been introduced into the traffic mix alongside conventional vehicles “CVs”. Based on the analysis of vehicle trajectories from VISSIM and subsequent analysis of traffic conflicts through the Surrogate Safety Assessment Model (SSAM), the research aims to evaluate the safety benefits of turbo-roundabouts where the lanes are physically separated by raised curbs, compared to roundabouts without such curbs. The paper will then describe the methodological path followed to build VISSIM models of turbo-roundabouts with and without raised curbs in …