Multi-lane Roundabout Capacity Evaluation

Šarić, Ammar; Lovrić, Ivan

doi:10.3389/fbuil.2017.00042

Cited by 12 publications

(4 citation statements)

References 27 publications

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“…The correction factor α of the influence of an existing flow was substituted by two parameters a 1 and a 2 . This model allows a capacity calculation for different legs in various types of turbo-roundabouts, and it has been used, for example, in case studies of the transformation of a standard roundabout into a turboroundabout [10][11][12][13]. According to the Fortuijn-Harte model, the single-lane capacity of a minor entry is given by the following equation: Brilon capacity model [14] is based on the Tanner´s basic idea [5] as well as the Wu model.…”

Section: Capacity Models For a Single-lane Minor Entrymentioning

confidence: 99%

“…The Hagring capacity model, considering traffic flow allocation into two circulatory lanes, has been used with some simplifications in several capacity studies of turbo-roundabouts: [13,[17][18][19][20][21]. Two of them used different critical headway values t c,i and t c,e to estimate the left-lane capacity of two-lane turbo-roundabout minor entries [17,18].…”

Section: Capacity Models For a Single-lane Minor Entrymentioning

confidence: 99%

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Capacity Model for Single-Lane Minor Entry at Turbo-Roundabouts

Kociánová

2021

Civil and Environmental Engineering

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Spirally arranged and physically separated traffic lanes in the circulatory carriageway of turbo-roundabouts force drivers to choose a particular entry lane and, subsequently, a circulatory traffic lane according to their intended destination. This specificity is taken into account in theoretical capacity models for two-lane turbo-roundabout entries typically evaluated by the lane-by-lane approach. Nevertheless, this specific path of movements is not considered in the most widely used capacity models for single-lane minor entries at oval turbo-roundabouts. In these models, only one entering traffic flow conflicted by two circulating traffic flows in front of the entry is considered. However, the entering traffic flow presents a mixed traffic flow of two movements (right-turning movement and left-turning and through movement) with different capacities due to different number of conflicting traffic streams and traffic volumes allocated into the outer and the inner circulatory lane. This fact is included in the capacity estimation for a single-lane minor entry presented in the article using the existing capacity formula for the mixed traffic flow on a shared minor lane at unsignalized intersections. The entry capacity reflects the proportion of the right-turning movement within a shared entry lane as well as the specific allocation of circulating traffic flow into the outer and the inner circulatory lane. This entry capacity is about 10 % to 30 % higher compared to a single-lane entry capacity estimated according to commonly used models described in the article. Higher entry capacity in a higher proportion of the right-turning traffic within mixed entry traffic flow is confirmed also by the results of average delays estimated by the theoretical delay model and microsimulation.

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Section: Capacity Models For a Single-lane Minor Entrymentioning

confidence: 99%

Section: Capacity Models For a Single-lane Minor Entrymentioning

confidence: 99%

Capacity Model for Single-Lane Minor Entry at Turbo-Roundabouts

Kociánová

2021

Civil and Environmental Engineering

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“…e authors concluded that the overall capacity of basic turbo roundabouts is superior to conventional two-lane roundabout's capacity under any circumstances. Finally, the authors added that minor approaches' capacity of turbo roundabouts is boosted as well [22].…”

Section: Literature Reviewmentioning

confidence: 99%

The Implications of Converting a High-Volume Multilane Roundabout into a Turbo Roundabout

Elhassy

Abou-Senna

Radwan

2020

Journal of Advanced Transportation

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With the growing number of vehicles utilizing roads in the city of Doha, Qatar, most intersections, particularly multilane roundabouts, have been facing traffic congestion dilemma, where traffic demand exceeds capacity. A new design for multilane roundabouts, known as a rotor turbo roundabout, was considered as an alternative to an existing highly congested multilane roundabout. The new design features spiral roadway markings and raised lane dividers which prevent maneuvering within the roundabout and eliminate cutting-offs and weavings. This design has achieved high capacity and low delay in many European countries. In this study, a traffic simulation program, VISSIM, is used to model the complex traffic operation of both the existing and proposed multilane roundabouts and to replicate the high traffic conditions and aggressive driving behavior prevalent among the Middle East countries. Three different rotor designs were examined in an attempt to have a valid comparison between the two types of roundabouts and to adhere to the standard design of the rotor roundabout without violating its essential features. The proposed designs performed slightly better on the minor approaches and managed to deliver an overall improved LOS compared to the conventional design. Major approaches, however, exhibited an increase in vehicle delay and queue lengths. The results showed that the capacity of the conventional three-lane roundabout was always superior to the capacity of the rotor roundabouts. It was concluded that rotor roundabouts may not be suitable for intersections with high demand volumes exceeding 4500 vehicles per hour, and whenever the traffic flow condition is oversaturated.

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“…The process of gap acceptance is one of the most commonly used techniques for capacity calculation at roundabouts [1][2][3]. It is based on gaps/ lags that are accepted and rejected by drivers from lower priority approaches.…”

Section: Introductionmentioning

confidence: 99%

Comparative Analysis of Critical Headway Estimation at Urban Single-Lane Roundabouts

Radović

Mohan

Bogdanović

2022

Promet

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According to models commonly used in practice, the capacity of roundabouts largely depends on the value of critical headway. The value of critical headway depends on the characteristics of vehicles, driving conditions, and geometric characteristics of intersections, but also on driver behaviour. Driver behaviour is the result of many factors that depend on the influence of the local environment, driver habits, mentality, etc. Accordingly, to calculate the capacity of roundabouts within the op-erational and planning analyses of roundabouts more accurately, it is necessary to use data that correspond to local conditions. In this paper, the critical headway was estimated at five urban single-lane roundabouts using five methods: Harders’, Logit, Raff’s, Wu’s, and the max-imum likelihood method. In order to determine which of the stated methods provides the most realistic estimate of critical headway, a comparison of field capacity values with theoretical capacity values was performed. Based on the comparative analysis performed in MATLAB, as well as the calculation of percentage prediction error, it was found that the Harders' method provides the most accurate estimate of critical headway at observed round-abouts in two cities in Bosnia and Herzegovina. Due to the similarity in the design of roundabouts and driver be-haviour, the results obtained in this paper can be applied in the surrounding countries, i.e., Southeast Europe

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Multi-lane Roundabout Capacity Evaluation

Cited by 12 publications

References 27 publications

Capacity Model for Single-Lane Minor Entry at Turbo-Roundabouts

Capacity Model for Single-Lane Minor Entry at Turbo-Roundabouts

The Implications of Converting a High-Volume Multilane Roundabout into a Turbo Roundabout

Comparative Analysis of Critical Headway Estimation at Urban Single-Lane Roundabouts

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