Modelling the operational effects of unconventional U-turns at a highway intersection

Shahi, Jalil; Choupani, Abdoul-Ahad

doi:10.1080/18128600902795042

Cited by 21 publications

(15 citation statements)

References 3 publications

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“…e main incentive for the implementation of unconventional designs is the particular shortcomings of standard roundabouts regarding actual specific circumstances. Generally, these shortcomings are underlined by low levels of capacities or traffic safety [21,22].…”

Section: Literature Reviewmentioning

confidence: 99%

Operational Evaluation of a Throughabout to Give Priority to Public Transport at Standard Roundabouts

Zakeri

Choupani

2021

Journal of Advanced Transportation

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The presence of roundabouts in the central business districts (CBD) of cities can reduce the travel speed of bus rapid transit (BRT) along the radial routes. A throughabout is an unconventional and low-cost design in which the central island is split to provide exclusive lanes for major traffic streams. Although the operation of throughabout has been limitedly investigated for private transport, it has been less considered by designers for public transport and for increasing the speed of the BRT system. The current study aims to evaluate the effects of throughabouts on private and public transports and to compare the design with standard roundabouts and conventional intersections. The calibrated and validated results of the microsimulation tool (AIMSUN) indicated that the throughabout improved the travel time of both public and private transports through better use of the space and kept the traffic flowing at all volume levels. The travel speed of the BRT in the throughabout was remarkably stable in both signal-controlled and unsignalized intersections. The standard roundabout was the second-best design. The throughabout can be very helpful in corridors along which the demand for the bus transit is high and the system needs to receive priority.

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Section: Literature Reviewmentioning

confidence: 99%

Operational Evaluation of a Throughabout to Give Priority to Public Transport at Standard Roundabouts

Zakeri

Choupani

2021

Journal of Advanced Transportation

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“…Simulation models are useful in the initial feasibility analysis of new types of intersections which do not have Highway Capacity Manual (HCM) procedures and in comparing them with current intersections [6][7][8][9][10][11][12][13][14]. Empirical models rely on field data to develop relationships between geometric design features and performance measures such as capacity and delay [15][16][17][18]. Analytical models are based on the concept of gap acceptance theory, conflict theory, or probability theory [19][20][21][22][23][24][25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

A Novel Methodology for Estimating the Capacity and Level of Service for the New Mega Elliptical Roundabout Intersection

Mohamed

Tan

2020

Journal of Advanced Transportation

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Mega elliptical roundabout is a new intersection on rural multilane highways. This intersection was developed in a previous paper using simulation data, and the authors found that it is better than interchange (full cloverleaf) in most scenarios of traffic flow. Basically, there are no guidelines or procedures for designing mega elliptical roundabout in AASHTO Green Book, Federal Highway Administration guides, and Highway Capacity Manual. Thus, the purpose of this study is to analyze the traffic operation performance and propose a methodology for calculating the capacity of mega elliptical roundabout and also the level of service by gap acceptance theory. Moreover, this research studied the influence of different values of truck ratios and also different values of a major highway speed on geometric design and traffic operation performance for mega elliptical roundabout. To validate the thoroughness of the proposed methodology, VISSIM simulations were conducted. This research will assist practitioners in determining the appropriate geometric design, assessing mega elliptical roundabout intersections, and making comparisons with other alternatives.

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“…According to the type of prohibited turning movements, the median U-turn intersection may involve (a) elimination of direct left turns from major or minor streets (the typical median U-turn intersection), (b) elimination of through movements from minor streets, (c) elimination of left turns and through movements from minor streets (the superstreet intersection), and (d) elimination of left turns from major streets and through movements from minor streets. In the development of the median U-turn intersections, extensive research has been devoted to their geometries [including the distance between the median crossover and the main intersection, the directional median crossovers, and the loons (2-7)], safety analysis (8)(9)(10)(11)(12), optimal design (13,14), and evaluation (15)(16)(17)(18)(19).…”

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confidence: 99%

Dynamic Turning Restriction Management for Signalized Road Network

Zhao

Head

et al. 2015

Transportation Research Record: Journal of the Transportation R

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Turning restrictions are a commonly used strategy for improving the capacity of signalized intersections in an urban network. To meet the needs of the pronounced variability of volumes in the network and to extend the application range of the turning restriction strategy, a dynamic turning restriction optimization method is developed for multiple signalized intersections. A lane-based optimization model is proposed for the integrated operation of prohibited movements, detour routes, the layout of the intersections, and signal timings. The capacity maximization problem is considered. A set of constraints is determined; the set meets the characteristics of dynamic control and ensures feasibility and safety of the optimization results. The optimization is formulated as a mixed-integer linear programming problem, which can be solved with the standard branch-and-bound technique. The results of numerical analysis show the effectiveness of the proposed method, as well as the promising property of helping transportation professionals make a proper selection of turning restriction types and avoid causing new bottleneck points.

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Modelling the operational effects of unconventional U-turns at a highway intersection

Cited by 21 publications

References 3 publications

Operational Evaluation of a Throughabout to Give Priority to Public Transport at Standard Roundabouts

Operational Evaluation of a Throughabout to Give Priority to Public Transport at Standard Roundabouts

A Novel Methodology for Estimating the Capacity and Level of Service for the New Mega Elliptical Roundabout Intersection

Dynamic Turning Restriction Management for Signalized Road Network

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