Merging process of U-turns at uncontrolled median openings under mixed traffic conditions

Sil, Gourab; Mohapatra, Smruti Sourava; Dey, Partha Pratim; Chandra, Satish

doi:10.3846/16484142.2016.1247295

Cited by 14 publications

(5 citation statements)

References 14 publications

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“…The speed at which a vehicle merges into a gap is an essential parameter to judge the driver's behaviour. The merging could be possible when the available gap is sufficiently large (greater than the critical gap); otherwise, vehicles should wait for the next suitable gap (Sil et al, 2016). Contrary to this norm, the behaviour of motorcyclists in the study area was found to be quite disruptive and impolite.…”

Section: Effect Of Approach Speed On Gap Acceptancementioning

confidence: 89%

Modelling Merging Behaviour of Drivers in Heterogeneous Traffic at Roundabouts

Ahmed

2024

European Transport/Trasporti Europei

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Roundabouts are among the widely used traffic control infrastructures, which function by defining priorities for various entry approaches and circulating traffic. In many developing countries, the priority rules are not implemented through pavement markings or road signs and drivers are also unaware of these rules. Thus, available gaps become the only criteria for merging and movement of vehicles through the roundabout. It has been observed that the gap acceptance behaviour of drivers also depends on the type of vehicle in heterogeneous traffic streams. The main objective of this study is to investigate the difference in gap acceptance behaviour of motorcycle riders and car drivers at roundabouts. The gaps accepted by car drivers and motorcycle riders under different traffic conditions are measured from the recorded video of the traffic stream at a selected roundabout using an unmanned aerial vehicle. The critical gap is estimated using Raff’s method and its relationship with circulatory volume and approach speed is analysed. The results show that the critical gap for motorcycles (2.46 seconds) is 23.3% smaller than the critical gap for cars (3.21 seconds). Motorcycles can move through smaller gaps in comparison with cars due to their size and ease of manoeuvring. Results also show that motorcycles tend to merge with greater approach speed as the available gap within the circulating vehicles reduces, whereas the cars are observed following an opposite trend.

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Section: Effect Of Approach Speed On Gap Acceptancementioning

confidence: 89%

Modelling Merging Behaviour of Drivers in Heterogeneous Traffic at Roundabouts

Ahmed

2024

European Transport/Trasporti Europei

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“…The U-turn is the maneuver of a vehicle that makes a 180 • turn in a specific area to reverse its direction [1]. Vehicles that need to make U-turns often create merging points with traffic approaching from other directions [2]. This not only reduces the efficiency and stability of the intersection but also increases the probability of accidents, taking into account the lane-changing and merging behavior of vehicles [3].…”

Section: Introductionmentioning

confidence: 99%

The Impact of Parallel U-Turns on Urban Intersection: Evidence from Chinese Cities

Shi,

Tian,

et al. 2023

Sustainability

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As the number of motor vehicles in China’s cities continues to increase, the imbalance between the capacity that existing urban roads have for construction and the demand for motor vehicles is becoming increasingly evident. Indeed, the design of the intersection U-turn scheme has garnered significant attention from researchers. However, as the number of vehicles requiring U-turns increases, the traditional U-turn in the median or U-turn at the intersection fails to meet the timely demand for U-turns. In such cases, vehicles needing to make U-turns are required to queue first. As the queue length grows, it ultimately impacts the operational efficiency of the intersection. To optimize the imbalance between supply and demand at these intersections and promote the sustainable development of intersections, an innovative form of U-turn organization called the Parallel U-turn has been developed. In the engineering practice of reconstructing existing intersections or constructing new ones, it is crucial to investigate the compatibility between various U-turn design forms and traffic volumes. This exploration helps ensure that the chosen U-turn design effectively accommodates the specific traffic demands at the intersection. Therefore, in this paper, a typical intersection in Xi’an was chosen as the study intersection to investigate traffic data. The researchers calibrated and simulated four U-turn organization schemes using VISSIM microsimulation software. The four schemes included a traditional U-turn at the intersection, a Parallel U-turn at the intersection, a traditional U-turn in the median, and a Parallel U-turn in the median. Then, the researchers used the entropy-weighted TOPSIS method (EWTM) to evaluate the compatibility of each U-turn organization scheme for different traffic combinations. This assessment was conducted based on three criteria: operational efficiency, environmental protection, and safety performance. The results of this study indicate that the Parallel U-turn design is advantageous for the XiaoZhai intersection in Xi’an, China, under specific traffic conditions. When the traffic volume at the intersection exceeds 5940 vehicles per hour but remains below the intersection’s maximum capacity, implementing the Parallel U-turn design could yield positive outcomes in terms of operational efficiency, safety performance, and a reduction in intersection pollution. In summary, by enhancing operational efficiency, safety, and environmental impact, the Parallel U-turn design promotes the overall performance and sustainability of the XiaoZhai intersection and the transportation system in Xi’an, China.

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“…Menendez et al [16] developed delay equations that can be applied to assess uncontrolled roudabouts involving two or three conflicting [C] or non-conflicting streams [NC] and validated with the HCM [17] control delay model in Zurich, Switzerland. Sil et al [18] studied influence of service delay (SD) on U-turn merging time (MT) for five vehicle categories considering conventional and forced merging situations based on time-distance plots. The authors also studied the effects of opposing traffic flow on U-turn merging time at uncontrolled median openings.…”

Section: Introductionmentioning

confidence: 99%

“…Swift and gradual merging were found to significantly different from each other under mixed traffic. Guller and Menendez [18] determined delay of priority and non-priority conflicting streams for five uncontrolled traffic facilities (4 nos. intersections and 1 no.…”

Section: Introductionmentioning

confidence: 99%

Microscopic simulation based uncontrolled intersection performance assessment

2020

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Performance of an urban corridor comprising of urban streets, signalized and unsignalized intersections gets highly influenced by the level of traffic operations at the unsignalized intersections. Unsignalized intersections under mixed traffic behave in uncontrolled manner due to lack of stop or yield signage. This study aims at assessing performance of urban uncontrolled intersections. Number of conflicting vehicles and their flow rates were used to develop mathematical models for service delay. Field service delays from 13 selected intersections form India were estimated and validated using PARAMICS after calibration using real time video data. Mean service delay for turning movements are analysed based on microscopic field investigation of driver travel time under different driver behavior. Two different traffic operational scenarios considering four-wheeler SUV stream at three-legged and four-legged intersections are compared. A thorough statistical investigation indicated that the conflict technique can predict 52% of field estimated service delays with a sensitivity of as low as 3 s/vehicle/lane for various traffic streams. The service delay, driver turning time and queue length models suggested can be utilized by practicing engineers to estimate intersection capacity and level of service of turning movements for better traffic operational management.

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Merging process of U-turns at uncontrolled median openings under mixed traffic conditions

Abstract: Merging process of U-turns at uncontrolled median openings under mixed traffic conditions

Cited by 14 publications

References 14 publications

Modelling Merging Behaviour of Drivers in Heterogeneous Traffic at Roundabouts

Modelling Merging Behaviour of Drivers in Heterogeneous Traffic at Roundabouts

The Impact of Parallel U-Turns on Urban Intersection: Evidence from Chinese Cities

Microscopic simulation based uncontrolled intersection performance assessment

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