Safety Performance of Unsignalized Median U-Turn Intersections

Kay, Jonathan J.; Gates, Timothy J.; Savolainen, Peter T.; Mahmud, Md Shakir

doi:10.1177/03611981221086936

Cited by 7 publications

(4 citation statements)

References 10 publications

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“…y j = y 1j , y 2j , y 3j , y 4j (13) For each of the 10 selected indicators, numbered 1 to 10. Among these indicators, the smaller the value of TTC, the better, and the larger the value of the remaining indicators, the better.…”

Section: Standardization Of Datamentioning

confidence: 99%

“…At the same time, researchers have utilized the critical gap [10,11] and various configurations of lanes [12] as the parameter, respectively, to calculate the optimum location for the median opening. Some researchers have assessed the performance of median openings from the safety and crash perspective [13]. In addition, it is imperative to study the delays incurred by U-turn vehicles [14] and the innovation of the mode of the intersection [15] to evaluate their impact on traffic congestion.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Standardization Of Datamentioning

confidence: 99%

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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“…Depending on the data being used, there are two common methods for evaluating the effectiveness of safety countermeasures: crash-based analysis and surrogate measure of safety (SMoS)-based analysis (7)(8)(9)(10)(11)(12)(13).…”

Section: Data For Effectiveness Evaluation Of Traffic Countermeasuresmentioning

confidence: 99%

Do Traffic Countermeasures Improve the Safety of Vulnerable Road Users at Signalized Intersections? A Combination of Case-Control and Cross-Sectional Studies Using Video-Based Traffic Conflicts

Shangguan,

Keung,

et al. 2023

Transportation Research Record: Journal of the Transportation R

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Driven by the vision of eliminating road fatalities, Vision Zero initiatives have been widely adopted by many cities around the world, with significant investment of resources in various safety countermeasures. However, there is still a lack of reliable quantitative evidence on the effectiveness of those countermeasures on the traffic conflict frequency at intersections. This research attempts to address this challenge with a combination of case-control and cross-sectional studies, aiming at quantifying the safety effects of three commonly applied Vision Zero countermeasures, namely, leading pedestrian interval, no right turn on red, and installation of a dedicated bicycle lane. A case study was conducted using video trajectory data from 10 signalized intersections in the City of Toronto, Canada. The traffic interactions between vehicles and vulnerable road users were extracted using a video data processing platform, and two surrogate measures of safety, including post-encroachment time and conflict speed, were obtained, and then used to classify the conflict severity into different levels. A comparative analysis using mixed-effects negative binomial regression was conducted to quantify the impacts of different treatments on the frequency of traffic conflicts under specific road weather and traffic conditions. The results show that these three types of traffic countermeasures can effectively reduce the frequency of high-risk and moderate-risk traffic conflicts, moderated by various traffic exposure and weather and environmental conditions and accessible pedestrian signals. These findings could help road safety engineers and decision makers make better informed decisions on their road safety initiatives and projects.

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“…According to the Jordan Traffic Institute (JTI, 2022) traffic accidents cost around $415 million in 2020 to $454 million in 2022 (JTI, 2022). The UAIDs are seen as viable solutions for alleviating traffic congestion at signalized intersections while also improving operating efficiency and safety (Kay et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

The Feasibility and Operational Performance of Implementation Median U-turn Intersections: A CRITIC Method

Alhadidi,

Matarneh,

Abu Tahoon

2024

Period. Polytech. Transp. Eng.

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Currently, a growing number of cities are adopting the Median-U-Turn (MUT) intersection design to enhance road capacity and traffic efficiency. The critical question in selecting the right intersection design is how significantly the implementation of MUT can enhance intersection performance, focusing on three key aspects: intersection efficiency, capacity, and the environmental impact of the design. To address this question, an evaluation of operational performance under various prevailing conditions (roadway and control) was conducted using VISSIM, a microscopic simulation platform. This evaluation involved five scenarios: conventional intersections (with increased cycle length, grade separation with a signalized at-grade intersection, grade separation with a roundabout), MUT, and signalized crossover MUT at a dense urban arterial intersection in Amman, Jordan's capital. The performance was compared using several metrics: average control delay, number of stops, average travel speed and time, average stopped delay, Carbon Monoxide (CO) emissions, fuel consumption, and vehicle safety. The Criteria Importance Through Intercriteria Correlation (CRITIC) technique was subsequently used to select the optimal design. The findings indicate that the existing intersection configuration is the least effective, while the MUT with signals at the crossing U-turn points is the most efficient solution.

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Safety Performance of Unsignalized Median U-Turn Intersections

Cited by 7 publications

References 10 publications

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

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

Do Traffic Countermeasures Improve the Safety of Vulnerable Road Users at Signalized Intersections? A Combination of Case-Control and Cross-Sectional Studies Using Video-Based Traffic Conflicts

The Feasibility and Operational Performance of Implementation Median U-turn Intersections: A CRITIC Method

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