When to Decide to Convert a Roundabout to a Signalized Intersection: Simulation Approach for Case Studies in Jeddah and Al-Madinah

Owais, Mahmoud; Abulwafa, Omar; Abbas, Y. A.

doi:10.1007/s13369-020-04479-6

Cited by 24 publications

(9 citation statements)

References 31 publications

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“…This measure has not seen much attention in the literature and may improve safety by combining benefits of both signals and roundabouts. Further, studies on conversion of signalised intersection to roundabouts were much more limited (Owais et al, 2020), as pointed out by Gross et al (2013). Future work would benefit from evaluating the effectiveness of such conversion in different situations with varying levels of traffic.…”

Section: Discussionmentioning

confidence: 99%

Engineering Countermeasures for Left Turns at Signalized Intersections: A Review

Samuel

Singh

Yamani

2022

JRS

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Left turn crashes can impact the safety of the drivers due to the speed and angle at which they occur. Left turns are specifically reported to affect older drivers more than the other types of crashes. This paper provides a review of the existing engineering countermeasures that have been evaluated to improve driver safety at left turns. Twentyeight studies on left turn signal displays (protected left turns, flashing yellow arrow, and digital countdown timers), intersection geometry (offset left turn lanes, diverging diamond interchange, roundabouts, exit lanes for left turn, left turn bay extension, and contraflow left turn lanes), and driver warning systems (infrastructure warning systems, and in-vehicle warning systems) are reviewed. Eighteen studies were evaluated in the field, nine in laboratory environments, and one online. All countermeasures demonstrated varying levels of effectiveness. We found protected left turns, roundabouts, and warning systems to be the most effective engineering countermeasures. Advantages and disadvantages of each countermeasure and research shortcomings of the evaluation studies are discussed. Review findings may help practitioners and researchers guide more effective countermeasures for left turns for older drivers.

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Section: Discussionmentioning

confidence: 99%

Engineering Countermeasures for Left Turns at Signalized Intersections: A Review

Samuel

Singh

Yamani

2022

JRS

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“…In recent years, roundabouts have been recognized by transportation researchers as an important aspect of road transportation, and it plays a key role in addressing traffic congestions and ensuring safety of pedestrians on the road, in addition to playing a significant role in creating an efficient alternative to traditional/classical road intersections designs. Roundabouts provide an efficient solution to low traffic volume junctions at road intersections to reduce vehicular traffic delays and improve road and vehicular safety [14][15][16][17]. The most common road safety benefits of using roundabouts are usually because of the geometry designs of road intersections and the priority rules associated with roundabouts, which minimize the speed of vehicles approaching roundabouts and reduce the likelihood of collision of vehicles at roundabouts.…”

Section: Discussionmentioning

confidence: 99%

Safety Evaluation of Flower Roundabout Considering Autonomous Vehicles Operation

et al. 2021

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With the significant technological growth that affected autonomous vehicles in the last decade, several consequences occurred as: human factor exclusion, entry and exit manoeuvres precision from roundabouts, and headway reduction. In this paper, it was carried out a microsimulation approach study that aims to evaluate benefits in terms of safety obtained with flower roundabouts in a scenario where traffic is characterized by conventional vehicles “CVs” and Connected Autonomous Vehicles “CAVs”. This study focused on the evaluation of CAVs and CVs operation with the presence of the so called “weak users” or rather, pedestrians and bikes. Then, simulated scenarios were characterized by the presence of zebra-crossings in main roads, positioned at 20 m from circulatory carriageway edges. Micro simulation choice is due to the absence of survey data collection because the presence of CAVs in ordinary traffic is still minimal. The micro simulation was carried out through VISSIM, so it was operated with a specific methodological path, consisting, in the application, of O–D matrix based on real cases, in order to achieve an assessment of potential conflicts in relation with the increase in CAVs. Simulation results showed that higher safety levels were achieved for special cases of O–D distribution and with CAVs present. Finally, considering crash absence in results related to CAVs presence, safety interventions of such roundabout types have to be thorough. There were 10 O/D matrices analysed through VISSIM considering parameters as: average tail length, maximum tail length, average speed, vehicles, and number of stops quantity. As reported in the conclusion section, O/D matrices that showed minimum conflicts and maximum dynamic performances were identified.

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“…Bertini et al used computerized microscopic traffic simulation programs Paramics and VISSIM to analyze a diamond interchange in Portland, Oregon [41]. Simulation models allow designers to analyze non-existing situations, like adding a new lane or turn bay and studying the impact of geometric changes, or optimizing traffic flow at toll plaza [42,43]. Mosseri et al studied a multi-modal urban corridor with complex geometry and traffic control in VISSIM [44].…”

Section: Microsimulation Of Traffic Congestionmentioning

confidence: 99%

High-Profile Convoy Disruptions: Exploring Socioeconomic and Environmental Ramifications of Road Closures

Zubair,

Javed,

Ud-Din

et al. 2024

Sustainability

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Congestion persists despite various demand management techniques, particularly for handling recurrent congestion. However, non-recurrent congestion from events like VIP movements poses unique challenges, especially during peak hours. This study investigates the environmental and economic impacts of road blockages due to VIP movements in developing countries, focusing on Pakistan. Considering practiced standard operating procedures associated with VIP movements, this study finds significant delays and economic burdens in debt-ridden economies. It uses discrete choice modeling and microsimulation techniques to evaluate the value of travel time and quantifies road blockage effects on fuel consumption, travel time, and carbon emissions. Data from central blockage locations in Rawalpindi and Islamabad reveal a value of travel time estimated at 1.77 USD/h, with income and gender significantly influencing mode choices during VIP movements. Moreover, road blockages exceeding two minutes substantially negatively impact the environment and economy, particularly in developing nations. Urgent action is needed for effective mitigation strategies and sustainable transportation policies to address the detrimental effects and promote alternative transportation modes. Recommendations include limiting VIP blockages to a maximum of two minutes and implementing policies to discourage private car usage. Despite limitations, the study emphasizes the critical role of sustainable transportation policies in enhancing the well-being of road users in developing nations.

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When to Decide to Convert a Roundabout to a Signalized Intersection: Simulation Approach for Case Studies in Jeddah and Al-Madinah

Cited by 24 publications

References 31 publications

Engineering Countermeasures for Left Turns at Signalized Intersections: A Review

Engineering Countermeasures for Left Turns at Signalized Intersections: A Review

Safety Evaluation of Flower Roundabout Considering Autonomous Vehicles Operation

High-Profile Convoy Disruptions: Exploring Socioeconomic and Environmental Ramifications of Road Closures

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