Safety and mobility effects of installing speed-humps within unconventional median U-turn intersections

Shahdah, Usama Elrawy; Azam, Abdelhalim

doi:10.1016/j.asej.2020.08.033

Cited by 12 publications

(3 citation statements)

References 20 publications

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“…A " ρ " value of "1.0" indicates no significant safety changes between the two designs. The statistical significance of the " ρ " can be estimated in the same fashion as the collision modification factors (CMFs) [21,26,27,54]. For the 5% significance level, it can be estimated as follows) [55,56]:…”

Section: Traffic Conflict Ratiomentioning

confidence: 99%

Safety and Mobility Performance Comparison of Two-Plus-One and Two-Lane Two-Way Roads: A Simulation Study

Shahdah,

Alanazi,

Azam

et al. 2024

Applied Sciences

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Two-plus-one (2+1) highways are a special configuration of two-lane two-way (TLTW) highways with a continuous center lane that is used to alternate passing lanes. The main objective of this paper is, therefore, to evaluate the suitability of the 2+1 design for Middle East conditions as a replacement for traditional TLTW roads with higher traffic volumes or as an interim solution before transforming TLTW roads into four-lane highways. In our analysis, we considered both safety and mobility performances by comparing the 2+1 and TLTW designs. The new suggested 2+1 designs were evaluated, with the first design prohibiting overtaking in the opposite direction, while the second design permitted it. Additionally, two-speed-limit strategies, uniform speed limit (USL), and differential speed limit (DSL) were also evaluated. The results showed that the 2+1 design, which prohibited overtaking in the opposite direction, was superior to TLTW in terms of mobility and safety, while the other design compromised safety compared to TLTW. The results provide valuable information to policymakers, urban planners, and transport authorities to guide evidence-based decisions on the integration of the 2+1 design as a viable solution for sustainable and efficient transportation.

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Section: Traffic Conflict Ratiomentioning

confidence: 99%

Safety and Mobility Performance Comparison of Two-Plus-One and Two-Lane Two-Way Roads: A Simulation Study

Shahdah,

Alanazi,

Azam

et al. 2024

Applied Sciences

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“…Very good results were shown in terms of road safety, reducing traffic conflicts and yielding the best safety result at 90 km/h due to the reduced number and severity of conflicts. [12]. To achieve this, the dynamics followed by the different types of vehicles in interaction must be taken into account.…”

Section: State Od the Artmentioning

confidence: 99%

Vehicular Conflict Assessment on a Road with Lane Reduction Using the SSAM Methodology

Del Valle,

La Rosa,

Silvera

et al. 2023

Proceedings of the 21th LACCEI International Multi-Conference for Engineering, Education and Technology (LACCEI 2023): “Leaders

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In this article, an evaluation of the number of vehicular conflicts is carried out, in a section of road that is part of a traffic light intersection, with constant presence of traffic jams. In the trajectory of this section there is a reduction in lanes, variable lane widths and little uniformity, causing a bottleneck that produces different types of conflicts between vehicles. To carry out the evaluation, the VISSIM microsimulation software was used, here the real situation of the intersection is modeled and two new scenarios are proposed, in which geometric redesign proposals are made in the infrastructure of the section of road, in order to analyze variability in the number of vehicular conflicts. For the automatic counting of conflicts, the Surrogate Safety model (SSAM) is used. Vehicular conflicts are categorized according to their crossing collision angle (crossing), rear end collision angle (rear end) and lane change (lane change), and their severity levels in relation to the time before collision (TTC). The results indicate a count of 3916 conflicts inthe microsimulation of the real situation. In the first proposed scenario, 2,231 conflicts were counted, which corresponds to a 43% reduction in relation to the current situation; while in the second scenario 3,835 conflicts were counted, a reduction of 2%. The TTCs ranged between 0.52 and 0.70, indicating a high risk of collision on the road.

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“…The car-following model of VISSIM could easily simulate and extract the trajectories of vehicles [27,28]. Therefore, the VISSIM is used to display vehicle distributions and operations in real time when the fire occurs [29], determining the locations of evacuating occupants and obstacles in the tunnel.…”

Section: Simulation Softwaresmentioning

confidence: 99%

Optimal exit choice during highway tunnel evacuations based on the fire locations

Wang

Liu

et al. 2021

PLoS ONE

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In the case of a fire, the choice of exit in the highway tunnel is strictly limited by fire location, which seriously affects the evacuation time. A spontaneous or disorderly exit choice might result in a decreased evacuation efficiency and utilization rate of exits. In this paper, we propose a strategy to obtain the optimal exit choice based on fire location during highway tunnel evacuations. In our strategy, first, the vehicle distributions and locations of evacuating occupants are determined in the traffic simulation program VISSIM. The evacuation simulation software BuildingEXODUS is employed to obtain the corresponding parameters of the evacuation process and analyze the impacts of different fire locations on the evacuation time. During the analysis, the optimal productivity statistics (OPS) is selected as the evaluation index. Then, the feature points of the crowding occupants are captured by the fuzzy c-means (FCM) cluster algorithm. Next, based on the feature points, the relationship between the location of the fire and boundary of the optimal exit choice under the optimal OPS is obtained through the polynomial regression model. It is found that the R-squared(R2) and sum of squares for error (SSE) of the polynomial regression model, reflecting the accuracy estimation, are 98.02% and 2.79×10−4, respectively. Moreover, different fire locations impact the evacuation time of tunnel entrance and evacuation passageway. This paper shows that the location of the fire and boundary of optimal exit choice have a negative linear correlation. Taking the fire 110 m away from the evacuation passageway as an example, the OPS of our strategy can be decreased by 35.6% when compared with no strategies. Our proposed strategy could be applied to determine the location of variable evacuation signs to help evacuating occupants make optimal exit choices.

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Safety and mobility effects of installing speed-humps within unconventional median U-turn intersections

Cited by 12 publications

References 20 publications

Safety and Mobility Performance Comparison of Two-Plus-One and Two-Lane Two-Way Roads: A Simulation Study

Safety and Mobility Performance Comparison of Two-Plus-One and Two-Lane Two-Way Roads: A Simulation Study

Vehicular Conflict Assessment on a Road with Lane Reduction Using the SSAM Methodology

Optimal exit choice during highway tunnel evacuations based on the fire locations

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