Development of conflict severity index for safety evaluation of severe crash types at unsignalized intersections under mixed traffic

2021 ◽  
Vol 144 ◽  
pp. 105432
Author(s):  
Madhumita Paul ◽  
Indrajit Ghosh
Keyword(s):  
Safety Evaluation ◽  
Severity Index ◽  
Mixed Traffic ◽  
Unsignalized Intersections ◽  
Crash Types

scholarly journals Capacity of Unsignalized Intersections under Mixed Traffic Conditions

2011 ◽  
Vol 16 ◽  
pp. 676-685 ◽  
Author(s):  
Joewono Prasetijo ◽  
Mehdi Hossein Pour ◽  
Seyed Mohammad Reza Ghadiri
Keyword(s):  
Mixed Traffic ◽  
Traffic Conditions ◽  
Unsignalized Intersections

scholarly journals Safety Evaluation of Shoulder Bypass Lanes at Unsignalized Intersections on Rural Two-Lane Roadways Using Cross Sectional Analysis

2016 ◽  
Author(s):  
Sunanda Dissanayake ◽  
Alireza Shams
Keyword(s):  
Low Cost ◽  
Safety Evaluation ◽  
Cross Sectional Study ◽  
Highway Safety ◽  
Sectional Study ◽  
Cross Sectional ◽  
Crash Data ◽  
Study Approach ◽  
Unsignalized Intersections ◽  
Before And After

Construction of bypass lanes at rural intersections has typically been considered a low-cost highway safety improvement by the transportation community. However, this needs to be quantitatively evaluated so that the decisions could be made on whether to continue with adding bypass lanes. Highway safety analyses utilize two common approaches to evaluate the effectiveness of a geometric treatment: before-and-after study and cross-sectional study. This paper explains the results using a cross-sectional study approach, where intersections with bypass lanes were compared to intersections with no bypass lanes for which crash data were obtained for more than 1,100 intersections in Kansas. Both 3-legged and 4-legged intersections were taken into consideration separately by looking at intersection-related crashes and crashes within an intersection box. According to the results, the number of crashes and crash severities were lower at 3-legged intersections with bypass lanes compared with 3-legged intersections without bypass lanes, even though these reductions were not statistically significant at 95% level. When considering a 300-ft. intersection box, statistically significant crash reductions were observed at 4-legged intersections, for all considered crash and crash rate categories. When considering 90% level, crash reduction at 3-legged intersections was also statistically significant when considering a 300-ft. intersection box. Crash modification factors (CMFs) calculated to evaluate safety effectiveness of bypass lanes at unsignalized rural intersections in Kansas showed values less than 1.0 for almost all cases, indicating safety benefits of bypass lanes. Accordingly, it is beneficial to continue with the practice of adding shoulder bypass lanes at rural unsignalized intersections on two-lane roads where the traffic volumes are relatively low.

scholarly journals PEDESTRIAN SAFETY EVALUATION OF SIGNALIZED INTERSECTIONS USING SURROGATE SAFETY MEASURES

Transport ◽  
2020 ◽  
Vol 35 (1) ◽  
pp. 48-56
Author(s):  
Sankaran Marisamynathan ◽  
Perumal Vedagiri
Keyword(s):  
Safety Evaluation ◽  
Pedestrian Safety ◽  
Signalized Intersections ◽  
Signalized Intersection ◽  
Mixed Traffic ◽  
Model Framework ◽  
Safety Measures ◽  
Severity Level ◽  
Traffic Conditions ◽  
Surrogate Safety Measures

The large proportions of pedestrian fatalities led researchers to make the improvements of pedestrian safety at intersections. Thus, this paper proposes a methodology to evaluate crosswalk safety at signalized intersections using Surrogate Safety Measures (SSM) under mixed traffic conditions. The required pedestrian, traffic, and geometric data were extracted based on the videographic survey conducted at signalized intersections in Mumbai (India). Post Encroachment Time (PET) for each pedestrian were segregated into three categories for estimating pedestrian–vehicle interactions and Cumulative Frequency Distribution (CDF) was plotted to calculate the threshold values for each interaction severity level. The Cumulative Logistic Regression (CLR) model was developed to predict the pedestrian mean PET values in the cross-walk at signalized intersections. The proposed model was validated with a new signalized intersection and the results were shown that the proposed PET ranges and model appropriate for Indian mixed traffic conditions. To assess the suitability of model framework, model transferability was carried out with data collected at signalized intersection in Kolkata (India). Finally, this study can be helpful to rank the severity level of pedestrian safety in the crosswalk and improve the existing facilities at signalized intersections.

Operational safety of automated and human driving in mixed traffic environments: A perspective of car-following behavior

2021 ◽  
pp. 1748006X2110506
Author(s):  
Tao Li ◽  
Xu Han ◽  
Jiaqi Ma ◽  
Marilia Ramos ◽  
Changju Lee
Keyword(s):  
Traffic Safety ◽  
Risk Mitigation ◽  
Safety Evaluation ◽  
Mixed Traffic ◽  
Trajectory Data ◽  
Road Transportation ◽  
Baseline Model ◽  
Car Following ◽  
On The Road ◽  
The Impact

The advent of automated vehicles (AVs) will provide opportunities for safer, smoother, and smarter road transportation. During the transition from the current human-driven vehicle (HV) to a fully AV traffic environment, there will be a mixed traffic flow including both HVs and AVs. The impact of introducing AVs into existing traffic, however, has not yet been fully understood. In this paper, we advance this understanding by conducting mixed traffic safety evaluation from the perspective of car-following behavior using real-world AV operational data of mixed traffic. To understand how the AVs impact other vehicles on the road, we analyzed the operational behaviors of HV-following-HV, AV-following-HV, and HV-following-AV. A selected car-following model is calibrated, and results show that there are significant differences between the HV-following-HV and the other two groups, indicating safe AV behavior and changes in HV behavior (i.e. less aggressive, safer) after the introduction of AVs into the traffic. Additionally, to understand AV behavioral safety, we investigate behavior predictions (one of the most critical inputs for AVs to make car-following decisions) of AVs and their surrounding vehicles using a mature baseline model and a new Conditional Variational Autoencoder (CVAE) framework. The result shows potential risks of inaccurate predictions of the baseline model and the necessity to consider additional factors, such as vehicle interactions and driver behavior, into the prediction for risk mitigation. Arterial vehicle trajectory data from the Lyft Level 5 Dataset is applied to test the proposed methodological framework to understand the car-following safety risks of HVs and AVs in the mixed traffic stream.

Effect of Roadside Development on the Safety of Intersections without Signals

2015 ◽  
Vol 802 ◽  
pp. 393-398
Author(s):  
Ashar Ahmed ◽  
Ahmad Farhan Mohd Sadullah ◽  
Ahmad Shukri Yahya
Keyword(s):  
Sustainable Development ◽  
Safety Evaluation ◽  
Access Point ◽  
Contributory Factors ◽  
Unsignalized Intersections ◽  
Bus Stops ◽  
Fire Stations

Roadside development plays an important role in the safety of the entire road in general and intersections in particular. Illegal and improper buildouts such as roadside kiosks, bus stops and fire stations are an accident hazard and a hindrance towards sustainable development. This paper presents the first account of analysis of safety evaluation of intersections with respect to roadside development in Malaysia. The data collected on 14 sites was analyzed. The results indicated that the bus stops and restaurants located right infront of the unsignalized intersections were the major contributory factors in decreasing the safety. Moreover it was found that facilities staggered away from the intersection such as another access point are less hazardous. It is recommended that relevant authorities should ensure the removal of such risky roadside developments.

scholarly journals Safety evaluation for roadside crashes by vehicle–object collision simulation

2018 ◽  
Vol 10 (10) ◽  
pp. 168781401880558 ◽  
Author(s):  
Kejun Long ◽  
Zhibo Gao ◽  
Quan Yuan ◽  
Wang Xiang ◽  
Wei Hao
Keyword(s):  
Evaluation Method ◽  
Center Of Mass ◽  
Safety Evaluation ◽  
Severity Index ◽  
Field Investigation ◽  
Crash Test ◽  
Crash Severity ◽  
Roadside Safety ◽  
Crash Data ◽  
Test Standards

In order to evaluate roadside crash severity and help making decision on roadside safety improvement alternatives, this article proposes a roadside crash severity evaluation method based on vehicle kinematics metric during the crash: Acceleration Severity Index. Based on the field investigation on 1917 km of representative roads, roadside crash test standards and parameters were determined. A total of 59 crash scenarios, involving 5 typical roadside obstacles, 2 types of guardrails, 15 embankment slopes, and 3 types of vehicles (car, bus, and truck), were designed for simulated crash testing with VPG3.2 and LS-DYNA971 software. The x-, y-, and z-direction acceleration (or deceleration) curves of a test vehicle’s center of mass during each crash test were collected for the calculation of the Acceleration Severity Index values. The Fisher optimal partition algorithm was used to cluster the Acceleration Severity Index values to identify an appropriate number of roadside crash severity levels and the corresponding threshold values that demarcate these levels. The results showed that the roadside crash severity classification produced by Acceleration Severity Index–based method is consistent with handbook Guideline for Implementation of Highway Safety Enhancement Project. Therefore, when crash data are missing, crash test could be a feasible surrogate method for roadside crash severity evaluation.

scholarly journals Safety evaluation of roundabouts at freeway ramp terminals and HSM calibration

2017 ◽  
Author(s):  
◽  
Jacob A. Berry
Keyword(s):  
Empirical Bayes ◽  
Safety Evaluation ◽  
Crash Severity ◽  
Site Specific ◽  
Crash Data ◽  
Highway Safety Manual ◽  
Time Period ◽  
Using Data ◽  
Crash Types ◽  
Project Level

Although the conventional understanding is that roundabouts have the potential to improve safety at intersections, particularly by reducing more severe crash types, there is limited knowledge on their safety impacts when utilized as part of an interchange system. This research utilizes multiple years of crash, traffic, and geometric data across a variety of roundabout interchange sites in Missouri to develop a two-level Empirical Bayes (EB) safety analysis at the project (entire interchange) and site-specific (ramp terminal only) levels. The results were then aggregated for both single-lane and dual-lane roundabout terminals. The project-level results for single-lane sites showed a decrease in fatal/injury crashes (FI) by 20.3 percent, property damage only (PDO) crashes by 26.0 percent and total crashes by 24.5 percent. The site-specific results for single-lane roundabout terminals indicated a reduction of FI crashes by 32.8 percent, PDO crashes by 23.1 percent, and total crashes by 24.4 percent. At the project-level, dual-lane roundabouts were shown to reduce FI crashes by 2.3 percent while increasing PDO and total crashes by 16.9 percent and 12.2 percent, respectively. The dual-lane site-specific results indicated an increase in FI crashes by 34.7 percent, PDO crashes by 53.9 percent, and total crashes by 50.0 percent at the ramp terminal specifically. This analysis directly compares observed crash data after roundabout implementation to the expected number of crashes over that time period if the roundabout were never constructed. Therefore, this indicates that single-lane roundabouts performed significantly better than their original configurations, while the dual-lane roundabout terminals were shown to be less-suitable for certain applications. Additionally, it was found that a high proportion of the roundabout crashes occurred at the exit ramp approach legs; this was illustrated in the collision diagrams and crash type distributions that were produced for the common observed crashes at both single and dual-lane roundabout terminals. As a separate part of this thesis research, an improved calibration of the Highway Safety Manual safety performance functions of four facility types was performed using data from 2012-2014 to calibrate for local Missouri conditions. Crash severity and crash type distributions were also developed for each facility type.

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