scholarly journals Safety Performance Evaluation of a Three-Leg Unsignalized Intersection Using Traffic Conflict Analysis

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Guoqiang Zhang ◽  
Jun Chen ◽  
Jingya Zhao
Keyword(s):  
Prediction Model ◽  
Video Camera ◽  
Conflict Analysis ◽  
Safety Performance ◽  
Time To Collision ◽  
Time Headway ◽  
Independent Variables ◽  
Minor Road ◽  
Traffic Conflicts ◽  
Traffic Conflict

Traffic conflicts were used to evaluate safety performance of a three-leg unsignalized intersection. With the aid of a video camera, data were collected at the intersection and 15-second time span was used in each observation to overcome the drawbacks of traditional methods of traffic conflict analysis. Time to collision (TTC), a widely accepted indicator, was used to identify whether an interaction between two vehicles was a traffic conflict. By using Poisson regression, a prediction model for traffic conflicts at the intersection was developed. Based upon the model, assuming that other factors remain constant, when time headway or speed of eastbound traffic on major road, which is crossed by left-turning traffic from minor road, increases, the number of traffic conflicts at the intersection decreases. When volume of left-turning traffic on minor road or speed of left-turning vehicles on minor road increases, the number of traffic conflicts at the intersection increases if other factors remain constant. Explanations for the influence of the factors, which were represented by independent variables of the prediction model, were then analyzed in detail.

scholarly journals Study on Traffic Conflict Prediction Model of Closed Lanes on the Outside of Expressway

Symmetry ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 926
Author(s):  
Huimin Ge ◽  
Mingyue Huang ◽  
Ying Lu ◽  
Yousen Yang
Keyword(s):  
Prediction Model ◽  
Traffic Accidents ◽  
Negative Binomial ◽  
Absolute Error ◽  
Vehicle Speed ◽  
Time To Collision ◽  
Traffic Characteristics ◽  
Traffic Conflicts ◽  
Traffic Conflict ◽  
Conflict Prediction

Due to the randomness and weak symmetry of traffic accidents occurring in the expressway maintenance operation area, it is difficult to use the number of traffic accidents to evaluate the safety of maintenance operation areas. In this paper, the traffic characteristics and traffic conflicts of the maintenance operation area with the lane closed on the outside of the two-way four-lane expressway are studied. By using the statistical method, the distribution of vehicle speed and time headway in different areas of the maintenance operation area are analyzed, and the queuing characteristics of vehicles in the upstream transition zone of the expressway are determined. Based on improved time to collision (TTC) model, the traffic conflict severity of expressway maintenance operation area is divided. The negative binomial distribution is used to establish a traffic conflict prediction model for the enclosed maintenance area of the outer lane of the expressway, and the validity of the traffic conflict prediction model is verified based on the average absolute error percentage (MAPE). The research results show that: when the 0 < TTC < 1.3 s, the traffic conflict is serious conflict; when 1.3 s < TTC, the traffic conflict is non-serious conflict. Furthermore, the traffic conflict prediction model has high accuracy, the MAPE of the warning area and the upstream transition area are 10.8% and 5.0%, respectively.

scholarly journals Intersection Safety Assessment Using Video-Based Traffic Conflict Analysis: The Case Study of Thailand

2021 ◽  
Vol 13 (22) ◽  
pp. 12722
Author(s):  
Nopadon Kronprasert ◽  
Chomphunut Sutheerakul ◽  
Thaned Satiennam ◽  
Paramet Luathep
Keyword(s):  
Road Transport ◽  
Conflict Analysis ◽  
Crash Risk ◽  
Future Research ◽  
Related Factors ◽  
Crash Data ◽  
Time To Collision ◽  
Risk Of Death ◽  
Traffic Conflict ◽  
Local Road

In the road transport network, intersections are among the most critical locations leading to a risk of death and serious injury. The traditional methods to assess the safety of intersections are based on statistical analyses that require crash data. However, such data may be under-reported and omit important crash-related factors. The conventional approaches, therefore, are not easily applied to making comparisons of intersection designs under different road classifications. This study developed a risk-based approach that incorporates video-based traffic conflict analysis to investigate vehicle conflicts under mixed traffic conditions including motorcycles and cars in Thailand. The study applied such conflict data to assess the risk of intersections in terms of time-to-collision and conflict speed. Five functional classes of intersections were investigated, including local-road/local-road, local-road/collector, collector/arterial, collector/collector, and arterial/arterial intersections. The results showed that intersection classes, characteristics, and control affect the behavior of motorists and the safety of intersections. The results found that the low-order intersections with stop/no control are high risks due to the short time-to-collision of motorcycle-related conflicts. They generate frequent conflicts with low chance of injury. The high-order intersections with signal control are high risks due to high conflicting speeds of motorcycle–car conflicts. They generate few conflicts but at a high chance of injury. The study presents the applicability of video-based traffic conflict analysis for systematically estimating the crash risk of intersections. The risk-based approach can be deemed as a supplement indicator in addition to limited crash data to evaluate the safety of intersections. However, future research is needed to explore the potential of other road infrastructure under different circumstances.

scholarly journals TRAFFIC CONFLICT IDENTIFICATION OF E-BIKES AT SIGNALIZED INTERSECTIONS

Transport ◽  
2020 ◽  
Vol 0 (0) ◽  
pp. 1-14
Author(s):  
Zhaowei Qu ◽  
Yuhong Gao ◽  
Xianmin Song ◽  
Yingji Xia ◽  
Lin Ma ◽  
...  
Keyword(s):  
Motor Vehicle ◽  
Space Time ◽  
Spatial Proximity ◽  
Time To Collision ◽  
Traffic Conflicts ◽  
Traffic Conflict ◽  
Discriminant Analyses ◽  
Change Trend ◽  
Conflict Identification ◽  
Conflict Types

The increase of e-bikes has raised traffic conflict concerns over past decade. Numerous conflict indicators are applied to measure traffic conflicts by detecting differences in temporal or spatial proximity between users. However, for traffic environment with plenty of e-bikes, these separate space-time approaching indicators may not be applicable. Thus, this study aims to propose a multi-variable conflict indicator and build a conflict identification method for e-bikes moving in the same direction. In particular, by analysing the conflict characteristics from e-bikes trajectories, a multi-variable conflict indicator utilizing change of forecast post encroachment time, change of relative speed and change of distance is derived. Mathematical statistics and cluster discriminant analyses are applied to identify types of conflict, including conflict existence identification and conflict severity identification. The experimental results show: in mixed traffic environments with many e-bikes, compared with time-to-collision and deceleration, accuracy of identifying e-bike conflict types based on proposed method is the highest and can reach more than 90%; that is, multi-variable indicator based on time and space are more suitable for identifying e-bike conflicts than separate space-time approaching indicators. Furthermore, setting of dividing strip between motor vehicle and non-motorized vehicle has significant influence on number and change trend of conflict types. The proposed method can not only provide a theoretical basis and technical support for automated conflict detection in mixed transportation, but also give the safety optimization sequence of e-bikes at different types of intersections.

scholarly journals Safety evaluation of unconventional outside left-turn lane using automated traffic conflict techniques

2016 ◽  
Vol 43 (7) ◽  
pp. 631-642 ◽  
Author(s):  
Yanyong Guo ◽  
Tarek Sayed ◽  
Mohamed H. Zaki ◽  
Pan Liu
Keyword(s):  
Urban Areas ◽  
Safety Evaluation ◽  
Signalized Intersections ◽  
Video Data ◽  
Contributing Factors ◽  
Left Turn ◽  
Time To Collision ◽  
Traffic Conflicts ◽  
Traffic Conflict ◽  
The Right

The objective of this study is to evaluate the safety impacts of unconventional outside left-turn lane at signalized intersections. New designed unconventional outside left-turn lanes are increasingly used at signalized intersections in urban areas in China. The unconventional outside left-turn lane design allows an exclusive left-turn lane to be located to the right of through lanes to improve the efficiency and increase the capacity of left-turn movements. However, the design also raises some concerns regarding potential negative safety impacts. The evaluation is conducted using an automated video-based traffic conflict technique. The traffic conflicts approach provides better understanding of collision contributing factors and the failure mechanism that leads to road collisions. Traffic conflicts are automatically detected and time to collision is calculated based on the analysis of the vehicles’ positions in space and time. Video data are collected from a signalized intersection in Nanjing, China, where both traditional inside and unconventional outside left-turn lanes are installed on two intersection approaches. The other two approaches have only inside left-turn lanes. The study compared frequency and severity of conflict for left-turning vehicles as well as the percentage of vehicles involved in conflicts from the inside and outside left-turn lanes. The results show that the intersection approaches with outside left-turn lanes had considerably more conflicts compared to approaches without outside left-turn lanes. As well, the approaches with outside left-turn lanes had significantly higher conflict severity than the approaches without outside left-turn lanes. As such, it is recommended that the trade-off between the improved mobility and negative safety impact of outside left-turn lanes be carefully considered before recommending their installation.

Research on Traffic Safety on Freeway Merging Sections Based on TTC and PET

2014 ◽  
Vol 587-589 ◽  
pp. 2224-2229
Author(s):  
Xiang Hai Meng ◽  
Zhi Zhao Zhang ◽  
Yong Yi Shi
Keyword(s):  
Statistical Analysis ◽  
Traffic Safety ◽  
Conflict Situation ◽  
Lane Change ◽  
Traffic Data ◽  
Time To Collision ◽  
Time Headway ◽  
Vehicle Type ◽  
Traffic Conflict ◽  
Surrogate Measures

Since the traffic safety of freeway interchange merging sections and the accidents occurred in this areas can not meet the requirement of statistical analysis, this paper employed traffic conflict technique to analyze the safety situation of freeway merging sections. The traffic data of vehicles through the merging sections are collected and analyzed. These data include the vehicle type, speed, time headway and others based on the features of individual vehicle. Then two methodologies are developed, the first is based on time to collision (TTC), which can calculate the rear-end conflict number, while the second is based on post encroachment time (PET), which can calculate the lane-change conflict number. The results show that these surrogate measures can quantitatively describe the rear-end conflict situation and lane-change conflict situation.

Comparison of Traffic Conflict Indicators for Crash Estimation using Peak Over Threshold Approach

2019 ◽  
Vol 2673 (5) ◽  
pp. 493-502 ◽  
Author(s):  
Lai Zheng ◽  
Tarek Sayed
Keyword(s):  
Confidence Intervals ◽  
Signalized Intersections ◽  
Estimation Methods ◽  
Crash Data ◽  
Time To Collision ◽  
Considerable Research ◽  
Traffic Conflicts ◽  
Peak Over Threshold ◽  
Traffic Conflict ◽  
Threshold Approach

Traffic conflict techniques have drawn considerable research interest and a number of conflict indicators have been developed. Previous studies have qualitatively analyzed indicator differences from their definitions and empirically investigated their similarities based on identified traffic conflicts. This study compares conflict indicators from a validity perspective by comparing crashes estimated from conflict indicators with observed crashes. The peak over threshold (POT) approach was employed for crash estimation. Four commonly used indicators are compared: time to collision (TTC), modified time to collision (MTTC), post encroachment time (PET), and deceleration to avoid a crash (DRAC). Based on the conflict and crash data collected from three signalized intersections, POT models are developed for different thresholds in the appropriate ranges, and crash estimation methods were proposed for individual conflict indicators. The identified conflicts and estimated crashes associated with different indicators are then compared. The results show that traffic conflicts identified by the four indicators vary, with MTTC generating the most accurate crash estimates. The crash estimates from TTC and PET are also reasonable but there is a tendency of overestimation for TTC and underestimation for PET. The crash estimates of DRAC are all outside the confidence intervals of observed crashes, which is likely related to the uncertainty of vehicle braking capacity.

scholarly journals Analisis Kinerja Simpang Bersinyal Untuk Meningkatkan Keselamatan Pada Simpang Depok Kota Depok

2019 ◽  
Vol 6 (1) ◽  
pp. 1-16
Author(s):  
Sony Widyawan ◽  
Rukman Rukman
Keyword(s):  
Traffic Congestion ◽  
Good Condition ◽  
Conflict Analysis ◽  
Phase 3 ◽  
Service Levels ◽  
The Third ◽  
Third Phase ◽  
Traffic Conflicts ◽  
Traffic Conflict

The problemof transportation isone of the problems faced in Depok, especially atintersections. Problems of traffic congestion and conflicts often occur at signalizedintersections, especially at the intersection of four signalized Depok Depok City where one ofthe efforts made to reduce conflicts in Depok intersection is done by setting the intersection.The methods used in the analysis of the performance of the intersection is the use ofcalculation on IHCM, while the traffic conflict analysis to determine the level of seriousnessof traffic conflicts is by using traffic conflict Technique (TCT) is compared to that conflictVisSim 10. Recommendation is done by using a scheme using a 3-phase elections and 3.5phase and then make a comparison with the third phase (existing) and selected the mostappropriate scenario. From the scheme of recommendations that were made by using thesoftware PTV VISSIM 10 obtained the most appropriate scheme that uses three-phasearrangement. The results of the simulation phase 3 was effective at reducing the number oftraffic conflicts and service levels are still in good condition

scholarly journals Evaluation of Collision Potential at Four- Legged Unsignalized Intersection Using Traffic Conflict Technique

2017 ◽  
Vol 2 (3) ◽  
pp. 1
Author(s):  
Biliyamin Adeoye Ibitoye ◽  
Rasheed AbdulWahab ◽  
Abigael Bamidele
Keyword(s):  
Sample Size ◽  
Traffic Flow ◽  
Confidence Level ◽  
Video Camera ◽  
Daily Basis ◽  
Traffic Conflicts ◽  
Close Relationship ◽  
Traffic Conflict ◽  
Traffic Volumes ◽  
Evening Peak

The counting of traffic conflict allows the estimation of accident potential at a particular location such as at-grade intersection. The objective of this paper is to examine the evasive action of driver occurs with some frequency at Shao intersection which may result in potential accident. This paper applied traffic conflict techniques to evaluate collision potential at unsignalized intersection located at Shao. The morning and evening peak traffic flow was captured using a video camera for seven days and then analyzed by playing back the video on daily basis. The 100 sample size of observed conflict was based on 95% confidence level, 5% permitted error and the proportion of the vehicles that were involved in a specific conflict for the observed traffic flow. The conflicts identified were compared with volume counts at minor approach. The daily peak hour approach traffic volumes were found to have a close relationship with the percentage values of conflict on the two minor approaches. It also showed that rear end collision accounted for more than 70 percent of traffic conflicts and it correlated well with the traffic volumes on WB and EB approaches.

scholarly journals A New Traffic Conflict Measure for Electric Bicycles at Intersections

2020 ◽  
Vol 32 (3) ◽  
pp. 309-320
Author(s):  
Zhizhou Wu ◽  
Xin Zeng ◽  
Ling Wang
Keyword(s):  
Traffic Safety ◽  
Video Recording ◽  
Time To Collision ◽  
Safety Improvement ◽  
Traffic Conflicts ◽  
Traffic Conflict ◽  
Relative Kinetic ◽  
Electric Bicycles ◽  
Conflict Risk ◽  
High Flexibility

As electric bicycles (e-bikes) are becoming popular in China, concerns have been raised about their safety conditions. A traffic conflict technique is commonly used in traffic safety analysis, and there are many conflict measures designed for cars. However, e-bikes have high flexibility to change speed and trajectories, which is different from cars, so the conflict measures defined for e-bikes need to be independently explored. Based on e-bike driving characteristics, this paper proposes a new measure, the Integrated Conflict Intensity (ICI), for traffic conflicts involving e-bikes at intersections. It measures the degree of dangerousness of a conflict process, with consideration of both conflict risk and conflict severity. Time to collision is used to measure the conflict risk. Relative kinetic energy is used to measure the conflict severity. ICI can be calculated based on video analysis. The method of determining ICI thresholds for three conflict levels (serious, less serious, and slight) and two conflict types (conflicts between two e-bikes, and conflicts between an e-bike and a car) is put forward based on the questionnaires about safety perception of e-bike riders, which is regarded as the criterion of e-bike safety conditions at intersections. The video recording and a questionnaire survey about conflicts involving e-bikes at intersections have been conducted, and the unified thresholds applicable to different intersections have been determined. It is verified that ICI and its thresholds meet the criterion of e-bike safety conditions. This work is expected to be used in the selection of intersections for safety improvement of e-bike traffic.

scholarly journals Time- and Resource-Efficient Time-to-Collision Forecasting for Indoor Pedestrian Obstacles Avoidance

2021 ◽  
Vol 7 (4) ◽  
pp. 61
Author(s):  
David Urban ◽  
Alice Caplier
Keyword(s):  
Neural Network ◽  
Autonomous Vehicles ◽  
Depth Estimation ◽  
Video Camera ◽  
Obstacle Detection ◽  
Navigation Systems ◽  
Time To Collision ◽  
Static Data ◽  
Monocular Depth ◽  
Fully Connected

As difficult vision-based tasks like object detection and monocular depth estimation are making their way in real-time applications and as more light weighted solutions for autonomous vehicles navigation systems are emerging, obstacle detection and collision prediction are two very challenging tasks for small embedded devices like drones. We propose a novel light weighted and time-efficient vision-based solution to predict Time-to-Collision from a monocular video camera embedded in a smartglasses device as a module of a navigation system for visually impaired pedestrians. It consists of two modules: a static data extractor made of a convolutional neural network to predict the obstacle position and distance and a dynamic data extractor that stacks the obstacle data from multiple frames and predicts the Time-to-Collision with a simple fully connected neural network. This paper focuses on the Time-to-Collision network’s ability to adapt to new sceneries with different types of obstacles with supervised learning.

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