scholarly journals Analysis of Freeway Secondary Crashes in Different Traffic Flow States by Three-Phase Traffic Theory

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Bo Yang ◽  
Yao Wu ◽  
Weihua Zhang
Keyword(s):  
Traffic Flow ◽  
Safety Performance ◽  
Crash Risk ◽  
Contributing Factors ◽  
Crash Data ◽  
Conditional Logit ◽  
Three Phase ◽  
Secondary Crashes ◽  
Traffic Theory ◽  
Flow States

The objective of this study is to analyse the relationship between secondary crash risk and traffic flow states and explore the contributing factors of secondary crashes in different traffic flow states. Crash data and traffic data were collected on the I-880 freeway in California from 2006 to 2011. The traffic flow states are categorised by three-phase traffic theory. The Bayesian conditional logit model has been established to analyse the statistical relationship between the secondary crash probability and various traffic flow states. The results showed that free flow (F) state has the best safety performance of secondary crash and synchronized flow (S) state has the worst safety performance of secondary crashes. The traditional logistic regression model has been used to analyse the contributing factors of secondary crashes in different traffic flow states. The results indicated that the contributing factors in different traffic flow states are significantly different.

scholarly journals Simulation Study of Rear-End Crash Evaluation considering Driver Experience Heterogeneity in the Framework of Three-Phase Traffic Theory

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Haifei Yang ◽  
Yao Wu ◽  
Huihui Xiao ◽  
Yi Zhao
Keyword(s):  
Traffic Flow ◽  
Performance Outcomes ◽  
Safety Performance ◽  
Safety Measure ◽  
Novice Drivers ◽  
Phase Theory ◽  
Car Following ◽  
Three Phase ◽  
Car Following Model ◽  
Traffic Theory

Driving safety is considered to have a strong relationship with traffic flow characteristics. However, very few studies have addressed the safety impacts in the three-phase traffic theory that has been demonstrated to be an advancement in explaining the empirical features of traffic flow. Another important issue affecting safety is driver experience heterogeneity, especially in developing countries experiencing a dramatic growth in the number of novice drivers. Thus, the primary objective of the current study is to develop a microsimulation environment for evaluating safety performance considering the presence of novice drivers in the framework of three-phase theory. First, a car-following model is developed by incorporating human physiological factors into the classical Intelligent Driver Model (IDM). Moreover, a surrogate safety measure based on the integration concept is modified to evaluate rear-end crashes in terms of probability and severity simultaneously. Based on a vehicle-mounted experiment, the field data of car-following behavior are collected by dividing the subjects into a novice group and an experienced group. These data are used to calibrate the proposed car-following model to explain driver experience heterogeneity. The results indicate that our simulation environment is capable of reproducing the three-phase theory, and the changes in the modified surrogate safety measure are highly correlated with traffic phases. We also discover that the presence of novice drivers leads to different safety performance outcomes across various traffic phases. The effect of driver experience heterogeneity is found to increase the probability of the rear-end crashes as well as the corresponding severity. The results of this study are expected to provide a scientific understanding of the mechanisms of crash occurrences and to provide application suggestions for improving traffic safety performance.

Using empirical traffic trajectory data for crash risk evaluation under three-phase traffic theory framework

2021 ◽  
Vol 157 ◽  
pp. 106191
Author(s):  
Tong Liu ◽  
Zhibin Li ◽  
Pan Liu ◽  
Chengcheng Xu ◽  
David A. Noyce
Keyword(s):  
Risk Evaluation ◽  
Crash Risk ◽  
Trajectory Data ◽  
Three Phase ◽  
Traffic Theory ◽  
Theory Framework

USING VARIABLE SPEED LIMITS TO ELIMINATE WIDE MOVING JAMS: A STUDY BASED ON THREE-PHASE TRAFFIC THEORY

2012 ◽  
Vol 23 (09) ◽  
pp. 1250060 ◽  
Author(s):  
YIZHI WANG ◽  
YI ZHANG ◽  
JIANMING HU ◽  
LI LI
Keyword(s):  
Traffic Flow ◽  
Control Strategies ◽  
Vehicle Speed ◽  
Variable Speed ◽  
Speed Limits ◽  
Congested Traffic ◽  
Three Phase ◽  
Variable Speed Limits ◽  
Ca Model ◽  
Traffic Theory

One frequently observed congested traffic flow pattern is wide moving jam (WMJ), in which the average vehicle speed is very low and the density is very high. In some recent studies, variable speed limits (VSL) were proposed as effective measures to eliminate or abate the influence of jam waves. However, in most of these studies, the stochastic features of driving behaviors and the resulting uncertainty of traffic flow dynamics were not fully considered. In this paper, we use cellular automaton (CA) model-based simulations to test the performances of different VSL control strategies and apply the three-phase traffic theory to further analyze the obtained results. Based on the simulation results, we got two novel findings. Firstly, we observed seven, instead of the previously assumed six, states of traffic flow in the evolution process of WMJ, when VSL were applied. Secondly and more importantly, we found that inappropriate speed limit may induce new WMJ and exaggerate congestions in two ways: one way corresponds to an F → J transition and the other corresponds to an F → S → J transition. Based on these findings, the appropriate lower bound of VSL was finally discussed in this paper.

Research on three-phase traffic flow modeling based on interaction range

2017 ◽  
Vol 31 (35) ◽  
pp. 1750328 ◽  
Author(s):  
Jun-Wei Zeng ◽  
Xu-Gang Yang ◽  
Yong-Sheng Qian ◽  
Xu-Ting Wei
Keyword(s):  
Traffic Flow ◽  
Traffic Congestion ◽  
Careful Consideration ◽  
Open Boundary ◽  
Range Interaction ◽  
Interaction Range ◽  
Flow Rates ◽  
Three Phase ◽  
Traffic Theory ◽  
The Relationship

On the basis of the multiple velocity difference effect (MVDE) model and under short-range interaction, a new three-phase traffic flow model (S-MVDE) is proposed through careful consideration of the influence of the relationship between the speeds of the two adjacent cars on the running state of the rear car. The random slowing rule in the MVDE model is modified in order to emphasize the influence of vehicle interaction between two vehicles on the probability of vehicles’ deceleration. A single-lane model which without bottleneck structure under periodic boundary conditions is simulated, and it is proved that the traffic flow simulated by S-MVDE model will generate the synchronous flow of three-phase traffic theory. Under the open boundary, the model is expanded by adding an on-ramp, the congestion pattern caused by the bottleneck is simulated at different main road flow rates and on-ramp flow rates, which is compared with the traffic congestion pattern observed by Kerner et al. and it is found that the results are consistent with the congestion characteristics in the three-phase traffic flow theory.

Effects of Operating Speed and Traffic Flow on Severe and Fatal Crashes using the U.S. Road Assessment Program Methodology and Field Data Verification

2020 ◽  
Vol 2674 (11) ◽  
pp. 30-41
Author(s):  
Fahmid Hossain ◽  
Juan C. Medina
Keyword(s):  
Traffic Flow ◽  
Safety Performance ◽  
Operating Speed ◽  
Crash Data ◽  
Assessment Program ◽  
Traffic Characteristics ◽  
Fatal Crashes ◽  
Roadway Safety ◽  
Traffic Volumes ◽  
The U.S

This paper explores the effects of operating speed and traffic flow on roadway safety in light of the methodology provided by the U.S. Road Assessment Program (usRAP). Unlike traditional approaches, usRAP produces a systemic expected roadway safety performance, more specifically the likelihood of being involved in a severe or a fatal crash, that is derived purely from roadway, roadside, and traffic characteristics, without need for detailed historical crash data. Data from over 7,000 mi of segments coded using the usRAP protocols and 5 years of crash data were used to examine changes in expected safety performance with changes in operating speed and traffic volumes. Speed and flow emerged as candidates for initial exploration as their effect is explicitly considered in the usRAP formulation for all crash types. The usRAP methodology indicated a gradual increase in the frequency of expected severe and fatal crashes with an increase in the operating speed, and such trends followed those observed in the field. Increase in traffic flow was generally associated to increase in severe and fatal crashes, but to a much smaller scale compared with the effect found for speed. Effects of traffic flow were more evident at smaller ranges, both in the field and in the usRAP results, with the safety effects diminishing and even reversing as the flow approached lane capacity. Crash data were examined using a risk ratio that considers the relative frequency of severe and fatal crashes to the exposure of a given segment group, as well as star rating scores and star ratings from usRAP outputs.

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