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 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.

Smart Estimation Ver-H.1.0

2018 ◽  
Author(s):  
Sigit Haryadi
Keyword(s):  
Sample Size ◽  
Confidence Level ◽  
Time Span ◽  
Regression Equation ◽  
Weight Factor ◽  
The Past ◽  
Level Of Confidence ◽  
The Future ◽  
Future Value ◽  
The Difference

We cannot be sure exactly what will happen, we can only estimate by using a particular method, where each method must have the formula to create a regression equation and a formula to calculate the confidence level of the estimated value. This paper conveys a method of estimating the future values, in which the formula for creating a regression equation is based on the assumption that the future value will depend on the difference of the past values divided by a weight factor which corresponding to the time span to the present, and the formula for calculating the level of confidence is to use "the Haryadi Index". The advantage of this method is to remain accurate regardless of the sample size and may ignore the past value that is considered irrelevant.

Multi-object-based Vessel Traffic Scheduling Optimisation in a Compound Waterway of a Large Harbour

2018 ◽  
Vol 72 (3) ◽  
pp. 609-627 ◽  
Author(s):  
Xinyu Zhang ◽  
Ruijie Li ◽  
Xiang Chen ◽  
Junjie Li ◽  
Chengbo Wang
Keyword(s):  
Genetic Algorithm ◽  
Traffic Flow ◽  
Simulation Experiment ◽  
Case Analysis ◽  
Slot Allocation ◽  
Traffic Scheduling ◽  
Multi Objective Genetic Algorithm ◽  
Object Based ◽  
Traffic Conflicts ◽  
Optimisation Model

In order to investigate the benefits of compound waterways more fully, this study reveals vessel navigational mode and traffic conflicts in a compound waterway through a case analysis, following which a type of simplified prototype of a compound waterway is proposed and three key conflict areas are specified. Based on the three key sub-models of slot allocation for vessels in a waterway entrance, traffic flow conversion of a main and auxiliary waterway in a precautionary area, and traffic flow coordination of division and confluence in a Y crossing area, a vessel traffic scheduling optimisation model is presented, with the minimum waterway occupancy time and minimum total waiting time of vessels as the objective. Furthermore, a multi-objective genetic algorithm is proposed to solve the model and a simulation experiment is carried out. By analysing the optimised solution and comparing it with other scheduling schemes in common use, the results indicate that this method can effectively improve navigation safety and efficiency in a compound waterway.

Analysis of Pedestrian Conflicts with Left-Turning Traffic

1996 ◽  
Vol 1538 (1) ◽  
pp. 61-67 ◽  
Author(s):  
Dominique Lord
Keyword(s):  
Data Collection ◽  
Statistical Tests ◽  
Computer Programs ◽  
Signalized Intersections ◽  
Laptop Computer ◽  
Expected Number ◽  
Positive Correlation ◽  
Data Collection Process ◽  
Traffic Conflicts ◽  
Traffic Conflict

The interaction between pedestrians and left-turning vehicles at signalized intersections are examined using the traffic conflict technique. Paramount was a comparison of the safety of left turns at two types intersections: T-intersections and X-intersections (cross-intersections). Previous research has indicated that T-intersections are more dangerous to pedestrians. In preparation for the comparison several traffic conflict definitions and their applications to pedestrians were evaluated. Use of a laptop computer for data collection was tested. Eight sites taken from intersections in Hamilton, Ontario, Canada, were selected. A conflict recording methodology was developed for T-intersections and X-intersections that consisted of recording data at various times along the paths of pedestrians and left-turning vehicles, and recording traffic conflicts. Two computer programs were written for the data collection process: one for vehicles and one for pedestrians. Several statistical tests to relate traffic conflicts and the expected number of accidents were performed. These tests indicate that a positive correlation between traffic conflicts and expected number of accidents exists; they also suggest that T-intersections have a higher traffic conflict rate than X-intersections.

Dirty-Face Game Analysis on Mixed Traffic Flow at Unsignalized Intersection

2011 ◽  
Vol 201-203 ◽  
pp. 2119-2125
Author(s):  
Lu Wang ◽  
Neng Gang Xie ◽  
Rui Meng
Keyword(s):  
Traffic Flow ◽  
Behavior Pattern ◽  
Urban Traffic ◽  
Mixed Traffic ◽  
Security Risks ◽  
Game Analysis ◽  
Mixed Traffic Flow ◽  
Traffic Capacity ◽  
Traffic Conflicts ◽  
Behavior Characteristics

Mixed traffic flow is the basic characteristic of urban traffic. In pedestrian crosswalk without signals, there are a lot of traffic conflicts between pedestrians and vehicles crossing the intersection, which badly affects the traffic capacity and increases security risks. Through an analysis on the behavior pattern of pedestrians and vehicles crossing through the crosswalk, the paper first proposes a model based on dirty-face game to study the behavior characteristics of intersection traffic, which perfects analysis approaches to the traffic capacity of road crossing and the mixed traffic flow theory.

Application of Extreme Value Theory for Before-After Road Safety Analysis

2019 ◽  
Vol 2673 (4) ◽  
pp. 1001-1010 ◽  
Author(s):  
Lai Zheng ◽  
Tarek Sayed
Keyword(s):  
Extreme Value Theory ◽  
Safety Analysis ◽  
Value Theory ◽  
Extreme Value ◽  
Data Traffic ◽  
Crash Data ◽  
Safety Improvement ◽  
Traffic Conflicts ◽  
Traffic Conflict ◽  
Generalized Pareto Distributions

Because of well-recognized quality and quantity problems associated with historical crash data, traffic conflict techniques have been increasingly used in before-after safety analysis in recent years. This study proposes using an extreme value theory (EVT) approach to conduct traffic conflict-based before-after analysis. The capability of providing confident estimation of extreme events by the EVT approach drives the before-after analysis to shift from normal traffic conflicts to more serious conflicts, which are relatively rare but have more in common with actual crashes. The approach is applied to evaluate the safety effects of converting channelized right-turn lanes into smart channels, based on traffic conflicts defined by time to collision (TTC) and collected from three treatment intersections and one control intersection in the city of Penticton, British Columbia. Odds ratios and treatment effects are calculated from extreme-serious conflicts, the frequencies of which are estimated from the generalized Pareto distributions of traffic conflicts with TTC⩽0.5 s. The results show approximately 34% reduction in total extreme-serious conflicts (i.e., combining merging conflicts and rear-end conflicts), indicating overall a remarkable safety improvement following the smart channel treatment. This finding is consistent with the analysis result based on traffic conflicts with TTC⩽3.0 s. It is also found that the reduction in extreme-serious merging conflicts is small and insignificant. This is caused by the phenomenon that TTC values of merging conflicts become smaller after the treatment, and it is possibly because drivers become more aggressive with the better view of approaching cross-street traffic provided by the smart channel.

scholarly journals Road safety assessment in preferential bus lanes through field analysis and microsimulation of traffic conflicts

2019 ◽  
pp. 87-100 ◽  
Author(s):  
Julián Darío Julián Otero-Niño ◽  
Juan David Heredia-Castiblanco ◽  
Paula Daniela Fonseca-Agudelo ◽  
Sebastián Cabrera-Pinzón ◽  
Alejandro Gómez-Mosquera ◽  
...  
Keyword(s):  
Public Transport ◽  
Road Safety ◽  
Safety Assessment ◽  
Stopping Time ◽  
Field Analysis ◽  
Road Users ◽  
Traffic Conflicts ◽  
Traffic Conflict ◽  
Field Information ◽  
The One

Preferential bus lanes are a widely use strategy to promote travelers to use public transport instead of private cars. Considering its relevance in the urban transportation planning and operation, it is crucial to evaluate them in terms of the operation and safety externality. We performed a road safety assessment in preferential public transport lanes with complex driving environment using a preventive approach on the 7 th Avenue, in Bogota (Colombia), between 39 th Street and 45 th Street. A detailed study of traffic conflicts was carried out under the guidelines of the Swedish technique, which uses the Time to accident and Conflicting speed to establish the severity of a conflict. A traffic conflict is defined as an incident where, if two road users on collision course maintain their speed and trajectory constant, the crash between them will be imminent. With the field information, we calibrated a VISSIM microsimulation model that correctly replicates its traffic operation. Using the SSAM tool, we validated the base model to identify the simulated traffic conflicts in VISSIM and compared them with the observed conflicts. Under the calibrated environment, we developed and assessed three different scenarios of countermeasures to reduce the number of conflicts observed. As a result, we found that the safest scenario is the one established in the regulations that normalize the operation in preferential lanes, currently not obeyed by most users. Based on our results, we recommend an adjustment in the normative measures, including regulating the stopping time and stopping zones of private vehicles and taxis.

Novel Area Occupancy–Based Method for Passenger Car Unit Estimation on Multilane Urban Roads Under Heterogeneous Traffic Scenario

2017 ◽  
Vol 2615 (1) ◽  
pp. 82-94 ◽  
Author(s):  
Raunak Mishra ◽  
Pallav Kumar ◽  
Shriniwas S. Arkatkar ◽  
Ashoke Kumar Sarkar ◽  
Gaurang J. Joshi
Keyword(s):  
Traffic Flow ◽  
Performance Measure ◽  
Area Ratio ◽  
Heterogeneous Traffic ◽  
Passenger Car ◽  
Traffic Conditions ◽  
Passenger Car Unit ◽  
Wide Range ◽  
Traffic Volumes ◽  
Measure Of Performance

This research was aimed at developing an area occupancy–based method for estimating passenger car unit (PCU) values for vehicle categories under heterogeneous traffic conditions on multilane urban roads for a wide range of traffic flow levels. First, PCU values of vehicle categories were determined according to the Transport and Road Research Laboratory definition and replaced the commonly considered measure of performance speed with area occupancy using simulation. The PCU values obtained were found to be significantly different for different volume-to-capacity ratios; this result shows that the PCU value is dynamic in nature. While the dynamic nature of PCU values is well appreciated, practitioners may prefer a single set of optimized PCU values (unique for each vehicle category). Hence, a new method with a matrix solution was proposed to estimate the optimized or unique set of PCU values with area occupancy as the performance measure. To check the credibility of the proposed method, the estimated PCU values were compared from existing guidelines regulated by the Indian Roads Congress (IRC) and values estimated with the widely accepted dynamic PCU concept of speed–area ratio. Results show that the PCU values suggested by IRC and the dynamic PCU concept using the speed–area ratio underestimate and overestimate the flows, respectively, at different traffic volumes. However, the values obtained with the area-occupancy concept were found to be consistent with the traffic flow in a cars-only traffic situation at different flow conditions. The derived set of optimized PCU values proposed can be useful for traffic engineers, researchers, and practitioners for capacity and level-of-service analysis under heterogeneous traffic conditions.

scholarly journals Will higher traffic flow lead to more traffic conflicts? A crash surrogate metric based analysis

PLoS ONE ◽  
2017 ◽  
Vol 12 (8) ◽  
pp. e0182458 ◽  
Author(s):  
Yan Kuang ◽  
Xiaobo Qu ◽  
Yadan Yan
Keyword(s):  
Traffic Flow ◽  
Traffic Conflicts ◽  
Crash Surrogate

On Determination of Sample Size to Evaluate Reliability Growth Plans

2011 ◽  
Author(s):  
X. Jin ◽  
P. Woytowitz ◽  
T. Tan
Keyword(s):  
Sample Size ◽  
Confidence Level ◽  
Semiconductor Manufacturing ◽  
Field Performance ◽  
Reliability Growth ◽  
Confidence Levels ◽  
Equipment Reliability ◽  
Margin Of Error ◽  
Reliability Performance

The reliability performance of Semiconductor Manufacturing Equipments (SME) is very important for both equipment manufacturers and customers. However, the response variables are random in nature and can significantly change due to many factors. In order to track the equipment reliability performance with certain confidence, this paper proposes an efficient methodology to calculate the number of samples needed to measure the reliability performance of the SME tools. This paper presents a frequency-based Statistics methodology to calculate the number of sampled tools to evaluate the SME reliability field performance based on certain confidence levels and error margins. One example case has been investigated to demonstrate the method. We demonstrate that the multiple weeks accumulated average reliability metrics of multiple tools do not equal the average of the multiple weeks accumulated average reliability metrics of these tools. We show how the number of required sampled tools increases when the reliability performance is improved and quantify the larger number of sampled tools required when a tighter margin of error or higher confidence level is needed.

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