Dynamic Modeling of VISSIM's Critical Gap Parameter at Unsignalized Intersections

Francesco Viti; Bart Wolput; Chris M. J. Tampère; Pieter Vandervelden

doi:10.3141/2395-02

Defining and Analyzing Forceful Gap Behavior at Unsignalized Intersections

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198120925258 ◽

2020 ◽

Vol 2674 (8) ◽

pp. 420-428

Author(s):

Mukti Advani ◽

Neelam J. Gupta ◽

S. Velmurugan ◽

Erramppalli Madhu ◽

Satish Chandra

Keyword(s):

Threshold Value ◽

Base Case ◽

Major Road ◽

Speed Reduction ◽

Critical Gap ◽

Traffic Conditions ◽

Unsignalized Intersections ◽

Definition Of ◽

Gap Creation ◽

Made In

Under mixed-mode traffic conditions prevailing on Indian roads at unsignalized intersections, it is commonly observed that vehicles entering from minor streets indulge in forceful gap creation/delay for the vehicles moving on the major road. Although this driving behavior has been reported in some of the published studies for Indian traffic conditions, a clear definition of such forceful entries is not available. An attempt has been made in this study to define this forceful entry phenomenon on the basis of changes in the speed of major streets’ vehicles approaching the intersection on a typical case of mixed-traffic environs. In this regard, field observations were recorded through videography to obtain the speed reduction threshold value for categorizing an entry as a forceful entry. To quantify the above, data in relation to various vehicle types approaching intersections and their associated speeds at the reference area were extracted at the approach arms of the intersection. On the basis of observations, collected data were divided into three scenarios: ( 1 ) vehicles on major roads reduce their speed when vehicles are absent on minor roads; ( 2 ) vehicles on major roads reduce their speed when vehicles are waiting on minor roads; and ( 3 ) vehicles on major roads reduce their speed when vehicles from minor roads have accepted the gap/lag for movement. The changes in speed in all the three scenarios were compared to identify forceful entries with the base case of normal traffic flow on the major road without the existence of forceful entry phenomenon. The study revealed that the speed reduction to the extent of 73% is considered as a forceful entry at the selected location. Furthermore, the study estimated the effect of forceful behavior on critical gap at unsignalized intersections.

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Analysis and Evaluation of the Capacity of Roundabouts

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/1572-12 ◽

1997 ◽

Vol 1572 (1) ◽

pp. 99-104 ◽

Cited By ~ 14

Author(s):

Abishai Polus ◽

Sitvanit Shmueli

Keyword(s):

The United States ◽

Gap Acceptance ◽

Highway Capacity ◽

Left Turn ◽

Highway Capacity Manual ◽

Explanatory Variables ◽

Geometric Characteristics ◽

Critical Gap ◽

Unsignalized Intersections ◽

German Model

Roundabouts are replacing conventional unsignalized intersections in many parts of the world and could become more widespread in the United States, although there are some limitations as well as clear advantages. Models for entry capacity into the rotary were developed. Entry capacity depends on the geometric characteristics of the roundabout, particularly the diameter of the outside circle of the intersection. The geometric characteristics determine the speed of vehicles around the central island and, therefore, have an impact on the gap-acceptance process and consequently the capacity. Traffic conditions that impede entry capacity involve the flow around the roundabout. Flow and geometric data from six small to medium-sized roundabouts were analyzed. Individual and aggregated entry-capacity models were calibrated by using the diameter and circulating flows as explanatory variables. Very good fits to the data were obtained; the results also fit models developed in other countries. The Australian model resulted in slightly higher entry capacities for moderate to low circulating flows and lower entry capacities for high circulating flows. Very close proximity to the German model was obtained, although it does not depend on the geometric characteristics of the circle. The roundabout provides an advantage over a conventional unsignalized intersection. A faithful concurrence between the model developed and the latest Highway Capacity Manual model for right-turn capacity at an unsignalized intersection is obtained if the circulating flow is replaced by the conflicting flow. The advantage of entry capacities of the roundabout over the calculated capacities of the Highway Capacity Manual left-turn model is shown. Further research is proposed to study the effect on entry capacity of two circulating lanes rather than one and the effect of the increase in circulating flows on the gap-acceptance process, particularly the reduction in critical gap at high flows.

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Critical Gaps at Unsignalized Intersections with Bending Right-of-Way

Communications - Scientific letters of the University of Zilina ◽

10.26552/com.c.2018.4.69-75 ◽

2018 ◽

Vol 20 (4) ◽

pp. 69-75

Author(s):

Andrea Kocianova ◽

Eva Pitlova

Keyword(s):

Calculation Procedure ◽

Gap Acceptance ◽

Driver Behaviour ◽

Critical Gap ◽

Right Of Way ◽

Unsignalized Intersections ◽

Capacity Calculation ◽

Rank 2 ◽

Gap Acceptance Theory ◽

Traffic Rules

The capacity calculation procedure for unsignalized intersections is based on the gap-acceptance theory in most of existing capacity regulations and it relies on one of the important parameters - critical gap. However, the capacity calculation procedure and values of critical gaps according to these regulations are valid only for intersections with standard right-of-way (major street leading straight). Nevertheless, in Slovakia, intersections with bending right-of-way (major street not leading straight, but bending) can be encountered. The specific mode of right-of-way results in different priority ranks of traffic movements (set by traffic rules of driving), more complicated traffic situation and therefore, different driver behaviour characteristics. To examine the gap acceptance behaviour of drivers under these specific conditions, an unsignalized four-leg intersection with bending right-of-way located in an urban area of Zilina, Slovakia, was selected. Three different methods (Raff, Wu, and MLM Troutbeck) were used for critical gap estimation from the field data. In the article, results of critical gaps for three through movements of different priority rank (major-street through movement of Rank 2 and minor-street through movements of Rank 3 and 4) are presented. The results show, that the values of critical gaps differ depending on the method by about 3-5 % only, which is not significant. Troutbeck ´s MLM method gives the highest values. The priority rank of movement has the greatest impact on the result. The values of critical gap for major-street through movement of Rank 2 are the smallest; they are approximately 1.3-2.1 s smaller than the values for minor-street through movements of Rank 3 or 4. The highest values of critical gap have been estimated for minor-street through movement of Rank 4 and they are higher compared to the current Slovak regulations TP 102 values for the same priority rank.

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Estimation of Critical Gap Based on Raff’s Definition

Computational Intelligence and Neuroscience ◽

10.1155/2014/236072 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7 ◽

Cited By ~ 7

Author(s):

Rui-jun Guo ◽

Xiao-jing Wang ◽

Wan-xiang Wang

Keyword(s):

Accurate Result ◽

Traffic Flows ◽

Application Field ◽

Critical Gap ◽

Unsignalized Intersections ◽

Minor Road ◽

New Models ◽

Definition Of ◽

Gap Acceptance Theory ◽

Calculation Models

Critical gap is an important parameter used to calculate the capacity and delay of minor road in gap acceptance theory of unsignalized intersections. At an unsignalized intersection with two one-way traffic flows, it is assumed that two events are independent between vehicles’ arrival of major stream and vehicles’ arrival of minor stream. The headways of major stream follow M3 distribution. Based on Raff’s definition of critical gap, two calculation models are derived, which are named M3 definition model and revised Raff’s model. Both models use total rejected coefficient. Different calculation models are compared by simulation and new models are found to be valid. The conclusion reveals that M3 definition model is simple and valid. Revised Raff’s model strictly obeys the definition of Raff’s critical gap and its application field is more extensive than Raff’s model. It can get a more accurate result than the former Raff’s model. The M3 definition model and revised Raff’s model can derive accordant result.

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A method for estimating pedestrian critical gap using microsimulation

TRANSPORTES ◽

10.14295/transportes.v29i1.2240 ◽

2021 ◽

Vol 29 (1) ◽

pp. 132-147

Author(s):

Talyson Pereira Pereira Bandeira ◽

Lisel Expósito Martín ◽

Manoel Mendonça de Castro Neto

Keyword(s):

Level Of Service ◽

Gap Acceptance ◽

Calibration Target ◽

Critical Gap ◽

Local Characteristics ◽

Pedestrian Level Of Service ◽

Gap Parameter

Estimating critical gap is crucial for modelling pedestrian level of service at crossings. Critical gap modelling becomes more challenging in signalized crossings because the proportion of pedestrians seeking gaps during red is usually unknown. Besides, the willingness – or lack of it – to cross during red signal indication varies by pedestrian and local characteristics, which makes gap acceptance modelling even more challenging. The main objective of this study is to propose a method for estimating pedestrian critical gap at signalized crossings using Vissim. The method considers that all pedestrians seek for gaps on red, and the critical gap parameter is calibrated for each pedestrian type having delay as calibration target. The results showed MAPE values of 2% and 9% for the two studied crossings. This method was compared to three existing methods of critical gap estimation. The results showed that the proposed method yielded the best estimations of delay, followed by the HCM’s.

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Safety time in critical gap of left turn manoeuvre from priority approach at TWSC unsignalized intersections

Physica A Statistical Mechanics and its Applications ◽

10.1016/j.physa.2018.04.043 ◽

2018 ◽

Vol 505 ◽

pp. 1196-1211 ◽

Cited By ~ 2

Author(s):

Ilija Tanackov ◽

Nemanja Deretić ◽

Vuk Bogdanović ◽

Nenad Ruškić ◽

Srđan Jović

Keyword(s):

Left Turn ◽

Critical Gap ◽

Unsignalized Intersections

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Analysis on Capacity of Unsignalized Intersection on Urban Arterial Road in Slight Snowy Weather

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.209-211.833 ◽

2012 ◽

Vol 209-211 ◽

pp. 833-836

Author(s):

Liang Xu ◽

Guo Zhu Cheng

Keyword(s):

Critical Gap ◽

Unsignalized Intersections ◽

Arterial Road ◽

Sunny Weather ◽

Operation Status ◽

Traffic Operation ◽

Urban Arterial

In order to evaluate traffic operation status of unsignalized intersection on arterial road in slight snowy weather, it was studied that the influence of slight snow on capacity of unsignalized intersection. Critical gap and following headway data of one unsignalized intersections were observed by video method. And gap accepting theory was adopted to calculate the capacity of unsignalized intersection. An example was given for calculating the capacity of an unsiglized intersection on normal pavement and slight snowy pavement. It showed that capacity of unsignalized intersection in slight snowy weather decreased by 11.26% compared with on sunny weather.

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