Critical gap acceptance at two-way stop controlled intersections

2021 ◽  
pp. 225-231
Author(s):  
B. Kent Lall ◽  
Kostaman Thayib ◽  
Michael Kyte
Keyword(s):  
Gap Acceptance ◽  
Critical Gap

scholarly journals Modeling and Predicting Stochastic Merging Behaviors at Freeway On-Ramp Bottlenecks

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Jian Sun ◽  
Kang Zuo ◽  
Shun Jiang ◽  
Zuduo Zheng
Keyword(s):  
Los Angeles ◽  
Great Influence ◽  
Data Sets ◽  
Gap Acceptance ◽  
Trajectory Data ◽  
Logistic Regression Models ◽  
Critical Gap ◽  
Merging Behavior ◽  
The Impact ◽  
Gap Acceptance Theory

Merging behavior is inevitable at on-ramp bottlenecks and is a significant factor in triggering traffic breakdown. In modeling merging behaviors, the gap acceptance theory is generally used. Gap acceptance theory holds that when a gap is larger than the critical gap, the vehicle will merge into the mainline. In this study, however, analyses not only focus on the accepted gaps, but also take the rejected gaps into account, and the impact on merging behavior with multi-rejected (more than once rejecting behavior) gaps was investigated; it shows that the multi-rejected gaps have a great influence on the estimation of critical gap and merging prediction. Two empirical trajectory data sets were collected and analyzed: one at Yan’an Expressway in Shanghai, China, and the other at Highway 101 in Los Angeles, USA. The study made three main contributions. First, it gives the quantitative measurement of the rejected gap which is also a detailed description of non-merging event and investigated the characteristics of the multi-rejected gaps; second, taking the multi-rejected gaps into consideration, it further expanded the concept of the “critical gap” which can be a statistic one and the distribution function of merging probability with respect to such gaps was analyzed by means of survival analysis. This way could make the full use of multi-rejected gaps and accepted gaps and reduce the sample bias, thus estimating the critical gap accurately; finally, considering multi-rejected gaps, it created logistic regression models to predict merging behavior. These models were tested using field data, and satisfactory performances were obtained.

Analysis and Evaluation of the Capacity of Roundabouts

1997 ◽  
Vol 1572 (1) ◽  
pp. 99-104 ◽  
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.

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

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.

Lane-changing gap acceptance model for freeway merging in simulation

2008 ◽  
Vol 35 (3) ◽  
pp. 301-311 ◽  
Author(s):  
Jin-Tae Kim ◽  
Joonhyon Kim ◽  
Myungsoon Chang
Keyword(s):  
Field Data ◽  
Gap Acceptance ◽  
Microscopic Simulation ◽  
Lane Changing ◽  
Lane Changes ◽  
Critical Gap ◽  
Proposed Model ◽  
Simulation Based ◽  
Single Vehicle ◽  
Acceptance Model

Existing techniques for microscopic simulation of lane changes utilize a single critical gap for a single vehicle. Freeway merging areas have been among the most difficult aspects of simulations due to the wide variety of merging behaviors in these areas. This paper proposes a gap acceptance model developed to update the size of the critical trailing gap for a merging vehicle during simulation based on the location of the vehicle in an acceleration lane. It also considers the relative speed and critical leading gap. Sets of critical trailing gap values for various situations are computed. The outputs from the microscopic simulations utilizing the proposed model were compared with field data, producing strong statistical evidence that the simulation results and field data were significantly comparable.

scholarly journals Capacity Prediction Model Based on Limited Priority Gap-Acceptance Theory at Multilane Roundabouts

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Zhaowei Qu ◽  
Yuzhou Duan ◽  
Xianmin Song ◽  
Hongyu Hu ◽  
Huanfeng Liu ◽  
...  
Keyword(s):  
Likelihood Estimation ◽  
Gap Acceptance ◽  
Modified Model ◽  
Field Surveys ◽  
Critical Gap ◽  
Proposed Model ◽  
Acceptance Model ◽  
The Relationship ◽  
Gap Acceptance Theory ◽  
Important Design

Capacity is an important design parameter for roundabouts, and it is the premise of computing their delay and queue. Roundabout capacity has been studied for decades, and empirical regression model and gap-acceptance model are the two main methods to predict it. Based on gap-acceptance theory, by considering the effect of limited priority, especially the relationship between limited priority factor and critical gap, a modified model was built to predict the roundabout capacity. We then compare the results between Raff’s method and maximum likelihood estimation (MLE) method, and the MLE method was used to predict the critical gaps. Finally, the predicted capacities from different models were compared, with the observed capacity by field surveys, which verifies the performance of the proposed model.

Evaluation of Intersection Conflict Warning System: A Critical Gap Analysis

2018 ◽  
Vol 2672 (21) ◽  
pp. 1-9 ◽  
Author(s):  
Raju Thapa ◽  
Shauna Hallmark ◽  
Neal Hawkins ◽  
Skylar Knickerbocker
Keyword(s):  
Rural Areas ◽  
Gap Analysis ◽  
Spillover Effect ◽  
Warning System ◽  
Video Camera ◽  
Gap Acceptance ◽  
Critical Gap ◽  
Intersection Safety ◽  
Fatal Crashes ◽  
Time Frames

Rural intersections account for around 30% of crashes in rural areas and 6% of all fatal crashes. An Intersection Conflict Warning System (ICWS) is a unique solution to address rural intersection safety. ICWS are typically installed at the minor approaches to two-way stop-controlled intersections to reduce the number of fatalities. Studies indicate these systems result in lower intersection approach speeds, reduced conflicts, and improved driver-gap selection. However, some sites have experienced increases in the number of minor crashes. Although there are positive ICWS examples, their overall effectiveness is not well established. The objective of this research was to evaluate driving behavior at stop-controlled approaches with and without ICWS and to evaluate the spillover effect of ICWS on other adjacent control intersections where the treatment has not been applied. The study examined behavior at five intersections (treatment sites) in Minnesota where an ICWS was installed. For comparison, an additional five similar (control sites) were identified in proximity to each treatment intersection. Data were collected using a video camera array at three different time frames: before, one month, and 12 months after the installation of system. The data were analyzed using a critical gap approach. The analysis shows that the ICWS improved driver gap acceptance at the treatment sites, only at the 12-month period, and that there was no “spillover effect” at the adjacent control sites. When gap acceptance was further compared by type of stop, critical gap selection was shown to increase for drivers making both complete and rolling stops.

scholarly journals Review of Roundabout Capacity Based on Gap Acceptance

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Ruijun Guo ◽  
Leilei Liu ◽  
Wanxiang Wang
Keyword(s):  
Queuing Theory ◽  
Field Capacity ◽  
Calculation Model ◽  
Gap Acceptance ◽  
Critical Gap ◽  
Stochastic Function ◽  
Headway Distribution ◽  
Calculation Results ◽  
Time Gap ◽  
A Minor

Circulating vehicles have priority at modern roundabouts. Entrance vehicles can enter the roundabout when there is a time gap larger than the critical gap; otherwise, the vehicles need to wait until there is a large enough gap. The gap acceptance theory was used to analyze the entrance capacity of roundabouts, which can be derived by queuing theory involving two vehicle streams. The paper introduces the main styles of headway distribution, which are named as bunched exponential distribution or M3 distribution. The calculation model of free stream ratio is also introduced. The entrance capacity models can be classified by different entrance vehicle types, which are piecewise function or linear function, or by different critical gap types, which are constant or stochastic function. For each form, the typical capacity expressions are given. The calculation values show a very small difference between these kinds of models. The capacity value based on the critical gap of stochastic function is more realistic and more complex in function style. Some conclusions were derived that drivers’ nonhomogeneous and inconsistent character is more realistic than the fixed critical gap and following gap. The calculation results of capacity are similar to the field capacity under the assumption of homogeneity and continuance, with only a minor percent deviation. Finally, the paper points out additional problems and the suggested research in capacity of roundabouts.

COMPARISON OF DIFFERENT CAPACITY MODELS FOR TRAFFIC CIRCLES

Transport ◽  
2009 ◽  
Vol 24 (4) ◽  
pp. 257-264 ◽  
Author(s):  
Pelin Çalışkanelli ◽  
Mustafa Özuysal ◽  
Serhan Tanyel ◽  
Nadir Yayla
Keyword(s):  
Regression Analysis ◽  
Field Method ◽  
Capacity Analysis ◽  
Gap Acceptance ◽  
Critical Gap ◽  
Analysis Methods ◽  
The World ◽  
Basic Goal

Traffic circles have been used in many countries all over the world. Traffic circles can be defined as intersections where traffic circulates around a center island where priority is given to the vehicles entering from branches and are designed considering weaving movements as the basic goal. There are two most common capacity analysis methods for traffic circles: the method of critical gap acceptance and the method of regression analysis. This study explains the methods of gap acceptance and regression analysis. Ashworth and Field method is investigated and the applicability of these capacity models in Turkey is discussed. The obtained results have shown that both methodologies give satisfactory results; however, the existing methods should be improved (modified) considering conditions.

scholarly journals Evaluation of Multi-legged Roundabout Using Surveyed Critical Gap Acceptance

2013 ◽  
Vol 13 (9) ◽  
pp. 400-409 ◽  
Author(s):  
Soon-Yong Park ◽  
Dong-Nyong Kim ◽  
Jun-Hwa Jeong
Keyword(s):  
Gap Acceptance ◽  
Critical Gap

scholarly journals A method for estimating pedestrian critical gap using microsimulation

TRANSPORTES ◽  
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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