scholarly journals Analysis of a Signalized Intersection with Dynamic Use of the Left-Turn Lane for Opposite through Traffic

2020 ◽  
Vol 12 (18) ◽  
pp. 7530
Author(s):  
Yongtao Zheng ◽  
Xuedong Hua ◽  
Wei Wang ◽  
Jialiang Xiao ◽  
Dongya Li
Keyword(s):  
Simulation Model ◽  
Queue Length ◽  
Field Data ◽  
Signalized Intersections ◽  
Signalized Intersection ◽  
Simulation Environment ◽  
Average Delay ◽  
Left Turn ◽  
Environment Parameters ◽  
Simulation Scheme

For signalized intersections with a quantitative imbalance between the approach and exit lanes, this study proposes a method for the dynamic use of the left-turn lane for opposite through traffic to improve the efficiency of the signalized intersection. The complete scheme of this method mainly consists of three parts: the location routes of the dynamic lane, the temporal scheme, and the spatial scheme. To demonstrate the effectiveness of this method, a simulation scheme comparing the intersection with and without the dynamic lane is designed using VISSIM. The parameters of the simulation model, including the traffic simulation environment parameters and built-in VISSIM models, are calibrated by the field data collected from an intersection in Nanjing, P. R. China. The results of the simulation indicate that this method decreases the average delay and average queue length of the intersection effectively for the intersection with a quantitative imbalance between the approach and exit lanes under the conditions of different through volumes or left-turn ratios. The maxima were 46.9% (average delay) and 68.3% (average queue length) for all situations. Lastly, some suggestions are presented for the application of this method.

scholarly journals Car-following Behavior Analysis of Left-turn Vehicles at Signalized Intersections

2020 ◽  
Vol 6 (1) ◽  
pp. 186-193 ◽  
Author(s):  
Fulu Wei ◽  
Long Chen ◽  
Yongqing Guo ◽  
Mingtao Chen ◽  
Jiaxiang Ma
Keyword(s):  
Field Data ◽  
Signalized Intersections ◽  
Signalized Intersection ◽  
Velocity Difference ◽  
Left Turn ◽  
Average Speed ◽  
Car Following ◽  
Turning Radius ◽  
The Stability ◽  
Stability And Accuracy

In order to enrich the car-following theory of urban signalized intersections, and reveal the car-following characteristics of left turn at signalized intersections, the car-following behavior of left turn at signalized intersections is studied. The car-following data acquisition test which was based on high precision GPS was designed. And the car-following characteristics of left-turning vehicles at signalized intersections with different turning radii were analyzed. Based on which, the influence of radius on the car-following behavior was explained, and the New Full Velocity Difference (NFVD) model was developed. The genetic algorithm was used to calibrate the parameters of the NFVD model. The stability and accuracy of the calibrated model was further analyzed by using field data. The results showed that the average speed of the following car increases with the turning radius of the signalized intersection; the car-following speed which the highest frequency occurs under different turning radii tends to increase with the enlargement of turning radius; the larger the average headway distance between the car-following vehicles, the more intense of the driver’s response to the deceleration of the front vehicle. These findings could be used in traffic simulation and to make engineering decisions.

A Capacity Estimation Model for a Contraflow Left-Turn Pocket Lane at Signalized Intersections

2018 ◽  
Vol 2672 (17) ◽  
pp. 22-34 ◽  
Author(s):  
Yi Zhao ◽  
Rachel M. James ◽  
Lin Xiao ◽  
Joe Bared
Keyword(s):  
Signalized Intersections ◽  
Signalized Intersection ◽  
Traffic Operations ◽  
Estimation Model ◽  
Capacity Estimation ◽  
Average Delay ◽  
Left Turn ◽  
Traffic Demand ◽  
Key Characteristics ◽  
The Impact

Alternative intersection designs are increasingly proposed and adopted by different agencies to meet the needs of growing traffic demand and constrained transportation resources. The left turn (LT) is one of the most critical movements at signalized intersections from both a safety and operations perspective. Heavy LT volumes are especially impactful to the operational efficiency of a signalized intersection and often result in queue spillback. A contraflow left-turn pocket lane (CLPL) is proposed to mitigate congestion caused by heavy LT demand and has been shown in simulation to greatly mitigate the impact of queue spillback. The CLPL dynamically uses the opposing through lane (OTL) as an additional LT lane within the signal cycle on a temporary basis when the OTL is not occupied by through traffic. While geometric design schematics and analytical procedures for estimating delay have been proposed and discussed in existing literature, methodologies for estimating capacity benefits and traffic operations are not yet well defined. This paper has three primary contributions to the literature: development of a probabilistic capacity estimation model, exploration of the impact of key characteristics (e.g., cycle length, LT demand, lane selection preference) on estimated intersection capacity, and recommendations for the real-world implementation of a CLPL. The simulation results indicate that the CLPL treatment can increase a signalized intersection’s throughput up to 25% and decrease the intersection’s average delay by 35%.

Modeling Capacity of Through Movement at Signalized Intersection Affected by Short Left-Turn Bay under Different Signal Settings

2021 ◽  
pp. 036119812110064
Author(s):  
Zihang Wei ◽  
Yunlong Zhang ◽  
Xiaoyu Guo ◽  
Xin Zhang
Keyword(s):  
Cycle Length ◽  
Signalized Intersections ◽  
Signalized Intersection ◽  
Essential Factor ◽  
Highway Capacity ◽  
Left Turn ◽  
Highway Capacity Manual ◽  
Proposed Model ◽  
Vehicle Demand ◽  
The One

Through movement capacity is an essential factor used to reflect intersection performance, especially for signalized intersections, where a large proportion of vehicle demand is making through movements. Generally, left-turn spillback is considered a key contributor to affect through movement capacity, and blockage to the left-turn bay is known to decrease left-turn capacity. Previous studies have focused primarily on estimating the through movement capacity under a lagging protected only left-turn (lagging POLT) signal setting, as a left-turn spillback is more likely to happen under such a condition. However, previous studies contained assumptions (e.g., omit spillback), or were dedicated to one specific signal setting. Therefore, in this study, through movement capacity models based on probabilistic modeling of spillback and blockage scenarios are established under four different signal settings (i.e., leading protected only left-turn [leading POLT], lagging left-turn, protected plus permitted left-turn, and permitted plus protected left-turn). Through microscopic simulations, the proposed models are validated, and compared with existing capacity models and the one in the Highway Capacity Manual (HCM). The results of the comparisons demonstrate that the proposed models achieved significant advantages over all the other models and obtained high accuracies in all signal settings. Each proposed model for a given signal setting maintains consistent accuracy across various left-turn bay lengths. The proposed models of this study have the potential to serve as useful tools, for practicing transportation engineers, when determining the appropriate length of a left-turn bay with the consideration of spillback and blockage, and the adequate cycle length with a given bay length.

Estimating Queue Length for Contraflow Left-Turn Lane Design at Signalized Intersections

2019 ◽  
Vol 145 (6) ◽  
pp. 04019020 ◽  
Author(s):  
Pan Liu ◽  
Jiaming Wu ◽  
Huaguo Zhou ◽  
Jie Bao ◽  
Zhao Yang
Keyword(s):  
Queue Length ◽  
Signalized Intersections ◽  
Left Turn

NETSIM-Based Approach to Evaluation of Bus Preemption Strategies

1996 ◽  
Vol 1554 (1) ◽  
pp. 80-89 ◽  
Author(s):  
Snehamay Khasnabis ◽  
Rajashekar R. Karnati ◽  
Rama K. Rudraraju
Keyword(s):  
Simulation Model ◽  
Field Data ◽  
Signalized Intersections ◽  
Preferential Treatment ◽  
Street Network ◽  
Experimental Site ◽  
Arrival Times ◽  
Ann Arbor ◽  
The Cross ◽  
Measures Of Effectiveness

Preemption techniques are designed to provide preferential treatment to buses at signalized intersections. Uncertainties resulting from variations in passenger boardings and unboardings at bus stops make the prediction of the exact arrival times of buses at intersections extremely difficult. A preemption strategy, if properly designed, can provide continuous green phases to buses at successive intersections. It is unfortunate that a validated technique that can be used to assess the possible consequences of signal preemption is not available. The authors present the application of a simulation model, NETSIM, to make such an assessment. NETSIM was selected because of its ability to microscopically simulate vehicular movements on a street network and its ability to track an individual vehicle from the source to the sink by the use of an animation feature. A major bus route in Ann Arbor, Michigan, was used as the experimental site. The major conclusions are that NETSIM, when properly validated, can generate delay and queue-related measures of effectiveness that are compatible with field data and that the animation feature of NETSIM can be used to assess the operational consequences of bus preemption on a series of intersections on a bus route. For the volume levels studied in the project, savings in delay along the bus route resulting from preemption exceed the increases in delay along the cross street. Further research is needed to determine whether the net savings in delay, when balanced against the costs of installing and maintaining the system and the inconvenience to motorists along the cross street, make the system worthwhile.

Safety Performance Functions for Signalized Intersections in Large Urban Areas

2005 ◽  
Vol 1908 (1) ◽  
pp. 165-171 ◽  
Author(s):  
Craig Lyon ◽  
Anwar Haq ◽  
Bhagwant Persaud ◽  
Steven T. Kodama
Keyword(s):  
Urban Areas ◽  
Empirical Bayes ◽  
Signalized Intersections ◽  
Safety Performance ◽  
Signalized Intersection ◽  
Left Turn ◽  
Side Impacts ◽  
Recent Interest ◽  
Safety Performance Functions ◽  
Network Screening

This paper describes the development of safety performance functions (SPFs) for 1,950 urban signalized intersections on the basis of 5 years of collision data in Toronto, Ontario, Canada. Because Toronto has one of the largest known, readily accessible, urban signalized intersection databases, it was possible to develop reliable, widely applicable SPFs for different intersection classifications, collision severities, and impact types. Such a comprehensive set of SPFs is not available for urban signalized intersections from data for a single jurisdiction, despite the considerable recent interest in use of these functions for analyses related to network screening, and the development, prioritization, and evaluation of treatments. The application of a straightforward recalibration process requiring relatively little data means that the SPFs calibrated can be used by researchers and practitioners for other jurisdictions for which these functions do not exist and are unlikely to exist for some time. The value of the functions is illustrated in an application to evaluate a topical safety measure—left-turn priority treatment for which existing knowledge is on a shaky foundation. The results of this empirical Bayes evaluation show that this treatment is quite effective for reducing collisions, particularly those involving left-turn side impacts.

scholarly journals Estimating saturation flow under weak discipline traffic conditions, case study: Iran

2018 ◽  
Vol 46 (2) ◽  
pp. 47-60 ◽  
Author(s):  
Maryam Dehghani-Zadeh ◽  
Mehdi Fallah Tafti
Keyword(s):  
Flow Rate ◽  
Field Data ◽  
Signalized Intersections ◽  
Optimal Timing ◽  
Effective Parameters ◽  
Highway Capacity ◽  
Left Turn ◽  
Saturation Flow Rate ◽  
Saturation Flow

Intersections, as the critical elements and the major bottleneck points of urban street networks, may have inconsistent performances in different countries. This is largely due to the fact that the factors affecting their performance e.g. driving behavior, vehicle characteristics, control methods, and environmental conditions may vary from one country to another. It is, therefore required to take into account these factors when developing or applying available models and methodologies for their capacity analysis or signal control setting. This is particularly important for the countries with heterogeneous and weak discipline traffic streams such as Iran. Meanwhile, estimating the saturation flow rate, which is a key parameter in capacity and delay analysis and in optimal timing of traffic signals, is of great importance. In this study, the possibility of identifying and or developing appropriate models for estimating the saturation flow rate at the signalized intersections in these situations has been explored. For this purpose, a case study performed at the signalized intersections located in the city of Yazd, a medium sized city located in the middle of Iran. Using the data obtained from several intersections together with the application of analytical procedures proposed by American, Australian, Canadian, Indonesian, Iranian and Malaysian highway capacity guides, the saturation flow rate was estimated from both field observations and analytical methods. A comparison of these results indicated that in the protected left-turn situations, the Australian guide produced the best comparable results with the field data. On the other hand, in the permitted left-turn situations, the method proposed in the American Highway Capacity Manual guide produced the best comparable results with the field data. Furthermore, three new models were developed for estimating the saturation flow rate in three different situations namely, unopposed mixed straight and turning traffic movements, opposed mixed straight and turning traffic movements and merely straight through movement. The effective width, traffic composition, and opposite oncoming through traffic flow were considered as the effective parameters in the proposed models. Moreover, using the multivariate regression analysis, the Passenger Car Equivalent coefficients for motorcycles and heavy vehicles were calculated as 0.51 and 2.09, respectively.

Effects of U-Turns on Capacities of Signalized Intersections

2005 ◽  
Vol 1920 (1) ◽  
pp. 74-80 ◽  
Author(s):  
Pan Liu ◽  
Jian John Lu ◽  
Jingjing Fan ◽  
Juan C. Pernia ◽  
Gary Sokolow
Keyword(s):  
Regression Model ◽  
Signalized Intersections ◽  
Signalized Intersection ◽  
Left Turn ◽  
Highway Capacity Manual ◽  
Bay Area ◽  
Study Team ◽  
Adjustment Factors ◽  
Left Turns ◽  
Saturation Flow

In Florida, the increased use of restrictive medians and directional median openings has generated many U-turns at signalized intersections. There is no widely accepted procedure for estimating the effects of U-turning vehicles on signalized intersection capacity. In the 2000 edition of the Highway Capacity Manual, U-turns are treated as left turns for estimation of saturation flow rates. However, the operational effects of U-turns and left turns are different. This study analyzed the effects of U-turning vehicles on the left-turn saturation flow rate. Data were collected at three signalized intersections in the Tampa Bay area in Florida. In total, the study team recorded the queue discharge times for 260 queues, including 571 U-turning vehicles and 1,441 left-turning vehicles. On the basis of the data collected in the field, a regression model was developed to estimate the relationship between the average queue discharge time for each turning vehicle and the various percentages of U-turning vehicles in the left-turn traffic stream. Adjustment factors for various percentages of U-turning vehicles were also developed by using the regression model. The adjustment factors developed in this study can be directly used to estimate the capacity reduction due to the presence of various percentages of U-turning vehicles at a signalized intersection.

Poisson Log-Linear Regression Model for Rural Signalized Intersection

2012 ◽  
Vol 594-597 ◽  
pp. 1391-1394
Author(s):  
Zhi Ping Ren
Keyword(s):  
Linear Regression ◽  
Regression Model ◽  
Traffic Safety ◽  
Linear Regression Model ◽  
Signalized Intersections ◽  
Signalized Intersection ◽  
Left Turn ◽  
Traffic Volumes ◽  
Input Variables ◽  
Log Linear

Safety performance of rural signalized intersections is critical for identifying high-risk sites and predicting the hazardousness. This paper aims to develop a predictive model that will describe the safety of rural signalized intersections based on various input variables. Data are examined from 124 rural signalized intersections over three states, and Poisson log-linear regression model is presented, which connected traffic number and the average traffic volumes, geometric characteristics and signalization characteristics variables together. The model and associated data analysis reveal that average daily traffic, media width, speed limit, degree of horizontal curvature and left-turn lane are the factors that have greatest overall effect on safety. The results show that the Poisson log-linear regression model is able to describe the rural signalized intersection safety accurately. Using this model, effective countermeasures can be applied for improving traffic safety.

Sign in / Sign up

Export Citation Format

Share Document