scholarly journals SETTINGS OF SHORT LEFT-TURN LANE AND SIGNAL PHASE SEQUENCE FOR ISOLATED SIGNALIZED INTERSECTIONS

Transport ◽  
2014 ◽  
Vol 31 (4) ◽  
pp. 416-426 ◽  
Author(s):  
Ronghan Yao
Keyword(s):  
Signalized Intersections ◽  
Level Of Service ◽  
Signal Phase ◽  
Left Turn ◽  
Practical Applications ◽  
Study Approach ◽  
Phase Sequence ◽  
Proposed Model ◽  
Group A ◽  
Common Signal

At signalized intersections, short left-turn lanes are often installed to improve capacity and level of service. However, the blockage or overflow of short left-turn lane often occurs when signal phasing is not coordinated with lane configuration and traffic demands. On the basis of probability theory, the probability of no blockage and overflow of the short left-turn lane is formulated under the three common signal phase plans when the lane next to a short leftturn lane is a through lane. For this case, it is shown that the left-through phasing should be adopted for the study approach when the short left-turn lane is very short and the volume of left-turn vehicles is high enough, and the leading or lagging left-turn phasing should be adopted for the study approach when the short left-turn lane is long enough and the volume of left-turn vehicles is low enough. To optimally allocate the space for each short left-turn lane and the green time for each lane group, a new optimization model is put forward to maximize intersection capacity and guarantee an acceptable level of service for each movement for isolated signalized intersections with short left-turn lanes. The usage of this model is demonstrated by an illustrative example. The results indicate that the intersection capacity can be maximized under the same level of service by integrating the configuration of traffic lanes and the split of signal phases. Finally, the procedure for using the proposed model is given for practical applications.

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.

scholarly journals Impact of Guideline Markings on Saturation Flow Rate at Signalized Intersections

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Zhengtao Qin ◽  
Jing Zhao ◽  
Shidong Liang ◽  
Jiao Yao
Keyword(s):  
Flow Rate ◽  
Signalized Intersections ◽  
Estimation Model ◽  
Left Turn ◽  
Proposed Model ◽  
Research Goal ◽  
Saturation Flow Rate ◽  
Saturation Flow ◽  
The Impact

Many intersections around the world are irregular crossings where the approach and exit lanes are offset or the two roads cross at oblique angles. These irregular intersections often confuse drivers and greatly affect operational efficiency. Although guideline markings are recommended in many design manuals and codes on traffic signs and markings to address these problems, the effectiveness and application conditions are ambiguous. The research goal was to analyze the impact of guideline markings on the saturation flow rate at signalized intersections. An adjustment estimation model was established based on field data collected at 33 intersections in Shanghai, China. The proposed model was validated using a before–after case study. The underlying reasons for the impact of intersection guideline markings on the saturation flow rate are discussed. The results reveal that the improvement in the saturation flow rate obtained from painting guide line markings is positively correlated with the number of traffic lanes, offset of through movement, and turning angle of left-turns. On average, improvements of 7.0% and 10.3% can be obtained for through and left-turn movements, respectively.

scholarly journals A Method for Determining the Capacity of an Exclusive Left Lane with a Permitted Phase under Nonstrict Priority

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Qiao-wen Bai ◽  
Zhao-wei Qu ◽  
Xian-min Song ◽  
Shuai Xiong ◽  
Ning-bo Cao
Keyword(s):  
Field Survey ◽  
Left Turn ◽  
Proposed Model ◽  
Group A ◽  
Two Stages ◽  
Intersection Geometry ◽  
Releasing Process ◽  
Strict Priority ◽  
Left Lane ◽  
Observation Results

A new method has been developed for estimating the capacity of an exclusive left lane with a permitted phase under nonstrict priority. Different from maneuvers under strict priority, these left-turning vehicles were released in the form of a left-turn group. A field survey was first conducted to explore the maximum number of vehicles in a left-turn group, and the releasing process of the permitted left turns. The observations revealed that (1) the maximum number is related to the intersection geometry and (2) the releasing process includes two stages: the first left-turn group crossing at the beginning of a permitted phase and the following left-turn groups crossing using gaps provided by opposing right turns. Next, a method based on probability theory and these observation results were applied to estimate the capacity of an exclusive left lane. The procedure contains two stages and eight steps. Finally, the estimation of the left-turn capacity using the proposed model was validated by comparing the capacity from the strict priority and actual maximum volumes.

scholarly journals Capacity Matching Based Model for Protected Left Turn Phases Design of Adjacent Signalized Intersections Along Arterial Roads

2015 ◽  
Vol 27 (1) ◽  
pp. 13-21
Author(s):  
Wei Wu ◽  
Wanjing Ma ◽  
Kejun Long
Keyword(s):  
Signalized Intersections ◽  
Linear Programs ◽  
Left Turn ◽  
Integer Linear Programs ◽  
Arterial Road ◽  
Proposed Model ◽  
Capacity Maximization ◽  
Phase Type ◽  
Set Up ◽  
Capacity Gap

A protected left turn phase is often used at intersections with heavy left turns. This may induce a capacity gap between adjacent intersections along the arterial road among which only parts of intersection are with protected left turn phase. A model for integrated optimization of protected left turn phases for adjacent intersections along the arterial road is developed to solve this problem. Two objectives are considered: capacity gap minimization and capacity maximization. The problems are formulated as Binary-Integer-Linear-Programs, which are solvable by standard branch-and-bound routine. A set of constraints have been set up to ensure the feasibility of the resulting optimal left turn phase type and signal settings. A field intersections group of the Wei-er Road of Ji’nan city is used to test the proposed model. The results show that the method can decrease the capacity gap between adjacent intersections, reduce the delay as well as increase the capacity in comparison with the field signal plan and signal plan optimized by Synchro. The sensitivity analysis has further demonstrated the potential of the proposed approach to be applied in coordinated design of left turn phases between adjacent intersections along the arterial road under different traffic demandpatterns.

scholarly journals Analysis of Red-Light Violation Behavior of Pedestrian Two-Stage Crossing at a Signalized Intersection

2019 ◽  
Vol 5 (2) ◽  
pp. 429 ◽  
Author(s):  
Yongqing Guo ◽  
Xiaoyuan Wang ◽  
Xinqiang Meng ◽  
Jie Wang ◽  
Yaqi Liu
Keyword(s):  
Red Light ◽  
Video Recording ◽  
Signalized Intersections ◽  
Signal Timing ◽  
Two Stage ◽  
Proposed Model ◽  
Group A ◽  
Two Stages ◽  
User Friendly ◽  
Time Selection

Studying pedestrians’ twice-crossing behavior is of great significance to enhance safety and efficiency for pedestrians at signalized intersections. However, researchers have paid little attention to analyze and model pedestrians’ red-light running behavior on a two-stage crossing at signalized intersections. This paper focuses on analyzing the characteristics of pedestrian red-light violation behavior at the two stages, including the time distribution of violation behavior, the consistency of violation behavior, and the violation behavior in group.  A goal-oriented and time-driven red-light violation behavior model was proposed for pedestrian two-stage crossing. A video-recording method was used to collect field data, and the results show that pedestrians in the two directions present different red-light violation behaviors in time selection and violation count, as well as, pedestrians in the two stages of a direction present different red-light violation behaviors in time selection. The main reasons leading to the phenomena were analyzed, regarding from people’s cognitive psychology and visual perception. The results also show that the proposed model is effective in simulating pedestrian red-light violation behavior of twice crossing. This research provides a theoretical basis for optimizing signal timing, improving pedestrian safety and developing user-friendly transportation system.

Delay Variability at Signalized Intersections

2000 ◽  
Vol 1710 (1) ◽  
pp. 215-221 ◽  
Author(s):  
Liping Fu ◽  
Bruce Hellinga
Keyword(s):  
Analytical Model ◽  
Signalized Intersections ◽  
Signalized Intersection ◽  
Level Of Service ◽  
Cycle Times ◽  
Traffic Conditions ◽  
Cycle Simulation ◽  
Proposed Model ◽  
Delay Variability ◽  
Practical Implications

Delays that individual vehicles may experience at a signalized intersection are usually subject to large variation because of the randomness of traffic arrivals and interruption caused by traffic signal controls. Although such variation may have important implications for the planning, design, and analysis of signal controls, currently no analytical model is available to quantify it. The development of an analytical model for predicting the variance of overall delay is described. The model is constructed on the basis of the delay evolution patterns under two extreme traffic conditions: highly undersaturated and highly oversaturated conditions. A discrete cycle-by-cycle simulation model is used to generate data for calibrating and validating the proposed model. The practical implications of the model are demonstrated through its use in determining optimal cycle times with respect to delay variability and in assessing level of service according to the percentiles of overall delay.

scholarly journals A Compositional Analysis of Unbalanced Usages of Multiple Left-turn Lanes

2017 ◽  
Vol 29 (3) ◽  
pp. 287-298
Author(s):  
Li Li ◽  
Qing-Chang Lu ◽  
Yun-Tao Chang ◽  
Zhong-Ren Peng
Keyword(s):  
Statistical Analysis ◽  
Traffic Control ◽  
Compositional Analysis ◽  
Signalized Intersections ◽  
Influential Factors ◽  
Segment Length ◽  
Signal Phase ◽  
Left Turn ◽  
Parameter Variance

Lane usage measures distribution of a specific traffic movement across multiple available lanes in a given time. Unbalanced lane usages decrease the capacity of subject segment. This paper took multiple left-turn lanes at signalized intersections as case study, and explored the influences of some factors on the lane usage balance. Lane usages were calculated from field collected lane volumes and the constant-sum constraint among them was explicitly considered in the statistical analysis. Classical and compositional analysis of variance was respectively conducted to identify significant influential factors. By comparing the results of compositional analysis and those of the classical one, the former ones have better interpretability. It was found that left-turn lane usages could be affected by parameter variance of geometric design or traffic control, such as length of turning curve, length of upstream segment, length of signal phase or cycle. These factors could make the lane usages achieve relative balance at different factor levels.

scholarly journals Optimizing signal phase plan, green splits and lane length for isolated signalized intersections

Transport ◽  
2017 ◽  
Vol 33 (2) ◽  
pp. 520-535 ◽  
Author(s):  
Ronghan Yao ◽  
Hongmei Zhou ◽  
Ying-En Ge
Keyword(s):  
Optimal Allocation ◽  
Impact Factors ◽  
Signal Phase ◽  
Left Turn ◽  
Demand Distribution ◽  
Time Space ◽  
Orthogonal Experiments ◽  
Phase Sequence ◽  
Secondary Factor ◽  
Better Than

At an isolated signalized intersection, short left-turn lanes may be provided to enhance intersection capacity and level of service. The capacity of an entire intersection depends not only on the effective green time per phase and the length of each short left-turn lane but also on the selected signal phase plan. This paper enumerates 16 typical signal phase plans for a four-leg intersection with protected left-turn phases. Given the existence of short left-turn lanes and the freedom to select signal phase plans, two optimization models are formulated. Numerical examples are carried out to illustrate the application of these models and show the sensitivity of the outcomes to impact factors. The orthogonal experiments show that the primary factor is whether a short left-turn lane is added on an approach and the demand distribution is the secondary factor in determining an optimal allocation of the time-space resources of an intersection. To analyse traffic flow operations under different signal phase sequences, the simulation tests are fulfilled using VISSIM under the assumption that the components of a signal phase plan and green splits are all identical. The simulated results indicate that the signal phase sequence for a specified approach may greatly affect traffic movements at an approach, and the leading green phasing is better than the lagging one for a specified approach when the left-turn bay length is short at the approach. Finally, two variations of the developed models are recommended for use and the procedure for the model application is provided in practice.

Generalized Delay Model for Signalized Intersections and Arterial Streets

1997 ◽  
Vol 1572 (1) ◽  
pp. 112-121 ◽  
Author(s):  
Daniel B. Fambro ◽  
Nagui M. Rouphail
Keyword(s):  
Performance Measure ◽  
Signalized Intersections ◽  
Level Of Service ◽  
Delay Model ◽  
Highway Capacity ◽  
Average Delay ◽  
Variable Demand ◽  
Highway Capacity Manual ◽  
Arterial Streets ◽  
Proposed Model

Average delay per vehicle is the primary measure for determining the level of service at signalized intersections. This performance measure is also a major component in the calculation of average travel speed used to determine the level of service on arterial streets. The most widely used models for estimating delay at signalized intersections are those in Chapters 9 ("Signalized Intersections") and 11 ("Urban and Suburban Arterials") of the Highway Capacity Manual. This research reviewed the literature on models for estimating delay at signalized intersections to identify limitations and formulate revised models to address those limitations. Specific problems that were addressed included the inability to account for actuated-control parameters, oversaturation and variable demand, and metering and filtering by upstream traffic signals. The research team developed a generalized delay model to address these limitations and then validated the generalized model with both field and simulation data. The proposed model is sensitive to actuated-control parameter settings, oversaturation and variable demand conditions, and filtering and metering effects of upstream signals. The proposed model is also a good predictor of delays observed in the field and estimated by microscopic traffic simulation programs for the conditions studied. The generalized delay model is recommended for inclusion in future editions of the Highway Capacity Manual.

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