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To alleviate traffic congestion in the city, an integrated waiting area is introduced to the signalized intersection in this paper. After the design idea and the typical form of the integrated waiting area is proposed, the control method at the signalized intersection is discussed. The coordination control process of the main and pre-signal at the...
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Citations
... The emerging technology of numerical simulation has found extensive application in various disciplines. In the field of transportation, numerous studies have shown the reliable, effective, and economic advantages of using VISSIM numerical simulation [25,26]. To ensure reliability and realism, it is essential to incorporate real traffic data in the development of the simulation model and the calibration of parameters to recreate specific traffic scenarios [27]. ...
Frequent consecutive lane changes and the barrier effect produced by trucks can always contribute to rapid access to the capacity bottleneck at expressway exits, thereby reducing operational performance. This paper proposes to retrofit the conventional interchange design to reduce lane changes and compares them with conventional design and passenger vehicle and truck separation (PVTS) design from multiple fields via VISSIM numerical simulation, which is developed and calibrated with traffic data collected on the eight-lane expressway in China at four levels of service (LOS). Comprehensive evaluation (CE) results reveal that the PVTS strategy improves operational performance by 10–20% at multilane expressway exits, while lane separation around interchanges also yields a similar gain. However, ramps on both the left and right sides show less effective improvement and are even negative at LOS-A and LOS-B. All PVTS and improved designs produce a better comprehensive improvement ratio with a LOS decrease, and improved designs achieve optimal performance below LOS-B with construction cost taken into consideration.
... Freight transport has been playing an important role in connecting producers and consumers in all sectors around the world [1]. However, as shown in recent work (e.g., [2]), mixed freight and regular traffic is susceptible to inconsistencies, resulting in an inefficient applications of traditional traffic control methods, especially at intersections, which are known to be the bottlenecks of traffic systems [3]. Hence, given the increasing number of freight vehicles in traffic streams, experts have been looking vigorously for new control methods capable of addressing the concomitant challenges. ...
The need for transporting commodities has led to more and more freight vehicles on urban roads. Specific operational constraints of such vehicles could induce non-homogeneities in the smooth movement of traffic, especially at intersections where acceleration/deceleration events occur frequently. This leads to unnecessary wasted time for all vehicles, even in low to moderate traffic conditions. Hence, the literature reports different proposals to enhance the continuity of traffic at intersections. Among them, the green extension strategy has attracted researchers’ attention, owing to its simplicity, flexibility and practicality. In this paper, we propose a new approximate probabilistic model for the expected waiting/wasted time of all vehicles at an intersection with green time extension in low to moderate traffic conditions. Accordingly, the optimal green extension interval that minimizes the total expected waiting time can then be determined in different conditions. The proposed analysis needs few pieces of information (as opposed to microsimulation models conventionally employed to analyze such systems) and is therefore, suitable for quickly deciding on the optimal strategy based on the current situation in a dynamic environment. We have validated our approximate analysis with simulations in the VISSIM simulation tool.
... Mainly, traffic management is carried out through sections of traffic signals. Additions to the supporting traffic light control solutions are used, such as the use of waiting zones [25], variable speed limits and ramp metering [26]. The formal model called "store-and-forward" is intensively used to define and solve optimization problems. ...
... Problem (25) contains as an argument only the duration of green light u. The application of the model predictive framework of the model allows the evaluation at each control step the value of the existing vehicles in intersection and a new problem (25) will define the solutions of u for the next control step. ...
... The aim of the study is to develop a traffic management model reducing the number of vehicles in sections of the urban transport network, taking into account the stochastic nature of the traffic. The optimization model (25) obtained in the previous Section 5 is used. The objective function reflects the stochastic nature of the traffic flow and our objective is to minimize the sum of all vehicles in the network and/or waiting at the traffic light at the intersection as functions of the green traffic light duration u. ...
An optimization model for traffic light control in an urban network of intersections is derived. The model is based on store-and-forward analytic relations, which account for the length of the queue of waiting vehicles in front of the traffic light intersection. The model is complicated with probabilistic relations that formalize the requirements for maintaining short queues of vehicles. Probabilistic inequalities apply to each intersection of the city network. Approximations of probability inequalities are given in the article. Quadratic deterministic inequalities, which are part of the set of the traffic flow control optimization problem, are derived. Numerical simulations are performed, applying mean estimated data for real traffic in an urban area of Sofia. The model predictive approach is applied to traffic light optimization and control. Empirical results give advantages of the obtained model compared to the classical store-and-forward optimization model for the total number of vehicles waiting in the considered urban network.
... The simulation findings showed that the second and third solutions reduced delay and improved LOS from D to C, respectively. Xia et al. (2019) investigated the impact of the Integrated Waiting Area (IWA) on signalized intersection operational performance. The fundamental principle behind the integrated waiting area is to use a portion of the approach lanes as left-turn and through waiting, zones to maximize space at a signalized intersection. ...
Signalized intersections are critical elements of the highway system, thus improving the attitude of these intersections significantly influences the overall operating performance of the highways in respect of delay and level of service (LOS). Reduction in capacity and increase in delay at signalized intersections could be a reflection of poor signal timing as well as inadequate road geometry variables. A better comprehension of the reasons that affect signalized intersections performance can be useful in reducing delay and improving the LOS. This study aims toreview some of thepublished works on the evaluation of traffic operation at signalized intersections using both Highway Capacity Manual 2010 (HCM 2010) and several optimization software. Different approaches were used to identify the main input data (traffic volume data, geometric characteristics, and signal timing) required for the HCM and different optimization proposals including video recording technique and field survey. The outcomes of thepublished investigations indicated to improve the operational performance of these intersections including cycle length, adding lanes, creating overpass, prohibiting approach traffic from the intersection, and a combination of some proposals.The research also seeks to add tothis review the limitations of using different software suchas SYNCHRO, CORSIM, HCS, SIDRAand the considerable variability of delays and LOS using these software’s so that it may be updated for future experimental and simulation investigations on signalized intersections
... Therefore, it is necessary to look for other solutions to ensure smooth and sustainable transport. A major problem of the road network is intersectionspoints where several traffic flows meet [7,8]. It is vital to enable actuated control (intelligent traffic management) at signal-controlled intersections, which will allow the maximum number to pass through and reduce the delay time. ...
In our paper, we have analyzed and compared fixed and actuated control at a chosen intersection, where we pointed out the importance of actuated control and its benefits. We have used traffic data from sensors in the roadway. The intersection was modelled in Aimsun, where we performed simulations. The research focused mainly on the impact of actuated control on the basic characteristics of the traffic flow, delay time and emissions. The outputs of simulations showed positive results of actuated control in all compared values. The environmental pollution topic is up-to-date and road transport has a significant impact on it. Furthermore, we want to continue with our research to investigate the impact of speed changes on emission production and the smoothness of the traffic flow under fixed and actuated control.
... Intersections are the key nodes in the urban road network, where many vehicles intersect with many conflicts (Xia et al., 2019). The contribution of the number of accidents is due to many distinct conflicting patterns at a signalized intersection that causes the vehicle movements (Bhuiyan et al., 2016). ...
... In order to keep the balance between the growth in travel demand and the supply of transportation capacity, policy-makers and researchers have adopted various approaches to optimize road infrastructures and enhance road capacity in the past decades, including left-turn waiting areas [3], variable approach lanes [4], dynamic lane assignments [5], and integrated waiting areas [6]. Nevertheless, congestion has gotten worse over the last several years. ...
Previous studies on Connected and Automated Vehicles (CAVs) demonstrated the potential to coordinate the behaviors of multiple connected vehicles for traffic improvements. In this paper, we first propose a Conflict Duration Graph-based (CDG-based) coordination framework to resolve collisions and improve the traffic capacity of signal-free intersections. Secondly, a Speed Control-based Intersection Coordination Model (SICM) is developed to identify complex constraints in multi-vehicle collision scenarios. Thirdly, a geometric Translation-based Intersection Coordination Algorithm (TICA) is proposed to calculate the ideal location of time blocks in CDGs and then obtain the near-optimal design speed in the form of combinatorial optimization. Twelve groups of test scenarios with different traffic volumes were designed and tested on a MATLAB-based simulation platform. Simulation results showed that the proposed method can resolve all the collisions and instruct the vehicles to pass signal-free intersections collaboratively without stopping in low to medium level of congestion.
... That reduces the capacity of the roads, increases traffic delay and reduces the safety on roads. According to [13], delays at road intersections account for more than 80% of the total road network delays, and 40% of traffic accidents happen in an intersection [14]. There are different types of intersection management methods, each type has its own characteristics, parameters, advantages and disadvantages. ...
The rapidly improving autonomous vehicle (AV) technology will have a significant impact on traffic safety and efficiency. This study introduces a game-theory-based priority control algorithm for autonomous vehicles to improve intersection safety and efficiency with mixed traffic. By using vehicle-to-infrastructure (V2I) communications, this model allows an AV to exchange information with the roadside units (RSU) to support the decision making of whether an ordinary vehicle (OV) or an AV should pass the intersection first. The safety of vehicles is taken in different stages of decisions to assure collision-free intersection operations. Two different mathematical models have been developed, where model one is for an AV/AV situation and model two is when an AV meets an OV. A simulation model was developed to implement the algorithm and compare the performance of each model with the conventional traffic control at a four-legged signalized intersection and at a roundabout. Three levels of traffic volume and speed combinations were tested in the simulation. The results show significant reductions in delay for both cases; for case (I), AV/AV model, a 65% reduction compared to a roundabout and 84% compared to a four-legged signalized intersection, and for case (II), AV/OV model, the reduction is 30% and 89%, respectively.
... In Beijing, the transport annual report stated that the average daily congestion duration was 2 h and 50 min in 2018 [1]. Intersections are the bottlenecks of the road network, where multiple traffic streams and people flow gather [2]. Traffic congestion usually occurs at intersections. ...
... This sum is divided by the number of headways after the fourth vehicle (i.e., divided by (n -4)) to obtain the average headway per vehicle under saturation flow. The saturation flow rate is 3600 divided by this average headway as expressed in Equation (2). In general, the measurement technique is used to obtain a saturation flow rate at operating intersections. ...
... (c) The average saturation headway can be extracted. (d) The saturation flow rate was calculated by Equation (2). There were two types of input parameters, one a static parameter and the other is a dynamic parameter, which were obtained through different methods. ...
Intersections are the bottlenecks of the road network. The capacity of signalized intersections restricts the operation of the road network. Dynamic estimation of capacity is necessary for signalized intersections refined management. With the development of technology, more and more detectors were installed near the intersection. It had been the information-rich environment, which provided support for dynamic estimation of capacity. A dynamic estimation method for a saturation flow rate based on a neural network was developed. It would grasp the dynamic change of saturation flow rates and influencing factors. The measure data at three scenarios (through lanes, shared right-turn and through lanes, shared left-turn and through lanes) of signalized intersections in Beijing were taken as examples to validate the proposed method. Firstly, the traffic flow characteristics of the three scenarios and factors affecting the saturation flow rate were analyzed. Secondly, neural network models of the three scenarios were established. Then the hyperparameters of neural network models were determined. After training, the neural network structure and parameters were saved. Lastly, the test set data was validated by the training model. At the same time, the proposed method was compared with the Highway Capacity Manual (HCM) method and the statistical regression method. The results show that both regression models and neural network models have better accuracy than HCM models. In a simple scenario, the neural network models are not much different from the regression models. With the increase of complexity of scenarios, the advantages of neural network models are highlighted. In through-left lane and through-right lane scenarios, the estimated saturation flow rates used by the proposed method were 7.02%, 4.70%, respectively. In the complexity of traffic scenarios, the proposed method can estimate the saturation flow rate accurately and timely. The results could be used for signal control schemes optimizing and operation managing at signalized intersections subtly.
... The emission problems, which are caused by traffic jams, are growing worse. Traffic congestion has become a key problem that restricts the sustainable development of cities. Intersections where multiple traffic flows converge are the important nodes in the road network [3]. In addition, because the capacity of intersections is less than the capacity of road section, intersections often become bottlenecks of the road networks. ...
... df means degree of freedom. 2 F means F-test statistic value.3 Sig. ...
An insufficient functional relationship between adjustment factors and saturation flow rate (SFR) in the U.S. Highway Capacity Manual (HCM) method increases an additional prediction bias. The error of SFR predictions can reach 8%–10%. To solve this problem, this paper proposes a comprehensive adjusted method that considers the effects of interactions between factors. Based on the data from 35 through lanes in Beijing and 25 shared through and left-turn lanes in Washington, DC, the interactions between lane width and percentage of heavy vehicles and proportion of left-turning vehicles were analyzed. Two comprehensive adjustment factor models were established and tested. The mean absolute percentage error (MAPE) of model 1 (considering the interaction between lane width and percentage of heavy vehicles) was 4.89% smaller than the MAPE of Chinese National Standard method (Standard Number is GB50647) at 13.64%. The MAPE of model 2 (considering the interaction between lane width and proportion of left-turning vehicles was 33.16% smaller than the MAPE of HCM method at 14.56%. This method could improve the accuracy of SFR prediction, provide support for traffic operation measures, alleviate the traffic congestion, and improve sustainable development of cities.
