Traffic Flow Distribution Research Articles

Impact of CAV platoon management on traffic flow considering degradation of control mode

As Connected and Automated Vehicles (CAVs) gradually occupy more market share, the mixed traffic flow composed of MVs and CAVs will exist for a long time. This paper mainly explores the impact of CAV platoon management and control mode degradation on the fundamental diagram, and further studies how they affect fuel consumption and pollutant emissions. First, in terms of platoon management, the mixed traffic flow configurations and distribution characteristics of four types of vehicles were proposed. Second, numerical analyses were conducted, and a fundamental diagram considering CAV platoons and degradation of the Cooperative Adaptive Cruise Control (CACC) system was proposed. To validate this fundamental diagram, the Intelligent Driver Model (IDM) and the Connected and Automated Vehicle (CAV) and CACC models proposed by the PATH lab were applied for simulations. Third, the influence of CAV platoons on the traffic environment was explored via micro simulations as well. Conclusions were drawn from the results of the simulations: The mixed traffic can obtain significant capacity gain due to the existence of CAV platoons, especially with high Market Penetration Rate (MPR). Moreover, capacity break-downs occurred in the diagram due to the adjustment of information flow topology, and the break-downs were more prominent with higher MPR. Additionally, CAV platoons can significantly reduce fuel consumption and emissions by 34.7% and 41.4% respectively. The first degradation raises fuel consumption and emissions by 44.5% and 60.1%, while the second one by 12.0% and 16.1%, with the initial vehicle speed set at 33 m/s and MPR set at 1.0. Finally, according to the sensitivity analysis, an optimal platoon size of 5 vehicles was suggested for CAV platoon management.

Exploring the Distribution of Traffic Flow for Shared Human and Autonomous Vehicle Roads

In order to explore the changes that autonomous vehicles would bring to the current traffic system, we analyze the car-following behavior of different traffic scenarios based on an anti-collision theory and establish a traffic flow model with an arbitrary proportion (p) of autonomous vehicles. Using calculus and difference methods, a speed transformation model is established which could make the autonomous/human-driven vehicles maintain synchronized speed changes. Based on multi-hydrodynamic theory, a mixed traffic flow model capable of numerical calculation is established to predict the changes in traffic flow under different proportions of autonomous vehicles, then obtain the redistribution characteristics of traffic flow. Results show that the reaction time of autonomous vehicles has a decisive influence on traffic capacity; the q-k curve for mixed human/autonomous traffic remains in the region between the q-k curves for 100% human and 100% autonomous traffic; the participation of autonomous vehicles won’t bring essential changes to road traffic parameters; the speed-following transformation model minimizes the safety distance and provides a reference for the bottom program design of autonomous vehicles. In general, the research could not only optimize the stability of transportation system operation but also save road resources.

Optimized allocation of scooter battery swapping station under demand uncertainty

Appropriately allocating battery swapping stations (BSSs) encourages drivers to use battery-operated scooters (ES) for reducing air pollution. The stochastic nature of battery swapping (BS) has not been widely discussed. Also, relatively few models have been proposed to, with particular reference to the possible demand for battery swapping, optimize the BSS locations and the appropriate number of batteries provided for the users of ESs to swap depleted batteries. Hence, this study aims to develop an optimized allocation model of grid-based scooter BSS (OAMSBSS) to be used to solve the abovementioned problem.First, using Monte Carlo simulation for problem-solving operations, along with the consideration given to the traffic flow and population distribution, the stochastic BS model used to predict the demand of stochastic BS was proposed to estimate the various possible scenarios of BSD. Each scenario involved the location decisions and the time distribution for battery swapping demand. Optimizers were adopted to optimally allocate the BSS to both satisfy the BS demand scenarios and achieve the minimal BSS construction cost. The optimized locations of BSSs are considered to not only cost lower land rentals but also help a large number of drivers faced with the problem of the demand for BS services.

Identification of Critical Links in Urban Road Network considering Cascading Failures

The identification of critical road links is greatly important to the management and control of the transportation system. Existing works fail to fully consider the influence of the distribution of traffic flow and its dynamic characteristics on critical road link identification. In this paper, we propose a criticality calculation method for urban road networks considering the effect of cascading failures which models the distribution change of traffic flow after a specific road link failed. Firstly, a sequence diagram calculation method is proposed to model how the traffic failure on one road link propagates to related links. Secondly, the diagram of the cascade failure sequence is divided into different stages according to the consistency of the objective function. The influence value of each stage is computed for the target road link. Finally, the failure probability model and the importance indicator are proposed to calculate the criticality for each road link. We evaluate our critical road link identification method on both simulated and read scenes. In our simulation, we achieve 90.6% and 91.7% for the accuracy on two key metrics, respectively, i.e., the length of failure road link and the total parking delay, which proves the feasibility of our method. Our method also achieves reasonable conclusions on real data and helps to find the critical road links.

The Research on Traffic Assignment Method Based on the Urban Road Network Topology

As our country urbanization and economic development accelerating, traffic problems become increasingly serious. In urban road network, the intersection delay has a major influence on road impedance even the choice of the path. In order to reflect the actual situation of traffic flow distribution more accurately, the transportation network assignment model was established based on the intersection flow of delays and traffic control.By comparing delay models of signal control and analyzing the intersection impedance, the intersection optimization model was built based on delay, queuing and traffic capacity. Then, we analyzed the structure of the road network topology and traffic assignment models, researched the advantages and disadvantages of the allocation algorithm in detail. Finally, the balanced allocation algorithm for FW algorithm convergence slowly was improved. The feasibility of the algorithm was verified by examples.

A collaborative planning method of distribution network including EV charging piles and Distributed Generations

With the growing penetration rate of distributed generations (DGs) and large number of unordered charging electric vehicles (EVs), the distribution network (DN) is facing more challenges than before. Therefore, the DN planning integrated of EVs and DGs is the primely problem. Firstly, an traffic network model and a distributed power supply output model are established to simulate the actual traffic network flow distribution through the principle of user equilibrium flow distribution. Secondly, an improved adaptive free search algorithm is proposed to coordinate site selection planning of EV charging pile and DG considering the factors of economy and users’ satisfaction of charging. Finally, taking the modified IEEE 33-node distribution network as an example, the proposed model and algorithm are simulated and verified. The simulation results show that the proposed model and programming method are feasible and effective.

Histogram Ordering

Frequency histograms are ubiquitous, being practically used in any field of science. In this paper, we present a partial order for frequency histograms and, to our knowledge, no order of this kind has been yet defined. This order is based on the stochastic order of discrete probability distributions and it has invariance properties that make it unique. First, we model a frequency histogram as a sequence of bins associated with a discrete probability (or relative frequency) distribution. Then, we consider that two histograms are ordered if they are defined on the same sequence of bins and their respective frequency distributions are stochastically ordered. The ordering can be easily spotted because the respective cumulative distribution functions of the frequencies of two ordered histograms do not cross each other. Finally, with each bin we can associate a representative value of the bin, and for two ordered histograms it holds that all quasi-arithmetic means (such as arithmetic, harmonic, and geometric mean) of the representative values weighted by the frequencies are ordered in the same direction than the histograms are. Our theoretical study is supported by three experiments in the fields of image processing, traffic flow, and income distribution.

Sanitary and Hygienic Characteristics of the Ambient Air of Major Roads in an Industrial City

Summary. Introduction: In the modern urbanized environment, there is a tendency of increasing environmental stress related to the growth of technical equipment, intensification of the use of urban areas and the development of the complex transport network, which is a source of noise and air pollution. Understanding of this problem served as an incentive to conduct a sanitary inspection of the main transport routes of Omsk, which is an industrial metropolis with an irrational distribution of traffic flows, a large number of cars, and a practical absence of roadside landscaping. Our objective was to assess the main transport routes in the city of Omsk by studying the intensity of traffic flows, measuring traffic noise level and carbon monoxide (CO) concentrations on the roadway and in adjacent residential areas. Materials and methods: All measurements were taken during off-peak hours. Vehicle traffic counting was used to establish the proportion of freight and public transport cars in the total number of passing vehicles. The study objects included traffic density (the number of vehicles per hour), the average velocity of the traffic flow, the type of roadway coverage, the presence of a dividing line, and the type of highway noise barriers used. Results: Our findings showed that road traffic noise levels and CO concentrations measured at the highways and at the border of adjacent residential areas exceeded their maximum permissible values. Measures to reduce adverse health effects of traffic noise pollution and on-road vehicle emissions of carbon monoxide are proposed.

Оценка матрицы корреспонденций методом Пуассона на основе данных онлайн-сервиса поиска автомобильных попутчиков

For effective functioning of transport systems, information on spatial distribution of transport flows is necessary both at the current moment and for future periods. Traditional methods of obtaining observation results require very high costs, In addition, there is a high probability of obtaining low-quality data due to the strong influence of the human factor. The disadvantage of automated methods of traffic flow inspection is the high cost of equipment. The paper proposes a method for obtaining data on spatial distribution of passenger flows using constant monitoring of the online service of joint trips. To illustrate the possibilities of this approach, the online service for searching for car companions was used on the example of Sverdlovsk region. The correspondence matrix is constructed using a gravitational model applying the Poisson method. The Gauss - Seidlitz iterative method is used to find unknown parameters of the model. The assessment of quality and adequacy of the constructed model values of correspondence was carried out. It is shown that the spatial distribution of traffic flows obtained on the basis of data from online services for searching for car companions is well described by a gravitational model with a piecewise constant gravity function. Based on the analysis of the observed correspondence matrix, it was found that traffic flows between Yekaterinburg and all other cities of the Sverdlovsk region significantly exceed traffic flows between these cities.

СУЧАСНА ІНФРАСТРУКТУРА КОМУНІКАЦІЙНИХ ТЕХНОЛОГІЙ У БІЗНЕС-СЕРЕДОВИЩІ: МОДЕЛЮВАННЯ МЕТОДУ «ЖИВОЇ МІГРАЦІЇ»

In order to meet data and service requirements, network operators are constantly expanding and improving their network infrastructure, resulting in increased capital and operating costs. However, due to intense competition and falling prices, the average income per user does not increase proportionally, which leads to a decrease in return on investment. Thus, to reduce costs and increase revenue, mobile networks need to make the next evolutionary leap towards 5G, which now applies not only to the mobile border, but also to the core network. The 5G micro-operator service architecture must also be developed together with various technologies such as SDN and NFV. SDN abstracts network architecture by separating network management and redirection functions, allowing network management to become directly programmable and the underlying infrastructure to be abstracted for applications and network services. The interaction between SDN and NFV allows the 5G network to abstractly build the system infrastructure and further increase network flexibility. Therefore, the article substantiates the possibility of market commercialization of the use of technologies of live migration of traffic flow, which allows to give the product unique characteristics. The existing approaches to the solution of the problem of load balancing of the network of 5G micro operators are analyzed. A number of advantages of the live migration method have been identified, namely the possibility of its application for the micro operator's network and efficient use of network resources. According to the results of the experiment, it was found that the method of live migration has better values µO_num (68.1% of traffic flow) than the mechanism of MLF (29.8% of traffic flow). It is proved that the mechanism of live migration can determine the priority of the user traffic flow according to the servers in the zone µO, and therefore it is expedient to apply in terms of optimizing the distribution of traffic flow. The proposed method should increase the utilization of network resources and traffic flow efficiency and lead to a higher level of experience quality (QoE) for network users.

Designing of turnarounds with different traffic direction priorities taking into account traffic flow distribution

Designing of turnarounds with different traffic direction priorities taking into account traffic flow distribution

Analysis of Traffic Flow Equilibrium in Urban Road Network Based on Floating Vehicle Data

Based on the floating vehicle data, this paper analyzes the equilibrium of urban road network traffic flow. This can guide traffic flow distribution and provide reliable basis for traffic control. This paper starts with the quantitative analysis of the traffic network equilibrium, on the basis of verifying the validity of the floating car data, divides the urban road network into regions, and constructs an analysis model of the traffic flow equilibrium of the urban road network. The urban road traffic distribution model is constructed in accordance with the number of road traffic segments. On this basis, gini coefficient index is introduced to judge the road network flow balance, which is used to analyze the balance of each sub-region. By means of traffic guidance, signal control and other traffic control means, the traffic flow in each sub-area is balanced, and the traffic flow in the whole road network becomes balanced.

Integrated pricing framework for optimal power and semi‐dynamic traffic flow problem

Large-scale fast charging of electric vehicles inextricably entwines the operation of power and transportation systems. This study examines the integrated pricing of electricity and roads to maximise the social welfare associated with the coupled systems, i.e. minimising the total travel time and energy generation costs. While electric demand and transportation network conditions vary significantly over the day, most of the work, however, considers only static network flows for a single time period. This study proposes a multi-period integrated pricing model that can describe the variations of electricity and travel demands. Specifically, the distribution of traffic flows is characterised by a semi-dynamic traffic assignment model to consider flow propagation between adjacent time periods. To determine the optimal prices of electricity and road tolls, a marginal-cost pricing scheme based on the first-best tolls and locational marginal prices is developed. Mathematically, the multi-period pricing model is formulated as a convex optimisation problem. Moreover, a decentralised collaborative pricing framework is developed for independent power and transportation system operators to attain the optimal pricing strategies. Numerical experiments are conducted to demonstrate the effectiveness of the pricing method.

Multi-Agent Based Optimal Scheduling and Trading for Multi-Microgrids Integrated With Urban Transportation Networks

This paper investigates multi-period optimal energy scheduling and trading for multi-microgrids (MMGs) integrated with an urban transportation network (UTN). Specifically, an optimization based multi-period traffic assignment model is built to characterize the vehicular flows considering rational drivers with time-flexible travel demand. Meanwhile, each microgrid (MG) is modeled to independently schedule its operation by trading energy with other MGs and charging electric vehicles (EVs) with its fast charging stations (FCSs). The EV charging prices could further influence traffic flow distribution of the UTN. To co-optimize the coupled system, a multi-agent based optimal scheduling and trading scheme is proposed, which is facilitated by peer-to-peer communication of transactive energy information among the agents, thus can preserve privacy of the market participants. Within the scheme, the MGs and EVs take their optimal decisions in response to MG energy trading and EV charging prices updated via multi-bilateral negotiation based on the demand-supply relationship. When an equilibrium of the coupled system is reached, each MG can minimize its operation cost, and the traffic condition could also be improved. Case studies of a MMG system coupled with a double-ring UTN are conducted to validate the effectiveness of the scheme.

Stability and Environmental Analysis of Mixed Traffic Flow – Using the Markov Probabilistic Theory

The rapid growth of CAV (Connected and Automated Vehicle) market penetration highlights the need to gain insight into the overall stability of mixed traffic flows in order to better deploy CAVs. Several studies have examined the modelling process and stability analysis of traffic flow in a mixed traffic environment without considering its inner spatial distribution. In this paper, an innovative Markov chain-based model is established for integrating the spatial distribution of mixed traffic flow in the model process of car-following behaviour. Then the linear stability analysis of the mixed traffic flow is conducted for different CAV market penetration rates, different CAV platoon strength and different cooperation efficiency between two continuous vehicles. Moreover, several simulations under open boundary conditions in multiple scenarios are performed to explicate how CAV market penetration rate, platoon strength and cooperation efficiency jointly influence the stability performance of the mixed traffic flow. The results reveal that the performance of this mixed traffic flow stability could be strengthened in these three factors. In addition to stability, an investigation of the fuel consumption and emission reduction under different market penetration rates and the platoon strength of CAVs are explored, suggesting that substantial potential fuel consumption and emission could be reduced under certain scenarios.

Закономірності формування і розподілу транспортних та пасажирських потоків

Decision-making to improve the functioning of route systems is an extremely necessary, but at the same time difficult task, as it determines the overall socio-economic development of the city, the stability and safety of its transport complex. The purpose of this work is to establish patterns of formation and distribution of passenger flows for the transport network of the city with a description of models of their operation. The traditional approach to determining the concentration of travel is described by "synthetic" models, such as gravity. A practical solution to the problems of transport planning is the modeling of behavioral demand, which is based on the concept of attractiveness function. The load of the transport network is determined by the number of vehicles on it. Download simulation is the distribution of inter-district correspondence along specific paths connecting district pairs. In normative models, the distribution of traffic flows is based on the optimization of some global criterion that characterizes the efficiency of the entire network. The descriptive approach is based on the principle according to which each participant seeks to minimize their own costs. The most effective is the model of finding the equilibrium distribution. One of the variants of which is used to distribute users of one class. In this way, the location of transport interchanges in the transport infrastructure of the city mainly determines their transport structure. The distribution of passenger correspondence between interacting infrastructure objects is described by a gravitational model. The equilibrium distribution search model should be used as a task to optimize the distribution of traffic flows.

A Conflict-free Trajectory Generation Method for Pre-tactical Phase in Trajectory Based Operation

Trajectory Based Operation (TBO) is the future vision of air traffic management, and provides efficiency, capacity and safety benefits by managing aircraft trajectories cooperatively. According to air traffic operational characteristic of responsibility airspace division, this paper presents a conflict-free trajectory generation for pre-tactical phase in TBO environment. Considering the traffic flow distribution and flight conflict, a detailed conflict-free trajectory planning algorithm based on waypoint trajectory constraint is developed. Some simulation results based on typical operational data are carried out to show the feasibility of proposed method. This work is of great significance to the development of trajectory management and decision tools to support TBO.

A Transportation Network Paradox: Consideration of Travel Time and Health Damage due to Pollution

In cities with serious air pollution, travel time and health damage significantly affect route choice by travelers (e.g., motorcycle and scooter drivers). Consequently, the classical Braess paradox is no longer realistic because it only considers the traveler’s value of time (VOT). In the current study, we describe a new transportation network paradox that considers both the VOT and the traveler’s perception of pollution damage. To examine the conditions that create the new paradox, we developed a novel method to compute a total comprehensive cost that combines the VOT with health damage. We analyzed the conditions for the new paradox and the system’s performance using a user equilibrium model and system optimization. Furthermore, an improved model is used to analyze how different transport modes influence the Braess paradox. We found that whether the new paradox occurs and the potential improvement of the system’s performance depend on whether the total travel demand falls within critical ranges. The bounds of these ranges depend on the values of the parameters in the function that describes the health damage and the link travel time function. In addition, high health damage significantly affects route choices and traffic flow distribution. This paper presents a new perspective for decision-making by transportation planners and for route choices in cities with serious air pollution.

Hotelling Model Analysis Based on Product Quality Difference with the Network Externality

A network externality was introduced into the two-stage dynamic Hotelling model with the quadratic function of transportation cost on the basis of the quality difference between two products. In consideration of three different position relations among the consumers’ indifference curve, quality preferences for the products and population distribution density, the existence condition of equilibrium price between two manufacturers about the Hotelling model were obtained. Attention was paid to traffic-flow distribution technology and infinite dimensional variational inequality. Finally, the influences of network externality, transportation cost, cost difference and quality difference on equilibrium prices between two manufactures were analyzed.

A numerical model for impacts of left-turn non-motorized vehicles on through lane capacity metrics

There is a conflict between through motor vehicles and the left-turn non-motorized vehicles, and the capacity of straight-line motor vehicles decreases. This study analyzes the impacts of left-turn non-motorized vehicles on the capacity of through motor vehicle lanes. A correction coefficient model for calculating the reduced capacity of through motor vehicle lanes has been developed based on analysis of the conflicting points at an intersection and the negative exponential function of traffic flow distribution. With consideration of intersection geometric design, channelization, and traffic characteristics, the correction coefficient model was further enhanced by regression to capture the impacts of left-turn non-motorized vehicles from the same and the opposite directions. A simulation with VISSIM is used to validate the developed model. It shows that the calculated capacity from the correction coefficient model is close to the simulation results. The experiment indicates that the derived model is highly accurate in calculating the capacity of through motor vehicle lanes and has potential application for situations of mixed traffic in China. The study shows that the capacity of a through traffic lane at the permitted phase decreases with the increase of left-turning non-motorized vehicles, and the impact of left-turning non-motorized vehicles from the same direction is more significant. The results show that the traffic capacity of straight-line motor vehicle decreases with the increase of the left-turn non-motorized vehicles flow rate and the influence of the left-turn non-motor vehicle is more obvious. It is suggested that in practice, the correction coeffi-cient of non-motor vehicle on the left turn should be 0.88, and the correction coefficient on the left turn should be 0.95, respectively. The study recommends coefficient values for both non-motorized vehicles from the same and opposite directions for use in real applications.