scholarly journals A Link Queue Model of Network Traffic Flow

2021 ◽  
Author(s):  
Wen-Long Jin
Keyword(s):  
Traffic Flow ◽  
Network Traffic ◽  
Transportation Network ◽  
Transmission Model ◽  
Cell Transmission Model ◽  
Rarefaction Waves ◽  
Fundamental Diagram ◽  
Modeling Framework ◽  
New Model ◽  
Queue Model

Fundamental to many transportation network studies, traffic flow models can be used to describe traffic dynamics determined by drivers’ car-following, lane-changing, merging, and diverging behaviors. In this study, we develop a deterministic queueing model of network traffic flow, in which traffic on each link is considered as a queue. In the link queue model (LQM), the demand and supply of a link queue are defined in the queue size (number of vehicles), and its in- and out-flows are computed from junction flux functions corresponding to macroscopic merging and diverging rules. The new model is a system of ordinary differential equations that is mathematically tractable and computationally efficient and can capture queue spillbacks and interactions among links. We further demonstrate that the LQM is fundamentally different from the cell transmission model (CTM) and link transmission model (LTM) for a road segment, a signalized ring road, and a diverge-merge network, with respect to the shock and rarefaction waves, network fundamental diagram, and stability property. In a sense, the new model is a space-continuous approximation of the kinematic wave model and can be a useful addition to the multiscale modeling framework of network traffic flow. The model has been applied to formulate and solve network traffic control and observation problems.

A wave-oriented variable cell transmission model in an urban road

2021 ◽  
Author(s):  
Zeyu Shi ◽  
Yangzhou Chen ◽  
Jingyuan Zhan ◽  
Xiangyu Guo ◽  
Shuke An
Keyword(s):  
Traffic Flow ◽  
Urban Traffic ◽  
Transmission Model ◽  
Hybrid Automata ◽  
State Variables ◽  
Cell Transmission Model ◽  
Fundamental Diagram ◽  
Influence Area ◽  
Cell Transmission ◽  
The Waves

To describe the dynamics of traffic flow in the urban link accurately, the waves which generate at intersections are adopted as the influencing factors of traffic flow. Based on the urban traffic waves, a wave-oriented variable cell transmission model (WVCTM) is proposed to illustrate the urban traffic flow. In this model, the average density and length are the state variables. The cells are divided by traffic waves. The upstream cell is the influence area of the waves at the upstream intersection, the downstream cell is the influence area of the waves at the downstream intersection, and the rest is the mediate cell. Consistent with the fundamental diagram and the cell division, the traffic states of urban links are divided into six modes. The variation of modes is explained by hybrid automata. Finally, an experiment is designed to verify the feasibility of WVCTM. The data in the experiment come from the actual scene. Compared with the cell transmission model (CTM) and variable-length CTM (VCTM), WVCTM possesses the valuable performance to predict the traffic states. Likewise, it is rational that WVCTM can correctly illustrate the urban traffic flow.

Width-Based Cell Transmission Model for Heterogeneous and Undisciplined Traffic Streams

2019 ◽  
Vol 2673 (5) ◽  
pp. 682-692 ◽  
Author(s):  
Afzal Ahmed ◽  
Satish V. Ukkusuri ◽  
Shahrukh Raza Mirza ◽  
Ausaja Hassan
Keyword(s):  
Traffic Flow ◽  
Behavior Modeling ◽  
Flow Diagram ◽  
Transmission Model ◽  
Flow Density ◽  
Cell Transmission Model ◽  
Fundamental Diagram ◽  
Flow Models ◽  
Cell Transmission ◽  
Traffic Flow Models

Traffic streams in many developing countries consist of various modes of transport, with high heterogeneity in driver behavior. Modeling these types of traffic streams, in which traffic rules (speed limit, lane discipline, etc.) are not strictly followed, is a complex task. A review of the existing literature shows that there is a lack of traffic flow models that model the behavior of heterogeneous and undisciplined traffic streams. Like other undisciplined traffic streams, there are no speed limits (hence no speed enforcement) on most of the roads in Karachi, Pakistan. Lane discipline is also not observed by drivers, which results in a varying number of traffic lanes on a road. Therefore, most of the existing traffic flow models/simulation packages developed for disciplined traffic streams cannot appropriately model traffic streams without lane discipline. This research proposes a width-based cell transmission model (WCTM) by developing a fundamental flow-density diagram whose parameters are a function of the road width. Extensive field data have been collected from a selected arterial in Karachi for development of the fundamental traffic flow diagram. The values of the computed parameters are significantly different than the values reported in the literature. The piecewise-linear flow-density relation is developed by optimally estimating the breakpoints. Results show that the quadrilateral and pentagonal-shaped fundamental diagrams fit better with the collected data in comparison with the triangular-shaped fundamental diagram. The proposed WCTM is applied to selected segments of an arterial and results show that the WCTM was able to accurately model different traffic conditions.

ANALYSIS OF CELL TRANSMISSION MODEL FOR TRAFFIC FLOW SIMULATION WITH APPLICATION TO NETWORK TRAFFIC

2021 ◽  
pp. 1-16
Author(s):  
A. S. MAULANA ◽  
S. R. PUDJAPRASETYA
Keyword(s):  
Shock Waves ◽  
Travel Time ◽  
Traffic Flow ◽  
Finite Volume ◽  
Kinematic Model ◽  
Transmission Model ◽  
Finite Volume Scheme ◽  
Cell Transmission Model ◽  
Rarefaction Waves ◽  
Cell Transmission

Abstract The cell transmission model (CTM) is a macroscopic model that describes the dynamics of traffic flow over time and space. The effectiveness and accuracy of the CTM are discussed in this paper. First, the CTM formula is recognized as a finite-volume discretization of the kinematic traffic model with a trapezoidal flux function. To validate the constructed scheme, the simulation of shock waves and rarefaction waves as two important elements of traffic dynamics was performed. Adaptation of the CTM for intersecting and splitting cells is discussed. Its implementation on the road segment with traffic influx produces results that are consistent with the analytical solution of the kinematic model. Furthermore, a simulation on a simple road network shows the back and forth propagation of shock waves and rarefaction waves. Our numerical result agrees well with the existing result of Godunov’s finite-volume scheme. In addition, from this accurately proven scheme, we can extract information for the average travel time on a certain route, which is the most important information a traveller needs. It appears from simulations of different scenarios that, depending on the circumstances, a longer route may have a shorter travel time. Finally, there is a discussion on the possible application for traffic management in Indonesia during the Eid al-Fitr exodus.

Analysis of cell transmission model for traffic flow simulation with application to network traffic

2021 ◽  
Vol 63 ◽  
pp. 84-99
Author(s):  
A. S. Maulana ◽  
Sri Redjeki Pudjaprasetya
Keyword(s):  
Shock Waves ◽  
Travel Time ◽  
Traffic Flow ◽  
Finite Volume ◽  
Kinematic Model ◽  
Transmission Model ◽  
Finite Volume Scheme ◽  
Cell Transmission Model ◽  
Rarefaction Waves ◽  
Cell Transmission

The cell transmission model (CTM) is a macroscopic model that describes the dynamics of traffic flow over time and space. The effectiveness and accuracy of the CTM are discussed in this paper. First, the CTM formula is recognized as a finite-volume discretization of the kinematic traffic model with a trapezoidal flux function. To validate the constructed scheme, the simulation of shock waves and rarefaction waves as two important elements of traffic dynamics was performed. Adaptation of the CTM for intersecting and splitting cells is discussed. Its implementation on the road segment with traffic influx produces results that are consistent with the analytical solution of the kinematic model. Furthermore, a simulation on a simple road network shows the back and forth propagation of shock waves and rarefaction waves. Our numerical result agrees well with the existing result of Godunov’s finite-volume scheme. In addition, from this accurately proven scheme, we can extract information for the average travel time on a certain route, which is the most important information a traveller needs. It appears from simulations of different scenarios that, depending on the circumstances, a longer route may have a shorter travel time. Finally, there is a discussion on the possible application for traffic management in Indonesia during the Eid al-Fitr exodus.   doi:10.1017/S1446181121000080

scholarly journals Research on Analysis Method of Traffic Congestion Mechanism Based on Improved Cell Transmission Model

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Hongzhao Dong ◽  
Shuai Ma ◽  
Mingfei Guo ◽  
Dongxu Liu
Keyword(s):  
Traffic Flow ◽  
Traffic Congestion ◽  
Road Network ◽  
Simulation Experiment ◽  
Transmission Model ◽  
Spatial Diffusion ◽  
Cell Transmission Model ◽  
Analysis Method ◽  
Proposed Model ◽  
Cell Transmission

To analyze the spreading regularity of the initial traffic congestion, the improved cell transmission model (CTM) is proposed to describe the evolution mechanism of traffic congestion in regional road grid. Ordinary cells and oriented cells are applied to render the crowd roads and their adjacent roads. Therefore the traffic flow could be simulated by these cells. Resorting to the proposed model, the duration of the initial traffic congestion could be predicted and the subsequent secondary congestion could be located. Accordingly, the spatial diffusion of traffic congestion could be estimated. At last, taking a road network region of Hangzhou city as an example, the simulation experiment is implemented to verify the proposed method by PARAMICS software. The result shows that the method could predict the duration of the initial congestion and estimate its spatial diffusion accurately.

Modelling Heterogeneous and Undisciplined Traffic Flow using Cell Transmission Model

2020 ◽  
Vol 02 (01) ◽  
pp. 01-05
Author(s):  
Afzal Ahmed ◽  
Mir Shabbar Ali ◽  
Toor Ansari
Keyword(s):  
Traffic Flow ◽  
Traffic Simulation ◽  
Flow Diagram ◽  
Transmission Model ◽  
Flow Density ◽  
Cell Transmission Model ◽  
Flow Models ◽  
Simulation And Optimization ◽  
Cell Transmission ◽  
Traffic Flow Models

This research calibrates Cell Transmission Model (CTM) for heterogeneous and non-lane disciplined traffic, as observed in Pakistan and some other developing countries by constructing a flow-density fundamental traffic flow diagram. Currently, most of the traffic simulation packages used for such heterogonous and non-lane-disciplined traffic are not calibrated for local traffic conditions and most of the traffic flow models are developed for comparatively less heterogeneous and lane-disciplined traffic. The flow-density fundamental traffic flow diagram is developed based on extensive field data collected from Karachi, Pakistan. The calibrated CTM model is validated by using actual data from another road and it was concluded that CTM is capable of modelling heterogeneous and non-lane disciplined traffic and performed very reasonably. The calibrated CTM will be a useful input for the application of traffic simulation and optimization packages such as TRANSYT, SIGMIX, DISCO, and CTMSIM.

scholarly journals Exploring Traffic Congestion on Urban Expressways Considering Drivers' Unreasonable Behavior at Merge/Diverge Sections

2018 ◽  
Author(s):  
Kejun Long ◽  
Qin Lin ◽  
Jian Gu ◽  
Wei Wu
Keyword(s):  
Traffic Flow ◽  
Traffic Congestion ◽  
Queue Length ◽  
Transmission Model ◽  
Cell Transmission Model ◽  
Spatiotemporal Evolution ◽  
Lane Changing ◽  
Road Design ◽  
Urban Expressway ◽  
Road Geometry

Mechanism of traffic congestion generation is more than complicated, due to complex geometric road design and complicated driving behavior at urban expressway in China. We employ Cell transmission model (CTM) to simulate traffic flow spatiotemporal evolution process along the expressway, and reveal the characteristics of traffic congestion occurrence and propagation. Here we apply the variable-length-cell CTM to adapt the complicated road geometry and configuration, and propose the merge section CTM considering drivers' mandatory lane-changing and other unreasonable behavior at on-ramp merge section, and propose the diverge section CTM considering queue length end extending expressway mainline to generate dynamic bottleneck at diverge section. In the new improved CTM model, we introduce merge ratio and diverge ratio to describe the effect of driver behavior at merge and diverge section. We conduct simulation on the real urban expressway in China, results show that merge section and diverge section are the original location of expressway traffic congestion generation, on/off-ramp traffic flow has great effect on expressway mainline operation. When on-ramp traffic volume increases by 40%, merge section delay increases by 35%. And when off-ramp capacity increases by 100 veh/hr, diverge section delay decreases about by 10%, which proves the strong interaction between expressway and adjacent road networks . Our results provide the underlying insights of traffic congestion mechanism in urban expressway in China, which can be used to better understand and manage this issue.

scholarly journals Analysis and comparison of traffic flow models: a new hybrid traffic flow model vs benchmark models

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Facundo Storani ◽  
Roberta Di Pace ◽  
Francesca Bruno ◽  
Chiara Fiori
Keyword(s):  
Cellular Automata ◽  
Traffic Flow ◽  
Flow Model ◽  
Boundary Region ◽  
Driver Model ◽  
Transmission Model ◽  
Cell Transmission Model ◽  
Traffic Flow Model ◽  
Microscopic Models ◽  
Cell Transmission

Abstract Background This paper compares a hybrid traffic flow model with benchmark macroscopic and microscopic models. The proposed hybrid traffic flow model may be applied considering a mixed traffic flow and is based on the combination of the macroscopic cell transmission model and the microscopic cellular automata. Modelled variables The hybrid model is compared against three microscopic models, namely the Krauß model, the intelligent driver model and the cellular automata, and against two macroscopic models, the Cell Transmission Model and the Cell Transmission Model with dispersion, respectively. To this end, three main applications were considered: (i) a link with a signalised junction at the end, (ii) a signalised artery, and (iii) a grid network with signalised junctions. Results The numerical simulations show that the model provides acceptable results. Especially in terms of travel times, it has similar behaviour to the microscopic model. By contrast, it produces lower values of queue propagation than microscopic models (intrinsically dominated by stochastic phenomena), which are closer to the values shown by the enhanced macroscopic cell transmission model and the cell transmission model with dispersion. The validation of the model regards the analysis of the wave propagation at the boundary region.

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