Investigating Transfer Flow between Urban Networks Based on a Macroscopic Fundamental Diagram

2018 ◽  
Vol 2672 (20) ◽  
pp. 75-85 ◽  
Author(s):  
Sunghoon Kim ◽  
Sehyun Tak ◽  
Hwasoo Yeo
Keyword(s):  
Spatial Inhomogeneity ◽  
Microscopic Simulation ◽  
Fundamental Diagram ◽  
Traffic Dynamics ◽  
Simulation Experiments ◽  
Urban Networks ◽  
Urban Road ◽  
Macroscopic Fundamental Diagram ◽  
Transfer Flow ◽  
Supply Level

The aim of the concept of perimeter control is to manage the transfer flow between urban road networks. However, there is a lack of description on the behavior of transfer flow between networks in relation to the macroscopic fundamental diagram (MFD). Hence, this paper suggests a description of transfer flow and investigates it with microscopic simulation experiments. The results found that the network outbound demand strongly influences the outflow regardless of spatial inhomogeneity. Another finding is that the boundary capacity influences the network outflow. The effect of restriction on outflow of a network due to limited supply level of a neighboring network was also checked. Furthermore, it was found that a network’s inflow and outflow in each direction (north, south, east, and west) is proportional to the demand ratio. Finally, the suggested description of transfer flow has been confirmed, and this can be useful for various analyses on inter-network traffic dynamics.

Investigation of Bimodal Macroscopic Fundamental Diagrams in Large-Scale Urban Networks: Empirical Study with GPS Data for Shenzhen City

2019 ◽  
Vol 2673 (6) ◽  
pp. 114-128 ◽  
Author(s):  
Chongxuan Huang ◽  
Nan Zheng ◽  
Jun Zhang
Keyword(s):  
Large Scale ◽  
Gps Data ◽  
Fundamental Diagram ◽  
Traffic Dynamics ◽  
Modeling Tools ◽  
Great Opportunity ◽  
Urban Networks ◽  
Macroscopic Fundamental Diagram ◽  
Analytical Approximations ◽  
Shenzhen City

This paper investigates traffic dynamics in bimodal urban networks utilizing the macroscopic fundamental diagram (MFD) and the three-dimensional macroscopic fundamental diagram (3D-MFD), which are network-level traffic flow modeling tools. Although the existence and the properties of the MFD have been extensively analyzed with field data in literature, few empirical studies examine these features of the 3D-MFDs for large-scale networks. For this work, GPS data for cars and buses running in the network of Shenzhen city in China are available for analysis and this offers a great opportunity for the investigation. Interestingly, both MFD and 3D-MFD dynamics are reflected in the data. Network partition is performed to reduce the hysteresis on the MFD and the network is split into two regions for further analysis. Then the investigation focuses on the MFD relationship for buses only. The average passenger occupancy is estimated and incorporated to generate a passenger MFD (pMFD) for buses. Moreover, bus operation on dedicated bus lanes is analyzed. Having understood traffic dynamics of cars, buses, and passengers respectively, the 3D-MFDs which illustrate the joint influence of car and bus accumulations on the global network-level traffic performance are presented. Given the scatter plot of the 3D-MFDs for the two partitioned regions, analytical approximations are provided, fitting by exponential functions. These results are promising, as they confirm the traffic features that were found from simulation-based studies in previous work.

scholarly journals Simulation-Based Design of Urban Bi-modal Transport Systems

2020 ◽  
Vol 1 ◽  
Author(s):  
Gabriel Tilg ◽  
Zain Ul Abedin ◽  
Sasan Amini ◽  
Fritz Busch
Keyword(s):  
Transport System ◽  
Three Dimensional ◽  
Optimization Techniques ◽  
Transport Systems ◽  
Fundamental Diagram ◽  
Urban Networks ◽  
Strategic Design ◽  
Macroscopic Fundamental Diagram ◽  
Simulation Based ◽  
Road Space

The three-dimensional passenger macroscopic fundamental diagram (pMFD) describes the relation of the network accumulation of public transport and private vehicles, and the passenger production. It allows for modeling the multi-modal traffic dynamics in urban networks and deriving innovative performance indicators. This paper integrates this concept into a multi-modal transport system design framework formulated as a simulation-based optimization problem. In doing so, we consider the competition for limited road space and the operational characteristics, such as congestion occurrences, at the strategic design level. We evaluate the proposed framework in a case study for the Sioux Falls network. Thereby, we deliver a proof of concept, and show that the proposed methodology indeed designs a transport system which benefits the overall system's performance. This paper further advances the integration of sequential model-based optimization techniques, macroscopic traffic flow concepts, and traffic simulation to design multi-modal transport systems. This supports transport planners and local authorities in composing efficient and robust transport networks.

scholarly journals Macroscopic Traffic Dynamics in Urban Networks during Incidents

2020 ◽  
Author(s):  
Sasan Amini ◽  
Gabriel Tilg ◽  
Fritz Busch
Keyword(s):  
Hysteresis Loop ◽  
Network Performance ◽  
Route Choice ◽  
Urban Traffic ◽  
Incident Management ◽  
Fundamental Diagram ◽  
Traffic Dynamics ◽  
Urban Networks ◽  
Wide Range ◽  
Traffic Incident Management

The degradation of road network performance due to incidents is a major concern to traffic operators. The development of urban traffic incident management systems requires a comprehensive understanding of traffic dynamics during incidents. Recently, the concept of the macroscopic fundamental diagram (MFD) contributed to such an understanding and has been used in a wide range of applications. However, the MFD is merely reproducible under recurring traffic patterns. Motivated by a few studies which argue the existence of the MFD with a clockwise hysteresis loop during incidents, we tackle this limitation of the MFD and propose a framework to study the characteristics of the MFD under non-recurring congestion. More specifically, we introduce a criticality score (CS) which represents network redundancy and postulate that links with a higher level of CS impose a larger hysteresis loop on the MFD. We design an experiment in a microscopic traffic simulation to study the relation of closed links and the resulting MFDs. The results confirm our postulation and we observe that links with similar CS have a comparable impact on the shape of the MFD. The main contribution of this paper is the possibility to develop a framework for incident detection in urban networks under limited sensor coverage. However, the findings of the study may strongly rely on the assumptions, for instance, the network structure, the OD pairs, and drivers route choice during incidents. Thus, future studies are required to study other network topologies as well as more realistic driver route choice during incidents.

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