| | Complex system [20] characteristic | Transportation system characteristic |
| | Large numbers of elements are manifold | Elements:
People (drivers, passengers, and pedestrian)
Vehicle (motor and nonmotor vehicle, train)
Facilities (road, tunnel, bridge, signal system, etc.)
Management (laws and regulations, management technique)
Environment (economic and culture) |
| | Interaction among the elements is more important than the element itself | The crux of transportation system’s maximum efficiency is the coordination of the elements |
| | Multiple causality among the elements | Transportation system consists of subsystems such as economy, number of vehicles, environment, travel demand, transport supply, and a traffic congestion subsystem. Every subsystem has causality and there is special causality among the subsystems [21] |
| | Dynamic and nonlinear | Transportation system’s elements are in a stochastic condition; that is, they vary with time and space; their linear relationship, because of complex causality, cannot satisfy the requirements of modeling to simulate real transportation, so the modeling method has undergone several processes: statistics, differential equations, system dynamic, the models of complex network, and modeling method based on Agent [22] |
| | Self-organization and self-adaptiveness | A transportation system, because of randomness and complexity, can only operate in orderly fashion by using a self-feedback function. This is, in order for traffic flow tend to be in ordered under certain conditions, the transportation system should self-adjust, based on real-time traffic status, by control and management technologies [23], so that it has self-organization and self-adaptiveness |
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