Fundamental Diagram of Traffic Flow - Basic Statements

Basic Statements

  • There is a connection between traffic density and vehicle velocity: The more vehicles are on a road, the slower their velocity will be.
  • To prevent congestion and to keep traffic flow stable, the number of vehicles entering the control zone has to be smaller or equal to the number of vehicles leaving the zone in the same time.
  • At a critical traffic density and a corresponding critical velocity the state of flow will change from stable to unstable.
  • If one of the vehicles brakes in unstable flow regime the flow will collapse.

The primary tool for graphically displaying information in the study traffic flow is the fundamental diagram. Fundamental diagrams consist of 3 different graphs: flow-density, speed-flow, and speed-density. The graphs are two dimensional graphs. All the graphs are related by the equation “flow = speed * density”; this equation is the essential equation in traffic flow. The fundamental diagrams were derived by the plotting of field data points and giving these data points a best fit curve. With the fundamental diagrams researchers can explore the relationship between speed, flow, and density of traffic.

Read more about this topic:  Fundamental Diagram Of Traffic Flow

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