Fundamental diagram of traffic flow

The fundamental diagram of traffic flow is a diagram showing the relationship between traffic volume ( vehicles per hour, as traffic flow called ) and represents the traffic density (vehicles per kilometer ). The fundamental diagram is based on a macroscopic traffic flow model, which describes the relationship between traffic density, traffic speed and traffic volume. The fundamental diagram statements about the transmissivity of a road section can meet. In addition, simulations can be carried out, how does the traffic flow at inflow regulation, speed limits or other measures.

Significant statements

• There is a relationship between traffic density and vehicle speed, the more vehicles are driving on a road section, the lower the speed.
• To avoid traffic congestion and to keep a steady flow of traffic, a maximum of only so many vehicles are allowed to enter into a section of road, as in the same period also extend from the section.
• At a critical vehicle density and an associated vehicle speed, the state of traffic flow is stable changes to unstable.

The fundamental diagram is of particular importance in the design of transport systems and traffic management systems.