Freeway Traffic Modeling and Control

The control of motorway networks provides great opportunities to prevent traffic jams and to reduce traffic emissions and fuel consumption.

The control design is based on macroscopic models which consider traffic as a compressible fluid and the flow is described using loop detector measurements of the traffic variables (i.e. traffic flow [veh/h], traffic density [veh/km], traffic mean speed [km/h]). These continuum models rely on the conservation law of vehicles and offer a basis for control design to avoid possible traffic jams, traffic shockwaves and the reducing of traffic emissions and consumption.

The most important control measures:
- dynamic speed limits: restricting flow speed, local capacity drop can be handled and traffic breakdown can be prevented.

- ramp metering: control of ramp flow merging the main lane provides opportunity for traffic flow stabilization.

With the joint use of these tools a multicriteria control can be designed in order to optimize travel times, fuel consumption and emissions.