Abstract :
The growing traffic congestion on national highways requires an increase in utilizing automarion in traffic control. One of the possibilities of improving the efficiency of controlling large stretches of highways is by using real-time computer control. Monitoring and sensing devices would be introduced and placed along a highway at selected places. One of the possible values to be measured is the cumulative count of vehicles at a certain place. This cumulative count should be recorded along with the appropriate real time. With this information on record, the flow rate and vehicle density at specific locations of the highway and at specific times, could be readily calculated. The data measured along the highway are transmitted to a central computer system and recorded in memory along with the appropriate times and places. The computations of flow rates, densities and other items that may be required, are performed by the same computer. A model representing the dynamics of the traffic flow will be adopted. Several possible models have already been proposed in the past. In the adopted model the vehicle flow rates, densities and velocities, will be connected by linearized difference equations which will serve as constraints in the optimization problems that will evolve. The equations representing the model (or several models available optionally) will be programmed and stored in the central computer. The equations will include the on- and off- ramp flow rates, which will constitute the control variables in many cases.
