Real-time capacity estimation for adaptive ramp metering

Ramp metering is an important traffic management measure the improve traffic conditions on the motorway. Ramp metering controls the flow of vehicles entering the motorway by means of a traffic light. The number of vehicles allowed to enter the motorway, or the metering rate, is determined by the ramp metering algorithm. In The Netherlands all ramp meters are equipped with the RWS ramp metering algorithm, which is a demand-capacity algorithm. This type of metering algorithm calculates the metering rate by subtracting the motorway traffic demand from the motorway capacity. For this purpose a value for the capacity is assumed by the control application in the ramp meter. However, the motorway capacity is not constant, but changes over time due to changes in, e.g., the weather, the driver population, or general travel purpose. Since the value for the assumed capacity determines the metering rate, the performance of a ramp meter will be as good as the quality of the assumption of the capacity. This project aims to improve the performance of the demand-capacity algorithm by adding an online capacity estimator to the control application in the ramp meter. This type of control is referred to as adaptive control.

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