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Predictive Algorithm Improvements for a Real-Time Ramp Control System

Description: The purpose of this project was to determine the feasibility and evaluate the usefulness of a predictive ramp-metering algorithm, an algorithm that anticipates bottlenecks (a bottleneck being a reduction in the traffic capacity of the freeway) one to two minutes before their occurrence. The predictive algorithm was tested on-line in the Washington State Department of Transportation's ramp-metering central computer. 

The predictive algorithm's accuracy in predicting bottlenecks on-line was very good, with a correct prediction rate of almost 80 percent. The measured increase in volume and decrease in occupancy during a portion of the morning peak period showed that the predictive algorithm reduced the number and/or severity of bottlenecks on the freeway test section.


  • Date Published: September, 1991
  • Publication Number: WA-RD 213.1
  • Last Modified: September 25, 2007
  • Authors: Nancy L. Nihan, David B. Berg.
  • Originator: Washington State Transportation Center (TRAC)
  • # of Pages: 55 p., 1,165 KB (PDF)
  • Subject: Accuracy, Algorithms, Bottlenecks, Forecasting, Freeways, Peak periods, Ramp metering, Real time control, Traffic flow.
  • Keywords: Ramp metering, ramp control, predictive algorithm, traffic bottlenecks.
  • Related Publications:

This abstract was last modified April 29, 2008