In this paper a computer-aided approach is presented for testing, calibrating and evaluating any ramp control strategy desired for a particular freeway section or system including adjacent arterials (corridors). The methodology employs a versatile, easy to use microscopic simulator, which was selected after evaluating the most widely used ones. The selection criteria included ease of use, versatility, code availability and documentation, performance, and proven effectiveness through extensive employment in real projects. The simulator was enhanced to include an interface that allows integration of any user specified ramp control scheme. Enhancements were also made to automatically collect and feed demand patterns to the simulator. The entire simulation, database, and control logic package can be effectively used to estimate parameters and compare/evaluate ramp control strategies iteratively. New control strategies can also be implemented, tested, and calibrated by the user with relative ease. As a "test case" application, the ramp control logic developed by the Minnesota Department of Transportation (MnDOT) was implemented on a 24-km southbound segment of I-35W in Minneapolis and compared with the no-control alternative. In this manner the benefits of this ramp control strategy are quantified and presented. Improvements to the control strategy as well as testing of others are being planned with this methodology.
Abstract