Applications of model-based Variable Speed Limit (VSL) control have shown promise in resolving capacity drops and time delays for a single location with recurring bottleneck conditions. Researchers studied the application of VSL controls to a broader scenario, freeway corridors with multiple segments and multiple bottlenecks. With the objective of reducing fuel consumption and greenhouse gas emissions, three VSL control scenarios were developed and compared: static speed limit (no VSL), flow-based control, and density-based control. The flow-based fuel consumption centered VSL control strategy was designed based on the characteristics of shockwaves between adjacent bottlenecks to suppress the negative shockwave effects and maintain a fuel-efficient speed in the controlled segments. The second density-based strategy was designed to keep the density of freeway segments around an optimal level by managing the difference between optimal density and actual density.
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