Signal Operations Research Laboratory for Development and Testing of Advanced Control Strategies, Phase II

A corridor simulation environment with the capability of modeling various types of traffic control strategies as external control modules is critically important in developing and improving corridor management strategies. In this research, a microscopic network simulation model, Vissim, is used to develop such an environment. The new stratified Mn/DOT metering algorithm was simulated using the 169 freeway, and its performance was compared with that of the fixed-metering method. Based on that analysis, an alternative approach to determining each entrance ramp's minimum metering rate was developed and coded, as well as an adaptive approach to automatically coordinating a freeway meter with the adjacent intersection signal. The results clearly show the advantage of reducing the overall delay at the ramp-intersection area, while producing higher or compatible total vehicle-miles compared with the conventional intersection-control methods, i.e., pre-timed and actuated, without employing ramp metering. The corridor evaluation environment can be used for future studies, including the continuous enhancement of the stratified metering algorithm to take advantage of the maximum allowable wait time, automatic identification of the most effective metering strategy depending on prevailing traffic conditions, and extension of the adaptive coordination method to multiple intersections adjacent to a freeway entrance ramp.