Evaluation of traffic operations at diamond interchanges using advanced actuated control

Abstract

This thesis documents an operational analysis of ographics. advanced actuated traffic control at signalized diamond interchanges. The study attempts to determine the benefits a "flexible'' phasing strategy provides to the interchange. Flexible phasing is implemented by changing the diamond interchange ring structure within the traffic signal controller. Modeling the performance of the signal strategies is conducted using hardware-in-the-loop simulation. This procedure requires that a traffic signal controller is used in conjunction with a computer simulation package to model traffic flow and the interactions with the traffic signal. For this research, the microscopic traffic simulation model TexSIM was used. The collected data was analyzed to compare the different strategies for signal control. Based upon the results of this analysis, it was concluded that no one controller strategy and phase pattern performs best over 21 of the scenarios tested. The basic S3-phase lag-lag phasing sequence outperforms many of the other strategies because of the flexibility this strategy provides. Specifically, the one controller strategy outperformed the 2-controller strategy because of the reduction of cycle length during periods of low traffic intensity at the interchange. It was also concluded that flexible strategies could lead to reduced delay for special circumstances.