Use of Binary Choice Decision Process for Adaptive Signal Control

Adaptive signal control based on a binary‐choice decision process for timing adjustment has the potential to replace traffic‐actuated control. This emerging control strategy divides time into small intervals. In each interval, a decision is made either to terminate the current green phase or to extend it for another interval. This decision process can produce signal operations that are more efficient than existing traffic‐actuated operations. However, there is little understanding of the essential features that should be built into such a process. This paper examines four related issues and gives the results of computer simulation. The analysis reveals that it is sufficient for the binary‐choice decision process to rely solely on detected vehicle arrivals for the evaluation of alternative timing decisions. No predictions of other arrivals are needed. It is also found that, for monitoring vehicle arrivals, detectors do not have to be placed at locations more than 8 sec of travel time from the stop line. Furthermore, the binary choice requires the evaluation of an extremely limited number of alternative extensions of the current green phase.