Self-Organizing Control Logic for Oversaturated Arterials

Abstract

Decentralized, actuated traffic signal control has many advantages, but it lacks mechanisms for coordinating with other signals along an arterial. When an intersection along an arterial is near or at oversaturation, coordination can play an important role in preserving and utilizing capacity by preventing spillback and starvation. Rules that can be added to a base of decentralized, clock-free actuated control are proposed for managing queues during periods of oversaturation. These rules are part of a larger framework for developing logic that will make arterial traffic signals self-organizing rather than organized around a common signal cycle. Features of the proposed logic include green truncation in case of intersection spillback, early green and double realization for left-turn phases prone to pocket spillback resulting from a limited turn-bay length, and dynamic coordination for groups of signals spaced too close together to hold a normal cycle's queue. With dynamic coordination, green waves are scheduled for each cycle following the critical intersection's critical arterial through phase, with noncritical intersections adjusting offsets based on queue counts and a logic. The proposed dynamic coordination logic allows temporary spillback at upstream intersections to prevent starvation at the critical intersection and temporary starvation at downstream intersections to prevent spillback at the critical intersection. Simulation tests using a benchmark network showed 45% less delay than standard coordinated control and 4% less than an optimizing control method designed for oversaturated arterials. Simulation tests on two realistic networks also showed delay reductions of 8% and 35% compared with coordinated control.

Short-Term Prediction of Signal Cycle on an Arterial With Actuated-Uncoordinated Control Using Sparse Time Series Models

“…Meanwhile, the Sparse VAR models perform better in predicting the next value of signal cycle among the five models, when the distance between signals is high (1000 meters) and the demand is high as well. Such mathematical findings can be interpreted in practical research that has been conducted by transportation scholars on self-organizing signal control (Moghimidarzi et al 2016, Furth and Cesme, 2013. It indicates that when signals are closely spaced, those signals should be synchronized together by having the same cycle length.…”

Investigation of Self-Organizing Traffic Signal Control with Graphical Signal Performance Measures

“…The results of Gershenson (8) might have resulted partly from the idealized test environment, as subsequent researchers (10,11) have observed. The initial study network had equally spaced intersections, a single lane on every approach, no turning traffic, and a grid of streets that "wrapped around" so that traffic disappearing off of the left side of the screen reappeared on the right side, enabling traffic patterns to converge.…”

“…Lämmer and Helbing proposed a similar control scheme (9). More recently, Cesme and Furth (10,11) examined whether selforganizing control could be implemented by adding new methods of phase extension to fully actuated control, and Xie et al (12) proposed a self-scheduling method that was based on identifying inbound platoons.…”

Performance Measures for Traffic Signal Systems: An Outcome-Oriented Approach

“…It is common to place recalls to make the controller rest in green along the major street. Variablecycle fully actuated systems are generally not coordinated, although there has been research into ways of coordinating neighboring intersections by adding extended features to the usual set of fully actuated control parameters (27).…”

“…Some adaptive systems predict or track platoons through the system or schedule green bands in advance (14). Some proposed algorithms may be able to accommodate platoons (32,33) or yield dynamic signal coordination as an emergent phenomenon (27,34). This discussion focuses on conventional coordination methods, since the central concepts apply to all methods of signal coordination.…”