00149215

Component

http://onlinepubs.trb.org...s/trr/1976/597/597-002.pdf

http://scholar.google.com...Shaw&publication_year=1976

The purpose of this paper is to investigate the long-term behavior of a class of closed-loop (feedback) traffic control systems that select an appropriate program from a prestored library on the basis of occupancy information. The subject of traffic control system instability is defined and expounded on. The effects of various factors on traffic control system behavior in general and on stability in particular are explored. Among the factors whose effects are scrutinized are sensor placement, degree of parameter smoothing (system damping), degree of directionality of the control-program library, and the value of threshold and hysteresis used for program selection. Sensor placement in locations sensitive to the formation of queues that require system action is advocated in combination with a threshold level composed in its entirety of a hysteresis band. Such a band is shown to provide a good match between traffic conditions and programs handling them and is also shown to reduce or eliminate unstable behavior under certain conditions. The results summarized in this paper were derived from simulating a closed-loop traffic control system operating on a four-intersection corridor. More than 600 simulation runs, each 1 h long (real time), were conducted for various combinations of parameter values. Aggregate delay is used as the measure of effectiveness for comparing these parameter-combination sets.

Publication of this paper sponsored by Committee on Traffic Control Devices. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.

01411453

FCP 42l1024

C-1-12

pp 10-18

1976

Transportation Research Record

0309025664

Digital/other

Figures (13) ; References (7)

Feedback control; Hysteresis; Libraries; Loops (Control systems); Sensors; Stability (Mechanics); Traffic control; Vehicle occupancy

Parameters; Thresholds

Highways; Operations and Traffic Management

TRIS, TRB

Mar 30 1977 12:00AM

• EVALUATION OF RAISED PAVEMENT MARKERS FOR REDUCING INCIDENCES OF WRONG-WAY DRIVING (ABRIDGMENT)
• GUIDELINES FOR APPLICATION OF SELECTED SIGNS AND MARKINGS ON LOW-VOLUME RURAL ROADS
• INDUCTIVE LOOP VEHICLE DETECTOR: INSTALLATION ACCEPTANCE CRITERIA AND MAINTENANCE TECHNIQUES (ABRIDGMENT)
• OPTIMAL CONTROL OF ISOLATED TRAFFIC SIGNALS (ABRIDGMENT)
• PLATOON DISPERSION CHARACTERISTICS ON ONE-WAY SIGNALIZED ARTERIALS (ABRIDGMENT)
• PROGRESSIVE SIGNAL SYSTEM IN A NETWORK OF ARTERIAL STREETS (ABRIDGMENT)
• SOME RESULTS ON GUIDELINES FOR TREATMENT OF THE TRAFFIC CONGESTION ON STREET NETWORKS
• SPEED REDUCTION IN SCHOOL ZONES (ABRIDGMENT)
• TRAFFIC-RESPONSIVE RAMP CONTROL THROUGH THE USE OF A MICROCOMPUTER (ABRIDGMENT)
• TRUCK BLOCKAGE OF SIGNALS