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.

Media Info

  • Media Type: Digital/other
  • Features: Figures; References;
  • Pagination: pp 10-18
  • Monograph Title: Traffic control: signals and other devices
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00149215
  • Record Type: Publication
  • ISBN: 0309025664
  • Report/Paper Numbers: FCP 42l1024
  • Contract Numbers: C-1-12
  • Files: TRIS, TRB
  • Created Date: Mar 30 1977 12:00AM