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Method for controlling traffic flow

  • US 4,322,801 A
  • Filed: 03/18/1980
  • Issued: 03/30/1982
  • Est. Priority Date: 03/18/1980
  • Status: Expired due to Term
First Claim
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1. In an intersection system for controlling signal indicators of selected phases at a plurality of intersections in a group, said system having at least a first subsystem and a second subsystem, said first subsystem having as input signals a master timer signal of a recursive fixed length background cycle and selected signal states of said signal indicators, said second subsystem having as input signals at least one signal state indicative of a service permit for each phase from said first subsystem and at least one signal state indicative of a service request for each phase from the intersection, a method for allocating access to the intersection among the phases separated by a time barrier, wherein each phase is allocated a subdivisional split of a recursive local cycle of variable length, and wherein at least one phase is a priority phase designated for priority service in synchronism with the background cycle, said method comprising:

  • synchronizing the local cycle to said background cycle by providing a Benchmark signal at the barrier preceding said priority phase for each local cycle;

    issuing from said first subsystem to said second subsystem a service permit signal for each phase at selected intervals in the local cycle in response to the Benchmark signal in a manner to assure service to said priority phase in synchronism with said background cycle; and

    switching, by means of said second subsystem, said intersection signal indicators of a phase to a condition of intersection access only upon confluence of said service permit signal and said service request signal in a manner to avoid conflict between said phases.

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