SOME IMAGINATIVE USES OF THE CALLING DETECTOR RELAY

BEFORE THE ADVENT OF LOOP DETECTORS, CALLING DETECTORS WERE OFTEN INSTALLED BETWEEN A PRESSURE DETECTOR AND A SIGNALIZED INTERSECTION TO HANDLE TRAFFIC ENTERING FROM LEGS BETWEEN THE DETECTOR AND THE SIGNAL. THIS MEANS THAT THE VEHICLE INTERVAL OF THE CONTROLLER CAN BE ACTUATED TWICE, CAUSING WASTED TIME. AS SUCH DETECTORS STILL HAVE THEIR USE, IT IS IMPORTANT THAT THEY CONTAIN A RELAY TO PREVENT THIS. THE CALLING DETECTOR RELAY CONSISTS OF A SINGLE, NORMALLY CLOSED RELAY THROUGH WHICH THE CALLING DETECTOR IS CONNECTED TO THE CONTROLLER. IN THIS WAY, BOTH THE CALLING DETECTOR AND THE NORMAL INTERSECTION DETECTOR CAN CALL FOR THE ASSOCIATED SIGNAL PHASE. ONCE THE SIGNAL TURNS GREEN TO THE ASSOCIATED PHASE, THE CALLING DETECTOR RELAY DISCONNECTS THE CALLING DETECTOR FROM THE CONTROLLER SO THAT IT CANNOT BE USED TO EXTEND THE GREEN TIME. OTHER USES OF THE RELAY CAN BE FOUND IN PEDESTRIAN-ACTUATED SIGNALS, RECALL OF THE CONTROLLER DURING PERIODS OF HEAVY PEDESTRIAN ACTIVITY, AND COORDINATION OF THE MINOR PHASES OF TWO ESSENTIALLY PARALLEL ARTERIAL STREETS IN A PROGRESSIVE TRAFFIC SIGNAL SYSTEM.

• Authors:
  • Orcutt, F L
• Publication Date: 1972-10

Media Info

• Features: Figures;
• Pagination: p. 42-5
• Serial:
  • Traffic Engineering, Inst Traffic Engr
  • Volume: 43
  • Issue Number: 1

Subject/Index Terms

• TRT Terms: Actuated traffic signal controllers; Pedestrian phase; Relays (Electricity); Traffic signal controllers; Vehicle detectors
• Old TRIS Terms: Actuated control; Calling detectors; Electric relays
• Subject Areas: Highways; Operations and Traffic Management;

Filing Info

• Accession Number: 00226584
• Record Type: Publication
• Files: TRIS
• Created Date: Apr 23 1973 12:00AM