A DISCRETE MARKOV RENEWAL MODEL OF A GAP-ACCEPTANCE ENTRANCE RAMP CONTROLLER FOR EXPRESSWAYS

IN A GAP-ACCEPTANCE ENTRANCE RAMP CONTROL SYSTEM, VEHICLES ARE RELEASED FROM A QUEUE ON AN ENTRANCE RAMP AND ARE INSERTED INTO THE GAPS IN THE RIGHT LANE OF THE FREEWAY STREAM. FOR THIS SYSTEM A GAP THRESHOLD, T, IS DEFINED TO BE THE MINIMUM ACCEPTABLE TIME-HEADWAY BETWEEN VEHICLES IN THE OUTSIDE LANE INTO WHICH A VEHICLE THAT IS WAITING ON THE RAMP MAY ATTEMPT TO MERGE. THE GAP THRESHOLD T, DETERMINES THE DYNAMICS OF THE RAMP CONTROL PROCESS. WHEN T IS CHOSEN TO BE TOO SMALL, MANY DRIVERS REJECT THE GAP THAT IS OFFERED TO THEM WHEN THEY REACH THE MERGE ZONE. THIS REJECTION CAUSES A DELAY TO ALL DRIVERS QUEUED AT THE CONTROL SIGNAL ON THE ENTRANCE RAMP. LIKEWISE, WHEN T IS CHOSEN LARGE THE MERGE OPPORTUNITIES OCCUR INFREQUENTLY AND AGAINST EXCESSIVE QUEUES DEVELOP. A DISCRETE MARKOV RENEWAL MODEL OF AN ENTRANCE RAMP CONTROL SYSTEM IS PRESENTED AND THIS MODEL IS UTILIZED TO DETERMINE THE VALUE OF THE GAP THRESHOLD WHICH MINIMIZES THE EXPECTED STATIONARY QUEUE LENGTH ON THE ENTRANCE RAMP. IT IS SHOWN THAT THIS OPTIMUM VALUE FOR T CAN BE READILY DETERMINED BY SIMPLE MEASUREMENTS AT THE ENTRANCE RAMP THUS PROVIDING THE BASIS FOR A TRAFFIC-DEPENDENT CONTROLLER.

• Supplemental Notes:
  • Vol 4, No 28 PP 151-161, 14 REF, 1 APP
• Corporate Authors:

  System Development Corporation

  2500 Colorado Avenue
  Santa Monica, CA  United States  90409
• Authors:
  • Wiener, R
  • Pignataro, L J
  • Yagoda, H N
• Publication Date: 0

Media Info

• Serial:
  • Transportation Research /UK/
  • Issue Number: 0
  • Publisher: Pergamon Press, Incorporated

Subject/Index Terms

• TRT Terms: Actuated traffic signal controllers; Expressways; Gap acceptance; Interchange ramps; Mathematical models; Merging traffic; On ramps; Queuing; Traffic actuated controllers; Traffic delays; Traffic simulation
• Old TRIS Terms: Freeway ramps
• Subject Areas: Highways; Operations and Traffic Management;

Filing Info

• Accession Number: 00227279
• Record Type: Publication
• Files: TRIS
• Created Date: Oct 13 1970 12:00AM