GAP ACCEPTANCE CHARACTERISTICS FOR RAMP-FREEWAY SURVEILLANCE AND CONTROL AND DISCUSSION

GAP ACCEPTANCE CHARACTERISTICS AND MERGING DELAY CHARACTERISTICS WERE DETERMINED ON 6 INBOUND ENTRANCE RAMPS OF THE GULF FREEWAY. MERGING VEHICLES WERE DIVIDED INTO 2 GROUPS' THOSE IN WHICH THE DRIVER REJECTED GAPS BEFORE FINALLY ACCEPTING A GAP AND THOSE IN WHICH THE DRIVER OF A RAMP VEHICLE ACCEPTED THE FIRST GAP. THE FORMER WAS REFERRED TO AS STOPPED VEHICLES AND THE LATTER AS MOVING VEHICLES. THE CRITICAL GAP FOR STOPPED VEHICLES WAS FOUND TO BE ABOUT 20 PERCENT HIGHER THAN FOR MOVING VEHICLES. IT WAS CONCLUDED THAT THE CRITICAL GAP /MEDIAN/ FOR THE MERGING MANEUVER FROM AN ENTRANCE RAMP IS INDEPENDENT OF THE FREEWAY VOLUME BUT IS APPARENTLY AFFECTED BY RAMP GEOMETRICS AND RAMP CONTROLS. A DISTRIBUTION OF CRITICAL GAPS WAS FORMED AND FITTED TO A GAMMA DISTRIBUTION. MERGING DELAY VALUES CALCULATED USING THIS DISTRIBUTION WERE SHOWN TO BE HIGHER THAN THOSE CALCULATED ASSUMING THAT ALL DRIVERS HAVE THE SAME FIXED CRITICAL GAP. IF THE DISTRIBUTION TIME SPENT BY THE MERGING VEHICLE AT THE HEAD OF THE QUEUE IS APPROXIMATED BY A GAMMA DISTRIBUTION, THE ENTRANCE RAMP MERGING OPERATION MAY BE CONSIDERED WITHIN THE CONTEXT OF CLASSICAL QUEUING THEORY. BASED ON THIS QUEUING MODEL, A RAMP METERING TECHNIQUE WAS DEVELOPED, WHICH TAKES INTO ACCOUNT THE INDIVIDUALITY OF ENTRANCE RAMPS. IT IS SHOWN THAT THE NEED EXISTS FOR AN AUTOMATIC RAMP CONTROL TECHNIQUE COMBINING THE MICROSCOPIC APPROACH DEVELOPED IN THIS PAPER WITH THE SYSTEMS OR MACROSCOPIC APPROACH WHICH HAS BEEN USED AS THE BASIS FOR THE PAST MANUAL RAMP METERING EXPERIMENTS ON THE GULF FREEWAY.

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/hrr/1967/157/157-004.pdf
• Supplemental Notes:
  • Paper sponsored by Committee on Characteristics of Traffic Flow and presented at the 45th Annual Meeting. 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.
• Authors:
  • DREW, DONALD R
• Discussers:
  • Cribbins, Paul D
  • Dawson, R F
  • Kell, James H
  • Drew, D R
• Publication Date: 1967

Language

• English

Media Info

• Media Type: Digital/other
• Features: Appendices; Figures; References; Tables;
• Pagination: pp 108-143
• Monograph Title: Freeway traffic characteristics and control
• Serial:
  • Highway Research Record
  • Issue Number: 157
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Gap acceptance; Interchange ramps; Mathematical models; Merging traffic; Motion; Motor vehicles; Queuing theory; Stopping; Traffic control
• Uncontrolled Terms: Models; Moving vehicles; Stopped vehicles
• Old TRIS Terms: Freeway ramps; Metering; Queueing theory
• Subject Areas: Highways; Operations and Traffic Management;

Filing Info

• Accession Number: 00227054
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Aug 13 2004 6:56PM