PREDICTION AND STABILITY OF FREEWAY GAPS AND ON-RAMP MERGING

MERGING OF VEHICLES FROM ON-RAMP TO FREEWAY IS THE MOST LIKELY CAUSE OF FREEWAY CONGESTION AND DISTURBANCE BESIDES GEOMETRIC BOTTLENECKS AND FREEWAY ACCIDENTS. ONE OF THE EFFECTIVE WAYS TO CONTROL THIS TYPE OF CONGESTION AND DISTURBANCE IS PREDICTING INTERVEHICULAR ACCEPTABLE GAP SIZES BY DETECTORS PLACED IN THE SHOULDER LANE AT SOME POINT UPSTREAM OF THE ON-RAMP. VEHICLES FROM THE CONTROLLED-RAMP SITE ARE RELEASED AND COORDINATED TO MERGE INTO THE TRAFFIC WHENEVER AN ACCEPTABLE GAP IS DETECTED. THIS PAPER GIVES THE ANALYSIS ON THE PREDICTION OF GAPS AND THEIR ASSOCIATED ERRORS FOR SINGLE- AND DOUBLE-LOOP DETECTORS. ANALTYICAL EXPRESSIONS FOR ERRORS IN GAP PREDICTION AND SPEED ESTIMATION WERE DERIVED AND VALIDATED AGAINST EXPERIMENTAL OBSERVATION OBTAINED FROM AERIAL PHOTOGRAPHIC DATA AND WERE RELATED TO DIFFERENT SENSING PULSE RATES AND DETECTOR LOCATIONS FOR SINGLE- AND DOUBLE-LOOP DETECTORS. THE PROBLEM OF GAP PREDICTION WAS ALSO RELATED TO THE STABILITY OF TRAFFIC IN THE VICINITY OF AN ON-RAMP. THE EFFECTS OF LANE CHANGING AND VARIATION IN SPEED OF THE INDIVIDUAL CAR BETWEEN THE DETECTOR LOCATION AND THE ON-RAMP MERGE POINT WERE ALSO ANALYZED FROM EXPERIMENTAL DATA. A COMPARISON OF FIXED-METERING STRATEGY AND GAP-PREDICTION STRATEGY IS MADE, AND THE FIXED-METERING RATE IS DETERMINED ACCORDING TO THE MEASURED OCCUPANCY FROM THE EXPERIMENTAL DATA. RESULTS INDICATE THAT THE GAP-PREDICTION STRATEGY HAS GREAT APPLICATION VALUE.

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/hrr/1973/469/469-003.pdf
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/030902255X
• Supplemental Notes:
  • Publication of this paper sponsored by Committee on Freeway Operations. 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:
  • Munjal, P K
  • Hsu, Yar-Sun
  • Lawrence, R L
• Discussers:
  • Sebastian, Oscar L
• Conference:
  • 52nd Annual Meeting of the Highway Research Board
  • Location: Washington District of Columbia, United States
  • Date: 1973-1-22 to 1973-1-26
• Publication Date: 1973

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: pp 26-39
• Monograph Title: Freeway operational improvements
• Serial:
  • Highway Research Record
  • Issue Number: 469
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Detectors; Forecasting; Gap grading; Interchange ramps; Merging traffic; Ramp metering; Traffic congestion; Weaving traffic
• Old TRIS Terms: Freeway ramps
• Subject Areas: Highways; Operations and Traffic Management;

Filing Info

• Accession Number: 00226857
• Record Type: Publication
• ISBN: 030902255X
• Files: TRIS, TRB
• Created Date: Apr 20 1974 12:00AM