DRIVER INTERACTIONS AND DELAYS IN FREEWAY TRAFFIC

THE AIM WAS TO DESCRIBE THE BEHAVIOR OF INDIVIDUAL DRIVERS IN NORMAL FREEWAY TRAFFIC. AN EXPERIMENTAL CAR WAS DRIVEN AT SLOW SPEEDS OF 50, 45, AND 40 MPH ALONG AN INTERSTATE HIGHWAY,CAUSING OVERTAKING DRIVERS TO REACT. WITHOUT THEIR AWARENESS, DRIVERS WERE PHOTOGRAPHED FROM A TOWER AND FROM THE EXPERIMENTAL VEHICLE ON THE ROAD. THE PHOTOGRAPHS WERE ANALYZED TO SHOW POSITIONAL RELATIONSHIPS OF THE EXPERIMENTAL CAR AND OVERTAKING DRIVERS AND TO SHOW CHANGES IN LEAD DISTANCE BETWEEN CARS AS A FUNCTION OF TIME. A DRIVER WHO APPROACHED IN A DIFFERENT LANE FROM THAT OF THE EXPERIMENTAL CAR AND WHO WAS UNOBSTRUCTED PASSED WITHOUT SLOWING. THE EXPERIMENTAL VEHICLE DID NOT INFLUENCE THE SPEED OF THESE PASSING DRIVERS. OBSTRUCTED DRIVERS, WHO CHANGED LANES TO PASS, ALSO DID NOT SLOW DOWN. ON THE BASIS OF THE DATA, IT SEEMS LIKELY THAT THE DECISION TO SHIFT IS MADE AT 250 FT OF SEPARATION DISTANCE OR LESS. NINE DRIVERS OF THE 166 STUDIED WERE OBSTRUCTED AND APPRECIABLY DELAYED. A TYPICAL OBSTRUCTED DRIVER SHOWS A THREE-PHASE RESPONSE. IN THE FIRST (APPROACH) PHASE, THE DRIVER MOVING AT HIS DESIRED PACE STARTS TO SLOW DOWN IN ANTICIPATION OF BEING BLOCKED. NEXT FOLLOWS A DELAYED PHASE OF FROM 15 TO 35 SECONDS, WHERE THE DRIVER MOVES TO A SLIGHTLY CLOSER POSITION OR MATCHES PACE WITH THE CAR IN FRONT. THIS PHASE IS RELATED TO TRADITIONAL CAR-FOLLOWING, BUT DRIVERS' RESPONSES ARE TOO INDIVIDUALISTIC TO BE REPRESENTED BY ANY SIMPLE CAR-FOLLOWING EQUATION. IN THE FINAL (PASSING) PHASE, THE DRIVER ASSUMES HIS ORIGINAL SPEED AND MOVES AHEAD OF THE CAR IN FRONT. THESE REACTIONS ARE PARTLY EXPLAINED BY THE DRIVER'S MOTIVATION TO MAINTAIN PACE AND MOVE AHEAD. PASSING DRIVERS AND BLOCKED DRIVERS DID NOT SLOW APPRECIABLY. ONLY WHEN THE DRIVER WAS EFFECTIVELY BLOCKED DID HE SLOW DOWN. TRADITIONAL CAR- FOLLOWING DID NOT OCCUR FREQUENTLY IN THIS STUDY, NOR DID DRIVERS APPEAR TO WANT TO FOLLOW THE CAR AHEAD. /AUTHOR/

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  • Supplemental Notes:
    • Paper sponsored by Committee on Road User Characteristics and presented at the 49th 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:
    • Gordon, Donald A
  • Publication Date: 1970

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 76-91
  • Monograph Title: Night visibility and driver behaviour
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00223441
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Jun 11 1971 12:00AM