SYSTEM EVALUATION OF FREEWAY DESIGN AND OPERATIONS

A SYSTEM EVALUATION WAS CONDUCTED OF FREEWAY DESIGN OF OPERATIONS BY STUDYING THE BAY AREA FREEWAY OPERATIONS. THE DATA COLLECTION AND EVALUATION PHASES HAD THE FOLLOWING OBJECTIVES: (1) TO PROVIDE AN INVENTORY OF EXISTING TRAFFIC CONDITIONS ON APPROXIMATELY 140 DIRECTIONAL MILES OF FREEWAY IN THE SAN FRANCISCO BAY AREA, (2) TO IDENTIFY CRITICAL AREAS, ASCERTAIN WHY THEY ARE CRITICAL, AND ESTIMATE THEIR EFFECTS ON TRAFFIC OPERATIONS, (3) TO CONDUCT PRELIMINARY INVESTIGATIONS OF MEANS FOR IMPROVING IDENTIFIED CRITICAL AREA AND PREPARE PRELIMINARY ESTIMATES OF BENEFITS, AND (4) TO PERFORM SUPPLEMENTARY INVESTIGATIONS; TO IMPROVE DATA COLLECTION TECHNIQUES AND TO EXTEND THE ANALYTICAL TECHNIQUES FOR GREATOR UNDERSTANDING OF FREEWAY OPERATIONS, THE TECHNIQUES ADOPTED AND THE RESULTS OBTAINED IN CONDUCTING THIS SYSTEM EVALUATION ARE BRIEFLY DISCUSSED. SOME 30 CRITICAL AREAS WERE IDENTIFIED ON THE 140 DIRECTIONAL MILES OF FREEWAY AND THE DESIGN AND OPERATIONAL DEFICIENCIES DETERMINED. THE EFFECTS OF EACH BOTTLENECK WERE ESTIMATED IN TERMS OF DELAY, AND VARIOUS DESIGN AND OPERATIONAL IMPROVEMENT PLANS EVALUATED. DELAYS AT 19 OF THE 31 CRITICAL AREAS WERE PARTLY ATTRIBUTED TO CAPACITY DEFICIENCIES CAUSED BY CHANGING DESIGN FEATURES. FOUR AREAS INVOLVED LOCATIONS WHERE THE NUMBER OF LANES WERE REDUCED; SEVEN INVOLVED LOCATIONS WHERE THE VERTICAL ALIGNMENT WAS CHANGED TO AN UPGRADE; AND 9 INVOLVED LOCATIONS WHERE WEAVING OR MERGING OR BOTH WERE MAJOR CONTRIBUTING FACTORS. OF SOME 5,000 VEHICLE HOURS OF DELAY OCCASIONED BY MOTORISTS DURING THE MORNING AND AFTERNOON PEAK PERIODS, APPROXIMATELY 60 PERCENT OCCURRED AT THESE LOCATIONS. OF THE 12 REMAINING CRITICAL AREAS, 11 ESSENTIALLY RESULTED FROM DEMAND INCREASES WITHOUT CORRESPONDING INCREASES IN CAPACITY. IT WAS DEMONSTRATED THAT A SYSTEM STUDY CAN DETERMINE THE LOCATION AND PRECISE CAUSE OF THE CONGESTION WHEN THE DETERMINATION IS MADE WITHIN THE CONTEXT OF FREEWAY DESIGN FEATURES.

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/sr/sr107/107-006.pdf
• Supplemental Notes:
  • 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
• Corporate Authors:

  Highway Research Board (HRB)

  Washington, DC   
• Authors:
  • Allen, Brian L
  • May, Adolf D
• Conference:
  • Second Western Summer Meeting
  • Location: Salt Lake City Utah, United States
  • Date: 1969-8-11 to 1969-8-13
• Publication Date: 1970

Media Info

• Media Type: Print
• Features: Figures; Tables;
• Pagination: p. 45-59
• Monograph Title: Highway safety
• Serial:
  • Highway Research Board Special Report
  • Issue Number: 107
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Bottlenecks; Data collection; Freeway operations; Freeways; Geometric design; Highway capacity; Highway design; Traffic congestion; Traffic delays
• Old TRIS Terms: Freeway design
• Subject Areas: Design; Highways; Operations and Traffic Management;

Filing Info

• Accession Number: 00203459
• Record Type: Publication
• Report/Paper Numbers: HS-011 158
• Files: HSL, TRIS, TRB, ATRI
• Created Date: Jul 21 1983 12:00AM