PRESSURIZED INTERSECTIONS

COMPARISON STUDIES ARE REPORTED ON CAPACITIES OF SIGNALIZED INTERSECTIONS IN THE BOSTON METROPOLITAN AREA COMPARED WITH RESULTS PRESENTED IN THE HIGHWAY CAPACITY MANUAL. DATA FROM 21 PRESSURIZED INTERSECTIONS (INTERSECTIONS WHERE THE APPROACH UNDERSTUDY HAD A CONTINUAL BACKLOG OF WAITING VEHICLES) INDICATED CAPACITIES IN EXCESS OF THOSE REPORTED IN THE MANUAL. VOLUMES ON APPROACHES AVERAGE 14% HIGHER THAN MANUAL AVERAGES. A MUCH HIGHER CAPACITY POTENTIAL, ESPECIALLY IN THE WIDER STREET WIDTH, IS INDICATED UNDER PRESSURIZED CONDITIONS WHICH MOTORISTS ARE CURRENTLY TOLERATING IN LARGER METROPOLITAN AREAS. THE FACTOR FOUND LOCALLY TO HAVE THE GREATEST INFLUENCE ON THE CAPACITIES WAS THE TURNING MOVEMENT. LEFT TURNS APPEAR TO HAVE A GREATER INITIAL EFFECT UNDER PRESSURIZED CONDITIONS THAN THE MANUAL INDICATES. LOCAL DATA INDICATES THAT WHEN LEFT-TURNING VOLUMES ARE EQUAL TO OR GREATER THAN 50% OF THE TOTAL APPROACH, THEY OPERATE AS THROUGH TRAFFIC WITH LITTLE REDUCTIVE EFFORT. THE EFFECT OF COMMERCIAL VEHICLES WAS FOUND CONSISTENT WITH THAT PROPOSED BY THE MANUAL. DATA INDICATE A GREATER EFFECT DUE TO THE PRESENCE OF COMMERCIAL VEHICLES WHEN THEY MAKE UP MORE THAN 20% OF THE TOTAL APPROACH VOLUME. THE STUDY INDICATES THAT THE REDUCTIVE EFFECT OF THE OPPOSING LEFT TURN IS SUFFICIENT TO BE EVALUATED ALONGSIDE THE USUAL LEFTS, RIGHTS, AND COMMERCIAL PERCENTAGES.

• Record URL:
  • http://onlinepubs.trb.org/Onlinepubs/hrbbulletin/167/167-004.pdf
• Supplemental Notes:
  • No 167, pp 42-62, 14 FIG. 1 TAB, 1 REF 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:
  • Blumenthal, Robert C
  • Horn, John W
• Publication Date: 1957

Media Info

• Monograph Title: Highway capacity studies
• Serial:
  • Highway Research Board Bulletin
  • Issue Number: 167
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Alternatives analysis; Commercial vehicles; Highway capacity; Intersections; Left turns; Manuals; Metropolitan areas; Traffic delays; Traffic surveys; Traffic volume; Turning traffic
• Uncontrolled Terms: Intersection capacity; Traffic studies; Turning movements
• Subject Areas: Highways; Operations and Traffic Management;

Filing Info

• Accession Number: 00225404
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Apr 28 1994 12:00AM