EFFECT OF TEMPORARY BRIDGE ON PARKWAY PERFORMANCE

AN ANALYSIS WAS CONDUCTED ON THE EFFECTS OF TEMPORARY BRIDGES ON PARKWAY TRAFFIC IN CONNECTICUT TO: (1)DETERMINE WHAT FACTORS LIMITED THE CAPACITY OF THE TWO BRIDGES IN THE WEST-BOUND LANES, AND (2) ANALYZE THE CHARACTERISTICS OF A RURAL FREEWAY TRAFFIC STREAM OPERATING UNDER CONGESTED CONDITIONS CAUSED BY CONTINUING SPEED-REDUCING ROADWAY CONDITIONS. THE AVERAGE SPEED OF VEHICLES WAS DETERMINED DURING UNCONGESTED PERIODS TO BE 37.9 MPH AT 560 FEET BEFORE THE BRIDGE AND 25.7 MPH AT A POINT 150 FEET BEFORE THE BRIDGE. AS DENSITY INCREASED THE MEAN SPEED OF VEHICLES WAS 10.3 MPH AT 560 FEET BEFORE THE BRIDGE AND 15.5 MPH AT 150 FEET. THE MEAN ESTIMATE OF HOURLY VOLUMES PASSING THE BRIDGE DURING CONGESTION PERIOD WAS 2,253 VPH FOR BOTH LANES AS DENSITY INCREASES, SPEED DECREASES IN A STRAIGHT-LINE RELATIONSHIP. SPEED DECREASED AS VOLUME INCREASED UP TO A POINT OF CRITICAL SPEED AND CORRESPONDING CRITICAL DENSITY. MINIMUM AVERAGE SPACINGS AS LOW AS 36.6 FEET AT 7.8 MPH WERE OBSERVED. THE REQUIREMENT OF MAINTAINING A MINIMUM SPACING AT LOW SPEEDS RESULTED IN A DECREASE IN THE NUMBER OF HEADWAYS UNDER TWO SECONDS. THIS INCREASED THE MEAN HEADWAY AND CONSEQUENTLY LIMITED THE VOLUMES OBSERVED AT THE BRIDGE.

• Record URL:
  • http://onlinepubs.trb.org/Onlinepubs/hrbbulletin/167/167-005.pdf
• Supplemental Notes:
  • No 167, pp 63-74, 8 FIG, 4 TAB, 4 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:
  • Huber, Matthew J
• 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: Analysis; Headways; Highway bridges; Highway capacity; Parkways; Performance; Rural highways; Spacing; Traffic; Traffic congestion; Traffic density; Traffic speed; Traffic volume
• Uncontrolled Terms: Temporary; Traffic analysis
• Subject Areas: Highways; Operations and Traffic Management;

Filing Info

• Accession Number: 00225405
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Apr 28 1994 12:00AM