TRAFFIC CAPACITY

A TRAFFIC STUDY WAS MADE TO DETERMINE THE RELATIVE CAPACITY OF TWO-LANE, THREE-LANE, AND FOUR-LANE ROAD-WAYS. CONGESTION WAS DEFINED AS THAT WHICH OCCURS ON A ROAD WHEN THE NUMBER OF VEHICLES IS GREAT ENOUGH TO FILL THE ROAD AND MAKE TURNING OUT IMPRACTICABLE AND THIS CONDITION MUST LAST A SUFFICIENT TIME TO BE NOTICEABLE. TRAFFIC COUNTING RESULTS ARE PRESENTED IN A TABLE. THE FOLLOWING CONCLUSIONS ARE DRAWN FROM THE DATA PRESENTED: (1) THE TWO-LANE ROAD IS PRACTICALLY FREE FROM CONGESTION UP TO 1,000 VEHICLES PER HOUR, (2) THE THREE-LANE ROAD IS PRACTICALLY FREE FROM CONGESTION UP TO 1600 VEHICLES PER HOUR, AND IS CONGESTED NOT TO EXCEED ONE-FIFTH OF THE TIME UP TO 1900 VEHICLES PER HOUR, (3) WITH FURTHER INCREASE IN THE NUMBER OF VEHICLES PER HOUR, CONGESTION INCREASES AT A MORE RAPID RATE ON A TWO-LANE ROAD THAN ON A THREE-LANE ROAD, AND (4) WHEN FOUR-FIFTHS OR MORE OF THE TRAFFIC IS IN ONE DIRECTION, THE TWO-LANE ROAD IS PRACTICALLY FREE FROM CONGESTION UP TO 1300 VEHICLES PER HOUR, AND THE THREE-LANE ROAD UP TO 2300 VEHICLES PER HOUR. MCKAY COMMENTS THAT THE QUESTION OF HOW MANY TRAFFIC LANES SHOULD BE PROVIDED FOR A COMPLETED PROJECT DEPENDS UPON KNOWLEDGE OF THE AMOUNT OF TRAFFIC. THE QUESTION AS TO WHO HAS THE RIGHT OF WAY IN THE MIDDLE LANE UNDER EQUAL TRAFFIC FLOW CONDITIONS ON A THREE-LANE ROADWAY IS RAISED.

  • Record URL:
  • Supplemental Notes:
    • Vol 10, pp 218-224, 2 FIG, 2 TAB; part of Report of Committee on Highway Traffic. 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:
    • Johnson, A N
  • Discussers:
    • McKay, J G
  • Publication Date: 1931

Media Info

  • Media Type: Digital/other
  • Features: Figures; Tables;
  • Pagination: p. 218-224
  • Monograph Title: Proceedings of the Tenth Annual Meeting of the Highway Research Board Held at Washington, D.C. December 11-12, 1930
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00227992
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Jun 1 1987 12:00AM