APPLICATIONS OF AUTOMATIC TRAFFIC RECORDER DATA IN HIGHWAY PLANNING

AUTOMATIC TRAFFIC RECORDERS ARE BEING USED IN 46 STATES TO OBTAIN CONTINUOUS DATA AT MORE THAN 500 LOCATIONS. DATA FROM TYPICAL STATIONS THROUGHOUT THE UNITED STATES HAVE BEEN ANALYZED TO MEASURE THE TIME DURING WHICH A HIGHWAY SECTION IS CONGESTED AND THE FRACTION OF THE YEAR'S TRAFFIC WHICH IS MOVED UNDER CONDITIONS OF CONGESTION; TO TEST THE RESULTS OF VARIOUS SCHEDULES OF OPERATION THAT ARE USED IN THE HIGHWAY PLANNING SURVEYS; TO ESTIMATE ANNUAL TRAFFIC VOLUME WHEN THE PERIOD OF COUNTING COVERS A SMALL PORTION OF THE YEAR; TO STUDY TRAFFIC TRENDS AND THEIR RELATIONSHIP TO ECONOMIC FACTORS AND TO PROBABLE FUTURE TRAFFIC. IT WAS FOUND THAT THERE WAS AN EXTREMELY WIDE VARIATION IN THE RATIOS BETWEEN MAXIMUM DAYS OR HOURS AND THE AVERAGE ANNUAL DAILY TRAFFIC, BUT THIS VARIATION WAS CONSIDERABLY LESS AT LOCATIONS IN THE SOUTHERN STATES AS COMPARED WITH THOSE IN NORTHERN STATES. THE MAXIMUM DAY IS NORMALLY 233 PER CENT AND THE MAXIMUM HOUR 25.4 PER CENT OF THE AVERAGE ANNUAL DAILY TRAFFIC. HOWEVER, THE VARIATION IN THESE RATIOS BETWEEN LOCATIONS IS SUCH THAT DETAILED DATA ARE NECESSARY FOR A COMPLETE ENGINEERING ANALYSIS OF THE TRAFFIC FACILITIES REQUIRED. TESTS OF VARIOUS SCHEDULES OF OPERATION THAT ARE USED IN HIGHWAY PLANNING SURVEYS INDICATE THAT EIGHTEEN 8-HR. COUNTS PROPERLY SCHEDULED THROUGHOUT THE YEAR PRODUCE RESULTS WITHIN PRACTICAL LIMITS OF ACCURACY; THAT AT OTHER LOCATIONS FOUR 8-HR. COUNTS SEASONALLY SPACED ARE ALSO SUFFICIENTLY ACCURATE WHEN USED IN CONJUNCTION WITH THE FORMER SCHEDULE; THAT THE SHORT COUNT SCHEDULE IS NOT SO ACCURATE, AND ITS USE IS LIMITED TO RELATIVELY COMPACT AREAS SUCH AS A CITY, WHERE TIME LOSS AND COST OF TRAVEL MAY BE REDUCED. A STUDY OF THE INVARIANCE IN SEASONAL AND OTHER TYPES OF TRAFFIC VARIATION OVER A PERIOD OF SEVERAL YEARS MEASURES THE LIMITATIONS IN THE USE OF "FACTORS" IN THE ESTIMATE OF ANNUAL TRAFFIC FROM OBSERVATIONS COVERING BUT A SMALL PERIOD OF TIME, POSSIBLY A FEW HOURS. THE RATHER REMARKABLE UNIFORMITY IN SUCH FACTORS PROVIDES CONSIDERABLE CONFIDENCE IN THE ACCURACY OF THE ESTIMATES. /AUTHOR/

  • Supplemental Notes:
    • Vol 20, pp 200-234, 20 FIG, 16 TAB
  • Authors:
    • Peabody, L E
    • Normann, O K
  • Publication Date: 1941

Media Info

  • Monograph Title: Proceedings of the Twentieth Annual Meeting of the Highway Research Board Held at Washington, D.C. December 3-6, 1940
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00200447
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Sep 6 1971 12:00AM