REPORT OF COMMITTEE ON SAFE APPROACH SPEEDS AT INTERSECTIONS

THE MEANS OF OBTAINING AN ACCURATE PICTURE OF PRESENT PRACTICAL USE OF SAFE APPROACH SPEED METHODS WAS TO DETERMINE TO WHAT EXTENT TRAFFIC ENGINEERS WERE APPLYING THEIR KNOWLEDGE OF THESE METHODS. MANY INTERESTING FACTS WERE BROUGHT TO LIGHT IN THE QUESTIONNAIRE SURVEY MADE OF 45 STATE TRAFFIC AND HIGHWAY ENGINEERS AND 46 CITY TRAFFIC ENGINEERS. THE SURVEY INDICATED THAT THERE SEEMS TO BE CONSIDERABLE CONFUSION AND LACK OF UNDERSTANDING OF THE BASIC PRINCIPLES OF SAFE APPROACH SPEED STUDIES. NUMEROUS ENGINEERS APPARENTLY THOUGHT OF THE PROBLEM SOLELY IN THE LIGHT OF STATED SPEED SIGNS AND OVERLOOKED THE MORE IMPORTANT ASPECTS OF THE PROBLEM. A FIELD PROJECT WAS UNDERTAKEN AND A NUMBER OF OBSERVATIONS MADE AT VARIOUS SELECTED INTERSECTIONS. A PATTERN OF DRIVER BEHAVIOR ON APPROACHING BLIND INTERSECTIONS WAS OBTAINED BY UTILIZING A NEW METHOD OF CHECKING VEHICLE SPEEDS. THE SPEEDS WERE CHECKED AT SIX OR MORE CONSECUTIVE INTERVALS IN A 176-FT. APPROACH TRAP. IN THE PAST AN 88-FT. OR 176-FT. SPEED TRAP WAS USED TO OBTAIN AN OVERALL AVERAGE SPEED ON INTERSECTION APPROACHES. THESE APPROACH SPEED PATTERNS MAY BE USED (1) TO DETERMINE ACTUAL VEHICLE OPERATION ON APPROACH TO BLIND CORNERS IN AN ENDEAVOR TO DETERMINE WHY PEOPLE REACT SAFELY TO CERTAIN BAD INTERSECTIONS AND NOT TO OTHERS; (2) TO ASSIST IN DETERMINING POINTS FROM WHICH TO MAKE VISUAL OBSERVATIONS; (3) AS A CHECK AGAINST COMPUTED SAFE APPROACH SPEEDS; AND (4) AS A RESEARCH APPROACH TO THE WHOLE PROBLEM OF SAFE APPROACH SPEEDS. THE REPORT INCLUDES A DESCRIPTION OF THE FIELD TEST PROCEDURE USED AND THE ANALYSES OF DATA FROM THREE TYPICAL INTERSECTIONS. THE COMMITTEE RECOMMENDS, AS A FUTURE RESEARCH PROJECT, THE FURTHER DEVELOPMENT AND EXPANSION OF THIS METHOD OF OBTAINING APPROACH SPEED PATTERNS, INCLUDING THE DEVELOPMENT OF EQUIPMENT FOR CHECKING SPEEDS AUTOMATICALLY. /AUTHOR/

• Record URL:
  https://onlinepubs.trb.org/Onlinepubs/hrbproceedings/20/20-038.pdf
• Supplemental Notes:
  • Vol 20, pp 653-672, FIGS, TABS. 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:
  • Hammond, H F
  • Forbes, T W
  • Greenshields, B D
  • Dickinson, H C
• Discussers:
  • Marsh, B
• Publication Date: 1941

Media Info

• Media Type: Digital/other
• Monograph Title: Proceedings of the Twentieth Annual Meeting of the Highway Research Board Held at Washington, D.C. December 3-6, 1940
• Serial:
  • Highway Research Board Proceedings
  • Volume: 20
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Approach; Drivers; Field tests; Intersections; Location; Reaction time; Speed; Stopping distances; Traffic regulations; Traffic signs; Warrants (Traffic control devices)
• Uncontrolled Terms: Driver reaction
• Old TRIS Terms: Approach speed; Traffic warrants
• Subject Areas: Highways; Law; Operations and Traffic Management; Safety and Human Factors;

Filing Info

• Accession Number: 00223485
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Aug 15 1971 12:00AM