MEASUREMENTS OF THE NIGHT-TIME VISIBILITY OF SIGNS AND DELINEATORS ON AN AUSTRALIAN RURAL ROAD

THE VISIBILITIES OF IN-SERVICE SIGNS AND DELINEATORS HAVE BEEN MEASURED UNDER PRACTICAL DRIVING CONDITIONS ON A FOUR-LANE DIVIDED HIGHWAY. THE NIGHT-TIME EXPERIMENTS WERE CONDUCTED USING AMERICAN-BRITISH DIPPED BEAMS. IT WAS FOUND THAT THE NIGHT-TIME LEGIBILITY DISTANCES OF REFLECTIVE SIGNS WERE ON AVERAGE HALF THOSE OBTAINED DURING THE DAYTIME. AGEING AND DIRT ACCUMULATION WERE SHOWN TO REDUCE SIGN LEGIBILITY DISTANCES BY 30 PERCENT OR MORE AT NIGHT. THESE SAME FACTORS WERE FOUND TO REDUCE THE REFLECTIVITY OF DELINEATORS ON GUIDE POSTS SET BACK 10 FT FROM THE PAVEMENT BY AS MUCH AS 18 TIMES. THE CORRESPONDING REDUCTION IN VISIBILITY WAS FROM 1,000 FT TO LESS THAN 100 FT. THE MEAN DETECTION DISTANCE FOR THE 3 FT GUIDE POSTS WAS 590 FT FOR NORMAL OBSERVERS. ON AVERAGE, THE GUIDE POSTS WERE FOUND TO BE SLIGHTLY MORE VISIBLE THAN THEIR RED DELINEATORS. FOR A COLOR DEFECTIVE (PROTANOMAL) OBSERVER, THE MEAN DETECTION DISTANCE OF THE DELINEATORS WAS HALF THAT OF THE GUIDE POST. HEAVY RAIN WAS FOUND TO HAVE LITTLE EFFECT ON THE PERFORMANCE OF ENCLOSED LESN REFLECTIVE SHEETING, ALTHOUGH OTHER EVIDENCE SUGGESTS THAT DRIZZLE CAN REDUCE ITS VISIBILITY CONSIDERABLY. THE DEPENDENCE OF CURRENT SIGNING AND DELINEATION PRACTICES IN AUSTRALIA UPON A HIGH LEVEL OF MAINTENANCE HAS THEREFORE BEEN SHOWN. THE STUDY ALSO INDICATES THAT THERE IS A NEED FOR A CAREFUL EXAMINATION OF THE PRESENT STANDARDS FOR DELINEATORS. /AUTHOR/

• Record URL:
  http://arrbknowledge.com
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00050164
• Authors:
  • Hills, B L
• Publication Date: 1972-12

Language

• English

Media Info

• Features: Figures; Photos; References; Tables;
• Pagination: p. 39-56
• Serial:
  • Australian Road Research
  • Volume: 4
  • Issue Number: 10
  • Publisher: ARRB
  • ISSN: 0005-0164

Subject/Index Terms

• TRT Terms: Color blindness; Guideposts; Highway delineators; Legibility; Maintenance; Measurement; Night; Rainfall; Reflectivity; Rural areas; Standards; Traffic signs; Transportation disadvantaged persons; Visibility
• Uncontrolled Terms: Disadvantaged persons
• Old TRIS Terms: Delineators (Traffic)
• Subject Areas: Highways; Maintenance and Preservation; Public Transportation; Safety and Human Factors;

Filing Info

• Accession Number: 00224733
• Record Type: Publication
• Source Agency: Transport and Road Research Laboratory (TRRL)
• Files: TRIS, ATRI
• Created Date: May 24 1974 12:00AM