NIGHTTIME VISIBILITY OF TURN PROHIBITION WITH 20/40 ACUITY

Twenty subjects artifically blurred to a level of 20/40 acuity were used to determine the minimum visibility distance of turn prohibition signs at several intersections during darkness hours. The details are described of the tests which revealed that the signs in Hamilton, Ontario (reflectorized signs mounted adjacent to the signal lights some 15 feet above the roadway and placed in the side of the intersection roadway that is remote from traffic as it approaches; night time illumination is limited to street lighting in the area of the sign and the signal light itself) have a very limited night-time visibility for drivers with 20/40 acuity. The tests also showed that: the sign is consistently visibile from a greater distance when the light is green than when it is red: there is considerable variation is mean visibility from intersection to intersection; and there is variation between distances measured from different subjects.

• Corporate Authors:

  Institute of Traffic Engineers

  2029 K Street, NW
  Washington, DC    20006
• Authors:
  • Attridge, J A
• Publication Date: 1976-5

Media Info

• Features: Figures; References; Tables;
• Pagination: p. 22-24
• Serial:
  • Traffic Engineering
  • Volume: 46
  • Issue Number: 5
  • Publisher: Institute of Traffic Engineers

Subject/Index Terms

• TRT Terms: Green interval; Hot rolling; Intersections; Night visibility; Red interval (Traffic signal cycle); Reflective signs; Signal lights; Street lighting; Visual perception
• Uncontrolled Terms: Mill scale
• Old TRIS Terms: No turn signal
• Subject Areas: Highways; Safety and Human Factors;

Filing Info

• Accession Number: 00135402
• Record Type: Publication
• Files: TRIS
• Created Date: Jul 22 1976 12:00AM