The purpose of this study was to evaluate the effects of dew and frost on the nighttime legibility of several possible combinations of retroreflective legend and background materials under headlight illumination. Observations were made over an 8-month period, from April through November, in central Kentucky. A total of 31 nights with observed natural dew or frost formation between 9:00 p.m. and midnight were selected for purposed of sign evaluation. The observation site was at Blue Grass Field, the Lexington-Fayette County, Kentucky, airport in a small valley surrounded on three sides by runways, taxiways, and airport service facilities. A National Oceanic and Atmospheric Administration weather service station at the airport provided ready access to needed atmospheric data. The performance of encapsulated-lens retroreflective sign materials was found to be far superior to that of enclode-lens material and equal (for light dew) or superior (for heavy dew) to button copy. The observed decreses in sign legibility and target value because of dew and frost formation were always more pronounced on the plywood-braced sign panels than on the plain aluminum panels.

Media Info

  • Media Type: Print
  • Features: Figures; Photos; References; Tables;
  • Pagination: pp 16-20
  • Monograph Title: Traffic control devices, visibility and geometrics
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00196633
  • Record Type: Publication
  • ISBN: 0309028264
  • Files: TRIS, TRB
  • Created Date: Sep 15 1979 12:00AM