This study sought to reduce the risks of wet, nighttime driving by determining the minimum visibility required of roadway delineators. To isolate the contributions that discrete delineators have on guidance vision and drivers' reactions, test subjects were shown electronically digitized photographs of wet, nighttime roadways to which simulated delineation was added. The delineators' apparent size, shape, spacing, and contrast were calculated from models describing the visible effects of various rain conditions and roadway geometries. Subjects' scores were based on the minimum delineator contrast required to correctly identify curve directions in various scenes. A disproportionate number of older drivers were tested because this group especially needs enhanced delineation under these adverse seeing conditions. Of the noncontrast delineator variables studied, only spacing provided a statistically significant difference for both right and left curve groups, with wider spacing requiring greater contrast for correct response. The delineator size effect was non-significant for both test groups. The evaluation of delineator shape produced the greatest inconsistency across test groups; delineator shape effects were significant for the left curve test group only. Age group was statistically significant for only one of the test groups, but as expected, subjects age 65 and over generally required greater contrast for correct identification of curve direction. Likewise, for the effects of rainfall, the trend was in the expected direction, with heavier levels of rainfall requiring greater contrast for a correct response.

  • Corporate Authors:

    Pennsylvania State University, University Park

    Pennsylvania Transportation Institute, Transportation Research Building
    University Park, PA  United States  16802

    Federal Highway Administration

    Turner-Fairbank Highway Research Center, 6300 Georgetown Pike
    McLean, VA  United States  22101
  • Authors:
    • Lee Jr, R L
    • Hostetter, R S
    • Leibowitz, H W
  • Publication Date: 1991-9

Media Info

  • Pagination: 59 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00622393
  • Record Type: Publication
  • Source Agency: Federal Highway Administration
  • Report/Paper Numbers: FHWA-RD-91-016, PTI 9113, 3A2A1272
  • Contract Numbers: DTFH61-88-C-00118
  • Files: TRIS, USDOT
  • Created Date: May 31 1992 12:00AM