New technologies have enabled the production of traffic signals with greater energy efficiency and lower maintenance costs than standard incandescent signals. Due to spatial differences in properties of the lamps, simple photometric measurements may be insufficient to ascertain whether these new signals are as visible as the older signals. The authors have developed a quality index termed the usability factor (UF) that can be used to evaluate the visibility of a new device relative to that of a standard reference lamp, and in combination with standard acceptance tests, to evaluate the suitability of a new type of traffic signal for use in the field. The UF is determined psychophysically, using heterochromatic flicker photometry; hence the measurement involves use of the entire visual pathway. The authors term this technique "ommatometry," and present it as a practical evolutionary extension of the science of photometry. Sample measurements of UFs for several test fixtures are reported.

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  • Corporate Authors:

    Lawrence Erlbaum Associates, Incorporated

    10 Industrial Avenue
    Mahwah, NJ  United States  07430-2262
  • Authors:
    • Greenhouse, D
    • Cohn, T E
  • Publication Date: 1999


  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 317-329
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00781969
  • Record Type: Publication
  • Files: TRIS, ATRI
  • Created Date: Jan 20 2000 12:00AM