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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

Airborne Evaluation of Retro-Reflective Beads

This project was undertaken by the Federal Aviation Administration (FAA) Airport Safety Technology Research and Development Sub-Team as part of an effort to determine the relative conspicuity, from an aircraft on approach, of Type I and Type III retro-reflective beads. Retro-reflective beads are designed to redirect and return light back to its source. The inclusion of retro-reflective beads in painted surface markings can increase their conspicuity. It has been suggested that Type III retro-reflective beads, which have a higher index of refraction (IOR) compared to Type I beads, will substantially increase the conspicuity of paint markings and could help prevent runway incursions. The FAA uses Federal Specification TT-B-1325D, “Beads (Glass Spheres) Retro-Reflective,” to specify retro-reflective beads. Previous studies by the United States Air Force and the FAA have shown that in cases where the light source is not in close proximity to the observer’s line of sight, the benefit of using higher IOR beads is negligible. Since 1994, all research on retro-reflective beads has been focused on surface markings from the ground to improve the conspicuity of taxiway hold position markings, which aid in the prevention of runway incursions. Due to advances in bead technology, it has been suggested that additional tests be conducted from the pilot’s perspective on approach to a runway. Type I and Type III retro-reflective beads were installed on the same type of airport pavement markings at opposite ends of Runway 13/31 at Atlantic City International Airport (ACY) for a period of 8 months and side by side on Runway 10 at Savannah/Hilton Head International Airport (SAV) for a period of 2 months. Subjective data was collected in the form of questionnaires completed by test subjects from aircraft approaching the runway at both locations. The test subjects were queried concerning ease of marking detection and conspicuity. Objective measurements were taken at the beginning and the end of the evaluation. The majority of the test subjects involved in the tests at both ACY and SAV stated they do not use runway markings as a visual cue on approach to a runway at night. They focus on the runway lights. Of the subjects participating, all but one reported no difference in ease of detection between Type I and Type III bead markings. The chromaticity and retro-reflectivity characteristics of the bead markings were acceptable following initial application and throughout the evaluation period. While the Type III beads had a greater retro-reflectivity reading after initial installation, the effects on conspicuity from a pilot’s perspective on approach to the runway were minimal. Also, the higher retro-reflectivity readings of the Type III beads only lasted a few months at ACY then leveled out to the same retro-reflectivity values as the Type I beads for the remainder of the markings’ useful life. This study revalidates the airborne research performed in 1994 and is consistent with other ground-based research performed to date including research completed in 2009.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Technical Note
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 56p

Subject/Index Terms

Filing Info

  • Accession Number: 01565449
  • Record Type: Publication
  • Report/Paper Numbers: DOT/FAA/AR-TN10/8
  • Files: TRIS, ATRI, USDOT
  • Created Date: Jun 1 2015 1:36PM