Evaluation of Retroreflective Pavement Markers for Precision and Nonprecision Runways.

The purpose of this program was to evaluate the use of retroreflective pavement markers, installed in a configuration duplicating runway centerline and touchdown zone lighting system of a Category II runway on Category I or Nonprecision Approach runways with edge lighting to determine if these retroreflective markers will enhance nighttime visual guidance to provide increased safety of operations and possible reduction in minimums, particularly under wet runway conditions. Visual contact height with the retroreflective pavement marker systems was not enhanced prior to reaching Minimum Descent Altitude (MDA) or Decision Height (DH) for nonprecision or Category I approaches respectively; therefore, this system will not permit the reduction in approach minimums for Category I precision or nonprecision approaches. However, the test program demonstrated that the system is effective in improving the safety of operation for final approach, flare and touchdown, landing rollout, and for takeoffs. Particularly under rainy, wet nighttime conditions, the pavement retroreflector significantly enhanced the visual guidance, supplementing that provided by the standard runway edge lights and paint markings which are difficult to see under wet conditions. (Author)