Taxiway Sign Effectiveness Under Reduced Visibility Conditions

An evaluation was conducted to determine whether any or all of the standard internally lighted taxiway guidance sign sizes, when located at the current recommended distance from the taxiway edge, provide adequate guidance in reduced visibility conditions. The L858R mandatory and L858Y informational types of
taxiway guidance signs were used for the evaluation. The three standard sizes of each type of sign were set up at the maximum recommended distance from the taxiway edge. Tests were conducted at the intersection of taxiway "B" and runway "4-22" on the Atlantic City International Airport. Data were collected during
periods of actual reduced visibility. Over 200 observations in visibilities between 400 to 1900 feet were collected. Typical "low-speed" taxi stopping distances were obtained through actual tests with a Boeing 727 aircraft. These stopping distance values were then compared to the actual recognition distances for the signs under low visibility conditions. From the data collected, all sizes of signs tested provided adequate guidance to allow a pilot to recognize the sign message and take appropriate actions when needed.

DOT/FAA/CT-TN90/20

Author: Paul H. Jones