Page 346 - Planning and Design of Airports

304 Airp o r t D e sign

developed, the runway edge lights were adopted as visual aids on a
runway. This was followed by the use of runway centerline and touch-
down zone lights for operations in very poor visibility. FAA Advisory
Circular 150/5340-30C provides guidance for the design and installa-
tion of runway and taxiway lighting systems. Those planning and
designing such systems should refer to the latest changes to this Advi-
sory Circular, commonly found at http://www.faa.gov.
Runway Edge Lights
Runway edge lighting systems outline the edge of runways during
nighttime and reduced visibility conditions. Runway edge lights are
classified by intensity, high intensity (HIRL), medium intensity (MIRL),
and low intensity (LIRL). LIRLs are typically installed on visual run-
ways and at rural airports. MIRLs are typically installed on visual
runways at larger airports and on nonprecision instrument runways,
HIRLs are installed on precision-instrument runways.
Recommended standards for the design and installation of run-
way edge lighting systems are published by the FAA [21] and are
contained in ICAO Annex 14 [1]. These light fixtures are usually
elevated units but semiflush lights are permitted. Each unit has a
specially designed lens which projects two main light beams down
the runway. Elevated runway lights are mounted on frangible fittings
and project no more than 30 in above the surface on which they are
installed. They are located along the edge of the runway not more than
10 ft from the edge of the full-strength pavement surface. The longi-
tudinal spacing is not more than 200 ft. Runway edge lights are white,
except that the last 2000 ft of an instrument runway in the direction of
aircraft operations these lights are yellow to indicate a caution zone.
A typical layout of low-intensity and medium-intensity runway edge
lights is shown in Fig. 8-9, and a typical layout of HIRLs are illus-
trated in Fig. 8-10. If the runway threshold is displaced, but the area
that is displaced is usable for takeoffs and taxiing, the runway edge
lights in the displaced area in the direction of aircraft operations are
red, as shown in Fig. 8-11.

Runway Centerline and Touchdown Zone Lights
As an aircraft traverses over the approach lights, pilots are looking at
relatively bright light sources on the extended runway centerline.
Over the runway threshold, pilots continue to look along the center-
line, but the principal source of guidance, namely, the runway edge
lights, has moved far to each side in their peripheral vision. The result
is that the central area appears excessively black, and pilots are virtu-
ally flying blind, except for the peripheral reference information, and
any reflection of the runway pavement from the aircraft’s landing
lights. Attempts to eliminate this “black hole” by increasing the inten-
sity of runway edge lights have proven ineffective. In order to reduce