22 August 2006
occurs at outdoor areas such as motor pools and sports fields.
Figure 3-1. Los Angeles, 1908 (left), Los Angeles, 1976 (right)
Figure 3-2. Unshielded and non-cutoff luminaires lead to light pollution.
To minimize light pollution, use fully shielded luminaires or IESNA full cut-off
type for area and roadway lighting as illustrated in Figure 3-3. The use of full cutoff
luminaires may reduce uniformity and therefore require greater pole heights or spacing.
Cutoff, semi-cutoff, and non-cutoff luminaires may also be used at low mounting heights
if the lumen output of the lamp is limited to 4200 lumens. These applications, such as
pedestrian and entry lighting, typically require greater vertical illuminance for facial
identity. For a more detailed description of full-cutoff, and cutoff luminaires, see Table
5-2 in Chapter 5, "Lighting Equipment". Provide uniform low glare lighting and do not
overlight exterior areas. Also, control lighting with time clocks, photocells, and motion
sensors such that lighting is only energized when needed.