b. Luminaires. Adjustable floodlights or road-
stairs and ramps, will require special treatment.
Crosswalks in the middle of the block will be
way luminaires, with beam pattern selected for
illuminated to 1.5 to 2 times the normal roadway
half over-lap, will be used as area lighting units.
To provide economical coverage, a minimum of 60
(2) Remote from roadways. Walkways and
percent of the beam lumens will fall within the
bike ways remote from roadways will have a
area to be lighted. Floodlights will be enclosed
minimum of 5 lux (0.5 footcandle) average illumi-
type, either Heavy Duty (Class HD) or General
nation measured on lo-foot intervals. Pedestrian
Purpose (Class GP). A description of floodlight
tunnels will have 40 lux (4.0 footcandles), stair-
construction requirements is discussed in chapter
ways will have 6 lux (0.6 footcandles), and over-
11. Use of Class 0 and Class 01 units, which are
passes will have 3 lux (0.3 footcandles) illumina-
open types and accumulate more dirt, will be
b. Pole design. Where pole-mounted lights illu-
c. Placement. Only areas with nighttime activi-
minate only walkways or bikeways, shorter poles
ties will be lighted. Floodlighting is not justified
are the most suitable, but luminaire height will
when used only for aesthetic purposes. Floodlights
not be less than 10 feet. Construction will be such
will be located on buildings, where practicable, or
as to minimize vandalism by use of break-resistant
on poles or metal towers. Roadway luminaires
lenses, tamperproof screws, and sturdy poles.
adjacent to areas to be floodlighted may be utilized
10-5. light Sources.
for both roadway and area lighting, where mount-
a. Selection. Selection of the light source will be
ing height and spacing of units is appropriate for
made from high intensity discharge (HID) sources
f o r apron and hardstands is covered in TM
because of their luminous efficacy. The advantages
and disadvantages of various lighting sources are
listed in table 10-3.
10-4. Walkway and Bikeway lighting Design.
Roadway lights and building exterior lights can
(1) HPS lighting is the most energy efficient
serve also as walkway and bikeway lights. Maxi-
source which has an acceptable color rendition.
(2) Metal halide lamps have a good color
mum use will be made of multiple-purpose lighting
rendition, but luminous efficacy, lumen mainte-
a . Intensities. Values are dependent upon
nance (lumen output diminishes more rapidly
throughout life), length of life, and restrike time
whether walkways and bikeways are adjacent to
roadways or isolated from vehicular traffic.
make them a less than desirable source for many
(1) Adjacent to roadways. Walkways and bike-
(3) Unacceptable sources. Fluorescent lighting
ways will be illuminated to not less than one-half
has not been included in table 10-3 due to its
roadways. Areas having changes in grade, such as
relatively low luminous efficacy and the limited
Luminous efficacy (lumens/watt)b
Lamp life (kilohours)
lamp life (years)c
Startup time (minutes)
Restrike time (minutes)
Neutral surface color effect
Courtesy of Keller & Gannon (Rev. 1991, per IES data).
Computed based on 4,000 burning hours a year.
Table 10-3. Characteristics of Light Sources.