5.5 Lighting for Displays and Signaling H3

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TRANSPORTATION

LIGHTING

13-53

Table

13-10

(Concluded)

TYPE

OF

EQUIP-

MENT

AND

USE

LOCATION

TYPE

OF

LAMP

(Incandescent

Filament)

COLOR

INDICATION

MOUNTING

SPAC-

ING

Tetrahedron

Same as Wind Tee

10-Watt,

115-

volt,

Red

on

left

Mounted

on low

Used

to

indicate

S-14

bulb,

me-

side,

green

friction

bearings

direction

of

land-

dium-screw base

on

right

side,

on

vertical

shaft

ing or

take-off

top

edge,

for free rotation

where

traffic

con-

and tip

with

wind when

trol is

exercised.

not

controlled

When

swinging

from

tower

free

indicates

true

ground wind di-

rection

Ceiling

projector

At a

known

dis-

420-Watt, 12-volt,

White

Projector

mounted

Used

to

determine

tance from ob-

G-25

bulb, mo-

to

direct

beam

cloud

strata

height

servation

point,

usually

1,000 ft

gul

prefocus

base

upward,

usually

90

degrees

Runway

light

(ele-

10 ft

out

from edge

30-

or

45-watt,

6.6-

White

on

full

Mounted

on

ground

200 ft

vated)

Strip

light

of

runway

paving

ampere,T-10bulb,

length of run-

or on a low

base

(elevated)

or

strip,

parallel

medium prefocus

way or

strip,

with

breakable

Used

on

runways

to

strip

or

run-

base; or

40-watt,

except

one-

joint

which

will

and strips

to

in-

way,

opposite

115-

volt,

T-10

half

white

give way if

light

dicate

the

area

each

other and

so bulb, medium

and

one-half

is struck acci-

available

for

land-

circuited that a

prefocus base

yellow

with-

dentally

by

an

ing

or

take-off.

single

runway

or

strip

may

be de-

lineated

as

a

unit

in

1,500

ft

of

each

end of

runway

airplane)]

Threshold

light (ele-

Across each

end

of

30-

or

45-watt,

6.6-

Green

Mounted

on

(see

lo-

vated)

runway

or

strip

ampere,

T-10

ground or on

a

cation)

Used

in

conjunc-

symmetrically bulb medium

low

base

with

tion

with

and

in

spaced

in

two

prefocus

base; or

breakable

joint

the

same

circuit

groups,

one

40-watt,

115-

which

will

give

as

the

elevated

group on each

volt, T-10

bulb,

way

if

light

is

strip

or

runway

side

of

runway

or

medium

prefo-

struck

accident-

light

to

indicate

strip, perpendic-

cus

base

ally

by

an air-

usable

limits

of

ular

to

runway

plane.

Maxi-

runway or

strip

or strip leaving

an 80-ft clearance

gap

at center

of

runway

or

strip

\

mum extension

30

in.abovesur-

face

*

If a

500-watt

lamp is used

with

a 24-inch beacon,

an

auxiliary

reflector is

required.

t

Can

be

used

only

in

special spherical

or

cylindrical

beacon.

I

Six

are

used

with runway

lights not more

than 220 feet

apart

opposite

each other,

eight

are used with

runway

lights

over

220 feet apart opposite each other. With

strip

lights,

only

six

elevated

lights necessary.

§

The landing

path prescribed

for low wind

conditions (less

than

5

knots) shall

have

the greatest

number

of

lights,

or,

in

the

absence

of

such

a

prescription,

the

longest

landing

path

shall

have

the

greatest

number

of

lights.

||

As

new

installation:

lights shall be

located 10

feet

out

from

edge

of

runway

paving opposite

each

other.

As

replacements:

lights shall

be mounted

on

top

of

flush

runway

light housings.

Maximum

extension

30

inches above

surface

for

all installations.

T[

As

new

installation,

lights

shall be

located 10-feet out

from

edge

of taxiway opposite

each

other. As

re-

placements, lights

shall be

mounted on top of flush taxiway

light housings.

Maximum extension

30

above

surface for

any

installation.

ILLUMINATED RAILROAD

SIGNALS

Illuminated

signals

provide

one means

whereby railroad

operating per-

sonnel

can

see

conditions

affecting

traffic

and

convey messages

beyond

the

range of

ordinary

unaided

vision. The

engineer perceives the

lighted

signal

by

the same

visual attentiveness

with which he w

7

atches

the track.

Functions

Performed

by

Light

Signals

The

information

to

be conveyed

with

the

aid

of

light signals

may be

considered

in

two

general categories

1.

Instructions

covering

a

forthcoming

movement

or

sequence

of

moves.

2.

Identification

and

location of

trains, switches, and other fixed in-

stallations

or

obstructions.



13-54

I E

S

LIGHTING HANDBOOK

FIG.

13-43

switch

marker

a.

Electric

switch

c.

Kerosene switch lamp

amp.

Reflex

Representative

of

the

function

of con-

veying

identification

and

location

informa-

tion,

the

switch light,

or

a

reflex

device

(such

as shown in

Fig.

13-43),

enables the

trainman

to

locate

a

switch

at

night,

and

tells

him

by

its

color

whether

the switch is

reversed

or

normal.

A

wayside

signal

locates

for

him

the

entrance

to

a

certain

territory and its

aspect

indicates

whether

the

way is

clear

to pro-

ceed.

The

display

of

a red light in

a

signal

indicates

that

a train

occupies

the

next block, or

that

a

switch

may

be

improperly

lined,

or

that

a rail

may

be

broken so as to

interrupt

automatic

operation.

The

appearance

of

the

light

is

similar to

that of

the red

hand

lantern

or

markers

that

must

be

lighted

at

night

on

the rear of

every train. Two

white

classification

lights,

such

as

shown

in Fig.

13-44,

displayed

on

the front of an

engine

at

night

identify

the train

as

an

extra.

Two

green

lights

displayed

in

the

same location

are

used on

all

sections

of

a train

except the

last, when

a

scheduled

train

is

operated

with

more

than

one

section.

Lighted

marker

lamps, such

as

shown in Fig. 13-44,

are

used to

indicate

the rear

of

a train

at

night.

Blue

lan-

terns

commonly

serve

to mark

the location

of

men

working

under

or about cars or locomotives and

warn

against

moving

or coupling

such

equipment.

FIG.

13-44.

a. Loco-

motive

classification

light, b.

Kerosene

tail-

marker

lamp.

Wayside

Signal Equipment

Wayside

signals had their beginnings in nonilluminated mechanical

devices,

such

as the

ball suspended from

a rope

(from

which

the

term

highball,

meaning

go

ahead, had its

origin). The

modernized

version

of the

old semaphore

signal, has permitted

continued

use for

daytime

indication

of

the

long

standard

nonilluminated

blade to

which is

added

a

light which

can

be

changed

in

color

in synchronism with

the blade position.

The

kerosene lamps

with which

the

early

lighted semaphore signals

were

equipped

were

satisfactory

for

night

signals,

but

not

bright

enough,

however,

for

daytime

color-light

indications.

In

lighted semaphores

the

change

of

color

is

accomplished by

mounting

colored

glass

roundels in

a

spectacle

near

the

fulcrum of

the semaphore

arm so

that

different

colored

glasses

swing

into position to intercept the white

beam

projected by

the

lamp

and

optical

system,

with

change

of

position

of the semaphore blade.



TRANSPORTATION LIGHTING

13-55

S

*

*4

•

L

FIG.

13-45.

a.

Position-light

signal,

b.

Color-light

signal, c.

Color-position-

light

signal,

d.

Searchlight

-type

of

color-light

signals.

With increased

candlepoAver

available

in

modern signal units utilizing

electric

sources

and

improved

lens design, it has

become

possible

to de-

pend

upon

visibility

of

the light for

both

day and

night operation.

To

ensure

contrast

of the

light with

its surroundings

in

the

daytime,

a

black

target

or

background

surrounds

the

light wherever

a

signal must

be

viewed

at

long

range. There

are

three types

of

signals currently recognized

by

the

Association

of

American Railroads

(A.A.R.)

which

depend

entirely

upon

lights. These are: color-light signals, position-light signals,

and

color-position-light

signals.

(See

Fig.

13-45.)

In

the searchlight type

of

color-light

signal

the change of

color

is

ac-

complished

by

an electrically-controlled mechanism

completely

enclosed

inside

the

signal

unit.

The

rays

from an

incandescent

filament

are col-

lected by

an ellipsoidal reflector which

focuses

them

to a

small

spot.

At

this

spot

the

rays

pass

through

any one of

three,

colored,

1-inch

diameter

glass

disks mounted

in

a

delicately balanced, pendulum-like spectacle.

An accurate lens system directs the light

to cover

the angle

of

approach.

The position-light

signal is

a

type of

wayside signal

which does not

de-

pend

upon

color

discrimination

by the engineer. In this

type, a

number of

lamps

(maximum nine)

are

mounted

on

a

circular

target:

eight

lights

arranged

in

a

circle,

one

in

the center. By operating

three

lamps at a

time, the

aspect

of

the signal may

be

a

vertical

row,

a

horizontal

row,

or

a

diagonal.

Each of

the

target

lamps

is focused

by

its

own projector

system

in

the

direction

of

the

approaching train.

The

color-position-light

signal is

a

type which

utilizes

a

combination of

the

principles of the color-light and

the

position-light systems.

Here

also

there

are

several

lights

on

a

target.

These may be

lighted

in

pairs:

vertical pair

(green)

;

horizontal

pair

(red)

;

right and left

diagonal pairs

(yellow

and

lunar white,

respectively).



13-56

I

E

S

LIGHTING

HANDBOOK

Locomotive

Cab

Signals

By

suitable

track circuits and electrical

receiving equipment

on

loco-

motives,

automatic

signal lights

inside

the

locomotive

cab

can

be

made

to

show

signal

aspects

corresponding

to

those

of

the

wayside

signals

gov-

erning the

train

movement.

This

is

useful

in

times

of

poor

visibility

caused

by

atmospheric

conditions

or

other obstructions.

Power

Sources

for

Lights

Complete dependability

required

of

wayside

signals has made

necessary

operation on the most reliable independent-power sources

possible.

There-

fore,

primary

or

storage

batteries

are

used

most frequently

alone,

or

as

standby

for

a-c

service.

However, many

switch

lamps

at

isolated

wayside

locations

and

markers

on

the

rear

of

trains

are

operated

by

kerosene

burners.

Oil

Burning

Signal

Lamps

and

Lanterns

The

kerosene

burner

light

source has

an

intensity of from about 1

to

3

candlepower,

depending

upon the

size

of

the wick, flame, and draft

con-

ditions.

When used with

a

clear

5f

inch diameter

by

3|

inch

focal length

Fresnel

(step) lens, such

as

shown in Fig. 13-46,

a

kero-

sene

burner

produces

an

axial

beam

of

approximately

60

candlepower.

The

beam

width

in this

case

is

established

by

the width of the

flame

and

may

range from

about

7

to

20

degrees

for

various

types

of

burners.

Additional spread

and

lower

candlepower

is

ob-

tained

with

spreading

lenses

with

vertical fluted

patterns

on

the

outside

surface.

The Fresnel type of prismatic

globe concentrates

the

light

in

a

horizontal beam with

a

maximum

candlepower

approximately

seven

times

that

of

the

same

lantern equipped

with

a

plain globe.

The vertical

beam

divergence

for

the

Fres-

nel

is about 6

to

9

degrees.

Oil-burning

tail-marker

lamps,

switch

lamps,

and

sem-

aphore

lamps

are

equipped

with lenses.

Electric

hand

lanterns

equipped

with dry

cells are

in extensive

use

where

white

light is

required;

how-

ever,

kerosene

lanterns

are

standard

where

a

colored

indi-

,,^

.,

,.

lantern,

cation

is

needed.

(See

Fig.

b.

Electric

hand lantern.

13-47.)

FIG.

13-46.

b.

Optical-type Fresnel

(step)

lens.

a.

Spreading-type lens. c.

Fresnel-lens-

type,

hand-lantern globe.



TRANSPORTATION

LIGHTING

13-57

FIG.

13-48.

Centralized

traffic

control

panel

with

illuminated

track

model and

lever

lights.

Signal-System Control Panels

In addition

to

the use

of signal

lights

on trains

and along

the right

of

way,

there

is

another

important

category

of

light

indications

in

a

signal

system.

These

are

the

indicator

lights on

the panel

from which an

opera-

tor

handles

an

interlocking,

or

centralized

traffic

control,

system.

On

such

a

panel

the operator has before him

levers that

operate electrical relays

for

switches

and

signals along

a

portion

of

the rail

line

or

yard.

(See

Fig.

13-48.)

Associated

lever

lights indicate the

response

of switches

and

signals to the

positions

of

the

control levers.

Accompanying

the

levers

is

a

track

diagram for

the

territory involved

which is studded

with

indicator

lights that

show

when

a

train

occupies

certain

sections

of

track

along

the

line.

Range

of

Light

Signals

The

range

of

a

railroad light signal

is determined

by

its daytime

visi-

bility

rather

than

by

its

night visibility. The formula which

is

in

general

use

for

relating the

beam candlepower

to

the maximum range

of

a

red

or

green

signal is

Range

in feet

=

\/2,000

bcp

where

bcp

=

beam candlepower

of the

signal equipped

with colorless

glass.

Yellow

will

have

somewhat

longer range.

The

formula

does

not

apply

to

purple

or

blue.

By

use

of

this

formula

and

the

candlepower

distribution

curve

of

a

signal

beam,

it is possible

to lay out

a

chart or

plan

that

shows the

ground

area

over

which this particular signal will

be

within

visible

range. This

signal

range

plan

can

be

superimposed over

a

track plan to see

whether

the

signal

would

have

visibility

over the

desired track

approach

to the



13-58

I

E

S

LIGHTING

HANDBOOK

2000

RANGE

IN

FEET

FIG.

13-49.

Range

chart

for

searchlight-type signal-unit

with

part

of

a

track

plan

superimposed

to show

range

of useful coverage.

signal.

For

convenience

in

using

this method, signal

manufacturing

companies

have

presented

range

charts

on

their various

signal units

with

a

celluloid

transparency on

which is

ruled

a

large

number of

representative

track

curves

which

can

be

laid

readily

on top

of

the signal

range charts.

(See

Fig. 13-49.)

Lamps

and Relation

of

Voltage

to Beam

Candlepower

Table

13-11

gives the

1,000-hour

ratings,

service ratings,

and

other

information

relative

to

lamps

used

with

searchlight-type

color-light sig-

nals.

The lamps

are the

precision,

two-pin,

candelabra-bayonet-base

type.

The

higher

wattage

lamps

produce

beams

of

high

candlepower

even

when

burned

at

the

recommended

reduced

voltage, thereby

obtain-

ing

average

life well in

excess

of

1,000

hours.

The

table

shows

the

aver-

age

axial beam

candlepower

obtained

with lens combinations for each

lamp

when burned

at

its

recommended

voltage.

Light

Control

and

Optical

Considerations

It

is important

that

signal-unit

optical

systems

be carefully

selected and

that

each

signal

unit

be properly

aligned

so as

to make

the

most

efficient

use

of the

light

available.

This is particularly important

in

daylight

signal

indications but applies

also

to kerosene

burners

and battery-operated

lamps that

give

night

indications

only.

A large

variety of

spreading

and

deflecting

types

of lenses

and

auxiliary

cover

glasses

are

in

use

for directing

the

rays

toward the

zone

where

a

signal must be seen.

A

deflecting

element

is necessary to

enable an engineer

at

very

close

range

to see a

signal

which

is

mounted

very

high

overhead,

as

in

Fig. 13-45,

or to

see

a

dwarf

signal which

is close

to

the

ground,

as

in

Fig.

13-50.

A

deflecting

or spread-

FIG.

13-50.

Dwarf search-

m

~

e

i

emen

t

is

necessary

to

provide

visibility

light signal

unit

with

up-

,°

,

,

,

i

ward deflecting roundels.

along

a

curved track

approach.



TRANSPORTATION

LIGHTING

13-59

Table

13-11.

Essential

Data on Lamps

for

Railroad

Searchlight

-Type,

Color-Light

Signals

LAMPS

VOLTS

WATTS

AXIAL

BEAM

CANDLE

POWER

8i-inch

Fresnel lens

81-inch

Compound

lens

1000-hr rating

Service rating

11.3

10.0

14.4

11.9

17,500

37,500

1000-hr

rating

Service rating

9.0

8.0

15.3

12.8

16,000

34,000

1000-hr

rating

Service

rating

4.0

4.0

3.0

3.0

Not recom-

mended

11,000

1000-hr rating

Service

rating

10.0

10.0

5.0

5.0

Not

recom-

mended

19,000

By

making

the front

surface

of

lenses

and

semaphore

signal

roundels

convex rather than

flat,

it is possible

to scatter

most

of

the

external light

reflected

from

the

front

surface

of the lens

so

that it w

T

ill

give

negligible

interference with

the function

of

the signal.

Frequently

flat

auxiliary

roundels inclined

at

specific

angles, or other special means

are used.

The

incorporation

of

reflectors

in the optics of

a

signal unit

involves

particu-

larly careful analysis

to

guard

against reflected

external

light.

Thus,

a

light-directing system that

may

be

entirely

satisfactory

for

ordinary

spot-

light or other

special

illuminating

purposes

may

be extremely dangerous

in

a

railroad

signal

since it can

flash spurious

indications.

Hoods

or

visors

projecting forward

from light-signal

units

are always

employed

as an

aid

in

reducing

reflection from

the

sky

and

as

a

protection against

snow

and

sleet

interference.

Signal

Colors

The colored

elements

in

lights used

in signaling

systems

in

the United

States

are

with

a

very few exceptions covered by

Association

of American

Railroads specifications

59

and

69.

The

A.A.R.

color specfications

are

explicit

both

as to the color

of resulting

signals

and

as to

the color

limit

samples

that

are to be used

for

inspecting colored glassware.

These

specifications are defined

in

terms of

the I.C.I,

color

diagram

and

in

terms

of

a

set of primary glass color standards

maintained in the

National

Bu-

reau

of

Standards

at

Washington,

D.

C.

That

Bureau certifies and issues

duplicate

w

r

orking

standards

representing the permissible

tolerance

on

color

variation

of

signal glassware. (See

Fig. 13-51.)

In

color-light

signaling, six distinguishable

colors

are considered

pos-

sible

: red, yellow,

green, blue, purple,

and

lunar white.

The use

of blue

and

purple

is

very

limited, because

incandescent

and

kerosene

light

sources

are

very low

in

output in the blue part

of the spectrum;

hence,

when

the

colored

lens or roundel

is

put over

the

light,

the resulting candle-



13-60

I

E

S

LIGHTING

HANDBOOK

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i n

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1

1

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1

1

1

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1

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0.60

0.50

0.40

T3

0.50

0.20

0.10

•op.57

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(LJ

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(y

=

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(X=0.44)

l,500*

s

^p.

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(y= 0.384)

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(X

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(y

=

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EQUAL

ENERGY

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0.46^'

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FTG.

13-51.

Railway

signal

color

specifications

plotted

on

I.C.I,

chromaticity

diagram.

power

is

low

and

the signal range short. Lunar

white

is

the name

assigned

to

the colorless

indication

obtained by

using

a

lens

of light blue glass

which makes

the light

appear a

high color-temperature

white

instead of

the usual yellowish

kerosene

or

incandescent filament

color.

Lunar

white

thus

provides

assistance in distinguishing

a

white

signal

from

ordinary

nonsignal

lights

along

the

wayside.

As

is

commonly

understood,

red

is associated

with

the

most

restrictive

signal

aspects,

green

with

the

least

restrictive,

and

yellow

with

interme-

diate

indications.

For

the specific

meanings of

the

many signal

aspects

made possible

by displaying two

or

more

lights simultaneously,

see

the

Manual

of

the

Signal

Section

of

the

A.A.R.

(Association

of American

Rail-

roads).

The yellow

used

in

position-light signals is

a

hue

somewhat paler

than

that covered

by A.A.R.

specification

for

yellow

color-light

signals

or



TRANSPORTATION

LIGHTING

13-61

lantern

purposes.

This

light

yellow is

distinctly different

from

nonsignal

wayside lights.

Railroad-grade-crossing

red warning

lights

are

main-

tained

by

the railroads

and

the color

governed

by

A.A.R.

specification.

AIRPLANE

HANGAR

LIGHTING

To

design

an

adequate

hangar-lighting

system, it is

necessary

to con-

sider both

the quality and

the

quantity

of

illumination

required

for

the

various

seeing

tasks involved. Therefore,

it

is

necessary

to

know

first

the

ultimate

usage

of the

hangar,

i.e., whether it

is for storage

or for

maintenance and repair.

The

values

in

Table

13-12

are

considered

to be

minimum

for

efficient,

safe, and accurate work.

Equipment Selection

Direct

lighting

equipment

generally

is considered

to be

most practical

for

hangar areas.

This

class

of

equipment may be used

with incandescent-

filament, mercury-

vapor-discharge, or fluorescent lamps.

When

using

filament-

or

mercury-lamp equipment, care

must

be taken

to

avoid

direct

or reflected

glare

as these

sources have

a

very

high bright-

ness.

To

minimize

direct glare, reflectors

should shield

the

lamp

as

indicated

in

Table

13-13.

To

prevent

reflected

glare,

open-type filament

or

mercury units should

not

be

used

where the

work surfaces

have

shiny

or

specular

surfaces.

Low-brightness

luminaires

are

suitable

where

spec-

ular

surfaces

must

be

worked upon.

To

obtain

the

best results from an

installation

:

Easy

access

to

all

light-

ing units

should

be

provided

by

installing

lowering

hangers,

catwalks,

or

traveling monorail

cranes.

Luminaires

should

be

accessible even when

a

hangar is

full

of airplanes.

A

regular cleaning

and

lamp

replacement

schedule

should

be

established.

Table

13-12.

Recommended Minimum Average

Maintained Illumination

for

Aircraft

Hangars

PRINCIPAL

OPERATION FOOTCANDLES*

Engine

repair

50

Frame

repair

30

Instrument repair

50

Paint

shop

20

Plane

maintenance (general)

30

Radio repair

50

Recovering

area 30

Storage

(live)

10

•

The

footcandle

values

represent

order

of

magnitude

rather than exact

levels

of

illumination.

Wherever

possible and

practical,

the general

lighting

system

should be

designed

to provide

adequate

illumination.

When

internal

work

or

shadowed parts

around

the

planes

cannot be

satisfactorily

lighted

by the

general

lighting

installation,

supplementary

luminaires

should

be

used.

Documents

5.5 Lighting for Displays and Signaling H3