TYPES OF LUMINAIRES

Conventional roadway lighting has been the cobra head luminaire mounted on a support arm and positioned at the edge of the roadway or, in some cases, out over the roadway. The base of the pole when a breakaway device is present should be a minimum of 15 ft (4570 mm) from the travelway, but 20 ft (6100 mm) is preferred on roadway sections with­out a curb. The travelway is defined as being a continuous traffic lane and does not include an acceleration or deceleration lane merging with a through lane. When a curb is present, the pole with its breakaway device is preferred to be 10 ft (3050 mm) from the face of the curb. If this is not possible, the pole should be closer than 2 ft (610 mm). This will ensure that an impacting vehicle strikes the pole at the designed impact height for proper break­away operation. Breakaway devices should not be used on any pole located where pedestrians are likely to be present, because of the danger to them if the pole falls.

Cobra head luminaires are available in a wide range of full cutoff, semicutoff, and noncutoff beam patterns. All cobra head luminaires have a horizontal lamp position that causes them to produce a large amount of light directly under the luminaire. This requires the designer to closely inspect the calculated average to minimum light level ratios to ensure compliance with values given in the illuminance tables.

Other luminaires that can be used in the same locations as cobra heads utilize a vertical lamp position. These produce a more uniform light pattern, since a smaller portion of their lumens are directed straight down, thus providing a more uniform light level. These luminaires are not available in cutoff types. The two major manufac­turers of this vertical lamp luminaire are Holophane and McGraw-Edison.

High mast luminaires are designed to be mounted on the lowering ring of a high mast pole. High mast luminaires are produced primarily in 400- and 1000-W sizes in a wide variety of beam patterns. New lamps are being developed that have lumen to watt ratios equal to or better than the 1000-W that do not demonstrate the same fragile tendencies [11]. Manufacturers use different designations for their own luminaires, but generally type 2 and type 5 beam patterns are most popular. The beam patterns are also referred to as long and narrow, and symmetrical and nonsymmetrical. Cutoff and

CLASSOTCATION FACTOR	RATING	UNLIT WEIGHT (A)	LIGHTED WB1GHT ffl)	DJFF. (A-B)	SCORE [RATING X (A-B)]
1	г	I	4	5
GEOMETRIC FACTORS
No. of Lories	4 or less					1.0	0.8	0.2
	> 3.6	3.6	3.3	з sa	<3.0	3.0	2.5	0.5
Median Openings per Mile	<4,0 or one-	4.0-0.0	8.1-12.0	12.0-15.0	>15.0 or no access control	5.0	3.0	2.0
Curb Cuts	< 107.	10*202.	20-30%	30-40%	>40%	5.0	3.0	2.0
Curves	<3.0-	3.1-6.01	6.1-8.0′	8.1-10.0“	>10*	13.0	5.0	8.0
Grades	< 3%	3.0-3,32.	4.0-4.97.	5.0-6.37.	7% or more	3.2	2.8	0.4
Sight Distances M	>215	150-215	30-150	60-30	<60	2.0	1.8	0.2
Parking	Prohibited both sides	L”d£,V°""	Off-peak		Permitted both sides	0.2	0.1	0.1
OPERATIONAL FACTORS							GEOMETRIC TOTAL
Signals	All major	Substantial majority of	intersections signalled	About half the intersections	Frequent "-signalized	3.0	2.8	0.2
Left Turn Lone	AU major or one-way operation	Substantial *et£rrtVf	Meet major	About half the^ major	Eh*"	5.0	4.0	1.0
Median Width (m)	A	6-3	3-6	0-L2	0-1,2	„	0.5	0.5
Operating Speed	40 or less	50	55	65	70 or greater	1.0	0.2	0,8
Pedestrian Traffic	Very fa«	0-50	50-100	100-200	> 200	1.5	0.5	1.0
ENVIRONMENTAL FACTORS							OPERATIONAL TOTAL
% Development	0	0-302	30-60%	60-30%	100%	0,5	0.3	0.2
	backup design	Residential	Half residential &/	Industrial or oommeroial	Strip industrial or commercial	0.5	0.3
Setback Distance (m)	> 60	45-60	30-45	15-30	< 15	0.5	0.3	0.2
Advertising or	—	0-40%	40-60%	60*80%	Essentially	3.0	1.0	2.0
Raised-Curb Median	None	Continuous	At all	At all signalized	A few	1.0	0.5	0.5
Crime Rata	Extremely low	city overage	City average	Higher than oity average	Extremely	1.0	0.5	0.5
ACCIDENTS							ENVIRONMENTAL TOTAL
Ratio of Night — to-Doy Accident	< 1.0	1.0-1.Z	1.2-1.5	1.5*2.0	2.0*	10.0	2.0	8.0
•Continuous Lighting Warranted	GEOMETRIC TOTAL =	ACCIDENT TOTAL
OPERATIONAL TOTAL =
ENVIRONMENTAL TOTAL =
	ACCIDENT TOTAL —
SUM = POINTS
WARRANTING CONDITION * 85 POINTS

FIGURE 7.61 Evaluation form for non-controlled-access facility lighting.

noncutoff types are used, although not all beam patterns are made in each category. The designer must be concerned with light trespass when using high mast luminaires and should locate them so as not to interfere with adjacent property usage. A tech­nique used by some designers, when high mast poles cannot be located in the middle of the area to be lighted, is to specify an offset-type luminaire mounted on the high

CLASSIFICATION FACTOR	RATING	UNLIT WEIGHT (A)	LIGHTED WEIGHT (B>	DIFF. (A-B)	SCORB [RATING X (A-B)]
1	2	3	4	5
GEOMETRIC FACTORS
Number of Legs		3		5	6 or more troff. c"9 circles)	3.0	2,5	0.5
Approach Lane Width	>3,6	3.6	3.3	3.0	<3.0	3.0	2.5	0.5
Ch™h-“"		Left turn lanes on mejor legs	Left turn lanes right turn lenos	Left end right turn lanes on major lags	Left and right alllegT” °П	2.0	1.0	1.0
Approach Sight Distance	>215	150-215	40-150	60-40	<60	2.0	1.8	0.2
Grades on Approach Streets	< 32	3.0-3,’42	4,0-4.47	5.0-6.42	72 or more	3.2	2.6	0.4
Curvature on Approach	< 3.0‘	3.0′-6.0‘	6.Г-8.0’	8.Г-10.0-	> 10′	13.0	5.0	6.0
Parking in Facility	Prohibited	Loading zones only	Off-peak only	Permitted	Permi ttad	0.2	0.1	0.1
							GEOMETRIC TOTAL
Operating Speed on Approach Legs (km/h)	40 or lass	50	55	65	70	1.0	0.2	e. a
Type of Control	All phases signalized (incl. turn lane)	Left turn lane signal control	Through-traffic signal control only	4-шау stop control	Stop control on minor legs or no control	3,0	2.7	0.3
Channelization	Left end right signal central	Left and right «gnel Control on major leqs	Left turn lane on ell legs	an major legs	No turn lone	3.0	2.0	i.0
Level of Service (Load Factor)	0.0	В 0-0.1	C 0,1-0,3	D 0.3-0,7	£ 0.7-1.0	1.0	0.2	0.8
Pedestrian Volume ipads/h)	Vary few	0-50	50-100	100-200	> 200	1.5	0.S	1.0
ENVIRONMENTAL							OPERATIONAL TOTAL
Percent Adjacent Development	0	0-3 0V.	30-607	60-407	1002	0.5	0.3	0.2
Predominant Development near	Undeveloped	Residential	507 residential 507 industrial or commercial	Industriol or	Strip industrial	0.5	0.3	0.2
Lighting in ImmedlOte Vicinitg		0-407.	40-607	60-402	1002	3.0	1.5	1.5
Crime Rote	Extremely	C! ty average		Highor than city ever age	Extremely high	1.0	0.5	0.5
ACCIDENTS							ENV1R0MENTAL TOTAL
Ratio of Night — to-Doy Accident Rates	1.0	1.0-1.2	1.2-1.5	1.5-2.0	2.0-	10.0	2.0	8.0
•intersection Lighting Warranted	GEOMETRIC TOTAL =	ACCIDENT TOTAL
OPERATIONAL TOTAL —
ENVIRONMENTAL TOTAL =
	ACCIDENT TOTAL =
SUM = POINTS
WARRANTING CONDITION = 75 POINTS

CLASSIFICATION FACTOR	RATING	UNLIT WEIGHT (A)	LIGHTED WEIGHT (Б)	DIFF. (A-B)	SCORE [RATING X (A-Bl]
1	2	5	4	5
GEOMETRIC FACTORS
Number of Lanes	4		б		> 8	1.0	0.8	0,2
Len* Wtdth	>3.6	3,6	3.3	3,0	<2,75	3.0	2.5	0.5
Median Width (m>	>12	7-12	3.7-7.0	1.2-3.3	0	1.0	0.5	0.5
Shoulders	3.8	2.4	1.8	0.8	0	1.0	0.5	0,5
Slopes	2 8:1	6:1	4:1	3:1	2:1	1.0	0.5	0.5
Curves	0-1/2′	1/2-1*	1-2*	2-3‘	3-4*	13.0	5.0	8,0
c*"“’	< 32	3-3.82	4-4,42	5-6.82	> 72	3.2	2.8	0.4
oK. t".",9′	6.4 km	4.8 km	3.2 km	1.6 km	>1.6 km	4.0	1.0	3.0
							GEOMETRIC TOTAL
Level of Service	«	В	C	0	Є	6.0	1.0	5.0
ENVIRONMENTAL							OPERATIONAL TOTAL
FACTORS
Z development	m	252	502	752	1002	3.5	0.5	3.0
Offset, to Development	би	45	30	15	<15	3.5	0.5	3.0
ACCtDENTS							ENVIRONMENTAL TOTAL
Ratio of Night — to-Ooy Accident Rates	1.0	1.0-1-2	t.2-1.5	1.5-2.0	2Я-	10.0	2.0	8.0
“Continuous Lighting Warranted	GEOMETRIC TOTAL =	ACCIDENT TOTAL
OPERATIONAL TOTAL —
ENVIRONMENTAL TOTAL =
	ACCIDENT TOTAL =
SUM 5 POINTS
WARRANTING CONDITION = 35 POINTS

CLASSIFICATION FACTOR	RATING	UNLIT WEIGHT (A)	LIGHTED «EIGHT (B> , IABI	SCORE [RATING X <A-B>]
1	2	J	4	5
GEOMETRIC FACTORS
n _ ‘ Direct Hemp lypes	Olafnond	cloverleaTs	Trumpet	i. T™.’"»	«	1.0	1.0
Classif ication			Continuous		intersections	2.0	1.0	1.0
frontage Roods			One-woy		Two-.ay	1.5	1,3	0.5
Freeway Lane Widths (ml	>3.6	3.6	3,3	3.0	<3.0	3.0	2.5	0.5
Frooway Median Widths	>1?	10-12	3,6-7.3	1.2-3.6	<1.2	1.0	0.5	0.5
Freeway Lories	4 or less		6		8 or more	1.0	0.8	0.2
Mam Lane Curves	< 1/2′	і-2′	2-3′	3-4-	>4-	13.0	5,0
0r=d"	3X	3-3,4/.	4-4.4X	5-6.4/	77. or more	3.2	2.8	0.4
Sight Distance Cross­road Intersection	>ЗЄ4	210-300	150-210	120-150	<120	2.0	1,8	0.2
							GEOMETRIC TOTAL
Level of Service	»	8	C	0	E	6,0	1.0	5,0
ENVIRONMENTAL FACTOR’S							OPERATIONAL TOTAL
X development		,,I“d	2,“”d	3„..d		2.0	0.5	1.5
Setback Distance	>60	45-60	30-45	15-30	<15	0,5	0.3	0.2
Crossroad	—		Partial		Complete	3,0	2.0	1,0
Freeway Lighting	None		Interchanges only "		Continuous	5.0	3.0	2.0
ACCIDENTS							ENVIRONMENTAL TOTAL
Ratio of Night,- to-Dou Accident.		1,0-1.2	1.2-..5	1.5-2.0	> 2.0-	10.0	2.0	8.0
GEOMETRIC TOTAL =
		OPERATIONAL TOTAL =
ENVIRONMENTAL TOTAL =
ACCIOENT TOTAL =
•Continuous Lighting War-or-ted	SUM = POINTS	ACCIOENT TOTAL
COMPLETE UGMTtNC
WARRANTING CONDITION = Я0 POINTS
	PARTIAL LIGHTING
WARRANTING CONDITION = 60 POINTS

mast lowering ring in lieu of the “traditional” high mast luminaire. This produces a more directional pattern that can reduce the amount of off-premise light.

In addition to the cutoff type fixture, some manufacturers have coined the term “Dark Skies” for fixtures that have a photometric design that not only limits the hori­zontal beam spread, but also limits or completely eliminates any component of uplight from the fixture. Property owners are very concerned about light trespass where com­mercial developments are in close proximity to residential areas. Unwanted light can affect the value of a parcel of property for certain types of usage.

The use of light emitting diodes (LED’s) has created a new type of light fixture. These units are still in the early stages of development but a limited number of manu­facturers do market exterior fixtures using this new technology. The installation costs of LED fixtures are comparable to conventional fixtures but the initial cost of the fix­tures exceeds that of conventional high pressure sodium or metal halide fixtures. However, energy costs using the LED fixtures are much lower than conventional fix­tures. The photometrics of LED fixtures can be controlled to prevent both uplight and trespass on adjacent areas. As the production costs decrease and different styles become available, the use of this type of fixture will likely increase.

Avoiding light trespass is very important near airport runways. Glare from improp­erly placed fixtures or the use of fixtures with uplight components can be a distraction to pilots on final approach. The area around an airport also has height restrictions due to FAA requirements. The lighting designer must be diligent in researching these requirements and using lighting standards that do not exceed the limits. One method is to use offset fixtures at lower mounting heights to comply with height limitations. Most manufacturers also provide shields that prevent overspill of the light output. The use of fixtures referenced above as “Dark Skies” will also aid in meeting the design requirements for a particular location or area.

Offset luminaires are manufactured by several companies under names such as Vector, Turnpike, Multimount, and Interstate. These luminaires are specifically designed for roadway use and resemble a floodlight in appearance but not in beam pat­tern. The offset luminaires are intended to be mounted well away from the roadway edge and aimed at an approximate 45° angle. This design was originally conceived in the 1960s, and a test installation along I-55 south of Memphis was very satisfactory. The original design was large and difficult to handle, but perhaps the greatest handicap that prevented widespread use was the resistance among maintenance personnel due to the difficulty in getting to the pole location when servicing was required. From a safety aspect, the offset was, and still is, a very good choice, since it can be located well away from the travelway and the beam pattern allows a wide spacing between the poles. The development of an individual lowering device has increased the number of locations where the offset can be installed. The individual lowering device (ILD) provides each luminaire with its own lowering cable and latch assembly, as distinguished from the high mast lowering device, which has all luminaires mounted on the same ring and lowered together. The cost of the ILD is much less than that of the high mast device when one to eight luminaires are located on the pole. Four ILDs are the maximum number used on a single pole, but one or two per pole is most commonly used.

Segmented reflectors are special-purpose luminaires that have been successfully used on top of concrete median barriers. The top of concrete safety shape barriers can be as wide as 12 in (300 mm). This limits the anchor bolt spacing, for attaching a luminaire pole, at 6 in (150 mm) in order to provide a minimum of 3 in (75 mm) of concrete around each bolt. The resultant anchor bolt spacing places a height restriction on the pole due to the structural needs required to counteract the overturn moments. Two options are to increase the width of the concrete barrier at the luminaire post, as in Fig. 7.65, or to use segmented reflector luminaires, which require less height to pro­vide proper lighting for multiple lanes.

Two of the segmented reflector luminaires when mounted 40 ft (12 m) high can light up to six or eight lanes on each side of the barrier depending on the width of the inside shoulder. This luminaire was originally developed for use in parking decks and uses a vertically mounted lamp with only a small portion of its lumens directed straight down. Exceptional uniformity ratios and the cutoff pattern make these lumi­naires a good choice when veiling luminance (glare) and light trespass are concerns. Other types of luminaires are also used on top of median barriers. The cobra head is often used, and a traditional high mast luminaire has been found to be very effective in this application, although veiling luminance is a potential problem.

Poles mounted on top of median barriers have a number of advantages and disad­vantages. One advantage is cost, since one pole in the middle of the lighted area can replace two roadside luminaires, requiring only one set of circuit conductors and conduits. The disadvantages include problems of traffic and maintenance safety. Placing the poles on top of the concrete median increases the probability of a pole being struck and landing in the opposing traffic lanes, when compared with offset luminaire pole locations. Maintenance crews are required to work with bucket trucks on the inside shoulder, requiring the closure of the inside traffic lane. Experience of over 10 years with median barrier-mounted poles indicates that few poles are actually struck and the majority of strikes that do occur take place late at night when traffic levels are low. The poles that were struck did not become detached from the anchor bolts, since breakaway devices are not used on the barrier rail poles. The use of bucket trucks to service these luminaires is a potential problem, because the knuckle of the boom can extend over an adjacent lane. The solution in at least one metropolitan area is to use the ILD (Fig. 7.60) with the luminaire, eliminating the need for a bucket truck. This facilitates traffic control and requires a smaller-size crew. Some maintenance depart­ments prefer the ILDs and request their installation on barrier lighting projects.

There have been several types of floodlights and sports lights used in roadway applications over the years as lighting designers have attempted to cope with the increasing numbers of lanes and the confining rights-of-way. In most cases, the high level of accuracy required for proper aiming and the need for special glare shields have limited their usefulness.