DC Streetlight Policy and Design Guidelines

District of Columbia

STREETLIGHT POLICY

AND

DESIGN GUIDELINES

Final Report

District Department of Transportation

2000 14th

Street, NW, 7th

Floor

Washington, DC 20009

March 2005

District Department of Transportation

d.District Department of Transportation

d.

District of Columbia Streetlight Policy and Design Guidelines Final Report

TABLE OF CONTENTS

ACKNOWLEDGMENT ............................................................................................................... iii

EXECUTIVE SUMMARY ....................................................................................................... ES-1

1. INTRODUCTION....................................................................................................................1

2. BACKGROUND INFORMATION .............................................................................................3

2.1 Definitions.................................................................................................................. 3

2.1.1 Optics ............................................................................................................. 3

2.1.2 Streetlight Hardware ...................................................................................... 5

2.2 AASHTO Roadway Lighting Requirements ............................................................. 7

2.3 Light Sources ........................................................................................................... 12

2.4 Poles......................................................................................................................... 14

2.5 Photosensor .............................................................................................................. 15

2.6 Globes ...................................................................................................................... 15

2.7 Lateral Distribution Patterns .................................................................................... 16

2.8 Pole Placement Configurations................................................................................ 17

2.9 Cutoff Fixtures ......................................................................................................... 18

3. EXISTING DDOT PRACTICE .............................................................................................20

3.1 Poles......................................................................................................................... 20

3.2 Lamps....................................................................................................................... 22

3.3 Wattage .................................................................................................................... 22

3.4 Illumination Levels .................................................................................................. 23

3.5 Special Requirements............................................................................................... 23

4. ILLUMINATION STANDARDS RECOMMENDATIONS...........................................................24

4.1 General Standards for Illumination Levels .............................................................. 24

4.2 Other Standards and Design Criteria ....................................................................... 25

4.2.1 Uniformity Ratios ........................................................................................ 25

4.2.2 Veiling Luminance Ratios ........................................................................... 25

4.2.3 Vertical Light Distribution Patterns............................................................. 26

4.2.4 Lateral Light Distribution Patterns .............................................................. 26

4.2.5 Minimum Light Pole Spacing...................................................................... 26

4.3 Lighting Illumination of Special Areas.................................................................... 27

5. GENERAL HARDWARE RECOMMENDATIONS ...................................................................28

5.1 Overview of Major Changes.................................................................................... 28

5.2 Miscellaneous Issues................................................................................................ 30

5.3 Factors Influencing the Hardware Selection............................................................ 30

5.3.1 Context......................................................................................................... 31

5.3.2 Historic significance .................................................................................... 31

5.3.3 Significance of street.................................................................................... 33

5.3.4 Location of electrical power line ................................................................. 36

5.4 Exempt Locations .................................................................................................... 36

March 2005 i


5.5 Hardware Recommendations ................................................................................... 37

5.6 Design Principles ..................................................................................................... 46

5.7 Design Examples ..................................................................................................... 48

6. NEXT STEPS .......................................................................................................................51

APPENDIX A: RESEARCH SUMMARY ......................................................................................52

March 2005 ii


ACKNOWLEDGMENT

This policy guide is an outcome of efforts from a number of people inside and outside

DDOT. The following people provided valuable contributions to this project in steering and

conducting the study, formulating the policies and providing inputs:

Jama Abdi Colleen Smith Hawkinson

Kristina N. Alg Susan Hinton

Laurence Aurbach Ray Kukulski

Samira Cook Ken Laden

John Deatrick Surekha Lingala

Michael Dorsey Mark Loud

Edwin Edokwe William McLeod

Manzur Elahi Jack McKay

Larry Green Elizabeth Miller

Nurul Haque Ann Simpson-Mason

Yavocka Young

March 2005 iii

District of Columbia Streetlight Grand Plan Final Report

EXECUTIVE SUMMARY

The District Department of Transportation (DDOT) undertook a comprehensive study

entitled District of Columbia Streetlight Policy and Design Guidelines to develop a uniform

streetlight policy throughout the City. This study aims at providing the District with well-

defined guidelines and standards for future streetlight deployment. The guidelines will be

implemented in an evolutionary fashion along with future road construction projects. The

streetlight pole replacements will follow the defined guidelines rather than the usual practice

of replacement-in-kind.

This study encompasses research on technology, design principles, and policies; vendor

interviews; interviews with other state agencies; review of existing DDOT practices; and

recommendations for implementation. During the study, DDOT formed a panel of advisors

to serve on a steering committee to ensure that the project addressed concerns from the

stakeholders. The steering committee consisted of representatives from various agencies and

citizen groups. The committee held a series of meetings to define the direction of the project,

evaluate various alternatives, and provide specific recommendations on various aspects of the

streetlight policy issues. Finally, the draft policy was kept open to public comments for a

period of time. This process included citizens' comments, review by other agencies and a

public meeting.

A summary of the policy recommendations is presented below.

OVERVIEW OF MAJOR CHANGES

The following significant deviations from the current practices were adopted:

1. The existing widely used Cobrahead fixtures may be substituted (except for 5A Alley

poles) by a new Teardrop fixture with decorative arms. Teardrop fixture was

preferred because of its aesthetic and architectural qualities for outdoor lighting.

However, the extent of substitution of the Cobrahead fixtures with Teardrop fixtures

depends entirely on the funding situation and priority, which the District Government

should evaluate before establishing the policy. A decorative arm with a Teardrop

fixture has been selected by DDOT.

2. Refractive, prismatic globes have been accepted for replacing the currently used plain

globes. Refractive globes are a major achievement in the field of optical technologies

and provide greater level of illumination with minimal light “loss” by redirecting

lights in the desired direction. The prismatic optical system directs the light into the

desired pattern, allows maximum spacing with excellent uniformity, and minimizes

upward wasted light. The refractive globe is expected to reduce direct glare by

softening and spreading the light being distributed from the light source.

3. White-light lamps may replace the yellow-light, high-pressure sodium lamps in the

future (except for alleys), when their life-cycle cost becomes comparable to that of

yellow-light lamps.

March 2005 ES-1


HARDWARE RECOMMENDATIONS

Various types of streetlight hardware are recommended for various conditions based on:

1. Non-historic streets (underground power line or overhead power line)

2. Historic streets

3. Special Streets

Some hardware selection will also be based on the context of the surroundings.

For non-historic areas with underground power lines, the citizens will be given an

opportunity to select either a Decorative Teardrop (alternatively Cobraheads, if cost

prohibits) or Upright poles in place of the existing Cobrahead pendant poles. The pendant

poles are recommended for non-historic streets, as they are economical. For non-historic

areas with overhead power lines, the lighting arm is the only option for selection. A

Decorative Teardrop arm is preferred; however, Cobraheads can be used, if cost prohibits.

The use of upright poles (e.g., Numbers 14, 16, 18) will continue for historic streets.

Several important streets were designated as Special Streets (alternatively known as Capital

Avenues), for which Twin-20 poles were generally recommended. A decorative Teardrop

arm will be used where overhead power lines exist.

The developed guidelines will apply to the City in general; however, areas with their own

regulations are exempt from these requirements or portions thereof. These exempt locations

include, but are not be limited to, the Downtown Streetscape Area, Business Improvement

Districts (BIDs), and Monumental Core Area. DDOT reserves the right to exempt certain

areas on a case-by-case basis and pick any special streetlight fixture.

DESIGN PRINCIPLES

The following design principles are made part of the policy:

1. The guidelines of the American Association of State Highway and Transportation

Officials (AASHTO) were adopted as the District's policy for lighting criteria.

2. The design should use maximum spacing of streetlight poles. A minimum spacing

between poles of 60 ft has been specified; however, it is not a recommendation, but

only an absolute minimum. The designer should ensure that the spacing fulfills the

following objectives, yet meeting the AASHTO guidelines:

Minimum number of poles

Lowest acceptable wattage

Maximum possible spacing

3. The design should be based on lower wattage lamps so as to provide flexibility for

using higher level of illumination in the future, if necessary. This can be easily done

by replacing lower wattage lamps with higher wattage lamps. For example, No. 16

March 2005 ES-2


poles should be designed for a maximum 250 Watt while up to 400 Watt is allowed;

No. 14 poles should be designed for a maximum of 100 Watt while up to 150 Watt is

allowed.

4. The design should avoid using 400-Watt conversion kits in residential areas.

5. The height of the pole should be determined based on the context of the surroundings,

such as the height of buildings, roadway width, sidewalk width, etc.

6. The design must consider reduction of glare into drivers' and pedestrians' eyes, and

enhancement of visibility. Appropriate refractive globes can effectively reduce direct

glare by softening and spreading the light distribution. Shields can also be used to aim

the lights so that they are not directly visible from the roads, alleys, pathways, and

windows, as needed.

CONCLUSIONS

DDOT should periodically review these guidelines and make any necessary modifications

within the general framework. AASHTO is currently developing a revised streetlighting

guideline and some of its contents have been used in this document. Once AASHTO finalizes

this guideline, any additional appropriate elements should be incorporated in DC Policies.

DDOT should also assess the overall technology and its cost-effectiveness from time to time

to take advantage of new developments offering enhanced safety, economy and aesthetics.

An extensive use of Teardrop remains a question of funding availability and agency priority.

Similarly, the use of metal halide or other similar white light-producing lamp is also a

question of cost; therefore, its cost should be monitored in future.

March 2005 ES-3


1. INTRODUCTION

Street-lighting in urban areas supports multiple objectives. Its primary and fundamental

objective is to provide the light necessary for safe passage of motorists and pedestrians at

night. In addition, it is an important aesthetic element of the street furniture and its

appearance often represents the significance and history of the area. Therefore, it is important

that the streetlight fixtures follow certain standards based on the needs and settings of the

area. In the past, the lack of a policy has resulted in non-uniform lighting hardware and

illumination levels throughout the city.

Washington is the nation's capital with an area of 68.25 square miles and a population of

approximately 600,000. Pierre-Charles L'Enfant designed the City's basic layout and plan,

which features from the Capitol building to parks. In terms of the City’s importance, it

houses the US Capitol, the White House, the Supreme Court, and many other important

government buildings, national landmarks, museums and memorials. In terms of look, this

city is very different than other US cities with its characteristic magnificent buildings with

limited heights and many historic areas. This uniqueness and the historic significance of the

City must be reflected through all aesthetic elements including the appearance of streetlights.

The District Department of Transportation (DDOT) undertook a study entitled District of

Columbia Streetlight Policy and Design Guidelines to develop a uniform streetlight policy

throughout the City indicating its significance. This study is aimed at providing the District

with well-defined guidelines for future streetlight construction. The guidelines will be

implemented in an evolutionary fashion along with future road construction and streetscape

projects. The streetlight pole replacements will follow the defined guidelines rather than the

usual practice of replacement-in-kind. This document outlines a policy and not a regulation

or standard.

The study involved conducting research, interviewing vendors and various state agencies,

reviewing existing DDOT practice and finally coming up with the recommendations. DDOT

formed a panel of advisors to serve on a committee to steer this study. The committee was

formed from members of relevant agencies, including citizen groups' representation. The

committee held a series of meetings and directed the course of the study, made evaluations of

various alternatives and provided specific recommendations on various aspects of the

streetlight policy issues. The research summary and the advisory committee meeting minutes

are presented in Appendix A. Finally, the draft policy was kept open to public comments for

a period of time. This process included citizens' comments, review by other agencies and a

public meeting.

This document contains a set of strategic policy recommendations for future construction of

streetlights in the District of Columbia. It includes four other chapters in addition to this

Introduction (Chapter 1) and an Appendix A. Chapter 2 presents background information

and basic definitions for streetlights. Chapter 3 describes the existing DDOT practice.

Chapter 4 describes the illumination standards recommended for the District. Chapter 5

discusses the streetlight hardware recommendations and presents a simplified streetlight

March 2005 1


design illustration of roadways going through various types of areas. Chapter 6 discusses the

recommendations for future.

March 2005 2


2. BACKGROUND INFORMATION

This chapter presents definitions of key terminologies related to streetlight design. It also

discusses fundamental concepts related to lighting.

2.1 DEFINITIONS

The definitions provided here are broadly classified in two different groups: 1) optics, and 2)

streetlight hardware. The definitions in each group are described below.

2.1.1 Optics

Average Initial Illuminance: The average level of horizontal illuminance on the

pavement area of a traveled way at the time the lighting system is installed with new

lamps and clean luminaries; expressed in average footcandles (lux) for the pavement

area.

Average Maintained Illuminance: The average level of horizontal illuminance on the

pavement when the output of the lamp and luminaire is reduced by the maintenance

factors; expressed in average footcandles (lux) for the pavement area.

Candela: The unit of luminous intensity. The term “candle” was formerly used.

Candlepower: The luminous intensity in a specified direction; which is expressed in

candelas.

Color rendering: A general expression used for the effect of a light source on the color

appearance of objects in conscious or subconscious comparison with their color

appearance under a reference light source.

Color Rendering Index (CRI): A measure of the color shift the objects undergo when

illuminated by the light source as compared with those same objects when illuminated by

a reference source of comparable color temperature.

Cutoff angle (of a luminaire): The angle that is measured up from nadir, between the

vertical axis and the first line of sight at which the bare source is not visible.

Footcandle: The illuminance on a one-square-foot surface in area, on which there is a

light flux of one lumen that is uniformly distributed. One footcandle = 10.76 lux.

Foot Lambert: The uniform luminance of a surface emitting or reflecting light at the rate

of one lumen per square foot. It is a unit of luminance or brightness.

Glare: The sensation produced within the visual field by luminance that exceeds the

eye’s ability to adapt. This can cause annoyance, discomfort, or loss in visual

performance and visibility.

March 2005 3


a. Nuisance glare: It is known as annoyance glare that causes complaints. The

Illuminating Engineering Society of North America (IESNA) defines nuisance

glare as the “light shining in my window” phenomenon.

b. Discomfort glare: The glare that causes physical discomfort but does not keep

the viewer from seeing an object.

c. Disability glare: The effect of a bright light source that causes the stray light to

scatter in the eye. The stray light obscures the primary image on the retina and

restricts the viewer from seeing the object.

Illuminance: The time rate of flow of light is defined as luminous flux. Illuminance is

the density of the luminous flux incident on a uniformly illuminated surface.

Light Pollution: The haze or “glow” that reduces the ability of a person to view the

nighttime sky. It is the stray light from luminaire, which is directed up into the skies; it is

also referred to as “sky glow.”

Light Trespass: The light from a luminaire that falls onto neighboring space, or into

windows of adjacent building. It is also referred to as “spill light.”

Louver (or louver grid): A series of baffles used to shield a source at certain angles, to

either absorb or block unwanted light, or to reflect or redirect light. They are usually

arranged in a geometric pattern.

Lumen: A unit of measure of the quantity of light. The amount of light that falls on an

area of one square foot, every point of which is one foot from the source (i.e., a sphere) of

one candela (candle), is defined as one lumen. A light source of one candela emits a total

of 12.57 lumens.

Lumen depreciation: The decrease in lamp lumen that occurs as a lamp is operated until

failure.

Luminaire: A complete lighting unit consisting of a lamp or lamps together with the

parts designed to distribute the light, to position and protect the lamps and ballast (where

applicable), and to connect the lamps to the power supply.

Luminaire dirt depreciation: The dirt or dust that accumulates on luminaires decreasing

the total output of light, lowering the overall efficiency of the system.

Luminaire efficiency: The ratio of luminous flux (lumens) emitted by a luminaire to

that emitted by the lamp or lamps used therein.

Luminance: The luminous intensity of a surface in a given direction per unit of that

surface as viewed from that direction.

Luminous Efficacy: The rate of converting the electrical energy into visible energy,

which is measured in lumens per watt.

March 2005 4


Lux: The International System (SI) unit of illuminance. It is defined as the amount of

light on a surface of one square meter all points of which are one meter from a uniform

source of one candela. One lux = 0.0929 footcandle.

Uniformity of Illuminance: The ratio of average footcandles (lux) of illuminance on the

surface area to the footcandles (lux) at the point of minimum illuminance on the

pavement. It is generally called the uniformity ratio.

Uniformity of Luminance: The Average-Level-To-Minimum Point method uses the

average luminance on a surface of the roadway design area between two adjacent

luminaries, divided by the lowest value at any point in the area. The Maximum-To-

Minimum Point method uses the maximum and minimum values between the same

adjacent luminaires. The uniformity of luminance (avg/min and max/min) considers the

traveled portion of the roadway, except for divided highways that has different designs on

each side.

Uplight: The percentage of lamp lumens directed at or above 90 degrees from a

luminaire.

Veiling Luminance: A luminance superimposed on the retinal image that reduces its

contrast, resulting in visual performance and decreased visibility; produced by bright

areas in the visual field.

2.1.2 Streetlight Hardware

Ballast: A coil of wire and/or related electronic components used to limit the amount or

electric current flowing through a lamp. Almost all lamps used in streetlighting require

ballasts except incandescent lamps.

Base: A lower part of a streetlight pole that supports the shaft.

Bracket (mast arm): An attachment to a pole from which a luminaire is suspended.

Breakaway Base: A base designed to yield when struck by a vehicle, thereby

minimizing injury to the occupants of the vehicles and damage to the vehicle itself.

Head: The part of the luminaire that holds the lamp socket and mounting hanger or

collar. The assembly will be referred as either the head or the body, when the mounting

collar is part of, or attached directly to, the reflector housing, as in a clamshell style.

High-Mast Lighting: The illumination of a large area by means of a group of luminaires

mounted on fixed orientation at the top of a high mast, generally 65 ft or higher.

Lamppost: A standard support provided with the necessary internal attachments for

wiring and the external attachments for the bracket and luminaire.

March 2005 5


Photocontrol: The device that is usually cylindrical and the size of a tin can, contains a

light sensitive element and other electromechanical or electronic components to turn the

lights on at night and off during the day.

Reflector: Any polished or light colored object used in optical control to change the

direction of light rays as opposed to just block or absorb it.

Refractor: A transparent panel or dish that also serves as a lamp cover and has molded

ridges to bend the light in desired directions.

Streetlight Pole: A pole used for the purpose of supporting street luminaire(s). The

luminaire(s) may be either installed on (upright poles) or suspended from the pole

(pendant poles). Figure 1 shows the different components of poles. The upright poles

include Nos. 18, 16, 14 and Twin-20; and the pendant poles include Cobrahead, 5A Alley

Pole and Teardrop.

Photo Control

Casing

Globe

Base

Shaft

Base

Shaft

Arms

Photo Control

Casing

Globe

Base

Shaft

BaseBase

ShaftShaft

BaseBase

ShaftShaft

Arms

Upright Pole Pendant Pole

Figure 1. Components of Streetlight Poles - Upright and Pendant

March 2005 6


2.2 AASHTO ROADWAY LIGHTING REQUIREMENTS

American Association of State Highway and Transportation Officials (AASHTO) and

Illumination Engineers Society (IES) of North America recommend Table 1 and Table 2 as

the guidelines for lighting design. These tables establish some threshold values, which a

roadway lighting designer meets by using either the illuminance technique or the luminance

technique.

Table 1. AASHTO & IES-Suggested Maintained Luminance Values for Roadways

Luminance

Lavg Uniformity

Veiling LuminanceRatio

Roadway Classification

(cd/m2)

foot-lamberts Lavg/Lmin Lmax/Lmin Lv(max)/Lavg

Freeway Class A a

0.6 0.17 3.5:1 6:1

Freeway Class B a

0.4 0.12 3.5:1 6:10.3:1

Commercial 1.0 0.29 3:1 5:1

Intermediate 0.8 0.23 3:1 5:1

Expresswayb

Residential 0.6 0.17 3.5:1 6:1

0.3:1

Commercial 1.2 0.35 3:1 5:1


Majorb

Residential 0.6 0.17 3.5:1 6:1

0.3:1

Commercial 0.8 0.23 3:1 5:1

Intermediate 0.6 0.17 3.5:1 6:1

Collectorb

Residential 0.4 0.12 4:1 8:1

0.4:1

Commercial 0.6 0.17 6:1 10:1


Localb

Residential 0.3 0.09 6:1 10:1

0.4:1

Commercial 0.4 0.12 6:1 10:1


Alleysb

Residential 0.2 0.06 6:1 10:1

0.4:1

a Source: The IESNA Lighting Standard Handbook, Ninth Edition, IES, 2000. Illuminating Engineering Society of North

America b

Source: An Informational Guide for Roadway Lighting, AASHTO, 1984.

March 2005 7


Table 2. AASHTO and IES-Suggested Maintained Illuminance Values for Roadways

Average Illuminance Pavement Classification

R1 R2 & R3 R4Roadway Classification

Foot-candles

Lux Foot-candles

Lux Foot-candles

Lux Uniformityavg/min

Freeway Class A a

0.6 6 0.8 9 0.7 8

Freeway Class B a

0.4 6 0.6 6 0.5 53:1

Commercial 0.9 10 1.3 14 1.2 13

Intermediate 0.7 8 1.1 12 0.9 10

Expressway b,c

Residential 0.6 6 0.8 9 0.7 8

3:1

Commercial 1.1 12 1.6 17 1.4 15

Intermediate 0.8 9 1.2 13 1.0 11

Major b

Residential 0.6 6 0.8 9 0.7 8

3:1

Commercial 0.7 8 1.1 12 0.9 10

Intermediate 0.6 6 0.8 9 0.7 8

Collector b

Residential 0.4 4 0.6 6 0.5 5

4:1

Commercial 0.6 6 0.8 9 0.7 8


Local b

Residential 0.3 3 0.4 4 0.4 4

6:1

Commercial 0.4 4 0.6 6 0.5 5


Alleys b

Residential 0.2 2 0.3 3 0.3 3

6:1

Commercial 0.9 10 1.3 14 1.2 13 3:1

Intermediate 0.6 6 0.8 9 0.7 8 4:1

Sidewalks b

Residential 0.3 3 0.4 4 0.4 4 6:1

Pedestrian Ways and Bicycle Lanesd

1.4 15 2.0 22 1.8 19 3:1 a

Source: The IESNA Lighting Standard Handbook, Ninth Edition, IES, 2000. Illuminating Engineering Society of NorthAmerica

b Source: An Informational Guide for Roadway Lighting, AASHTO, 1984.

cBoth mainline and ramps. Expressways with full control of access are covered in the section on Freeways.

dThis assumes a separate facility. Facilities adjacent to a vehicular roadway should use the illuminance or luminance levelsfor that roadway.

AASHTO is currently updating the design guide and Table 3 provides the suggested lighting

design values proposed in the AASHTO’s Roadway Lighting Design Guide Ballot Draft

version.

Generally, the illuminance technique is used for streetlighting design. The selection of

threshold values is based upon several factors, as stated below:

1. Functional classification of the facility (e.g., arterial, collector, etc.)

2. Type of land use (e.g., commercial, residential, etc.)

3. Classification of pavement (e.g., R1, R2, etc., based on type of pavement material)

March 2005 8

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60.6

90.8

90.8

80.7

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0.6

0.1

73.5

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0.3

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10

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15

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0.7

11

1.0

11

1.0

10

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0.9

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63:1

5:1

0.3

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50.5

70.7

70.7

70.7

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0.6

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73.5

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r

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:1

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90.8

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40.4

60.6

60.6

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0.4

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8:1

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:1

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60.6

90.8

90.8

80.7

6:1

0.6

0.1

76:1

10:1

0.4

:1

Inte

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te5

0.5

70.7

70.7

60.6

6:1

0.5

0.1

56:1

10:1

0.4

:1

Resid

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30.3

40.4

40.4

40.4

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0.3

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96:1

10:1

0.4

:1

All

ey

s

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40.4

60.6

60.6

50.5

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0.4

0.1

26:1

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:1

Inte

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te3

0.3

40.4

40.4

40.4

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0.3

0.0

96:1

10:1

0.4

:1

Resid

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20.2

30.3

30.3

30.3

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0.2

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66:1

10:1

0.4

:1

Sid

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alk

s

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14

1.3

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1.3

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90.8

90.8

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40.4

40.4

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leL

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19

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3:1

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itia

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Th

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itu

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.

Mar

ch 2

00

59


The factors used in the above tables are discussed below.

Functional Classification of the Facility

The following classifications are those recommended by the Illuminating Engineering

Society of North America1 and AASHTO2.

1. Freeway: This is a divided major roadway with full control of access and with no

crossing at grade. It applies to toll as well as non-toll roads.

a. Freeway A: This designates roadways with greater visual complexity and high

traffic volumes. This type of freeway is usually found in major metropolitan

areas in or near the central core. It operates through much of the early evening

hours of darkness at or near design capacity.

b. Freeway B: This designates all other divided roadways with full control of access

where lighting is needed.

2. Expressway: A divided major roadway for through traffic with partial control of

access and generally at major crossroads with interchanges. Parkways are generally

known as expressways for non-commercial traffic within parks and park-like areas.

3. Major/Principal Arterial: That part of the roadway system serving as the principal

network for through traffic flow. The routes connect important rural highways

entering the city and areas of principal traffic generation.

4. Minor Arterial: The roadway that provides relatively high speeds and least

interference to through traffic flow with little or no access control. It provides direct

access to abutting properties, have frequent at-grade intersections, have pedestrian

movements along and across the roadway, accommodate bicyclist unless specifically

limited and support public transportation.

5. Collector: The roadways servicing traffic between major and local roadways. These

are roadways used mostly for traffic movements within residential, commercial, and

industrial areas.

6. Local: The roadways used mainly for direct access to residential, commercial,

industrial, or other abutting property. They do not include roadways that carry

through traffic. The long local roadways are generally divided into short sections by

collector roadway systems.

7. Alley: A narrow public ways within a block, which is generally used for vehicular

access to the rear of abutting properties.

8. Sidewalk: A paved or otherwise improved areas for pedestrian use, located within the

public street right-of-way, which also contains roadways for vehicular traffic.

9. Pedestrian Walkway: A public facility for pedestrian traffic not necessarily within

the right-of-way of a vehicular traffic roadway. They include skywalks (pedestrian

1 American National Standard Practice for Roadway Lighting, ANSI/IES RP-8.1983; Illuminating Engineering

Society of North America.2 Roadway Lighting Design Guide Ballot Draft, AASHTO, 2004.

March 2005 10


overpasses), subwalks (pedestrian tunnels), walkways giving access to parks or block

interiors, and midblock street crossings.

10. Bicycle lane: A portion of roadway, or shoulder, or any facility that has been

explicitly designated for the use by bicyclists.

Area Classifications

1. Commercial: A business development of a municipality where ordinarily there are

many pedestrians during night hours. This definition applies to densely developed

business areas outside, as well as within, the central section of a municipality. The

area contains land use that attracts a relatively heavy volume of nighttime vehicular

traffic or pedestrian traffic, or both, on a frequent basis.

2. Intermediate: Those areas often characterized by moderately heavy nighttime

pedestrian activities such as in blocks having libraries, community recreation centers,

large apartment buildings, industrial buildings, or neighborhood retail stores of a

municipality.

3. Residential: A residential area, or a mixture of residential and small commercial

establishments characterized by few pedestrians at night. This includes areas with

single-family homes, townhouses, and small apartment buildings.

Certain land uses, such as office and industrial parks, may fit into any of the above

classifications. The classification selected should be consistent with the expected nighttime

pedestrian activities.

Road Surface Classification

The road surface classifications (as shown in Table 4) are used when designing a roadway

lighting system. It is divided into four categories (R1, R2, R3 and R4) depending on the

reflectance characteristics of the pavement. Each category has its own values of reflectance

for specified angles.

Table 4. Road Surface Classification3

Class Qo*

Description Mode of Reflectance

R1 0.10 Portland cement concrete road surface. Asphalt road surface withminimum of 15 percent of the aggregate composed of artificialbrightener (e.g., Synopal) aggregates (e.g., labradorite, quartzite)

Mostly diffuse

R2 0.07 Asphalt road surface with an aggregate composed of a minimum60 percent gravel (size greater than 10 millimeters)Asphalt road surface with 10 to 60 percent artificial brightener inaggregate mix. (Not normally used in North America)

Mixed (diffuse and specular)

R3 0.07 Asphalt road surface (regular and carpet seal) with darkaggregates (e.g., trap rock, blast furnace slag); rough textureafter some month of use (typical highways)

Slightly specular

R4 0.08 Asphalt road surface with very smooth texture Mostly specular*

Qo = representative mean luminance coefficient

3 Source: American National Standard Practice for Roadway Lighting. ANSI/IES RP-8.1983; Illuminating

Engineering Society of North America.

March 2005 11


2.3 LIGHT SOURCES

The light source is the most important element of illumination equipment. It is the principal

determinant of visual quality, illumination efficiency, energy conservation, and the economic

aspects of the lighting system. There are numerous types of light sources that are being used

in roadway lighting. They include Mercury Vapor, Metal Halide, High-Pressure Sodium

(HPS), Low-Pressure Sodium, and Fluorescent.

The light sources are generally compared on the basis of four major characteristics:

1. Luminous efficacy (i.e., the number of lumens produced per watt of energy)

2. Color rendition (i.e., color quality)

3. Lamp life (i.e., number of operating hours)

4. Optical control

As mentioned earlier, HPS, Metal Halide, Mercury Vapor, Fluorescent and Incandescent

lamps are generally used. HPS is the most efficient option with a long life, while Metal

Halide has an excellent color rendition. Incandescent and Mercury Vapor are being phased

out. The comparison of various lamp types is shown in Table 5.

Table 5. Comparison of Lamps

Option Method Advantages Disadvantages

Incandescent Lamps which produce light byusing electric current to heat a filament

Instant on Low initial cost Excellent color renditionCan be dimmedCompact in size

Short life (500-5,000 hrs) Inefficient to operateHigh heat output

Fluorescent Lamps that pass electricitythrough a gas enclosed tube to create lightUsually used indoor and in somecases for signage

Twice the light and less than halfthe heat of an Incandescent bulbof equal wattage.Long life (10,000-15,000 hrs)EfficientGood color rendition

Temperature sensitive

MercuryVapor

A high-intensity discharge deviceproducing light by excitation ofmercury vapors (or passing electricity through a gas) to emita bluish white light

Long life (16,000-24,000 hrs)Low initial cost

Inefficient operationLight output drops over life(2-3 yrs)Delayed hot restart

Metal Halide High intensity discharge arc tubein which light is produced byradiation of exited Metal Halide

Excellent color renditionSparkling white light that imitatesdaylight conditions, used in sportsstadiums, car dealer lots, etc. 100-watt bulb lasts 10K hrs Works well with CCTV

Hot restart can take several minutesHigh initial costMost expensive light to install and maintain

HighPressureSodium

High intensity discharge arc tubein which light is produced byradiation from sodium vapor operating under pressure

Very long life (20K-28K hrs) Can cut through fog and allowgreater visibility (used on streetand parking lots)In some cases, it can be used with CCTV

High initial cost of fixtures Hot restart can take several minutes

March 2005 12


A summary of properties of various lamps is presented in Table 6. The number of hours the

lamp remains functional is considered as the life of the lamp. The efficacy is a measure of

the "efficiency" of a lamp, measured in lumens per watt (i.e., knowing how much light is

given out for a given amount power input), allows comparisons of energy efficiency to be

made. The Color Rendering Index (CRI) is a relative measure of the shift in surface color of

an object when lit by a particular lamp, compared with how the object would appear under a

reference light source of similar color temperature. The higher the CRI of the light source,

the "truer" it renders color.

Table 6. Summary of Lamp Properties

Option Life (hrs) Efficacy (lpw) Color Rendering Index Color of light

High Pressure Sodium 20,000-24,000 50-110 40 (approx. 22) Orange

Metal Halide 6,000-15,000 72-76 75-90 White

Mercury Vapor 16,000-24,000 30-50 40-60 Blue-White

Fluorescent 10,000-24,000 40-140 20-80 White

A lamp's lumen output declines rapidly during its life; therefore, a designer should initially

provide more lumens than is required so that as the lamp declines with age, a sufficient

amount of light is still available. Figure 2 shows typical lamp lumen depreciation over time

for three light sources – Low Pressure Sodium (LPS), High Pressure Sodium (HPS) and

Metal Halide Pulse Start Horizontal (MH).

Typical Lamp Life for Three Light Sources

50

60

70

80

90

100

0 4800 9600 14400 19200 24000

Time in Hours

% O

utp

ut

(Lu

me

n)

LPS

HPS Range

MH

Legend

Figure 2. Typical Lamp Lumen Depreciation

Advances in HPS lamp technology have led to the development of a new color corrected

HPS lamp. Color corrected HPS lamps are made by using optical coatings; however, the

coating often gets burnt out. Even with greatly improved Color Rendering Index (about 80),

March 2005 13


the color corrected HPS lamp still delivers yellow light for sometime when the bulb is

switched on, and is not as white as the Metal Halide. It has been further reported that the

color coating becomes ineffective at about half-life of the lamp.

In Europe, induction lamps are widely used and have a number of advantages. It has a long

life – 100,000 hours rated average life4. It provides a Color Rendering Index of 80+ CRI,

which is almost twice as much as that of mercury vapor (45 CRI) and almost four times as

much as that of HPS (21 CRI). Even though it has a higher initial cost, its long life reduces

the operations and maintenance costs. Starting operation is instant with no flickering. The

disadvantages include the unavailability of moderate to high wattage lamps. The lamp will

not "burn out" but will just get so dim that it no longer supplies adequate light for a given

application. Although it has a long life, the ballasts may fail sooner, requiring the

replacement of both the lamp and the ballast.

2.4 POLES

There are four types of poles used for luminaire support; these are Fiberglass, Aluminum,

Steel and Concrete poles. The advantages and disadvantages are discussed in Table 7. The

District mostly uses steel poles and is phasing out Fiberglass.

Table 7. Comparison of Poles

Option Advantages Disadvantages

Fiberglass Pole Direct burial pole is easy to install, and requires no waiting for concrete to cure. Some fiberglass poles are available for mounting to an anchor base.Electrically non-conductiveCorrosion resistantFiberglass materials should be ‘solid-core’so that scratches and gashes in the polewill be less noticeableLower cost option than many metal polesLighter, less expensive to ship to sites Should have above ground access door, otherwise it’s a maintenance problem

Needs to be painted every 15 yearsbecause the color fades with time Appears to be cheaper and less durablethan metal polesPole has texture that looks un-metallic if standard paint finish is applied. Smooth paint finishes help to get rid of turn marks Weed whackers beat up the base of fiberglass polesIf not stored carefully, heat can warp the pole

Aluminum Pole Good quality appearance. Fluting andother relief details are easy options.Factory-installed paint finish often more durable than fiberglass pole finish. Thepre-treatment and base coating of the pole is critical to paint and pole durability.With good-quality multi-stage paint finish in factory, corrosion is minimal, especiallywhen low-copper aluminum alloy is usedModerate cost: Tapered aluminum polesare less expensive than straight aluminumpoles in sizes greater than 14’Aluminum has scrap value at the end of it’s life

Electrically conductiveMore difficult to install than fiberglass because it requires anchor base

4 Based on 11 hours average usage per day, 7 days a week.

March 2005 14


Option Advantages Disadvantages

Steel Pole Low initial cost Electrically conductiveCorrodes easily. Needs frequent paintingMore difficult to install because it requiresanchor baseHeavier to ship to jobsite than either aluminum or fiberglass poles

Concrete Pole Durable, non-corrodingElectrically non-conductiveEasy, direct burial installation, that requires no waiting for concrete to cure Several color options for appearanceCan function as a barrier againstvehicular traffic for pedestrians, but willnot breakaway if struck by vehicle

Non-traditional appearance (doesn’t look like metal)Must be re-coated with preserving finishevery 15 yearsHard to add accessories such as bannersor parking signs. Requires stainless steelbands around the pole unless pole is pre-drilled for these attachments.Limited number of appearance optionsbeyond color and aggregateHigher initial cost than fiberglass or aluminum poles

2.5 PHOTOSENSOR

The streetlight has a photosensor that turns off when exposed to light and vice versa. There

are two types of photosensors- button type and twist-lock. The button type photosensors need

to be avoided as they have a high failure rate. This must be installed in the luminaire and

should be done in the factory as the field personnel complain that it is too difficult and time

consuming to install it in the field. The ‘Twist-lock’ photosensors are preferred and are

mounted to bracket arms on the poles rather than the luminaire.

2.6 GLOBES

The Washington globes are made either of glass or plastic. The glass globes were originally

being used, but were discontinued, as they are not safe. Therefore D.C. went from glass to

plastic. The cost of a glass globe is approximately $300, an acrylic globe is $125 and a

prismatic acrylic globe is $200. The comparisons between the globes are shown in Table 8.

March 2005 15


Table 8. Comparison of Globes

Option Facts Advantages Disadvantages

Plastic (Acrylic) Globe ‘DR Acrylic’ is tougherform of acrylic that willnot yellow from UV radiation. Not asresistant to breakage as polycarbonate.Excellent choice for both MH and HPSlamps. This impact resistant acrylic will last 10-15 years.

Acrylic does not yellowwith exposure to UVradiation from eitherdaylight or lamps.

Standard acrylic is easily cracked andbroken, so it is not recommended to be used as post-toplighting

Plastic (Polycarbonate)Globe

Seldom used with MH lamps because MHemits larger amount of UV rays than HPS lamps do.Polycarbonate lensesand globes have a life of only 5-10 years.

Very tough form of plastic

Yellows when exposeto UV radiation and become brittle withtime.

Glass Globe Plain Glass Very durable materialthat does not changecolor (yellow) over time

Very heavyNot safe, as it could tear the cars tires or harm someone whenbroken.

2.7 LATERAL DISTRIBUTION PATTERNS

The Illuminating Engineering Society (IES) establishes a series of lateral distribution patterns

designated as Types I, II, III, IV and V. Types I and V represent symmetric lighting

distribution and the luminaires are usually mounted over the center of the roadway. Types II,

III and IV are asymmetric distribution and the luminaires are usually mounted near the edge

of the roadway. Type I applies to rectangular patterns on narrow street, Type II to narrow

streets, Type III to street of medium width, Type IV to wide streets and Types V to areas

where light is to be distributed evenly in all directions. These are illustrated in the Figure 3.

March 2005 16


Type I – A luminaire designed for

center mounting over streets up to

2.0 mounting heights in width.

Type II – A luminaire designed for center

mounting over curb line of street width

less than 1.5 mounting heights.

Type III – A luminaire designed for

center mounting over curb line of street

width up to 2.0 mounting heights.

Type IV – A luminaire designed for


width greater than 2.0 mounting heights.

Type V – A luminaire designed to

distribute light equally in all lateral

directions.

Type I – A luminaire designed for

center mounting over streets up to

2.0 mounting heights in width.

Type II – A luminaire designed for center

mounting over curb line of street width

less than 1.5 mounting heights.

Type III – A luminaire designed for


width up to 2.0 mounting heights.

Type IV – A luminaire designed for


width greater than 2.0 mounting heights.

Type V – A luminaire designed to

distribute light equally in all lateral

directions.

Figure 3. Type of Lighting Distribution5

2.8 POLE PLACEMENT CONFIGURATIONS

The luminaire placement is an integral part of an effective street-lighting design. The

luminaires are mounted at a given height above the roadway, depending on the lamp output

and characteristics of the roadway to be lighted at specific points along the roadway.

Roadways with no medians may have the luminaires installed in a “house-side” location,

which may be further described as a “one-side” system, a “staggered” system, or an

“opposite” system. Roadways with wide medians and barriers may have the luminaire

installed on a “median lighting” system, which provides very effective lighting at less cost

because of the savings in luminaire supports and electrical conductors. The pole can be

placed in various configurations as shown in Figure 4.

5 Source: American National Standard Practice for Roadway Lighting. ANSI/IES RP-8.1983; Illuminating

Engineering Society of North America.

March 2005 17


S

Off Roadway – Staggered – Both Sides

SS

Off Roadway – Staggered – Both Sides

One Sided

S

One Sided

SS

Staggered – Both Sides

S

Staggered – Both Sides

SS

Opposite – Both Sides

SS

S

Center Mounted Arrangement

Cable

S

Center Mounted Arrangement

Cable

S

Median Mounted

S

Median Mounted

S – Pole Spacing

Figure 4. Typical Mounting Configurations6

2.9 CUTOFF FIXTURES

It is important to control the distribution of light flux emission above the beam of maximum

candlepower. At higher vertical angles, light flux emission generally contributes substantially

6 Source: Roadway Lighting Handbook, Washington, DC, U.S. Department of Transportation, 1983.

March 2005 18


to increased pavement brightness, but it also contributes greatly to increased disability and

discomfort glare. The light flux emission above the beam of maximum candlepower needs to

be controlled to achieve balanced performance. The categories of control are presented in

Table 9 with some facts, advantages and disadvantages of each option.

Table 9. Comparison of Cutoff Levels

Option Facts Advantages Disadvantages

Full Cutoff A luminaire light distribution with zero candela (intensity)at an angle of 90° or above.The candela per 1000 lamp

lumens is 100 (10%) at80

overtical angle

No uplight allowed

Perceived reduction in ‘skyglow’Excellent light control at property line Limits spill light Reduces perceived glare

Reduces pole spacing, increases pole and luminaire quantity Least cost effective of all cutoff categories Concentrated down light component results in maximum reflected uplight Decreased uniformity due to higher light levels under pole

900 – No Light,

0% Light

80 0 – 100 CD/1000 LM,10% Light

900 – No Light,

0% Light

80 0 – 100 CD/1000 LM,10% Light

CutoffA luminaire light distribution where the candela per 1000

lumens is 25 (2.5%) at anangle of 90

° or more.

The candela per 1000 lamp lumens does not exceed 100 (10%) at a vertical angle of 80

o.

0% to 16% uplight

Small increase in high-angle light compared to full cutoff Good light control at propertylinePotential for increased pole spacing and lowering overall power consumption whencompared to full cutoff

Can allow uplight, a problem where uplight is not desired Light control at property line less than full cutoffHigher amount of reflected light off pavement can contribute to sky glow

Semi-CutoffA luminaire light distribution where the candela per 1000

lumens is 50 (5%) at 90o

angle or above. The candela per 1000 lamp

lumens is 200 (20%) at80

overtical angle

1% to 32% uplight

Potential for increased pole spacing and lowering overall power consumption whencompared to full cutoffHigh angle light accents taller surfacesLess reflected light off pavement than cutoff luminaries Vertical illumination increases pedestrian security and safety

Greater potential for direct uplight component than cutoffLight trespass a concern near residential areasIncreased high angle light compared to cutoff

Non-CutoffA luminaire light distribution there is no candelarestriction at any angle.No restriction on uplight

Potential for increased pole spacing and lowering overall power consumption whencompared to full cutoffAccents taller surfaces Highest vertical illumination increases pedestrian safety & securityPotential for excellent uniformityLeast amount of reflected light off pavement ‘Open visual environment’ provides vertical surfacevisibility

Greater potential for direct uplight component than cutoffLeast control of uplightIncreased high angle light compared to cutoff

900 – 25 CD/1000 LM,2.5% Light

800 – 100CD/1000 LM,10% Light

900 – 25 CD/1000 LM,2.5% Light

800 – 100CD/1000 LM,10% Light

900 – 50CD/1000 LM,

5% Light

800 – 200 CD/1000 LM,20% Light

900 – 50CD/1000 LM,

5% Light

800 – 200 CD/1000 LM,20% Light

Source: HOLOPHANE

March 2005 19


3. EXISTING DDOT PRACTICE

This chapter presents the current District practice for streetlight usage. It includes types of

poles, lamps, wattages, illumination levels, special requirements, etc.

3.1 POLES

Figure 5 through Figure 7 show the various streetlight poles used in the District (referred to

as Washington Family of Streetlight Poles in this document). Several streetlight poles are

being phased out or have already been rendered obsolete. The different types of poles are

described below.

Older Types

Figure 5 shows some obsolete poles. The 10th

Street Mall poles have a few installations in L

'Enfant Plaza and are being phased out. The New York Avenue Rotary Type poles are no

longer used and the RLA poles are being phased out.

Figure 5. Washington Family --Older Types

Washington Upright Poles

This group includes Nos. 716, 16, 18, 13N, 14, 17M, 19M, Twin-20 and State Department

Twin-20. The Nos. 13N, 17 M, 19M and State Department Twin-20 poles are now obsolete.

March 2005 20


The Washington Upright poles (e.g., Nos. 716, 14, 16, 18, and Twin-20) are used in the

historic districts/streets. No. 16 is the most commonly used upright pole; No. 716 is

considered to be an inexpensive version of No.16 ($5000 vs. $2500). In the Downtown area

near Foggy Bottom, No. 18 poles are used. The Twin-20 poles are used in Downtown, in

historic districts and several entry points into Washington, DC.

The Nos. 16 and 18 poles use 24-inch bases and 15-inch bolt circles and can accommodate

70-400 Watt lamps. The No. 14 pole, on the other hand, uses a 17-inch base and 10.5-inch

bolt circles and can accommodate 70-150 Watt lamps, since it is limited by the size of the

casing. 716 poles are steel octaflute with a 9.5 inches bolt circle. AD11 poles, a variation of

No. 716 poles, are used for traffic signals.

In a pole, the shaft is always made of steel, whereas the base, arm and casing can be cast iron

or aluminum. In the past, fiberglass poles were used, but are obsolete now. All the poles in

DC are powder coated and most of the times have a breakaway base (except near signalized

intersections).

716 13/14/16/18 19M TWIN-20 STATE DEPT.

TWIN-20716716 13/14/16/1813/14/16/18 19M19M TWIN-20TWIN-20 STATE DEPT.

TWIN-20

STATE DEPT.

TWIN-20

Figure 6. Washington Family – Upright Poles

Pendant Post and 5A Alley Poles

The Pendant Post poles are installed citywide and can accommodate 70-400 Watt lamps with

either single or twin arm(s). The District typically uses Cobrahead type arms and fixtures

(although there are limited installations of Teardrop fixtures, another type of Pendant Post

implementation). Pendant Post poles have an octaflute type of cross-section.

The most widely used Pendant Post poles are 28 feet –6 inches tall; 38 feet-6 inches tall poles

are also used. There are a few high-mast (70 feet-100 feet tall) Pendant Post poles in the City

that use 1000 Watt High Pressure Sodium (HPS) lamps.

March 2005 21


The 5A Alley post is widely used in alleys.

Figure 7. Washington Family – Pendant Posts and 5A Alley Poles

3.2 LAMPS

The lamps generally used in the District are HPS, Metal Halide (MH), Mercury Vapor,

Fluorescent and Incandescent. HPS is extensively used for sign and streetlighting. Because of

its relatively low maintenance requirement, the District has been using HPS universally,

except for the Monumental Core. MH lamps currently have very limited use (only in the

Monumental Core area). Twenty (20) percent of the existing lights use incandescent lamps.

Mercury Vapor is used for sign lighting and Florescent is used for underpasses. Mercury

Vapor and Incandescent lights are being phased out and replaced by HPS.

3.3 WATTAGE

The District is currently considering a policy to design streetlights based on a lower wattage,

so as to keep an extra cushion for higher level of illumination in future. If needed in future,

the lower wattage lamps can be replaced by higher wattages. For example, No. 16 poles

should be designed for a maximum of 250 Watt (while allowed is up to 400 Watt) and No. 14

poles should be designed for a maximum of 100 Watt (while allowed is up to 150 Watt).

This will provide the flexibility of using higher wattages in future.

DDOT also discourages using 400 Watt conversion kits in residential areas.

March 2005 22


3.4 ILLUMINATION LEVELS

DDOT uses AASHTO guidelines for roadway lighting for any new design.

3.5 SPECIAL REQUIREMENTS

The Downtown Streetscape Regulation determines the streetlight poles, spacing and pattern

in downtown area. There are several Business Improvement Districts (BIDs) in DC. These

include Georgetown, Downtown, Golden Triangle and North of Massachusetts Avenue

(NOMA) BIDs. The No. 18 poles are generally used in the BIDS. The Downtown BID

specifies the pole type and the Golden Triangle BID specifies the color of the pole to be

black (Federal 27038). The NOMA BID is being formed, and therefore, its standards are yet

to be determined.

The Monumental Core area uses black upright poles (No. 16 or Twin-20) with 400 Watt MH

conversion kits. In the District, MH lights are currently being used only in Monumental Core.

The District is in the process of defining Gateways (i.e., significant entry points) into the city.

There are approximately 55 Gateways into the District. The Twin-20 poles have been used

on Georgia Avenue (inside the DC line) and on New York Avenue (inside the City). 16th

Street is also going to have Twin-20 poles.

March 2005 23


4. ILLUMINATION STANDARDS RECOMMENDATIONS

4.1 GENERAL STANDARDS FOR ILLUMINATION LEVELS

AASHTO guidelines have been adopted as a basis for DC streetlight illumination standards.

The design values proposed in the current Ballot Draft version of AASHTO guide is used in

this policy. Any subsequent future modifications in AASHTO standards will be reviewed by

DDOT for inclusion in this policy.

Table 10 lists the recommended ranges for the average maintained illuminance levels for the

various roadway classifications as defined by DDOT. The average maintained illuminance

represents the output of the lamp and luminaire, after reduced by the maintenance factors

(e.g., light loss depreciation and dirt depreciation); expressed in average foot-candles (lux)

for the pavement area. The light loss depreciation is defined as the decline in the light lumen

that occurs as a lamp is operated over time. Dirt accumulates on luminaires, decreases the

total output of light and lowers the overall efficiency of the system. This process is called

luminaire dirt depreciation. The table is derived for all types of road surface classification.

Most of the roadway pavements in the District are either R2 or R3 class.

Table 10. Recommended Average Maintained Illuminance for District Roadways7

Recommended Average MaintainedIlluminance

(foot-candle)DC Street Classification Land Use

R1 R2 & R3 R4

Interstate ResidentialIntermediateCommercial

0.6 to 0.7 0.7 to 0.9 0.7 to 1.1

0.6 to 0.7 0.7 to 0.9 0.7 to 1.1

0.6 to 0.7 0.7 to 0.9 0.7 to 1.1

Other freeways and Expressway

ResidentialIntermediateCommercial

0.60.70.9

0.81.11.3

0.70.91.2

Principal Arterials ResidentialIntermediateCommercial

0.60.81.1

0.81.21.6

0.71.01.4

Minor Arterial ResidentialIntermediateCommercial

0.50.70.9

0.71.01.4

0.70.91.0

Collector ResidentialIntermediateCommercial

0.40.60.7

0.60.81.1

0.50.70.9

Local Street ResidentialIntermediateCommercial

0.30.50.6

0.40.70.8

0.40.60.7

Alleys ResidentialIntermediateCommercial

0.20.30.4

0.30.40.6

0.30.40.5

7 Recommendations based on Roadway Lighting Design Guide Ballot Draft, AASHTO, 2004.

March 2005 24


For illuminated sidewalk areas, the following average maintained illumination levels should

be designed along all DDOT roadway classifications for either R2 or R3 class with the

criteria based on the level of commercial development.

Table 11. Recommended Average Maintained Illuminance for Sidewalks8

Recommended Average Maintained Illuminance(foot-candle)DC Sidewalk Locations

R1 R2 & R3 R4

Residential Areas 0.3 0.4 0.4

Intermediate Areas 0.6 0.8 0.7

Commercial Areas 0.9 1.3 1.2

4.2 OTHER STANDARDS AND DESIGN CRITERIA

4.2.1 Uniformity Ratios

For the DDOT roadway classifications shown below, the following uniformity ratios

(average-to-minimum) should be used as a guideline in the design of the lighting system.

Table 12. Recommended Average-to-Minimum Uniformity Ratios

DC Street Classification Average-to-Minimum Uniformity Ratio

Interstate 3:1 or 4:1

Other freeways and Expressway 3:1

Principal Arterials 3:1

Minor Arterial 4:1

Collector 4:1

Local Street 6:1

Alleys 6:1

4.2.2 Veiling Luminance Ratios

AASHTO is currently updating the design guide, which states that the veiling luminance

ratio requirement should be used as a design guideline along with uniformity ratios in the

design of the lighting system. The veiling luminance ratio will need to be satisfied in order to

insure that the disability glare is minimized to reduce the blinding effect from light shining

directly into the eyes of drivers and pedestrians. The veiling luminance ratios shown in Table

13 are from the current Ballot Draft version of AASHTO guide. DDOT will review any

future modification in AASHTO standards for inclusion in this policy.


March 2005 25


Table 13. Recommended Veiling Luminance Ratios9

DC Street Classification Veiling Luminance Ratio

Interstate 0.3:1

Other freeways and Expressway 0.3:1

Principal Arterials 0.3:1

Minor Arterial 0.3:1

Collector 0.4:1

Local Street 0.4:1

Alleys 0.4:1

4.2.3 Vertical Light Distribution Patterns10

For residential areas, mixed-use and commercial areas, all luminaires must have a Full cutoff

luminaire light distribution with zero candelas (intensity) at an angle of 90 degrees or above,

or a Cutoff luminaire light distribution where the candela per 1,000 lumens does not exceed

25 (2.5%) at an angle of 90 degrees or above.

By establishing the standards for lighting fixtures in residential, intermediate, and

commercial areas, rear obtrusive light can be minimized.

4.2.4 Lateral Light Distribution Patterns

The following lateral light distributions should be used for the DDOT roadway

classifications:

Table 14. Recommended Light Distribution Patterns11

DC Street Classification Lighting Distribution Pattern

Interstate Roadway Type III or Type IV

Freeway/Expressway Type III or Type IV

Principal Arterial Type III or Type IV

Minor Arterial Type III

Collector Type III

Local Street Type II or Type III

Alleys Type II

If lighting poles are located in the medians of roadways or within islands that have traffic

flows on both sides of island, a Type V lateral lighting distribution pattern may be used.

4.2.5 Minimum Light Pole Spacing

For all DDOT roadway classifications, a pole height and lighting fixture must be chosen to

meet the average maintained illumination levels and uniformity ratios identified earlier, and

to have pole spacings at 60 feet or greater. In cases where lighting designs require pole

9 Recommendations based on: Roadway Lighting Design Guide Ballot Draft, AASHTO, 2004.10 Recommendations based on: City and County of Denver Rules and Regulations for Outdoor Lighting.11 Recommendations based on: American National Standard Practice for Roadway Lighting.

March 2005 26


spacings to be less than 60 feet to reach the desired illumination levels and uniformity ratios,

a different pole and/or lighting fixture must be considered first to meet or exceed a 60- foot

minimum spacing requirement. For pole spacing less than 60 feet, exceptions must be

approved by DDOT.

4.3 LIGHTING ILLUMINATION OF SPECIAL AREAS

For special areas of the City, as defined by DDOT, higher average maintained illumination

levels than those identified earlier might be desirable to draw special attention to the area.

These could include, but not be limited to, Gateways of the City, Monumental Core Areas,

and BID Areas. If these locations have their own regulations regarding the level of

illumination, designs should be based on those regulations. Furthermore, DDOT will make

the determination whether an area should be designed with different lighting criteria than

those identified above (BIDS, National Park Service, Monumental Core, etc., are exempted

as of the publication of this report).

March 2005 27


5. GENERAL HARDWARE RECOMMENDATIONS

This chapter presents recommendations for the streetlight hardware. The selection of

hardware was mostly performed through a series of Streetlight Policy Advisory Committee

meetings. The selection has been made as specific as possible, yet some flexibility for final

selection has been left to the citizens.

The recommendations are made for all neighborhoods in general; however, areas within the

District, having their own regulations will be exempt from the requirements of this policy

guideline. A separate discussion is provided in this chapter on these exempt locations, which

override this guideline.

In addition, historic and new bridges may deviate from these guidelines and may be designed

with special decorative streetlight hardware to signify their importance.

5.1 OVERVIEW OF MAJOR CHANGES

The following deviations from the current practices are deemed significant and hence noted:

1. The existing widely used Cobrahead fixtures may be substituted (except for 5A Alley

poles) by a new Teardrop fixture with decorative arms. Teardrop fixture was naturally

preferred because of its aesthetic and architectural qualities for outdoor lighting.

However, the extent of substitution of Cobrahead with Teardrop fixtures depends

entirely on the funding situation and priority, which the District Government should

evaluate before establishing the policy. A cost comparison is shown below.

Table 15 presents a vendor-provided comparison between a Teardrop and a

Cobrahead installation, for a particular scenario (40' wide street, 30' high pole, 6' arm

and 2' offset from the curb). The use of this data results in per-mile capital costs of

pole and fixture (excluding conduits, cables, etc.) to be $119,000 and $140,400,

respectively, for Cobrahead and Teardrop.

Table 15. Comparison between Teardrop and Cobrahead

Comparison Criteria Teardrop Cobrahead

Spacing 318 feet 294 feet

Initial Cost $ 800 $ 400

Lamp Life 6 Years 6 Years

Ballast Replacement Cost $ 100 $ 90

Photocell Life 10 Years 10 Years

Globe Replacement Cost $ 100 $ 60

Life Expectancy 30 Years 20 Years

A decorative arm with a Teardrop fixture has been selected by DDOT. The fixture

(not the arm) is shown in Figure 8.

March 2005 28


Figure 8. Selected Teardrop Fixture

March 2005 29


2. Refractive, prismatic globes have been accepted for replacing the currently used plain

globes. Refractive globes are a major achievement in the field of optical technologies

and provide greater level of illumination with minimal light “loss” by redirecting

lights in the desired direction. The prismatic optical system directs the light into the

desired pattern, allows maximum spacing with excellent uniformity, and minimizes

upward wasted light. The refractive globe is expected to reduce direct glare by

softening and spreading the light being distributed from the light source.

3. White lights may replace yellow lights produced by HPS lamps (except for alleys) in

the future, when their life-cycle costs become comparable to yellow light sources.

5.2 MISCELLANEOUS ISSUES

The following miscellaneous items are included in the policy:

1. DDOT reserves the right to exempt certain areas on a case-by-case basis and pick any

special streetlight fixture.

2. Prismatic globes will be used for new designs only. Since the prismatic globes have a

different photometric pattern, it cannot replace a plain globe one to one and therefore,

it cannot be retrofitted into existing light poles.

3. Alleys have a different illumination level requirement and hardware recommendation

than streets. However, there are alleys that serve as access to households and

therefore, regular requirements for alleys may not apply to them. The illumination

level can be higher for such alleys and regular roadway requirements can be used.

However, pole type will still have to be typical direct-buried type alley light pole (i.e.,

5A Alley Pole), since alleys do not have additional right-of-way for the pole

foundations. The fixtures and arms of the pole (other than regular 5A arm and

cobrahead) can be selected on a case-by-case (such as a 3' decorative arm with

teardrop fixture) depending on zoning, usage and historic significance of the alley.

4. The policy for house side shields and painting the globes black depends on the

citizens and will be considered on a case-by-case basis.

5.3 FACTORS INFLUENCING THE HARDWARE SELECTION

A number of factors contribute to the determination of streetlight hardware requirements.

They include the following:

Context

Historic significance

Significance of the streets

Location of electrical power line

March 2005 30


5.3.1 Context

Another important factor for streetlight hardware selection is the context of the surrounding.

The height of the pole, lamp wattage, shielding method are based on the surrounding. The

context of the surrounding includes the characteristics of a street, such as:

1. Roadway Width

2. Sidewalk Width

3. Height of the building

4. Setback of the building

5.3.2 Historic significance

Washington's significance is attributed to the national landmarks and monuments as well as

the historic neighborhoods and local landmarks that make the city unique. The city had

ninety-six historic places that bring the 200 years of history of the city to life. The

preservation of the historic attributes of these areas is an important goal of the City.

Streetlighting hardware is a significant element of these attributes.

The streets in the City can be broadly classified into two groups – historic and non-historic.

As the name implies, historic streets need to preserve the tradition of the City in terms of

streetlight hardware appearance. Non-historic streets do not have that requirement; however,

certain standards are set up for these to promote uniformity and consistency.

The historic streets, shown in Figure 9, are defined to include:

1. Road network within the designated historic areas

2. Other streets designated as historic (i.e., in non-historic areas)

March 2005 31


Non-Historic Streets

Historic Streets

Historic Areas

Legend

North


Historic Streets

Historic Areas

Legend


Historic Streets

Historic Areas

Legend

North

Figure 9. Historic Streets in Washington, DC

March 2005 32


Furthermore, certain streets are designated as the monumental core streets and are shown in

Figure 10.

Monumental Core

Legend

Monumental Core

Legend

Monumental Core

Legend

Figure 10. Monumental Core Streets

5.3.3 Significance of street

Another factor for the streetlight hardware selection is the significance of the street. A set of

streets has been designated as Special Streets (alternatively, Capital Avenues), as shown in

Figure 11 and Table 16. The list includes roads playing significant role in carrying motorists

and tourists in and out of the City as well as several streets belonging to the historic L 'Enfant

Plan. The following categories of streets are included in this group12:

1. National Highway System (NHS) streets. These streets are federally designated

streets of importance (with respect to nation's economy, defense, and mobility) that

receive federal aid. Nationally, the Federal Government has designated approximately

160,000 miles (256,000 kilometers) of NHS streets.

2. Gateway streets. The District has designated key entry points to the City as Gateways.

These gateways lead motorists and tourists into the heart of the City through major

streets. These routes have been included in the Special Street category.

12 Designated by the Streetlight Policy Advisory Committee in the meeting on May 19, 2004 and subsequently

modified through reviewers' feedbacks during the study.

March 2005 33


3. Other important streets. Part of historic L' Enfant Plan is included in the Special

Street designation. Several other key streets that have been identified in District

community development plans were also included in the list.

The Special Streets have been designated to have Washington signature streetlight treatment.

Street Type

Recom m ended Pole

Type for Over Head

Pow erlines

Recom m ended Pole

Type for Underground

Pow erlines

Special Streets Decorative Tear Drop Tw in 20


Decorative Tear Drop

(Alt. Cobra Head)


(Alt. Cobra Head), Upright

Poles (#14, 16, 18)

Historic Streets


(Alt. Cobra Head)Upright Poles, Tw in 20

Figure 11. Special and Historic Streets in Washington, DC

March 2005 34


Table 16. List of Special Streets

Special Streets Starta

Enda

14th

Street 14th

Street Bridge, SW DC Line, NW

16th

Street H Street, NW DC Line, NW

Benning Road H Street, NE DC Line, SE

Bladensburg Road H Street, NE DC Line, NE

Blair Road DC Line, NW Hamilton Street, NE

Branch Avenue Randle Circle, SE DC Line, SE

Brentwood Roadb

T Street, NE Rhode Island Avenue, NE

Canal Road Chain Bridge, NW M Street, NW

Connecticut Avenue H Street, NW DC Line, NW

Dalecarlia Parkway DC Line, NW Loughboro Road, NW

East Capitol Street 1st Street, NE/SE DC Line, NE/SE

Eastern Avenue 16th

Street, NW Southern Avenue

Florida Avenue P Street, NW Benning Road, NE

Georgia Avenue – 7th

Street Maine Avenue, SW DC Line, NW

H Streetb

Virginia Avenue, 15th

Street, NE

Interstate 295-AnacostiaFreeway-Kenilworth Avenue

DC Line, SE DC Line, NE

Interstate 395 14th

Street Bridge, SW New York Avenue, NE

Southeast-Southwest Freeway I-395, SW Pennsylvania Avenue, SE

Interstate 66 Ohio Dr., NW (Approx.) 26th

Street, NW (Approx.)

K Streetb

Wisconsin Avenue, NW Florida Avenue, NE

Laurel Street Blair Road, NE DC Line, NE

Loughboro Road McArthur Boulevard, NW Foxhall Road, NW

M Streetb

Canal Road, NW Florida Avenue, NE

MacArthur Boulevard DC Line, NW Foxhall Road, NW

Massachusetts Avenue DC Line, NW DC Line, SE

Military Road DC Line, NW 16th

Street, NW

Missouri Avenue 16th

Street, NW North Capitol Street

Nebraska Avenue Foxhall Road, NW Oregon Avenue, NW

New Hampshire Avenue Park Road, NW DC Line, NE

New York Avenue 14th

Street, NW DC Line, NE

North Capitol Street D Street, NE/NW Blair Road, NE/NW

Pennsylvania Avenue M Street, NW DC Line, SE

Rhode Island Avenue Connecticut Avenue, NW DC Line, NE

South Capitol Street DC Line, SE/SW Independence Avenue, SE/SW

Southern Avenue South Capitol Street, SE Eastern Avenue, NE

Suitland Parkway South Capitol, SE DC Line, SE

Western Avenue Massachusetts Avenue, NW Oregon Avenue, NW

Whitehurst Freeway M Street, NW K Street, NW

Wisconsin Avenue DC Line, NWSouth of K Street, NW (Up toPotomac River)

NOTES:a

No limits are assigned to the special streets and generally, the designations end at the physical ends of the roadways or at DC line. Therefore, the "start" and "end"do not represent any limits, but the actual physical ends of the roadways.

bThere are other short segment(s) of the roadway beyond the start and end points. However, these segments have different contexts and therefore, are not includedas Special Streets. The streetlight designs for these segments will be based upon their contexts.

March 2005 35


5.3.4 Location of electrical power line

Another factor in the selection of streetlight hardware in the District is whether the PEPCO

power line is underground or overhead. For areas with underground power line, streetlight

power feeds may also be routed through underground conduits and, as a result, standard poles

(with arms) can be used as necessary.

In areas with overhead PEPCO power lines, there is an abundance of wooden utility poles.

In order to minimize the cost, the utility poles are used for mounting streetlight fixtures, with

direct overhead power feeds from PEPCO lines. Thus, no separate streetlight poles are

necessary in these areas and, therefore, only arm and luminaire are specified.

5.4 EXEMPT LOCATIONS

The guidelines presented in the preceding chapters apply to the City in general; however,

areas with their own regulations are exempt from these requirements or portions thereof,

which will be overridden by the area-specific regulations. These exempt locations include,

but are not be limited to:

1. Downtown streetscape area

2. Business Improvement Districts (BIDs)

3. Monumental Core area

The Downtown Streetscape Regulations dictates the standard streetlight fixtures for the

Downtown Streetscape Area. The upright poles No. 16, 18, and Twin 20 are used for

midblock and pendant poles for intersections. The regulation specifies the color of the pole as

black for upright poles and battleship gray for pendant poles. The arm of a Twin 20 pole

should be parallel to the curb. The Downtown Streetscape Area boundaries are as shown in

the Figure 12.

March 2005 36


Legend

Streetscape Impact Area

Boundaries

M St.

3rd

St.

Massachusetts Ave

2n

dS

t. H St.

No

rth

Ca

pito

lS

t.

D St.

New

Jersey

Avenue

Lou

isia

naA

veC St.

1stS

t.

Constitution Ave

Pennsylvania Ave

15

thS

t.

15

thS

t.

K St.

Massachusetts Ave

Legend


Boundaries

Legend


Boundaries

M St.

3rd

St.

Massachusetts Ave

2n

dS

t. H St.

No

rth

Ca

pito

lS

t.

D St.

New

Jersey

Avenue

Lou

isia

naA

veC St.

1stS

t.

Constitution Ave

Pennsylvania Ave

15

thS

t.

15

thS

t.

K St.

Massachusetts Ave

Figure 12. Downtown Streetscape Area Boundaries

There are several BIDs in the District, and as of the publication date of this document, the

following BIDs are considered exempt from this guideline - Georgetown, Downtown,

Golden Triangle and North of Massachusetts Avenue (NOMA). The No. 18 poles are

generally used in the BIDs. The Georgetown and Downtown BIDs specify the wattage used

and the Golden Triangle BID specifies the color of the pole to be black (Federal Chip 27038).

The NOMA BID is being formed and, therefore, its standards are yet to be determined.

DDOT will make determination on the exempt status on any future new BIDs.

The Monumental Core area, as specified in the Inter-Mall Roads Streetscape Plan, uses black

upright poles (No. 16 or Twin 20) with 400-Watt Metal Halide conversion kits. In the

District, Metal Halide lights are currently being used only in Monumental Core.

5.5 HARDWARE RECOMMENDATIONS

Hardware recommendations have been derived for the following scenarios:

1. Non-historic streets

Underground power line

Overhead power line

2. Historic streets

3. Special streets

The hardware recommendations for these scenarios are described in the following

paragraphs.

March 2005 37


1. Non-Historic Areas

Table 17 shows the streetlight hardware standards for the non-historic areas with

underground power lines. In residential areas, the citizens will be given the choice to

select either a Decorative Teardrop (alternatively Cobraheads if costs prohibit) or

Upright poles in place of the existing Cobrahead poles. The Pendant Posts are

recommended for non-historic streets, as they are economical.

The standards for the non-historic areas with overhead power lines are shown in

Table 18. Bridges and tunnels/underpasses are not applicable to this scenario. The

lighting arm is the only option for overhead power lines, as it is attached to the utility

wooden poles. A Decorative Teardrop arm is preferred; however, Cobraheads can be

used if cost prohibits.

2. Historic Areas

Table 19 presents the standards for historic areas and streets with underground power

lines. The requirements do not apply to Tunnels/Underpasses and alleys.

The standards for historic areas and streets with overhead power lines are shown in

Table 20. Bridges and tunnels/underpasses are not applicable to historic areas and

streets with overhead power lines.

3. Special Streets

Table 21 and Table 22 present standards for special streets with underground and

overhead power lines, respectively. A decorative teardrop arm is used for special

streets with overhead power lines. The requirements do not apply to alleys and

Tunnels/Underpasses for special streets with underground power lines. Bridges, alley

and tunnels/underpasses are not applicable to special streets with overhead power

lines.

March 2005 38

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rop

is p

refe

rre

d,

Co

bra

he

ad

is a

n a

lte

rna

tive

in

co

st-

pro

hib

itiv

e s

itu

atio

n.

bR

ep

lace

Up

rig

ht

in k

ind

an

d C

ob

rah

ea

d c

ha

ng

es t

o T

ea

rdro

p o

r U

pri

gh

t.c

Re

pla

ce

Up

rig

ht

in k

ind

an

d C

ob

rah

ea

d c

ha

ng

es t

o T

ea

rdro

p.

Th

ep

ole

ca

n b

e a

ny s

pe

cia

l d

eco

rative

po

le d

esig

ne

d p

art

icu

larl

yfo

r a

brid

ge

, b

ut

it c

an

no

t b

e C

ob

rah

ea

d.

dF

or

Sp

ecia

l C

ase

, th

e sp

acin

g ca

n b

e le

ss th

an

re

co

mm

en

de

d,

bu

tit m

ust

be

ju

stifie

d.

Min

imum

sp

acin

g b

etw

ee

n p

ole

s (6

0 ft

) is

n

ot

are

co

mm

en

da

tio

n,

bu

t a

n a

bso

lute

min

imu

m.

eB

rid

ge

s m

ay d

evia

te f

rom

th

ese

gu

ide

line

s a

nd

ma

y b

e d

esig

ne

d w

ith

sp

ecia

l d

eco

rative

str

ee

tlig

ht

ha

rdw

are

to

sig

nify

the

ir im

po

rta

nce

, e

sp

ecia

lly in

th

e e

ntr

y t

o t

he

City.

f#

14

, #

16

, #

18

Po

les d

ep

en

din

g o

n t

he

he

igh

t o

f su

rro

un

din

gs.

Mar

ch 2

00

539

Dis

tric

t o

f C

olu

mbia

Str

eetl

ight

Po

licy

and

Des

ign

Gu

idel

ines

Fin

al R

epo

rt

Ta

ble

18

. S

tan

da

rds

for

No

n-H

isto

ric

Str

eets

wit

h O

verh

ead

Po

wer

Lin

es

Ro

ad

wa

y/A

rea

Typ

e

Item

Co

mm

erc

ial

Inte

rmed

iate

(Mix

ed

Use)

Resid

en

tial

Bri

dg

es

All

ey

Fre

ew

ay

Tu

nn

els

/U

nd

erp

ass

es

Co

mm

en

ts

Lig

hti

ng

Hard

ware

Typ

e

Decora

tive

Teard

rop (

Alt.

Cobra

he

ad

a)

Decora

tive

Teard

rop (

Alt.

Cobra

he

ad

a)

Decora

tive

Teard

rop (

Alt.

Cobra

he

ad

a)

N/A

Cobra

he

ad (

5A

)C

obra

he

ad

N/A

On

ly lig

htin

g

arm

is t

o b

e

used

Cu

toff

Cri

teri

a

Full

Cuto

ff o

r C

uto

ffF

ull

Cuto

ff o

r C

uto

ffF

ull

Cuto

ff o

r C

uto

ffN

/AF

ull

Cuto

ff o

r C

uto

ffF

ull

Cuto

ff,

Cuto

ff

N/A

Co

lor

of

Arm

Gra

yG

ray

Gra

yN

/AG

ray

Gra

yN

/AC

urr

ently u

sed

Pre

ferr

ed

Ori

en

tati

on

Sta

ggere

dS

taggere

dS

taggere

dN

/AS

taggere

dS

taggere

dN

/A

Sta

ggere

dchosen f

or

uniform

ity o

f lig

ht

Min

Sp

acin

gb

etw

een

Po

les

b60 f

t m

in (

on o

ne s

ide)

- all

ori

enta

tions

N/A

60 f

t m

in (

on o

ne

sid

e)

- all

orie

nta

tions

60 f

t m

in (

on o

ne

sid

e)

- all

orie

nta

tions

N/A

He

igh

t o

f P

ole

Dep

ends

on P

ole

Type

N/A

Dep

ends o

n P

ole

Type

Dep

ends o

n P

ole

Type

N/A

Ba

se

of

Po

le

Dep

ends

on P

ole

Type

N/A

Dep

ends o

n P

ole

Type

Dep

ends o

n P

ole

Type

N/A

Ma

teri

al

of

Po

leD

ep

ends

on t

he p

reva

iling t

echno

log

yN

/AD

ep

ends o

n t

he

pre

va

iling

techno

log

y

Dep

ends o

n t

he

pre

va

iling

techno

log

yN

/A

aA

lth

ou

gh

Te

ard

rop

is p

refe

rre

d,

Co

bra

he

ad

is a

n a

lte

rna

tive

in

co

st-

pro

hib

itiv

e s

itu

atio

n.

bF

or

Sp

ecia

l C

ase

, th

e s

pa

cin

g c

an

be

le

ss t

ha

n r

eco

mm

en

de

d,

bu

t it m

ust

be

ju

stified

. M

inim

um

sp

acin

g b

etw

ee

n p

ole

s (

60

ft)

is n

ot

a r

eco

mm

en

da

tio

nb

ut

an

ab

so

lute

min

imu

m.

Mar

ch 2

00

540

Dis

tric

t o

f C

olu

mbia

Str

eetl

ight

Po

licy

and

Des

ign

Gu

idel

ines

Fin

al R

epo

rt

Table

19

. S

tan

dard

s fo

r H

isto

ric

Str

eets

wit

h U

nder

gro

un

d P

ow

er L

ines

Ro

ad

way/A

rea T

yp

eC

rite

ria

Co

mm

erc

ial

Inte

rmed

iate

(Mix

ed

Use)

Resid

en

tial

Bri

dg

es

cA

lle

yF

reew

ay

Tu

nn

els

/U

nd

erp

ass

es

Co

mm

en

ts

Lig

hti

ng

Hard

ware

Typ

e

#14,

#16,

#18,

Tw

in 2

0b

#14,

#16,

#18,

Tw

in 2

0b

#14,

#16,

#18

#14,

#16,

#18,

Tw

in 2

0b

(Note

:R

epla

ce

His

toric

Upright

in

kin

d)

Cobra

-hea

d (

5A

) C

obra

-hea

d

Wall

packs

for

vehic

ula

rT

unnels

#14,

#16,

#18 f

or

ped

estr

ian

tunne

ls

Upright

pole

s a

re c

urr

ently

used f

or

his

tori

c a

reas.

They

are

tru

lyhis

tori

cal to

DC

an

daesth

etically

more

ple

asin

g

Cu

toff

Cri

teri

a

Full

Cuto

ff o

r C

uto

ffF

ull

Cuto

ff o

r C

uto

ffF

ull

Cuto

ff o

r C

uto

ffF

ull

Cuto

ff o

r C

uto

ffF

ull

Cuto

ff

or

Cuto

ff

Full

Cuto

ff

or

Cuto

ffN

/A

Co

lor

of

Po

leB

lack

Bla

ck

Bla

ck

Dep

ends o

n

Bridge D

esig

nB

lack

Bla

ck

N/A

Exis

ting c

olo

r

Pre

ferr

ed

Ori

en

tati

on

Sta

ggere

dS

taggere

dS

taggere

dO

pposite

Sta

ggere

dS

taggere

dN

/A

Sta

ggere

d c

ho

sen b

ecause

of

uniform

ity o

f lig

ht

Opposite f

or

bri

dge f

or

aesth

etics a

nd

sym

metr

y

Min

Sp

acin

gb

etw

een

Po

les

a60 f

t m

in (

on o

ne s

ide)

– a

ll o

rienta

tions

N/A

He

igh

t o

f P

ole

Dep

ends

on P

ole

Type

N/A

Ba

se

of

Po

le

Dep

ends

on P

ole

Type

N/A

Ma

teri

al

of

Po

leD

ep

ends

on t

he p

reva

iling t

echno

log

yN

/A

aF

or

Sp

ecia

l C

ase

, th

e s

pa

cin

g c

an

be

le

ss t

ha

n r

eco

mm

en

de

d,

bu

t it m

ust

be

ju

stifie

d.

Min

imu

m s

pa

cin

g b

etw

ee

n t

he

po

les (

60

ft)

is n

ot

a r

eco

mm

en

da

tio

n b

ut

on

ly a

n a

bso

lute

min

imu

m.

bT

win

20

no

t n

ece

ssa

rily

de

sir

ab

le u

nle

ss it

is a

Sp

ecia

l C

ase

. c

Bri

dg

es m

ay d

evia

te f

rom

th

ese

gu

ide

line

s a

nd

ma

y b

e d

esig

ne

d w

ith

sp

ecia

l d

eco

rative

str

ee

tlig

ht

ha

rdw

are

to

sig

nify

the

ir im

po

rta

nce

, e

sp

ecia

lly in

th

e e

ntr

y t

o t

he

City.

No

tes:

1.

Fo

r S

ign

aliz

ed

In

ters

ectio

ns,

if m

ast

arm

is n

ot

requ

ire

d,

for

up

rig

ht

po

les (

#1

4,

#1

6 &

#1

8),

#1

8 c

om

bin

atio

n p

ole

sh

ou

ld b

e u

se

d;

an

d f

or

Tw

in 2

0,

the

sa

me

sh

ou

ld b

e u

se

d a

s

co

mb

ina

tio

n p

ole

. 2

.F

or

Sig

na

lize

d I

nte

rse

ctio

ns,

if m

ast

arm

is r

eq

uir

ed

, P

en

da

nt

po

le s

ho

uld

be

use

d a

s c

om

bin

atio

n p

ole

; d

eco

rative

arm

with

Te

ard

rop

fixtu

re c

an b

e u

sed.

3.

Fo

r U

nsig

na

lize

d I

nte

rse

ctio

ns,

the

sa

me

po

le s

ho

uld

be

use

d a

t th

e i

nte

rse

ctio

ns.

If t

he

se

lecte

d p

ole

do

esn

’t i

llum

ina

te t

he

in

ters

ectio

n u

nifo

rmly

, th

e n

ext

talle

r p

ole

th

at

illu

min

ate

s t

he

inte

rse

ctio

n u

nifo

rmly

sh

ou

ld b

e s

ele

cte

d.

Mar

ch 2

00

541

Dis

tric

t o

f C

olu

mbia

Str

eetl

ight

Po

licy

and

Des

ign

Gu

idel

ines

Fin

al R

epo

rt

Ta

ble

20

. S

tan

da

rds

for

His

tori

c S

tree

ts w

ith

Ove

rhea

d P

ow

er L

ines

Ro

ad

wa

y/A

rea

Typ

eC

rite

ria

Co

mm

erc

ial

Inte

rmed

iate

(Mix

ed

Use)

Resid

en

tial

Bri

dg

es

All

ey

Fre

ew

ay

Tu

nn

els

/U

nd

erp

ass

es

Co

mm

en

ts

Lig

hti

ng

Hard

ware

Typ

e

Decora

tive

Teard

rop

(Alt.

Cobra

he

ad

a)

Decora

tive

Teard

rop (

Alt.

Cobra

he

ad

a)

Decora

tive

Teard

rop

(Alt.

Cobra

he

ad

a)

N/A

Cobra

he

ad

(5A

)C

obra

he

ad

N/A

On

ly lig

htin

g a

rm is t

o b

e

used

Cu

toff

Cri

teri

a

Full

Cuto

ff o

r C

uto

ffF

ull

Cuto

ff o

r C

uto

ffF

ull

Cuto

ff o

r C

uto

ffN

/AF

ull

Cuto

ff

or

Cuto

ff

Full

Cuto

ff

or

Cuto

ffN

/A

Co

lor

of

Arm

Bla

ck

Bla

ck

Bla

ck

N/A

Bla

ck

Bla

ck

N/A

Exis

ting c

olo

r

Pre

ferr

ed

Ori

en

tati

on

Sta

ggere

dS

taggere

dS

taggere

dN

/AS

taggere

dS

taggere

dN

/AS

taggere

d c

ho

sen b

ecause

of

uniform

ity o

f lig

ht

Min

Sp

acin

gb

etw

een

Po

les

b60 f

t m

in (

on o

ne s

ide)

– a

ll o

rienta

tions

N/A

60 f

t m

in

(on o

ne

sid

e)

– a

llorie

nta

tions

60 f

t m

in

(on o

ne

sid

e)

– a

llorie

nta

tions

N/A

He

igh

t o

f P

ole

Dep

ends

on P

ole

Type

N/A

Dep

ends

on P

ole

Type

Dep

ends

on P

ole

Type

N/A

Ba

se

of

Po

le

Dep

ends

on P

ole

Type

N/A

Dep

ends

on P

ole

Type

Dep

ends

on P

ole

Type

N/A

Ma

teri

al

of

Po

leD

ep

ends

on t

he p

reva

iling t

echno

log

yN

/A

Dep

ends

on t

he

pre

va

iling

techno

log

y

Dep

ends

on t

he

pre

va

iling

techno

log

y

N/A

aA

lth

ou

gh

Te

ard

rop

is p

refe

rre

d,

Co

bra

he

ad

is a

n a

lte

rna

tive

in

co

st-

pro

hib

itiv

e s

itu

atio

n.

bF

or

Sp

ecia

l C

ase

, th

e s

pa

cin

g c

an

be

le

ss t

ha

n r

eco

mm

en

de

d,

bu

t it m

ust

be

ju

stifie

d.

Min

imu

m s

pa

cin

g b

etw

ee

n t

he

po

les (

60

ft)

is n

ot

a r

eco

mm

en

da

tio

n b

ut

on

ly a

n a

bso

lute

min

imu

m.

Mar

ch 2

00

542

Dis

tric

t o

f C

olu

mbia

Str

eetl

ight

Po

licy

and

Des

ign

Gu

idel

ines

Fin

al R

epo

rt

Table

21. S

tan

dard

s fo

r S

pec

ial

Str

eets

wit

h U

nder

gro

un

d P

ow

er L

ines

Ro

ad

wa

y/A

rea

Typ

eC

rite

ria

Co

mm

erc

ial

Inte

rmed

iate

(Mix

ed

Use)

Resid

en

tial

Bri

dg

es

bA

lle

yF

reew

ay

Tu

nn

els

/U

nd

erp

ass

es

Co

mm

en

ts

Lig

hti

ng

Hard

ware

Typ

eT

win

20

Tw

in 2

0

Tw

in 2

0T

win

20

N/A

Decora

tive

Teard

rop

N/A

Tw

in 2

0s a

re D

Csig

natu

re p

ole

s a

nd

aesth

etically

more

ple

asin

g

Cu

toff

Cri

teri

a

Full

Cuto

ff o

r C

uto

ffF

ull

Cuto

ff o

r C

uto

ffF

ull

Cuto

ff o

r C

uto

ffF

ull

Cuto

ff o

r C

uto

ffN

/AF

ull

Cuto

ff o

r C

uto

ffN

/A

Co

lor

of

Po

leB

lack

Bla

ck

Bla

ck

Dep

ends o

n

Bridge D

esig

nN

/AB

lack

N/A

Pre

ferr

ed

Ori

en

tati

on

Opposite

Opposite m

ay

be

aesth

etically

more

ple

asin

gO

pposite

Opposite

Opposite

N/A

Sta

ggere

dN

/A

Min

Sp

acin

gb

etw

een

Po

les

a

60 f

t, m

in (

on

one s

ide)

- all

orie

nta

tions

60 f

t, m

in (

on o

ne s

ide)

- all

ori

enta

tions

N/A

N/A

Dep

ends o

n

Pole

Type

He

igh

t o

f P

ole

Dep

ends

on P

ole

Type

N/A

N/A

Dep

ends o

n

Pole

Type

Ba

se

of

Po

le

Dep

ends

on P

ole

Type

N/A

N/A

Dep

ends o

n

the p

reva

iling

techno

log

y

Ma

teri

al

of

Po

leD

ep

ends

on t

he p

reva

iling t

echno

log

yN

/AN

/A

aF

or

Sp

ecia

l C

ase

, th

e s

pa

cin

g c

an

be

le

ss t

ha

n r

eco

mm

en

de

d,

bu

tit m

ust

be

ju

stifie

d.

Min

imu

m s

pa

cin

g b

etw

ee

n t

he

po

les (

60

ft)

is n

ot

a r

eco

mm

en

da

tio

n b

ut

on

ly a

n a

bso

lute

min

imu

m.

bB

rid

ge

s m

ay d

evia

te f

rom

th

ese

gu

ide

line

s a

nd

ma

y b

e d

esig

ne

d w

ith

sp

ecia

l d

eco

rative

str

ee

tlig

ht

ha

rdw

are

to

sig

nify

the

ir im

po

rta

nce

, e

sp

ecia

lly in

th

e e

ntr

y t

o t

he

City.

Note

:1

.F

or

Sig

na

lize

d I

nte

rse

ctio

ns,

if m

ast

arm

is n

ot

req

uir

ed

, T

win

20

sh

ou

ld b

e u

se

d a

s c

om

bin

atio

n p

ole

. 2

.F

or

Sig

na

lize

d I

nte

rse

ctio

ns,

if m

ast

arm

is r

eq

uir

ed

, P

en

da

nt

po

le s

ho

uld

be

use

d a

s c

om

bin

atio

n p

ole

; d

eco

rative

arm

with

Te

ard

rop

fixtu

re c

an b

e u

sed.

3.

Fo

r U

nsig

na

lize

d I

nte

rse

ctio

ns,

the

sa

me

po

le s

ho

uld

be

use

d a

t th

e i

nte

rse

ctio

ns.

If t

he

se

lecte

d p

ole

do

esn

’t i

llum

ina

te t

he

in

ters

ectio

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The minimum spacing between poles (i.e., 60 ft) is not a recommendation, but only an

absolute minimum. The designer should ensure that the spacing fulfills the following

objectives, yet meeting the AASHTO standards:




The height of the pole should be determined based on the context of the surroundings, such

as the height of building, roadway width, sidewalk width, etc.

The order of precedence also influences the hardware selection and is as follows:

1. Exempt locations, such as Monumental Core/BIDS/Downtown Streetscape

2. Special streets

3. Historic streets

4. Non-Historic streets

The Washington Upright poles Nos. 14, 16, 18 and Twin-20 that are recommended in the

standards are shown below.

14/16/18 TWIN-2014/16/18 TWIN-2014/16/1814/16/18 TWIN-20TWIN-20

Figure 13. Types of Upright Poles for Use in DC (#14, #16, #18 and Twin-20)

The Pendant poles recommended for the District are Cobrahead, 5A Alley Post and

Decorative Teardrop (shown in Figure 12). The Cobrahead and 5A Alley Poles are installed

citywide.

March 2005 45


COBRAHEAD 5A ALLEY

POST

TEARDROPCOBRAHEAD 5A ALLEY

POST

TEARDROP

Figure 14. Types of Pendant Poles for Use in DC (Cobrahead, 5A Alley Post and

Teardrop)

5.6 DESIGN PRINCIPLES

The following design principles should be observed during any streetlight design process and

are made part of the policy:

1. The design must be based on AASHTO recommendations for the average maintained

illuminance levels for the various roadway classifications defined by DDOT (Table

23). Table 24 presents the required average maintained illumination levels for

illuminated sidewalk areas, along all DDOT roadway classifications, with the criteria

based on the type of land use. Table 25 presents the criteria for required uniformity

and veiling luminance ratios.

March 2005 46


Table 23. Recommended Average Maintained Illuminance for District Roadways13

Recommended Average MaintainedIlluminance (foot-candle) DC Street Classification Land Use

R1 R2 & R3 R4

Interstate ResidentialIntermediateCommercial

0.6 to 0.7 0.7 to 0.9 0.7 to 1.1

0.6 to 0.7 0.7 to 0.9 0.7 to 1.1

0.6 to 0.7 0.7 to 0.9 0.7 to 1.1


ResidentialIntermediateCommercial

0.60.70.9

0.81.11.3

0.70.91.2

Principal Arterials ResidentialIntermediateCommercial

0.60.81.1

0.81.21.6

0.71.01.4

Minor Arterial ResidentialIntermediateCommercial

0.50.70.9

0.71.01.4

0.70.91.0

Collector ResidentialIntermediateCommercial

0.40.60.7

0.60.81.1

0.50.70.9

Local Street ResidentialIntermediateCommercial

0.30.50.6

0.40.70.8

0.40.60.7

Alleys ResidentialIntermediateCommercial

0.20.30.4

0.30.40.6

0.30.40.5

Table 24. Recommended Average Maintained Illuminance for Sidewalks

Recommended Average Maintained Illuminance(foot-candle)DC Sidewalk Locations

R1 R2 & R3 R4

Residential Areas 0.3 0.4 0.4

Intermediate Areas 0.6 0.8 0.7

Commercial Areas 0.9 1.3 1.2

Table 25. Recommended Average-to-Minimum Uniformity and Veiling Luminance Ratios

DC Street Classification Average-to-MinimumUniformity Ratio

Veiling Luminance Ratio

Interstate 3:1 or 4:1 0.3:1


3:1 0.3:1

Principal Arterials 3:1 0.3:1

Minor Arterial 4:1 0.3:1

Collector 4:1 0.4:1

Local Street 6:1 0.4:1

Alleys 6:1 0.4:1

2. The design should use maximum spacing of streetlight poles. A minimum spacing

between poles (i.e., 60 ft) has been specified; however, it is not a recommendation,


March 2005 47


but only an absolute minimum. The designer should ensure that the spacing fulfills

the following objectives, yet meeting the AASHTO standards:




3. The design should be based on lower wattage lamps, so as to keep an extra cushion

for higher level of illumination in future, if necessary, which can be easily done by

replacing the lower wattage lamps with higher wattages. For example, No. 16 poles

should be designed for a maximum 250 Watt, while up to 400 Watt is allowed; No.

14 poles should be designed for a maximum of 100 Watt, while up to 150 Watt is

allowed.

4. The design should avoid using 400 Watt conversion kits in residential areas.

5. The height of the pole should be determined based on the context of the surroundings

such as the height of building, roadway width, sidewalk width, etc.

6. The design must consider reduction of glare into drivers' and pedestrians' eyes, and

enhancement of visibility. Appropriate refractive globes can effectively reduce direct

glare by softening and spreading the light distribution. Shields can also be used to aim

the lights so that they are not directly visible from the roads, alleys, pathways, and

windows, as needed.

5.7 DESIGN EXAMPLES

A simplified streetlight design, based on this policy, for North Capitol Street and Michigan

Avenue/Columbia Road is illustrated in Figure 15. The entire North Capitol Street segment

shown belongs to the Special Street category. On the other hand, Michigan Avenue/

Columbia Road is a minor arterial that changes from Non-historic to Historic and back to

Non-historic. In the figure below, the ‘Existing’ refers to the existing condition and

‘Proposed’ refers to the design as per this streetlight policy guideline.

March 2005 48


Historic

District

North

SPECIAL STREET (Entire Segment)

Pole T yp e:

Spacing:

Color:

Lamp:

Pole Orientation:

Characteristics

Cobra head

100 ft

Gray

250 W H PS

Staggered

Existing

Twin 20

To be deter mined

Black

250 W MH

Opposite

Proposed

NO N-HISTO RIC STREET

Pole Type:

l

Spacing:

Color:

Lamp:

ll

Pole Orientation:

Characteristics

No. 16, Cobra

head

50 – 100 ft

Gray

250 W H PS in

No.16, 400W HPSin Cobra head

Staggered

Existing

No. 16

j

To be deter mined

Gray

250 W MH

ll

Staggered

Proposed

HISTO RIC STREET

Pole Type:

Spacing:

Color:

Lamp:

Pole Orientation:

Characteristics

Cobra head

75 – 100 ft

Gray

400 W H PS

Staggered

Existing

No. 16

To be deter mined

Black

250 W MH

Staggered

Proposed

Historic

District

NorthNorth


Pole T yp e:

Spacing:

Color:

Lamp:

Pole Orientation:

Characteristics

Cobra head

100 ft

Gray

250 W H PS

Staggered

Existing

Twin 20

To be deter mined

Black

250 W MH

Opposite

Proposed


Pole T yp e:

Spacing:

Color:

Lamp:

Pole Orientation:

Characteristics

Cobra head

100 ft

Gray

250 W H PS

Staggered

Existing

Cobra head

100 ft

Gray

250 W H PS

Staggered

Existing

Twin 20

To be deter mined

Black

250 W MH

Opposite

Proposed

Twin 20

To be deter mined

Black

250 W MH

Opposite

Proposed


Pole Type:

l

Spacing:

Color:

Lamp:

ll

Pole Orientation:

Characteristics

No. 16, Cobra

head

50 – 100 ft

Gray

250 W H PS in


Staggered

Existing

No. 16

j

To be deter mined

Gray

250 W MH

ll

Staggered

Proposed


Pole Type:

l

Spacing:

Color:

Lamp:

ll

Pole Orientation:

Characteristics

No. 16, Cobra

head

50 – 100 ft

Gray

250 W H PS in


Staggered

Existing

No. 16, Cobra

head

50 – 100 ft

Gray

250 W H PS in


Staggered

Existing

No. 16

j

To be deter mined

Gray

250 W MH

ll

Staggered

Proposed

No. 16

j

To be deter mined

Gray

250 W MH

ll

Staggered

Proposed

HISTO RIC STREET

Pole Type:

Spacing:

Color:

Lamp:

Pole Orientation:

Characteristics

Cobra head

75 – 100 ft

Gray

400 W H PS

Staggered

Existing

No. 16

To be deter mined

Black

250 W MH

Staggered

Proposed

HISTO RIC STREET

Pole Type:

Spacing:

Color:

Lamp:

Pole Orientation:

Characteristics

Cobra head

75 – 100 ft

Gray

400 W H PS

Staggered

Existing

Cobra head

75 – 100 ft

Gray

400 W H PS

Staggered

Existing

No. 16

To be deter mined

Black

250 W MH

Staggered

Proposed

No. 16

To be deter mined

Black

250 W MH

Staggered

Proposed

Figure 15. Illustration of North Capitol Street and Michigan Avenue/Columbia Road

Another illustration of streetlight design for Cathedral Avenue and Connecticut Avenue (Old

Woodley Park Area) is shown in Figure 16. The entire Connecticut Avenue segment shown

belongs to the Special Street category. On the other hand, Cathedral Avenue is a collector

road that changes from Non-historic to Historic. At the intersection, the roadway right-of-

way (ROW) controls the color and other properties of the streetlighting hardware. The

Special Streets supersede Historic Streets/Districts and Historic Streets supersede Non-

Historic Streets. When a Special Street passes through any Historic District, it will continue

to have the color and other properties of Special Street. At the intersection of a Historic

Street with a Non-Historic Street, the ROW will control the color and other properties as

shown at the bottom of the figure.

March 2005 49


Historic DistrictHistoric District

Non-Historic AreaNon-Historic Area

ROW

ROW

ROW

ROW

ROW ROW

ROW ROW

Note: At the intersection, the right-of-way (ROW)

controls the color and other properties. Special Streets

supersede Historic Streets and Historic Streets

supersede Non-Historic Streets.

SPECIAL STREET ( Entire Segment)

Pole Type:

Spacing:

Color:

Lamp:

Pole Orientation:

Characteristics

Cobra head

110 ft

Gray

400 W H PS

Staggered

Existing

Twin 20

To be deter mined

Black

250 W MH

Opposite

Proposed


Pole Type:

l

Spacing:

Color:

Lamp: l

Pole Orientation:

Characteristics

No. 16, Cobra

head

75 – 100 ft

Gray

250 W H PS

Staggered

Existing

No. 16

j

To be deter mined

Gray

250 W MH

Staggered

Proposed

HISTO RIC STREET

Pole Type:

Spacing:

Color:

Lamp:

Pole Orientation:

Characteristics

Cobra head

100 ft

Gray

250 W H PS

Staggered

Existing

No. 16

To be deter mined

Black

250 W MH

Staggered

Proposed

28

thS

T.

Cathedral

Ave.Non-Historic

Historic

Legend

Historic DistrictHistoric District

Non-Historic AreaNon-Historic Area

ROW

ROW

ROW

ROW

ROW ROW

ROW ROW

Note: At the intersection, the right-of-way (ROW)

controls the color and other properties. Special Streets

supersede Historic Streets and Historic Streets

supersede Non-Historic Streets.


Pole Type:

Spacing:

Color:

Lamp:

Pole Orientation:

Characteristics

Cobra head

110 ft

Gray

400 W H PS

Staggered

Existing

Twin 20

To be deter mined

Black

250 W MH

Opposite

Proposed


Pole Type:

Spacing:

Color:

Lamp:

Pole Orientation:

Characteristics

Cobra head

110 ft

Gray

400 W H PS

Staggered

Existing

Cobra head

110 ft

Gray

400 W H PS

Staggered

Existing

Twin 20

To be deter mined

Black

250 W MH

Opposite

Proposed

Twin 20

To be deter mined

Black

250 W MH

Opposite

Proposed


Pole Type:

l

Spacing:

Color:

Lamp: l

Pole Orientation:

Characteristics

No. 16, Cobra

head

75 – 100 ft

Gray

250 W H PS

Staggered

Existing

No. 16

j

To be deter mined

Gray

250 W MH

Staggered

Proposed


Pole Type:

l

Spacing:

Color:

Lamp: l

Pole Orientation:

Characteristics

No. 16, Cobra

head

75 – 100 ft

Gray

250 W H PS

Staggered

Existing

No. 16, Cobra

head

75 – 100 ft

Gray

250 W H PS

Staggered

Existing

No. 16

j

To be deter mined

Gray

250 W MH

Staggered

Proposed

No. 16

j

To be deter mined

Gray

250 W MH

Staggered

Proposed

HISTO RIC STREET

Pole Type:

Spacing:

Color:

Lamp:

Pole Orientation:

Characteristics

Cobra head

100 ft

Gray

250 W H PS

Staggered

Existing

No. 16

To be deter mined

Black

250 W MH

Staggered

Proposed

HISTO RIC STREET

Pole Type:

Spacing:

Color:

Lamp:

Pole Orientation:

Characteristics

Cobra head

100 ft

Gray

250 W H PS

Staggered

Existing

Cobra head

100 ft

Gray

250 W H PS

Staggered

Existing

No. 16

To be deter mined

Black

250 W MH

Staggered

Proposed

No. 16

To be deter mined

Black

250 W MH

Staggered

Proposed

28

thS

T.

Cathedral

Ave.Non-Historic

Historic

Legend

Non-Historic

Historic

Legend

Figure 16. Illustration of Cathedral Avenue and Connecticut Avenue (Old Woodley Park)

March 2005 50


6. NEXT STEPS

DDOT should follow certain next steps, as listed below for successful implementation of this

strategic plan:

1. DDOT should periodically review these guidelines and make any necessary

modifications within the general framework.

2. Continual monitoring is required to review lamp technologies and related costs in the

future. Currently, white light sources are not economically feasible compared to long

life HPS lamps. Special attention needs to be paid to white light sources (such as

metal halide or some other future technologies) to determine when its life-cycle costs

become comparable to inexpensive HPS light sources. Implementation of white light

sources may be deemed viable at that time.

3. The overall technology should be assessed from time to time to take advantage of

new developments offering economy and safety. For example, poles of various

materials are becoming available and some may offer a safer environment (such as

non-conductive pole base).

4. DDOT needs to evaluate its funding situation and priorities to determine the usage of

Teardrop fixtures over Cobraheads. Although desired, a complete substitution of

Cobrahead by Teardrop fixtures is likely to be cost-prohibitive.

5. New York City’s Department of Design and Construction, in association with the

City’s Department of Transportation, has launched an international design

competition for a new streetlight pole for the City of New York. Its main objective is

to select a new streetlight hardware that will become a standard for the City.

Therefore, DDOT should monitor the results from the competition and learn from it.

March 2005 51

District of Columbia Streetlight Policy and Design Guidelines Appendix A: Research Summary

APPENDIX A: RESEARCH SUMMARY

March 2005 52


A.1. INTRODUCTION

This appendix provides the background information and data collected during the conduct of

the study. It includes the research summary as well as the meeting minutes of the advisory

committee. This appendix will help the reader understand the evolution of the recommended

policies. The information contained in this appendix is as follows:

Section A.2: Market reviews

Section A.3: Other agency practices

Section A.4: Streetlight Policy Advisory Committee.

March 2005 53


A.2. MARKET REVIEWS

A.2.1 VENDOR INTERVIEWS

The Study Team interviewed a number of vendors to explore the different types of current

and upcoming technologies offered by them, and to learn about their opinions on the existing

systems, advantages and disadvantages of different technologies, etc. HADCO, Traffic

System and Technology (representing Union Metal and others), HOLOPHANE and

Commercial Lighting Sales Inc. (representing Spring City, Valmont, and General Electrics)

are among the vendors that supply different streetlighting components to DC. The summaries

are as follows:

HADCO supplies plastic globes, such as acrylic, fixtures, and poles up to 20 feet,

with base and casing. They manufacture a high performance post top refractive globe

that produces greater illumination, higher light levels and better uniformity, while

reducing glare and energy costs. This refractive globe costs less to purchase and

maintain than the popular Cobrahead.

HADCO also supplies aluminum and plastic bases. The plastic base is made of

polyethylene that will not break, does not need to be painted, is durable even in the

harshest environments, withstands high impacts, is ultra-violate (UV) resistant, and is

safe against shock hazard and corrosion resistant.

HADCO recommended that a Type V globe non-cutoff is a good alternative to

existing plain globes.

Traffic System and Technology represents Union Metal and others. Union Metal

supplies octaflute Pendant Post that has a height of 28, 38 and 80 feet. It offers a

prefabricated foundation that is hydraulically driven into the ground, LED light,

Acorn globes and induction lights. Induction lamps have a long life (100,000 hours);

however, the ballast doesn’t last long, and therefore, the failure rate is very high.

HOLOPHANE supplies glass and plastic globes, casing and Teardrop fixtures. They

also manufacture refractive globes with better control of light. Their design leaves the

ballasts under the casing, thus the globes are affected less as it produces less heat.

They claim to provide higher ambient temperature specification and a vibration test

for the globes. They recommended that a glass globe is a good alternative for the

Monumental Core.

Commercial Lighting Sales represents manufacturers like Spring City, Valmont, and

General Electrics. Spring City offers cast iron poles, luminaires, arms and Teardrop

fixtures. Its Type III and V of Columbian Series are available in glass and plastic

globes. They have designed a special No. 16 pole with narrow base (17 inches as

opposed to 24 inches) to help comply with ADA requirements for narrow sidewalks.

They also supply refractive globes and Induction lamp.

Valmont supplies their Pendant Post to Commercial Lighting Sales and GE supplies

their luminaire and conversion kit.

March 2005 54


A more detailed interview minutes are provided below.

HADCO

DCI met with Donald Fentress (Vice President) and Jim Lilley (Sales Representative) from

HADCO. HADCO supplies globes, fixtures, and poles. The Fine Arts Commission picked

Washington Globes as Standard 25 years ago. Cobraheads and Washington Globes are

dominant in D.C. The Washington Globe is one of the most pleasing lighting fixtures

architecturally. It was originally made in glass, but glass globes were discontinued, as they

are not safe. The glass was 1inch thick and when it falls, it breaks and could tear car tires,

and the sharp edges of the glass could hurt someone. Therefore D.C. went from glass to

plastic. All the glass Globes were thrown in a dumpster 15 years ago. Holophane, Spring City

and HADCO manufacture Washington Globes. The present Washington Globe provides 15%

light on ground with a 150-Watt lamp. HADCO took the Washington Globe and

architecturally copied and put in the prisms to use the light effectively. The results were

29.1% of light was on ground with a 150-Watt lamp. Therefore, the refractive globes are best

for dark skies. The demonstration of HADCO refractive globes is in front of the FBI building

(Penn Ave & 9th

St). There are different types of prismatic globes, i.e., the way the prisms are

molded in the globe, for different types of lighting patterns. It was mentioned that the glare in

the prismatic globes generally corresponds to the wattage of the lamp rather than the globe

itself.

Types I, II, III, IV, V are the optical pattern light puts out with reflectors and prisms. Types

III and V were discussed in detail. Type III produces better light, but also a little glare. Thus,

the strong illumination can distract the driver. This is used in Baltimore’s Inner Harbor and

New Jersey’s Atlantic City. But by using reflectors, 51.3% light is put on the street. If you

put reflectors over the bulb it will loose 10% of light. Generally, taller poles spread the light

around but the light coming down on the street decreases. Type V Globes have been used in

DC. Reflectors can be in louver form. It was claimed that the use of a louver is not that

efficient and would produce a max/min ratio of 13, while a refractive globe could produce

6.5.

The globes out on the streets were designed/tested for 250 Watt. If a higher wattage is used,

it could melt the globe. There are many in D.C. where globes are melting as they are using

400 Watt when the globes are designed for 250 Watt. HADCO uses Acrylic materials. Plastic

Globes made of Polycarbonate are strong and will never break. But after 5 years they will

yellow because of UV rays and the light from the bulb. In addition they will become brittle

with age, and as a result, when a rock is thrown at it, it will break. Generally, heat

accelerates the deterioration process. A Poly-ethylene pole will never break, never needs to

be painted, has a long life finish, maintains durability even in the harshest environments,

withstands high impacts, is UV resistant, provides safety against shock hazard and is

corrosion resistant. There is one plastic base installed in D.C.

HADCO uses the lights manufactured by Philips. It was recommended that a Type V globe

non-cutoff be used as a good trade off. It was mentioned that DDOT doesn’t use reflectors all

the time, but uses them only when required. HOLOPHANE generally uses Type III. Twin-20

with a mounting light unit at a lower height is being replaced with Teardrops on I-395. A

March 2005 55


copy of the article, The Dallas, Oregon & QL Induction Lighting on Philips’ Website, was

given to DCI. (From the article, – QL is much whiter than HPS, offers undistorted high color

rendering, and provides softer lighting effects with less glare compared to MH.) Frederick

(MD), Oregon and Stanford (CT) have used QL Induction Light.

HADCO’s Teardrop TR 4 Series is light in weight; it is made of acrylic and not glass. It does

not use a button type but instead uses a twist lock. Black is the best color to be used for

fading. A woman in NY was electrocuted after stepping on an electrified metal plate while

walking her dog. It was mentioned that care should be taken regarding the wires dangling

from light poles and service boxes exposed to the elements. HADCO demonstrated a plastic

base, free from electrification problems.

20 feet poles with architectural fixtures are too difficult as the pole is too high to install.

HADCO makes poles up to 20 feet, with bases and casing. A height of 12-16 feet is optimal

for maximum output of light; thus, Twin-20 are a bit of a stretch. Sidewalks should be

considered in the lighting design to enable motorists to see pedestrian movements. HADCO

designed globes with 150-Watt light (no reflector), which can be equivalent to 250-Watt light

with standard globes. HADCO provided DCI with a CD showing the installation of a plastic

globe. A copy of the history of NY streetlights and literature about white and yellow light of

an ophthalmologist were also given. A tour around Baltimore was offered to DCI to give a

better visual understanding.

Over 15 years dirt may settle in the globes and the light output will be generally reduced.

This is a maintenance issue for both glass and plastic globes. Baltimore City has been using

refractive globes for the past 8 years and has standardized the practice. HADCO offered DCI

a refractive globe casing with different types of lamp attachments (HPS, color corrected HPS

and Induction lamp). It was found that the color corrected HPS was not as white as the

Induction Lamp, even though it was whiter than HPS itself.

Traffic System And Technology

DCI met with Sam Dominick. Traffic System and Technology has been providing Traffic

and Lighting products since 1984. They operate as both a manufacturer’s representative and

distributor of various products. They represent many manufacturers, a few of them are,

Union Metal Corporation, King Luminaire, Electronic Integrated System (EIS), Precision

Solar Control, etc. They offer a prefabricated foundation (SAFE) that is quick in installation

and can be hydraulically pressed into the ground. It costs as much as concrete foundation.

LumiTrack offers sign lighting maintenance systems that are installed on the SE/SW freeway

and cannot be installed on cantilever beams.

Union Metal was established in the 1900s and offers the Nostalgia series. King Luminaire

manufactures Spun Concrete, Ferronite Cast Iron, Cast Iron Base/Steel Shaft and Aluminum

poles. They also offer luminaries, arms and bollards. The concrete poles need no

maintenance and are installed at Washington Center and the US Soldier home. Traffic

System and Technology offers octaflute poles (28, 38 and 80 feet) and LED lights.

March 2005 56


For sign lighting, SHA uses Mercury Vapor, Virginia uses HPS, and DC uses HPS, MH and

Mercury Vapor. Induction lamp is an emerging technology that is widely being used in

Europe. It has a long life (100,000 hrs), however, the ballast doesn’t last long and the failure

rate is very high.

The Teardrop luminaires are made by Union Metal and King Luminaire. M.C. Dean (a

contractor used by DDOT) uses King Luminaire products. King Luminaire still makes glass

globes. The standard globes produce 78% efficiency. Polycarbonate yellows in 3 years while

acrylic is good for 12 years. A CD with King Luminaire products was given to DCI.

Holophane

DCI met with Benjamin M. Prichard (Newark), John A. Vlah (Annapolis) and Ken Roth

(Pennsylvania). The prismatic Washington Globe casing was shown in the meeting and it

was manufactured without sacrificing its historical identity. Some of these installations were

in Georgetown and on 9th

Street, but were removed later. They stated that this installation

saves energy, will take any kind of abuse, and is easy to maintain. The casing is the same for

Nos.16, 18 and Twin-20.

The prismatic structure is molded in the Globe. The prismatic structure is the same for glass

and acrylic. UL testing is performed for 40o

ambient temperature. This type of globe saves

energy, has greater illumination, has a cost reduction, maintenance reduction and also

provides visual comfort. A clear and clean visual range is obtained from such globes. The

prismatic structure has no sharp edges because sharp edges cause glare and therefore the

edges are rounded instead. A glass globe with a perforated shield was shown. Generally

uplight shield reduces uplight roughly by 2%. Uplight Shield has advantages and

disadvantages. The globes are made of acrylic plastic (V 8 25 HID) which is better under any

weather conditions. It is protected from UV rays not only from the sun but also from the

source. Heat sources are generally from core and coil.

Holophane suggested using acrylic for high crime rate areas and glass otherwise, as nothing

is bullet proof. The glass globe was suggested for the commercial areas and acrylic for

residential areas. The color corrected HPS was not as efficient as the HPS, as the optical

coating gets burnt out.

It was mentioned that MH is becoming more popular in other countries. Holophane prefers

glass globes under normal conditions as they last forever and plastic degrades with time.

Generally, degradation depends on location and exposure to sun.

Holophane suggested glass globes for Downtown/Monumental Core as there would be no

discoloration and the light would be whiter. The cost of glass (expensive) and acrylic (less

expensive) are pretty close. Holophane has been testing acrylic for 6 years. The index is

between 1 and 2 on a scale of 1 to 10, with 1 being the best. It was mentioned that the heat is

generated from the lamp and the ballast.

IES defines an index called the Yellowing Index (ranges from 1-10, 1 being good, 10 being

bad). Polycarbonate has an Index of 5 (IES Handbook), which is a tougher material when

March 2005 57


compared to acrylic. But acrylic has better optical properties and holds up better to heat.

When the pole bends along with the wind, the lens comes off, but acrylics won’t do that with

fixtures. Generally, the fixture life reduces half for each 10o

increase in temperature above

the ambient temperature.

Photocells can be placed in the casting by cutting a small opening in the neck of the casting.

But DDOT requires the photocell at 45o

minimum. If the photocell is perpendicular it will

shoot out straight. Holophane suggested that a prism could be put on photocell so that it

shoots down on the ground.

Vibration testing is important, as the globe may tend to fall under high winds. Holophane 's

globe passes the vibration test. The casting that was brought for demonstration was tested for

150 Watt HPS that fits No. 16 and Pendant pole. (i.e. 3 inch x 3 inch tenants). It did not have

a photocell but would generally use a button type photocell. The Acrylic Globes are tested

for up to 400 Watt HPS for 45oC ambient temperature. The globe is not a concern as it is

tested for 400 Watt but the casing may need to be bigger for 400 Watt HPS. 9th

Street has a

Holophane Washington Globe demonstration.

The globe size is not flexible (diameter) but the neck of the globe can be changed to fit in the

existing casting. Plastic is easy to form or mold, but glass is difficult. An existing model/pole

needs to be tested for whether the casting can be fixed to the tenant of the existing poles in

D.C. or globe to the existing casting in D.C. Holophane suggested that a collar can be used to

fit the globe on the existing casting.

The Holophane's Glass and Acrylic Globes are Type III optical distribution. Type V has a

circular distribution (application - Islands and Parks), Type IV has a wider oval distribution

and Type III has a narrower oval distribution. Type V can be used for residential areas with

household shields at 90o, 40

o,etc. The efficiency is about the same for Types III, IV and V

The globes installed on the street have 50% of the light going up but with Holophane’s globe

only 25% of the light is going up.

Holophane’s Teardrop poles are installed on 16th

and Kennedy Streets. They are very

efficient and save energy. This type of pole combines efficiency and aesthetics. The

manufacturers are performing some tests to make them better, i.e., more decorative, functions

like Pendant Posts, etc. Holophane also came up with the prismatic design of the Teardrop

globe that was used in the1996 Olympics in Salt Lake City and in Silver Spring. If you

replace Cobraheads with Teardrop they perform very well but it depends on the height and

road width. For narrow streets (less than 30ft), Cobraheads are better and for wider streets

(85-90 feet), Teardrops are better. The Teardrop fixtures come in cutoff. If you have a lower

uniformity ratio, Teardrops make it brighter. The manufacturers showed 2 sizes of Teardrops,

for roadways (bigger, Type V) and pedestrians (smaller, Types III, IV). When light is needed

on the road as well as for pedestrian traffic, cutoff can be used. Cutoff has advantages (good

light control on the property line) and also disadvantages (reduces vertical illumination and

efficiency). It was stated that DC uprights were designed for Incandescent lights, and hence

use conversion kits now. DDOT requested cost information regarding retrofits and new

installations for globes, kits and casings.

March 2005 58


Commercial Lighting Sales, Inc.

DCI met with Jim Wheeler from Commercial Lighting Sales. Commercial Lighting Sales

represents Spring City (manufactures cast iron posts, luminaire, arms, etc), Valmont

(manufactures Cobrahead) and GE (manufactures Cobrahead Fixtures, Ballast conversion kit,

etc). For narrow sidewalks, Spring City came up with 17 inches diameter for a No. 16 pole

with a narrow base and 12 inches bolt circles, accepted by DDOT. The shafts that are being

used fit in narrow bases (interchangeable). It can use the same casing and the globe can

withstand 400 Watt. The No. 14 narrow base poles are being used mostly on Ohio Drive. It

was mentioned that a higher pole means a higher wattage, and a higher wattage means a

higher conduit. But wider bolt circles will have better stability and a clearer opening for more

conduits.

In Chinatown, the Teardrop has been cast and fixtures were manufactured by Spring City.

They mentioned that dark skies are very conflicting because sometimes it is required to

illuminate the building for safety reasons. The District sometimes uses Finial. A Pineapple

Finial is mounted on a No. 16 pole when used as a traffic post. The ballast kit fits inside the

existing casing. The luminaire used is GE (M-400A2). It has two doors underneath – 1) for

the light, and 2) for the ballast (this second door is called the power door). This separate

power door allows for quick maintenance. There are 4 bolts on the Pendant pole with two

clamps. If maintenance person or electric cranks up one clamp there is another. The main

issue is that there is not enough spacing for wires, as in other products. The Cobrahead has a

twist lock photocell and all the other posts have a button type.

The Induction lamp has been used in Europe for quite some time. The only problem is that it

has a lower wattage (130-150 Watt) but has a long life. Plain plastic globes are generally

used in the District. The formed plastic globe is made of stipple polycarbonate. The stipple

Acrylic Globe does not yellow like plastic and therefore is a better way to go, as plastic

becomes brittle with age. Acrylic is also better for higher wattages. The refractive globes

demonstration is in front of the FBI building. When reflectors are used (for Type III – an

asymmetric lighting pattern), maintenance people need to be aware of the distribution of light

so that the light should be focused on the streets (and not on the building). Generally, beam

control fixtures (louvers and refractive globes) have maintenance issues, as they need more

time to service (need to be taken to the shop for service, no onsite service). Commercial

Lighting Sales are supplying louvered acorn globes for Pennsylvania Avenue’s Streetlight

project.

The Federal Colors are 16099 – Gray and 27038 - Black. DC’s gray is not same as 16099.

DC’s gray is more dark gray and 16099 has bluish tint. The Downtown BID requires black

color (27038). They developed their own spacing criteria; so standard spacing is already

available for the Downtown BID. National Park Services mostly use the black color. The

black color is used for decorative purposes and the aluminum finish is used for Cobraheads.

The globes that are used currently have a dimple like pattern and are not refractive. Fluting

Pattern, i.e., 16 flat flute, is available for the Twin-20 pole and No. 16. (Standard for DC).

Sharp flute (8) is available for Pendant poles. The steel shaft is provided for the Twin-20 and

the Pendant pole; and the cast iron shaft is generally used for other types, such as the Nos.16,

March 2005 59


14, and 18. On Georgia Avenue, the No.18 pole is being used and people are discontent with

No.18 poles and want to get back to the No.16 pole. In Monumental Core, No.18 poles are

used for traffic poles (can also use No. 716). Generally both the Nos. 18 and 16 can be used

as traffic poles. The No. 716 pole is used under Chinatown fixtures. It is a 14 feet tall pole

and it is a less expensive version of the No.16 pole. Sometimes the No.716 pole is used for

signs (generally mounted on the side). The T-base is not painted, but generally galvanized.

The only time it was painted was in Chinatown, where it was painted green, and the pole was

painted red. The No. 716 pole, when used with traffic control devices, uses 16099 color and a

galvanized T-Base.

Teardrops, a Columbian Series in Type III and V, are available. Glass and plastic globes are

available for it. As glass is heavy, it is easier to service the plastic globes. It can be mounted

on regular Pendant poles.

March 2005 60


A.3. OTHER AGENCY PRACTICES

A.3.1 AGENCY INTERVIEWS

The Study Team conducted interviews with other jurisdictions in order to determine the

prevailing lighting practices. The questionnaire that was provided to other agencies is

presented at the end of this subsection (Section A.3.3). Listed below are a summary of the

jurisdictions interviewed and their current lighting practices/standards:

City of Indianapolis

Ms. Sherry Powell, City of Indianapolis Department of Public Works, was interviewed. Ms.

Powell indicated that the City is currently utilizing HPS and MH lighting fixtures. However,

the current goal of the City is to convert all fixtures to HPS due to the longer life spans and

lower initial costs. The City currently uses wood, aluminum and fiberglass poles. Within the

historic districts of the City, refractive globes are used with HPS lighting fixtures. Within the

residential areas, Cobrahead lighting poles with HPS lighting fixtures are primarily used.

Maryland State Highway Administration (MDSHA)

Mr. Charles Rupp from MDSHA’s Office of Traffic & Safety was interviewed. Mr. Rupp

indicated that MDSHA’s policy is to use HPS lighting fixtures in all areas. The primary

lighting pole type used within the State is the Cobrahead lighting pole with HPS lighting

fixtures with full-cutoff distribution and a Type III lighting pattern to minimize rear spillover

light. On bridges within historic areas, refractive lighting globes are occasionally used with

HPS fixtures. In addition, along interstate roadways, high mast lighting poles with mounting

heights between 100 and 120 feet are also used with 1,000 Watt HPS luminaires with a Type

IV lighting pattern. However, Mr. Rupp indicated that high mast poles are currently being

used on a lesser scale due to spill over complaints from adjacent residential communities.

Virginia Department of Transportation (VDOT)

Ms. Pamela Brookes, VDOT Headquarters, Richmond, Virginia, was interviewed. Ms.

Brookes indicated that VDOT’s primary lighting pole and fixture is an offset hinged lighting

fixture (Holophane’s Vector Pole) with a 250 Watt HPS lighting fixture. However, VDOT is

currently utilizing Holophane’s Mongoose lighting pole fixture on a greater scale (similar to

the Cobrahead lighting pole) that allows for a full cutoff to semi-cutoff lighting distribution

to minimize rear spillover lighting.

City of Boston

Mr. Glen Cooper, City of Boston Department of Public Works, was interviewed. Mr. Cooper

indicated that the City uses aluminum, concrete and cast iron lighting poles. The City uses

the following poles and lighting fixtures: a rectangular 250 or 400 Watt Mercury Vapor

acrylic prismatic fixture on an aluminum post with a 15 inch bracket arm; a rectangular 150,

250 or 400 Watt Mercury Vapor acrylic prismatic fixture on a concrete pole with a 22.5 inch

bracket arm; a Boston City Neighborhood Globe (polycarbonate) with a Type III lighting

March 2005 61


pattern and with a semi-cutoff distribution; and a Boston Boulevard Pendant Twin (similar to

a Teardrop pole) with a 26 foot mounting height and a 250 Watt Mercury Vapor lighting

fixture.

City of New York

Mr. Moktar Gabriel, P.E., Deputy Chief Engineer, City of New York Department of

Transportation, was interviewed. The lighting illumination ranges used as a guideline within

the City of New York are slightly higher than the recommended ranges within AASHTO.

The recommended uniformity ratios are similar to the AASHTO guidelines. The primary

poles and luminaires used within the City are Cobrahead lighting poles with 100, 150 or 250

Watt HPS luminaires. In designated “Special Areas”, Globe type fixtures are used with

luminaires ranging from 100 to 400 Watt HPS. In “Decorative Areas”, Teardrop style

lighting poles with 150 or 250 Watt HPS or MH luminaires are used. For overhead signs,

175 Watt MH lighting fixtures are used.

A.3.2 INTERNET RESEARCH

In addition, limited research was conducted on the Internet to determine the lighting practices

of other jurisdictions. The following summarizes the findings:

Oregon Department of Transportation (ODOT)

ODOT uses the Cobrahead lighting fixture as their primary lighting pole along most

roadways with a 70 to 400 Watt HPS luminaire. ODOT’s lighting guidelines with regards to:

minimum point values, average maintained illuminance, average-to-minimum ratios,

maximum-to-minimum ratios follow the American Association of State Highway and

Transportation Officials (AASHTO) Informational Guide for Roadway Lighting. For

interstate roadways, high mast lighting poles are used with HPS fixtures ranging from 400 to

1,000 Watt. For lighted overhead signs, ODOT uses Mercury Vapor lighting fixtures.

New York State Energy Research and Development Authority (NYSERDA)

NYSERDA conducted a research study to determine the most cost-efficient lighting methods

to be used within the State of New York. Based on a total annualized cost formula that

included the initial costs, energy consumption, and maintenance costs over a 20-year period,

NYSERDA determined that a 250 Watt HPS luminaire on a sharp cutoff (shoebox type)

lighting pole provided the most cost efficient lighting solution. However, the report also

indicated that the fair (yellowish) color properties of the HPS luminaire must also be

considered in the design.

City of Kent, Washington State

The City of Kent lighting guidelines provide many lighting criteria that include uniformity

ratios and minimum lighting values that are consistent with AASHTO lighting standards.

The City of Kent has chosen the following two (2) lighting pole options: HADCO Series 21

and Series 22 Aluminum Streetlight Standards and Mast Arms, or Valmont Series 21 and

Series 22 Aluminum Streetlight Standards and Mast Arms. Both of these lighting poles

March 2005 62


require the usage of HPS lamps with a flat lens, medium cutoff distribution, and a Type III

lighting pattern.

Other Cities

Prismatic globes have become the standard practice for many jurisdictions now. Examples in

the metropolitan area are Baltimore, Frederick, and Falls Church. The City of Rehoboth

Beach has developed, as a part of the streetscape project, a unique streetlight design, with

twin arm, teardrop lights in the median and concrete poles with prismatic, Washington-type

globes on the sidewalks. They use pendant poles to support traffic signals over the

intersections.

More information on these implementations will be provided in the Final Document.

A.3.3 LIGHTING QUESTIONNAIRE

Date ________________________________

City:_________________________________

Point of Contact:________________________

_____________________________________

1. What are your illumination standards for residential areas, commercial areas, and

other areas (if applicable)? If you have specific criteria, please include the following

information:

i) Average Maintained Illuminance Level (foot-candle) ______________

ii) Average-to-Minimum Ratios ____________________

iii) Maximum-to-Minimum Ratios ___________________

iv) Minimum Point Level Illumination_________________

1. What lighting type distributions are utilized (e.g. Type 3 cutoff distribution)?

_____________________________________________________________

2. What types of luminaires are utilized in various areas (i.e. High Pressure Sodium,

Metal Halide, Mercury Vapor, inductive lamp, etc.)?

_____________________________________________________________________

________________________

What is your experience about them? _____________________________________

___________________________________________________________________

___________________________________________________________________

Any remarks on inductive lamps (if used) __________________________________

March 2005 63


What types of pole (by material) are used in various areas (i.e. aluminum, steel, cast

iron, concrete, fiberglass, wood, etc.)? ____________________________________

___________________________________________________________________


___________________________________________________________________

___________________________________________________________________

Any remarks on concrete poles (if used) ___________________________________

3. What types of pole (by type) are used in various areas (e.g., Upright, Cobrahead,

etc.)?

i) Historic district ______________

ii) Commercial area____________________

iii) Residential _________________________

iii) Other _____________________________

4. What type of fixtures do you use for tunnel lighting? __________________________

Underpass lighting? ___________________________


___________________________________________________________________

___________________________________________________________________

5. What type of fixtures do you use for sign lighting? ___________________________


___________________________________________________________________

___________________________________________________________________

Is there any particular type that you'd use to provide the true color of signs?

_____________________________________________________________________

6. What lighting manufacturers are used for the poles and lighting fixtures?

___________________________________________________________________

___________________________________________________________________

7. Specific Issues/agency solutions:

i) Dark skies. What do you do to achieve dark skies?

Refractive globe or lens _____, shield ______, any other____

ii) ADA requirement (36" sidewalk). What do you do when you have an already-

narrow sidewalk ________________________________________

_____________________________________________________________

March 2005 64


A.4. STREETLIGHT POLICY ADVISORY COMMITTEE

DDOT formed a panel of advisors to serve on a committee to steer this study. The

committee was formed from members of relevant agencies and citizen groups. The

committee held a series of meetings and directed the course of the study, made evaluations of

various alternatives and provided specific recommendations on various aspects of the

streetlight policy issues.

In order to help understand the rationales and how some of the requirements were generated

in these meetings, the minutes are included in this section.

March 2005 65


MINUTES OF THE MEETING HELD ON 3-10-04

Introductions and Goals

Kristina Alg –

Consistent streetlight policy – varying size, type of lights, etc for different types of streets

Concern about installation of streetlights

Jack McKay–

Finding a “happy medium” of lights in Mt. Pleasant

Need of guidelines

Larry Aurbach–

Illuminating bridge structures

Presentation

1. A number of technical clarification questions concerning watts, location etc.

2. Request for the study to compare the budgets of overhead lines and underground

lines.

3. John Deatrick wants recommendations about current ongoing bridgework using

standard lighting.

4. Comments were brought about AASHTO standards resulting in lighting being either

over lit or under lit.

5. Slide 42 of the presentation – need to quantify measures.

6. Recommendation of a lighting control that rely less on PEPCO.

7. Take sidewalk width into consideration when choosing a pole (e.g. pole base No. 14

vs. 16)

8. We need to also consider night pollution and efficiency

9. Concerns about lighting and crime perception in the Historic Anacostia area.

10. Consider pole color/type.

11. Understanding of current conditions is needed to gain an idea of variations of

illuminants.

12. How do we market guidelines/get info to the public?

Action Items

1. Mike Dorsey and Jama Abdi will create a drive-through tour of lighting types. This

tour will occur during a date and time, TBD in March. Advisory Committee members

can participate in this tour or go out on their own.

2. Colleen Smith Hawkinson will email light routes (to include Barracks Row and street

specifications such as width and type) for those who are interested in touring

independent of the group.

3. Samira Cook will create a matrix using the suggested characteristics (see evaluation

criteria and preliminary sample chart below)

March 2005 66


4. Light readings will be taken to get an understanding of lighting strength

5. Lighting tours should be conducted in March before the next meeting

6. Tentative Next Meetings: April 14th

at 10 am

May 12th

at 10 am

May 25th

at 10 am

All future meetings will be held in DDOT’s Traffic Services Administration’s 7th

floor

Conference Room. You will take the elevator to the 7th

floor and go to your left through the

double glass doors. Continue down this hallway until you see another set of elevators on your

left. Turn right at this elevator and go through another set of glass doors. The receptionist

will direct you to the room.

Evaluation Criteria as determined by Advisory Committee

Efficiency

Aesthetics

Color of light

Level of light pollution

Type of roadway (highway, corridor, residential, commercial)

Type of fixture

Ability to standardize

Spacing of poles

March 2005 67


MINUTES OF THE MEETING AND THE FIELD TRIP HELD ON 3-24-04

Meeting

1. Discussion about the AASHTO standards minimum resulting in lighting being over-

lit.

2. We need light on the pavement and the light above the luminaire is not generally

desired. Very little light is directed on the ground while most of the light is wasted

sideward and upward.

3. Recommended the poles to be placed uniformly for uniform distribution of light.

4. As cost is a major issue, what is the cost difference between the glass, plastic and

refractive globes?

5. HPS (approximately 5-6 years) has a long life compared to Incandescent

(approximately 6 months) and MH (approximately 3 years).

6. 14N – predominant in Georgetown. Mostly No.16 is used in other areas.

7. Cobraheads or Pendant poles are generally used for signals and walk signs.

8. A narrow base that is used to fit on a narrow sidewalk may look very disproportional.

9. An area with a high crime rate can change and also the technology may change with

the passing of time.

Field Trip

1. Mike Dorsey and Jama Abdi took the Advisory Committee members for a tour of

lighting types.

2. MH is used in Monumental Core (National Park Service regulation).

3. The 150 Watt HPS refractive/prismatic globe is better lit than 250 Watt HPS regular

globe.

4. Spring City, HADCO and HOLOPHANE refractive/prismatic globes are on

Pennsylvania Avenue for a demonstration. The prismatic globe casts a bright band on

the adjacent building but the pavement is better lit.

5. The 400 Watt MH and 400 Watt Mercury Vapor have the same brightness.

6. The light level on the sidewalk on M Street, SE across from Navy Yard under an

upright (No. 18) pole with standard Washington Globe and Twin-20 was almost the

same.

7. Should the matrix include light levels (for upright, Pendant, Twin-20 and other

commonly used poles for commonly used wattage) on sidewalks and between the

poles at the same distance from the pole or curb and at the centerline of the street? It

should be recorded where the lamps are in their life cycle, i.e. newly installed, mid

life or end life.

March 2005 68



A Streetlight Advisory Committee Meeting was held in Conference room, 6th

Floor, District

Department of Transportation on 4-14-04. The minutes of the meeting are as follows.

Summary

1. Ken Laden started off the meeting at 10:05 a.m. He briefly summarized the scope of

the project. He mentioned that DCI is the consultant working on the project and will

look into different jurisdiction’s streetlight standards and come up with

recommendations for DC.

2. Colleen Hawkinson stated that it was the second Streetlight Advisory Committee

Meeting that was being held. She mentioned that a field trip was made on March 24th

in DC and the participants were able to see different types of lights and luminaires,

and take the light readings. She also pointed out that the recommendations are going

to be a range of lighting standards (i.e., 2-3 types of poles, different illumination

levels, etc.) rather than a single given standard. She said that a draft for this project

would be presented to the Committee around the middle or end of May and will be

distributed to the Committee. Public Meetings are also going to be held and the

resulting feedback will be incorporated in the Final Draft, which will be completed in

early July. It will include a presentation to Fine Arts Commission.

3. Larry Green presented the task status and the updated comparison tables. He

mentioned that a range of illumination levels for various road classifications would be

recommended. He showed figures for a typical average illumination field survey

procedure, various lighting types, poles and other fixtures. A focus group is going to

be formed to discuss the AASHTO Standards, lower and upper lighting illumination

limits, and the new technologies. He also spoke about the typical colors that are used

for poles, DC typically uses black (27038) and gray (16099), Golden Triangle BID

requires black (27038) and the National Park Services mostly use black.

4. During the course of the presentation, several items were discussed or suggested:

The prismatic acrylic globe reduces the wattage requirement to provide the same

level of illumination, because the light is directional, and therefore, a fewer

number of shorter poles can be used. Also, it does not cause uplights and

subsequent light pollution.

The committee wanted to know the benefits of glass over plastic globes, a case

study where glass globes are being used and the lifetime cost of the globes. The

group was also interested to know the list of places where prismatic globes are

used in Baltimore. It was suggested that the height of the building and the poles

needed to be considered in the design of streetlights.

The policy should include a range of illumination standards, as the AASHTO

standards may appear to be too bright for some neighborhoods. The range of

levels will allow a community to have too bright light if they want and vice versa.

There was a suggestion to look into the uniformity of the light distribution on the

road, along with the illumination levels. It was mentioned that the prismatic

globes will not help with the uniformity and it would still depend on the pole

March 2005 69


height and the spacing between them.

Commercial lights (from stores, shopping centers, etc.) contribute to the

prevailing lighting levels on the roadways/sidewalks. There was a discussion

whether it should be considered in the design of streetlights. It was concluded that

there was no control over these lights (as to when it would come on or go off); so

it was not feasible to use in the design. Moreover, commercial lights are in

commercial areas, where bright light may not be a problem.

In the case of narrow sidewalks, instead of using a pole with a smaller base, a

shorter pole (proportional with narrow base) should be considered, as the pole

may not look proportional with a narrow base.

There was a recommendation to look into the role of the pole bases. For example,

a square base, also known as a transformer base, has a maintenance issue, is prone

to vandalism and often gets rusted out. Mike Dorsey explained that these bases

were used to house transformers for mercury vapor lamps and thus, called a

transformer base. Although Mercury Vapor lamps are being phased out, the

access door in the transformer base continues to provide the ease of cable

maintenance. Anchor based poles with hand holes can be alternatives; however,

these are not used.

The steel and cast iron poles when painted with the same color look different.

Therefore, even if the same color is picked for a neighborhood, the color may

vary depending on the material of pole. Poles used to be painted every 7 years;

now, they are powder coated.

In general, DC uses gray and NPS uses black colored poles. The poles on the

bridges are usually colored different than these.

Intersections should have different design criteria. The consultant needs to look

into mid-block vs. intersection criteria.

The recommendations of the study should be a multi-dimensional matrix, the

contexts for which should include: a) roadway functional class, b) area type (e.g.,

residential, commercial, etc.), and c) special areas, such as historic districts,

bridges, etc.

In the alleys, generally a full-cutoff luminaire is used. New installations are there

on the south side of U Street, near Reeve's Center.

A suggestion was made for the use of short poles in the case of trees. The design

should also consider handicap accessibilities.

The final product should have an illustration with a small area map indicating the

standards applied to various contexts within the map. A list of definitions needs to

be included for a better understanding. The lit pictures of the prismatic globes can

also be presented to have a visual understanding.

One very important thing is to educate public regarding the brightness, safety, etc.

Most people think that if an area is bright, then there is no crime; but in some

cases, it was found that bright light has attracted some criminals.

March 2005 70


5. There was a discussion on the evaluation matrix, as follows:

The evaluation matrix will be used to compare various alternatives; however, it

will be used as a general guide and multiple candidate alternatives will be

selected.

For the first table, it was suggested that the level of pollution should be

considered not only for the upward direction, but for sideways direction also.

Historic, Monumental Core and Special streets should also be considered for type

of roadways. The height of the pole should also be considered along with the

spacing of the poles, because height is one of the contributors for bright light.

For the second table, among the lamp alternatives, Mercury Vapor and

Incandescent light were being phasing out (towards HPS) and therefore, did not

need to be evaluated. MH has been used mostly in Monumental Core. New

technologies like the LED Light and Induction Lights should be evaluated.

Induction lights have been used a lot in Europe, and the lamp and ballast is one

assembly. This lamp has a life of 25 years and is generally used in residential

areas, but needs 100% cutoff. The quality of light, consistency and illumination

levels should also be considered. The life cycle cost should be used as one of the

evaluation criteria. Instead of a cost figure, subjective qualitative rating (e.g.,

high, medium and low) or numerical grades (e.g., 1-10) can be assigned for the

life cycle cost.

The third table needs to tailor to suite the context of the area of usage. Type of

area (residential/commercial) should be considered. The height of the building,

sidewalk width, roadway width, and public space width should also be

considered. It was concluded that different matrices would be generated for each

different context.

6. There will be a follow-up meeting for evaluation using the matrix on May 28 (10 a.m.

- Noon). DCI will work on setting up the matrix and send out to the Committee

ahead of time.

March 2005 71



A Streetlight Advisory Committee Meeting was held in the Conference room, 6th

Floor,

District Department of Transportation on 4-28-04. The minutes of the meeting are as

follows.

Summary

1. Colleen Hawkinson started off the meeting at 10:15 a.m. She mentioned that the main

purpose of the meeting was to discuss the Evaluation Matrix framework.

2. Manzur Elahi presented the Evaluation Matrix framework. An evaluation framework

was developed for the evaluation of several streetlighting elements, as listed below:

o Lamp alternatives

o Globe alternatives

o Shielding/Cutoff alternatives

o Pole alternatives

A set of matrices had been developed for evaluating various alternatives. Also, a set

of contexts had been identified for evaluation of items under possible scenarios. The

objective of this evaluation was to gain knowledge of the collective preference of the

Streetlight Advisory Committee. This framework will be used to compare various

alternatives; however, it will be used as a general guide and multiple candidate

alternatives will be selected.

3. The following table presents the Advisory Committee input to identify evaluation

criteria for the streetlight policy from the two previous meetings. The identified

criteria were examined to see whether they are quantifiable and how they fit in the

evaluation framework. A few of them were quantifiable, others were contexts rather

than criteria for evaluation and several others were design issues.

Criterions Suggested by Advisory Committee

Criteria Suggested by AdvisoryCommittee

Comment Way toQuantify

Efficiency Need to be presented as identifiableitems, such as: a) life duration, b) power consumption, c) light output/distribution, etc.

Subjectiverating (1-10)

Aesthetics Applies only to structural element Subjectiverating (1-10)

Color of light Applicable only for lamp/luminaire Subjectiverating (1-10)

Level of light pollution(upward & sideways)

Applicable only for lamp/luminaire Subjectiverating (1-10)

Roadway classification(Interstate, Other Freeway & Expressway, Principal Arterial, Minor Arterial, Collector, Local and Alley)

Does not represent an objectivefunction that can be rated oroptimized. It is a context for evaluation. It is also design issueand the study will have criteria for them.

N/A

March 2005 72


Criteria Suggested by AdvisoryCommittee

Comment Way toQuantify

Area Type(Commercial, Intermediate & Residential)


N/A

Special Type(Gateways, Monumental Core, BIDS)


N/A

Tunnels/Underpass Does not represent an objectivefunction that can be rated oroptimized. It is a context for evaluation. It is also design issueand the study will have criteria for them.

N/A

Bridges Does not represent an objectivefunction that can be rated oroptimized. It is a context for evaluation. It is also design issueand the study will have criteria for them.

N/A

Type of fixture This is an item for evaluation, not acriterion.

N/A

Ability to standardize Does not represent an objectivefunction that can be rated oroptimized. It is a design issue and the study will have criteria for them.

N/A

Spacing of poles Does not represent an objectivefunction that can be rated oroptimized. It is a design issue and the study will have criteria for them.

N/A

Height of the pole Does not represent an objectivefunction that can be rated oroptimized. It is a design issue and the study will have criteria for them.

N/A

Height of the building Does not represent an objectivefunction that can be rated oroptimized. It is a design issue and the study will have criteria for them.

N/A

Base of the pole Does not represent an objectivefunction that can be rated oroptimized. It is a design issue and the study will have criteria for them.

N/A

Road Width Does not represent an objectivefunction that can be rated oroptimized. It is a design issue and the study will have criteria for them.

N/A

Sidewalk Width Does not represent an objectivefunction that can be rated oroptimized. It is a design issue and the study will have criteria for them.

N/A

Crime Rate Does not represent an objectivefunction that can be rated oroptimized. It is a design issue and the study will have criteria for them.

N/A

* Rating 1-10, 10 being most preferred.

March 2005 73


4. The quantifiable evaluation criteria suggested by the Committee are shown in the

following table. It also presents two additional criteria identified. However, all

identified criteria were not applicable to evaluating each individual item. Therefore,

appropriate criteria were identified for each evaluation item (e.g., lamp, globe,

shielding and pole). The matrix can be further expanded if DDOT/Committee feels

more items are to be evaluated.

Quantifiable evaluation criteria

Applicable Criteria for Each Item Evaluation Criteria Lamp Alternatives

(HPS, Metal Halide, Inductive,

etc.)

GlobeAlternatives

(Plain,prismatic)

ShieldingAlternatives

(Cutoff, semi-cutoff, full cutoff)

PoleAlternatives

Efficiency (based on the following, as applicable)

Life duration

Power consumption

Light output/distribution, etc.

YES YES YES YES

Aesthetics -- YES YES YES

Color of light (rendition) YES -- -- --

Level of Light Pollution(upward & sideways)

-- YES YES --

Existing Usage* YES YES YES YES

Lifecycle Cost Initial Cost

Operational & Maintenance CostYES YES YES YES

* Represents preserving existing investment

5. The following table lists the variables that generate various contexts for evaluation.

The context determines the weight of the evaluation criteria and therefore, the

evaluation of the same item under two different scenarios (i.e., contexts) can result in

two different sets of weights, and subsequently, outcomes can be different.

The context list was examined for each of the evaluation items to determine whether

the desirability (i.e., weight of the criteria) of the item changes with respect to the

context. The context type can be grouped together if the item was independent of the

context type. For example, all Roadway Functional Classifications for lamp

alternatives can be grouped as one, as the lamp alternatives are independent of the

Functional Classifications. In some cases, the evaluation alternative was

predetermined for a specific context. For example, the shielding and the pole

alternatives are predetermined for Interstate/Other Freeway & Expressway and for

Alleys. Few of the contexts, such as the Commercial and Intermediate/Residential,

change the desirability of the shielding alternatives.

In the Special Type context, the pole alternatives need to be determined for Historic,

Gateways and Bridges.

March 2005 74


Context applicability to each item

Context Applicability to Each Item

Context List Lamp Alternatives (HPS,

Metal Halide, Inductive, etc.)

Globe Alternatives (Plain,

prismatic)

Shielding Alternatives

(Cutoff, semi-cutoff, full

cutoff)

Pole Alternatives

Functional type

(Interstate, Other Freeway &

Expressway, Principal Arterial,

Minor Arterial, Collector, Local

and Alley)

All - Independent All - Independent

Interstate/Other Freeway &

Expressway and Alley –

Predetermined

Others - Independent

Interstate/Other Freeway &

Expressway and Alley –

Predetermined


Area Type

(Commercial, Intermediate &

Residential)

All - Independent All - IndependentCommercial and Intermediate/

Residential – ChangesAll – Independent (??)

Special Type

(Gateways, Monumental Core,

BIDS, Tunnel/Underpass,

Bridges, Historic)

Monumental Core and Each

BIDS – Predetermined

Gateway – To be determined


Gateway – To be determined

Others – Independent

Tunnel/Underpass – N/A

All - Independent

Monumental Core and Each

BIDS – Predetermined

Historic, Gateway and Bridges –

To be determined

Tunnel/Underpass – N/A

Scenarios

1. All Inclusive (General)

Special Type N/A

2. Special Type - Gateway


Special Type N/A


1. Commercial

2. Intermediate/ Residential


Special Type N/A


3. Special Type - Bridges

4. Special Type - Historic

6. The Evaluation Matrices for Lamps are as follows:

Scenario Context - Functional Class = All, Area type = All, Special Types = N/A

Candidate Alternative Rating*Evaluation Criteria Weight(w) HPS Metal

HalideInductive Fluorescent

Efficiency (based on the following, asapplicable)

Life duration

Power consumption


10 6 6 6

Aesthetics

Color of light 6 10 9 8


Existing Usage 10 2 0 0


Operational & Maintenance Cost6 5 6 10

Composite Index


March 2005 75


Scenario Context - Functional Class = N/A, Area type = N/A, Special Types = Gateway

Candidate Alternative Rating*Evaluation Criteria Weight(w) HPS Metal

HalideInductive Fluorescent

Efficiency (based on the following, asapplicable)

Life duration

Power consumption


10 6 6 6

Aesthetics

Color of light 6 10 9 8Level of Light Pollution(upward & sideways)

Existing Usage 10 2 0 0Lifecycle Cost Initial Cost


Composite Index


7. The Evaluation Matrices for Globes are as follows:

Scenario Context - Functional Class = All, Area type = Commercial, Special Types = N/A

Candidate Alternative Rating*Evaluation Criteria Weight(w) Plain Prismatic Plain with

shielding

Efficiency (based on thefollowing, as applicable)

Life duration

Power consumption


5 8 8

Aesthetics 8 8 8

Color of light


1 8 8

Existing Usage 8 2 0


Operational & Maintenance Cost10 9 8

Composite Index


Scenario Context - Functional Class = All, Area type = Intermediate/Residential, Special

Types = N/A


shielding


Life duration

Power consumption


5 8 8

March 2005 76



shielding

Aesthetics 8 8 8

Color of light


1 8 8




Composite Index




shielding


Life duration

Power consumption


5 8 8

Aesthetics 8 8 8

Color of light


1 8 8




Composite Index


8. The Evaluation Matrices for Shielding are as follows:

Scenario Context - Functional Class = All (except Interstate/Other Freeway & Expressway

and Alley), Area type = Commercial, Special Types = All

Candidate Alternative Rating*Evaluation Criteria Weight(w) Cutoff Semi Cutoff Full Cutoff

Efficiency (based on the following,

as applicable)

Life duration

Power consumption


8 6 10

Aesthetics 8 8 8

Color of light

Level of Light Pollution

(upward & sideways)8 6 10


Lifecycle Cost

Initial Cost

Operational & Maintenance Cost

Composite Index


March 2005 77



and Alley), Area type = Intermediate/Residential, Special Types = All

Candidate Alternative Rating*Evaluation Criteria Weight(w) Cutoff Semi Cutoff Full Cutoff

Efficiency (based on the following,as applicable)

Life duration

Power consumption


8 6 10

Aesthetics 8 8 8

Color of light


8 6 10



Operational & Maintenance Cost

Composite Index


9. The Evaluation Matrices for Poles are as follows:


and Alley), Area type = All, Special Types = N/A

Candidate Alternative Rating*Evaluation Criteria Weight(w) Upright

PolesTwin-

20Pendant

PoleTeardrop


Life duration

Power consumption


7 6 10 9

Aesthetics 9 10 5 7

Color of light





Composite Index




PolesTwin-

20Pendant

PoleTeardrop


Life duration

Power consumption


7 6 10 9

Aesthetics 9 10 5 7

March 2005 78



PolesTwin-

20Pendant

PoleTeardrop

Color of light





Composite Index


Scenario Context - Functional Class = N/A Area type = N/A, Special Types = Bridges


PolesTwin-

20Pendant

PoleTeardrop


Life duration

Power consumption


7 6 10 9

Aesthetics 9 10 5 7

Color of light





Composite Index


Scenario Context - Functional Class = N/A, Area type = N/A, Special Types = Historic


PolesTwin-

20Pendant

PoleTeardrop


Life duration

Power consumption


7 6 10 9

Aesthetics 9 10 5 7

Color of light





Composite Index


10. Larry Aurbach suggested including “Brightness” as a criterion.

March 2005 79


11. The Streetlight Advisory Committee suggested that the Matrix should be designed in

a different way that will be more focused for the designers and citizens.

12. The Committee recommended that the heights of the poles, spacing between the

poles, etc, be considered as important criteria that need to be evaluated. It was

suggested that the neighbors should be given a choice to choose the wattage but the

spacing and the height of the poles should be standard. The poles will be there for the

next 50 years but the bulbs can be changed for brighter or dimmer neighborhoods.

13. The matrix should consider a road that changes its functional classification and/or

area type from one segment to another. For example, New York Avenue changes

from Industrial Collector in the East to Downtown in the West.

14. It was mentioned that “Light Pollution” is not always desirable but sometimes is

needed/required. For example in Downtown, uplight may be desired.

15. Based upon the above discussions, Elizabeth Miller suggested using a chart similar to

the one below that could be used for evaluation. The committee agreed that this was

the best guide to use. A full chart will be prepared for the next meeting.

Suggested Matrix

Commercial

(Sidewalk

width)

Intermediate

(Mixed Use)

Residential Monumental

Core

Historic

City and

Street

Spacing of

poles

Height of the

pole

Base of the pole

Aesthetics

16. It was noted that HPS is preferred at this time in spite of its orange light because of its

long life (i.e., 6 years) and energy efficiency when compared to MH, which has a life

of 3 years. The MH initial cost is approximately 10% more than HPS. Inductive

lamps also produce white light, are long lasting and energy efficient. They are widely

used in Europe, however they have not yet been converted into a technology for wide

use in the States. The research continues and it is expected to become a viable

alternative in the next few years.

17. The Committee noted that the “Color of Light” (e.g., white, yellow, etc.) needed to be

considered and not the type of lamp (e.g., HPS, MH, etc.). It was agreed upon that

“White light” is preferred for all areas/scenarios as the future strategy of the District;

however, the cost consideration must be made. The committee agreed on the

following when determining the color that bulbs emit.

March 2005 80


White light is preferred.

HPS lamps will continue to be used, until such time when the lifecycle cost of

white light (e.g., MH, inductive or other feasible technology) is comparable to

HPS.

The consistency in the neighborhood must be maintained (i.e., there should not be

a mismatch of light color in the same neighborhood).

18. Since, the migration to total white light has to wait for technology to catch up, the

committee agreed upon the following strategies for typical maintenance replacement

of lights in the interim:

Change HPS to HPS.

Change Incandescent (white) to another white (MH).

Change MH to MH.

19. For now, MH is being used only in Monumental Core. It was mentioned that the

Historic Districts and Historic Streets are treated the same by DDOT and the

Downtown BID will need to follow DDOT.

20. It was suggested that the neighborhoods should be given a range of options to select

the wattage of a bulb. Wattage will be discussed further at the next meeting.

21. The placement of poles is based on the existing infrastructure (i.e. utilities, trees, etc.

dictate to some degree where a pole cannot be placed). The Committee suggested that

a preferred placement be selected, which can be adjusted according to the

infrastructure constraints.

22. The Advisory Committee had full consensus on the use of “Prismatic Globes”,

because it contributes to more control on light distribution and also saves power

consumption. No objection was received when asked for.

Next Meeting Schedule:

The next meeting is scheduled tentatively for Wednesday, May 5, 2004 from 10:00am –

12:00am. A separate meeting reminder will be sent at a later date. The Committee was

requested to think about the following items for discussion in the next meeting:

Height of the pole

Spacing between the poles

Base of the pole

Color of the pole

Materials of the pole

Bulb Wattage

March 2005 81




Floor,

District Department of Transportation on 5-5-04. The minutes of the meeting are as follows.

Summary

1. Colleen Hawkinson started off the meeting at 10:15 a.m. She mentioned that the main

purpose of the meeting was to discuss the Evaluation Matrix.

2. The committee recommended the same matrix to be used for 3 different scenarios:

(1) Historic, (2) Non Historic, and (3) Special Street (may change)

3. It was brought to notice that the Special Street supersedes Historic Street that means,

all Historic Streets are not Special but all Special Streets are Historic.

4. Need to consider Alley [in row], and color of pole, material of pole and placement

(staggered, one sided, etc)

5. It will be assumed that prismatic globes (vs. standard/plain globes) are used for

upright poles. This will help address the glare issues and prismatic globe fixtures

guide light onto the sidewalks and street rather than into the sky.

6. The committee was interested to see some pictures of the luminaries, fixtures and

poles from the vendors’ catalogue to have a visual understanding of different types of

poles. These catalogues will be made available at the next meeting. Samples may be

found on the Holophane and Spring City websites.

7. Generally Upright poles are used for the mid-block and Pendant poles for the

intersections. For the intersection, the committee recommended No. 16, No. 18 and

Twin-20 needs to be evaluated first (whether they are in compliance with all the

signal standards) before considering the Pendant pole, so that the consistency can be

maintained with the midblock. If none of the Upright poles are in compliance then a

decorative Pendant pole (for e.g.: Teardrop) that is aesthetically pleasing can be used.

8. The approximate cost of a Cobrahead is $200 and a Teardrop is $500-$600.

9. The Committee was interested to see the results/output for a standard globe vs.

prismatic globe vs. Pendant pole for a certain roadway width and sidewalk width.

10. For Special Streets, the type of pole should remain consistent, however communities

should have a say on the pole spacing and wattage.

11. It was mentioned that the spacing between the poles will depend on the placement

(staggered, one sided, opposite, etc). This placement is dependent on existing

underground or overhead infrastructure and other factors such as trees, fire hydrants,

utilities, etc.

12. For the Special Street Scenario, the Committee is leaning toward Twin-20 and

decorative Pendant poles for the pole type of a Commercial Area. The minimum

spacing between the poles for a staggered placement was suggested as 60 feet for a

Commercial area and Special Street Scenario. It was recommended that for any utility

problem for placing a pole at distance of 60 feet, not to go lower but can go higher

than 60 feet. This cannot be done always as this raises an issue for uniform

March 2005 82


distribution of light. Further discussion on establishing minimum spacing

requirements will occur during next meeting.

13. For a Commercial area, the amount of light on the street and the sidewalk needs to be

considered. For an Intermediate area, the amount of light on the street and the house

needs to be considered. For a Residential area, no light is required on the house.

14. Monumental Core and BIDs are taken off the table as they have been or will be

dictated.


The next meeting is scheduled tentatively for Friday, May 14, 2004 from 10:00am –12:00am.

A separate meeting reminder will be sent at a later date. The Consultant and the Committee

was requested to fill in the updated matrix with their recommendation.

March 2005 83




Floor,

Reeve’s Center on 5-13-04. The minutes of the meeting are as follows.

Summary

1. Colleen Hawkinson started off the meeting at 10:15 a.m.

2. The main purpose of the meeting was to discuss and come to a consensus about the

Evaluation Matrices. The consultant presented four Evaluation Matrices for Special

Streets (NHS & Gateways), Historic Areas/Streets, Non-Historic for Overhead and

Underground Power lines. The Committee’s input from earlier meetings and also the

consultant’s recommendations were incorporated in the presented Matrices.

3. The following Matrix was presented to the Committee for the Non-Historic Streets

with Underground Powerlines. The bolded options are the Consultants

recommendation and depend on Committee to decide which option to choose.

Presented DRAFT Matrix for Non-Historic Streets (with Underground Powerlines)

It was suggested to include a footnote that mentions the height of the building,

sidewalk width and roadway width be considered as a contextual item. As the height

of the building, sidewalk width and roadway width vary so much from one

neighborhood to another, it couldn’t be included in the matrix but it should be

considered contextually for a case specific study.

It was suggested that the industrial Cobrahead Pendant pole be phased out and instead

a decorative Teardrop be used except in Alleys (Cobrahead – 5A). It was noted that

for Residential areas the light on the sidewalk is important. There were concerns

about Pendant poles being efficient enough to light the sidewalks, as most of the time

Criteria CommercialIntermediate

(Mixed Use)Residential Bridges Alley

Tunnels/

UnderpassesComments

Pole Type

Cobra Head,

Dec. Tear Drop,

#14, #16, #18

Cobra Head,

Dec. Tear Drop,

#14, #16, #18

Cobra Head,

Dec. Tear Drop,

#14, #16, #18

Cobra Head,

Dec. Tear Drop,

#14, #16, #18

Cobra Head Wall packs- Citizens to choose from (Bold

is our preferred)

- Pendant Posts are economical

- Currently being widely used

Spacing of

poles

60 ft, min (on one

side) - all orientations

60 ft, min (on one


60 ft, min (on one

side) - all

orientations

60 ft, min (on one

side) - all

orientations

60 ft, min (on one

side) - all

orientationsN/A

Height of pole N/A

Base of pole N/A

Color of poleGrey Grey Grey Grey Grey

N/A- Currently used

Material of

poleN/A

Preferred

Orientation

Staggered Staggered Staggered Opposite Staggered

N/A

-Staggered chosen because of

uniformity

- Opposite for bridge for

aesthetics/symmetry

Depends on the prevailing technology

Depends on Pole Type


March 2005 84


the trees cover the arm thus reducing the downward light. Tree trimming was

recommended as a solution to this. In Residential areas and on Bridges, it was

recommended to replace Upright poles (#14, 16, 18) in kind and Cobrahead by

decorative Teardrop. For Tunnels/Underpasses, suggestion was made to use Upright

poles for pedestrian Tunnels and Wall packs for vehicular Tunnels.

For the spacing between the poles, a footnote was suggested that states, for special

case when the spacing has to be less than the recommended, it must be justified as to

why. This will give an option to a neighborhood to have poles closer if they wanted to

(if that makes them feel safe). Regarding the color of the poles on the bridges, it was

mentioned that the poles are generally matched to the bridge color. A question was

raised whether the color of the pole should be a part of this study or the citizens

should be given a choice to choose the color they want. It was noted that a single

color would help the maintenance program. The updated matrix after incorporating

the inputs is as follows:

Revised Matrix for Non-Historic Streets (with Underground Powerlines)



Tunnels/

UnderpassesComments

Pole Type

Dec. Tear Drop,

#14, #16, #18

Dec. Tear Drop,

#14, #16, #18

Dec. Tear Drop,

#14, #16, #18

(Note: Replace

Upright in kind and

Cobrahead changes

to Tear Drop)

Dec. Tear Drop,

#14, #16, #18

(Note: Replace

Upright in kind and

Cobrahead changes

to Tear Drop)

Cobra Head (5A) Wall packs for

vehicular Tunnels,

#14, #16, #18 for

pedestrain Tunnels

- Citizens to choose from

(Bold is our preferred)

- Pendant Posts are

economical

- Currently being widely

used

Cutoff

Criteria

Full Cutoff / Cutoff Full Cutoff / Cutoff Full Cutoff / Cutoff Full Cutoff / Cutoff Full Cutoff / CutoffN/A

Minimum

Spacing btw

poles*

60 ft, min (on one


60 ft, min (on one


60 ft, min (on one


60 ft, min (on one


60 ft, min (on one

side) - all orientationsN/A

- For special case one can

use spacing less than

recommended, but needs to

be justified.

Height of pole N/A

Base of pole N/A

Color of poleGrey Grey Grey N/A Grey

N/A- Currently used (needs to be

checked)

Material of

poleN/A

Preferred

OrientationStaggered Staggered Staggered Opposite Staggered N/A

-Staggered chosen because

of uniformity

- Opposite for bridge for

aesthetics/symmetry

Note: * For Special Case, the spacing can be less than recommended, but it must be justified




4. The following Matrix was presented to the Committee for the Non-Historic Streets

with Overhead Powerlines.

March 2005 85


Presented DRAFT Matrix for Non-Historic Streets (with Overhead Powerlines)


(Mixed Use)Residential Alley Bridges

Tunnels/

UnderpassesComments

Pole Type

Full Cutoff:

Cobra Head,

Alt: Dec. Tear Drop

Full Cutoff:

Cobra Head,

Alt: Dec. Tear Drop

Full Cutoff:

Cobra Head,

Alt: Dec. Tear Drop

Cobra Head N/A N/A- Only lighting arm is

to be used

Spacing of

poles

60 ft, min (on one

side) - all

orientations

60 ft, min (on one

side) - all

orientations

60 ft, min (on one

side) - all

orientations

60 ft, min (on one

side) - all orientations N/A N/A

Height of

poleN/A N/A

Base of pole N/A N/A

Color of

pole/armGrey Grey Grey Grey N/A N/A - Currently being used

Material of

poleN/A N/A

Preferred

OrientationStaggered Staggered Staggered Staggered N/A N/A




* Note: Existing Upright poles in overhead area will be phased out for consistency.

The lighting arm is the only option as it is attached to the utility wooden poles. Since

the industrial Cobrahead is going to be phased out, a decorative Teardrop arm will be

used except in Alleys (Cobrahead – 5A). It was mentioned that a full-cutoff is not

always preferred, as sometimes uplight is needed for lighting a building. The updated

Matrix after incorporating the input is as follows:

Revised Matrix for Non-Historic Streets (with Overhead Powerlines)


(Mixed Use)Residential Alley Bridges

Tunnels/

UnderpassesComments

Pole Type** Dec. Tear Drop Dec. Tear Drop Dec. Tear Drop Cobra Head (5A) N/A N/A- Only lighting arm is

to be used

Cutoff

Criteria

Full Cutoff / Cutoff Full Cutoff / Cutoff Full Cutoff / Cutoff Full Cutoff / CutoffN/A N/A

Minimum

Spacing btw

poles*

60 ft, min (on one

side) - all

orientations

60 ft, min (on one

side) - all

orientations

60 ft, min (on one

side) - all

orientations

60 ft, min (on one

side) - all orientations N/A N/A

Height of

poleN/A N/A

Base of pole N/A N/A

Color of

pole/armGrey Grey Grey Grey N/A N/A - Currently being used

Material of

poleN/A N/A

Preferred

OrientationStaggered Staggered Staggered Staggered N/A N/A


** Existing Upright poles in overhead area will be phased out for consistency.




March 2005 86


Presented DRAFT Matrix for Historic Areas/Streets



Tunnels/

UnderpassesComments

Pole Type

#14, #16, #18, Twin

20

#14, #16, #18, Twin

20

#14, #16, #18, Twin

20

#14, #16, #18,

Twin 20

Cobra Head (?) N/A - Currently used for

historic areas.

- Truly historical t

- Aesthetically

pleasing

Spacing of

poles

60 ft, min (on one

side) - all

orientations

60 ft, min (on one

side) - all

orientations

60 ft, min (on one

side) - all

orientations

60 ft, min (on

one side) - all

orientations

60 ft, min (on one

side) - all

orientations

N/A

Height of

pole

N/A

Base of

pole

N/A

Color of

pole

Grey Grey Grey Grey Grey N/A

-Existing colo

o DC

more

r

Material of

pole

N/A

Preferred

OrientationStaggered Staggered Staggered Opposite Staggered

N/A




5. The Evaluation Matrix for Historic Areas/Streets was presented as follows:

It was suggested that the Twin-20 be used if necessary and the justifications need to

be mentioned for using it. Signalized Intersections will use the shortest pole that

meets signal requirements. Unsignalized intersections will use the shortest pole that

will illuminate the center of the intersection uniformly. The updated matrix is as

follows:

March 2005 87


Revised Matrix for Historic Areas/Streets

Criteria

Pole Type

Cutoff

Criteria

Minimum

Spacing btw

poles*orientations orientations orientations orientations orientations

Height of poleN/A

Base of poleN/A

Color of poleGrey Grey Grey Grey Grey N/A

-Existing colo

CommercialIntermediate


Tunnels/

UnderpassesComments

#14, #16, #18, Twin

20**

#14, #16, #18, Twin

20**

#14, #16, #18 #14, #16, #18, Twin

20**

Cobra Head (5A) N/A - Currently used for

historic areas.

- Truly historical to DC

- Aesthetically more

pleasing

-For Signalized

Intersection, the shortest

possible pole that will meet

the trafic signal criterion

- For Unsignalized

Intersection, the shortest

possible pole that will

illuminate the intersection

uniformly

Full Cutoff / Cutoff Full Cutoff / Cutoff Full Cutoff / Cutoff Full Cutoff / Cutoff Full Cutoff / Cutoff N/A

60 ft, min (on one

side) - all

60 ft, min (on one

side) - all

60 ft, min (on one

side) - all

60 ft, min (on one

side) - all

60 ft, min (on one

side) - all

N/A

r

Material of

pole

N/A

Preferred

OrientationStaggered Staggered Staggered Opposite Staggered

N/A


** Twin 20 not necessarily desirable unless special




6. The matrix for the Special Street that includes Gateways and NHS was presented

to the Committee:

March 2005 88


Presented DRAFT Matrix for Special Street (Gateways and NHS)


(Mixed Use)Residential Bridges Tunnels/ Underpasses Comments

Pole Type

Twin 20**,

Alt: Decorative Tear

Drop

Twin 20,


Drop

Twin 20,


Drop

Twin 20,


DropN/A

- Twin 20s are DC signature

poles

-Aesthetically more pleasing

Minimum

Spacing

btw poles

60 ft, min (on one side) -

all orientations


all orientations


all orientations


all orientations N/A

Height of

poleN/A

Base of

poleN/A

Color of

poleGrey Grey Grey Grey N/A

- DC Grey is DC Signature

Material of

poleN/A

Preferred

OrientationOpposite Opposite Opposite Opposite N/A

- Opposite may be aestheticall

more pleasing

** Committee can decide




y

It was mentioned that the BIDS and NPS areas use Black as their pole color. It was

noted that Twin-20; can be used with different wattage and photometric distribution

to achieve different lighting levels for different type of areas. It was suggested that

the discussion on glare include in the document.

Revised Matrix for Special Street (Gateways and NHS)


(Mixed Use)Residential Bridges Tunnels/ Underpasses Comments

Pole Type

Twin 20**,


Drop

Twin 20**,


Drop

Twin 20**,


Drop

Twin 20**,


DropN/A

- Twin 20s are DC signature

poles

-Aesthetically more pleasing

Cutoff

Criteria

Full Cutoff / Cutoff Full Cutoff / Cutoff Full Cutoff / Cutoff Full Cutoff / CutoffN/A

Minimum

Spacing btw

poles*


all orientations


all orientations


all orientations


all orientations N/A

Height of pole N/A

Base of pole N/A

Color of pole Grey/Black*** Grey Grey Grey N/A- DC Grey is DC Signature

Material of

poleN/A

Preferred

OrientationOpposite Opposite Opposite Opposite N/A

- Opposite may be aesthetically

more pleasing


** Committee can decide

*** Black for BIDS and NPS areas





The next meeting is scheduled for Wednesday, May 19, 2004 from 10:00am –12:00am. The

Committee was requested to

March 2005 89


Think whether color should be a part of this study or not and if so, what color is

suggested

Review the updated matrices,

Think about the pole type on Special Streets,

To determine hierarchy of Special Streets vs. Historic Streets.

March 2005 90




Floor,

Reeve’s Center on 5-19-04. The minutes of the meeting are as follows.

Summary

1. Colleen Hawkinson started off the meeting at 10:15 a.m. She mentioned that it was

the last SAC Meeting and the Committee should give their final opinion about the

evaluation matrices and what needs to be included in the Policy. The Draft Streetlight

Grand Plan will be completed and distributed to the Committee by June 11. After all

the comments from the Committee are incorporated in the document, it will be

presented to the Fine Arts Commission, NCPC, ANCs and the other members of

DDOT.

2. Mike Dorsey showed several samples of colors that are generally used in DC

streetlight poles. They were Bridge Green color (# 140020) currently being used on

Key Bridge, Gray (#16099) and Black. DDOT prefers least number of colors for the

ease of maintenance. The poles in the District are painted every 7 years. The

recommended colors will be used for the new contracts. The Committee came to a

consensus about the following color considerations:

The poles on the Bridge should be based on existing color and bridge color

The color should be the same for the Uprights and the Pendant poles

The color should be same for the Traffic Signal and the Streetlight poles

Black color should be used for Gateways and historic (for overhead and

underground)

Non-historic will have gray color

3. Special Streets have been defined as the following. Historic Districts/Streets and

National Highway System Streets. Elizabeth Miller proposed streets that fall within

the L’Enfant Plan for inclusion. Elizabeth mentioned that she would double check

with Office of Planning for different streets that are Special. A list of Special streets is

attached.

4. With regards to the minimum spacing between the poles, the Committee asked the

consultant to include a footnote stating that 60 feet is not a recommended minimum,

but it is an absolute minimum. The Committee also suggested the inclusion of an

explanation of how spacing would be determined.

5. When more than one pole is recommended for any scenario, a pole that meets the

following criterion and also the AASHTO standards should be chosen.



Maximum Spacing

Height of the pole (based on context like height of the building, roadway width,

sidewalk width, etc)

March 2005 91


6. The Committee suggested the Residential neighborhoods should be allowed to choose

between Pendant (Teardrop) and Upright poles (#14, 16, 18). For a Teardrop Pendant

pole, a decorative arm with a fixture still needs to be chosen by DDOT.

7. The Committee suggested defining the Historic Areas and Streets in glossary or a

footnote in the final document. The Committee recommended to make a note that,

any Special District that have adopted their standards through rule making process are

exempt from this policy. An example is the Downtown Business Improvement

District.

8. The Committee was interested to see the Photometric for Teardrop vs. Cobrahead

(whether it is 1:1?) and Twin-20 throughout (mid-block and intersection) vs. Twin-20

at intersection and uprights at mid-blocks (which one is more economical). The

Consultant will prepare this information.

9. The Committee was requested to think about an appropriate name that defines all

Special Streets in order to give them a sense of importance/grandeur.

10. The Committee suggested few footnotes and comments to be added in the Evaluation

Matrices. The updated matrices are as shown in Table 17, Table 18, Table 19, and

Table 21.


The next meeting is scheduled tentatively for Wednesday, June 16, 2004 from 10:00am –

12:00am. In this meeting, the consultant will present the document. A separate meeting

reminder will be sent at a later date.

March 2005 92

Documents

DC Streetlight Policy and Design Guidelines