H-3.11 STREETLIGHTS

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GENERAL

1. Description

This standard identifies minimum requirements that shall be met for Streetlights in the design and construction of elements for Arlington County Horizontal Design Standards. The development of this standard is to provide greater guidance in the design and construction of streetlights while meeting the County’s guiding principles for increasing pedestrian safety and accessibility, decreasing county infrastructure costs and balancing the use of the Right-of-Way between all modes of transportation.

2. Related Arlington County Standards

A. Arlington County Construction Standards and Specifications B. Arlington County Horizontal Standards H-3.7 Crosswalks C. Arlington County Horizontal Standards H-3.10 Sidewalks D. Arlington County Master Transportation Plan – Pedestrian Element E. Arlington County Master Transportation Plan – Streets Element F. Arlington County Signal and Street Lighting Standards and Specifications

3. Applicable Standards and Specifications

A. IES Roadway Lighting Guideline RP-8-00 B. AASHTO Roadway Lighting Design Guides C. Americans with Disabilities Act - Accessibility Guidelines for Building and Facilities

(ADAAG) D. American with Disabilities Accessibility Guidelines for Public Rights-of-Way

(PROWAG)

4. Quality Assurance

A. Reserved

5. Submittals

A. Design and placement of all streetlights shall be approved by DES Transportation Engineering and Operations (TE&O) Bureau Chief.

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DESIGN CONSIDERATIONS

A. Definition & Purpose Streetlights - Street lighting is a continuous fixed lighting system used for roadways. Street lighting includes pedestrian and bike lane lighting when it is associated with the public right-of-way. The principal purpose of street lighting in the County is to provide visibility at night for the safety of all roadway users, at the same time maintaining dark sky compliance through reduced light pollution.

LAYOUT & PLACEMENT

A. Layout 1. Streetlights shall be placed on both sides of the street for all street categories

within the County, except for neighborhood minor streets. 2. On neighborhood minor streets over 36’ in width, street lighting should be placed

on both sides of the street. 3. Where only one sidewalk is present, streetlights should be placed on the side of

the street with the sidewalk if feasible. 4. Streetlight spacing shall be determined by the IES / AASHTO minimum lighting

level design requirements. Property lines shall not be used as a basis for determining streetlight spacing, but strong consideration shall be given to spacing adjustment when the result can be property line placement.

5. Care should be taken by the designer to ensure that streetlight foundations do not conflict with underground utilities.

B. Placement

Streetlights shall be placed within the ROW as follows: 1. Streetlights shall be placed in the Landscape & Utilities Zone, with the front edge

of the light placed 1.5’ from the face of the curb. 2. If a Landscape & Utility zone is not present and the pedestrian clear zone is less

than 6’ in width, streetlights may be placed behind the Pedestrian Clear zone, but not more than 8’ from the face of the curb.

3. If a Landscape & Utility zone is not present and the light cannot be placed behind the Pedestrian Clear zone, it may be placed within the Pedestrian Clear zone. When a light is placed within the Pedestrian Clear zone the front edge of the light shall be located 1.0’ to 1.5’ from the face of the curb and a pedestrian clear access route shall be maintained, that is 4’ wide and ADA compliant.

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DESIGN

A. Design Criteria

1. Crosswalk lighting requirements

a. At the intersection of all street categories except those that involve 2 neighborhood minor streets, all crosswalks (marked and unmarked) shall have an average illuminance level of 2.2fc. (foot candle)

b. At the intersection of 2 neighborhood minor streets all crosswalks (marked and unmarked) shall have an average illuminance level of 0.8 – 1.4fc.

c. It is recommended that the designer restart the streetlight spacing at each intersection and ensure at least 2 lights are located diagonally opposite each other to provide the required illuminance level at the crosswalks.

2. Streetlight Types

a. Carlyle streetlights should be used on all street categories, except as noted herein and as otherwise approved.

b. Cobra or teardrop streetlights shall be used at signalized intersections. c. Double globe streetlights are generally used on arterial or neighborhood

principal streets. d. If double globe streetlights are used, they shall be placed so that the bracket is

parallel to the curb.

3. Street Category Lighting Requirements a. Arterial – Photogrammetric plans shall be required for all arterial street

lighting projects using the following design variables: i. LLF (Light Loss Factor): 0.95 ii. Avg fc: (min Illuminance level) 1.3 – 3.0 (dependant on district) iii. Minimum Uniformity Ratio (ave/min) 4:1 iv. Max/Min 20:1 v. Mounting Height 15.5’, 17.5’ or 19’ vi. Pole Heights 14’ or 16’

b. Neighborhood Principal - Photogrammetric plans shall be required for all neighborhood principal street lighting projects using the following design variables: i. LLF (Light Loss Factor): 0.95 ii. Avg fc: (min Illuminance level) 0.7 – 0.9 (Com.) 0.4 – 0.7 (Res.) iii. Minimum Uniformity Ratio (ave/min) 4:1 iv. Max/Min 20:1 v. Mounting Height 13.5’or 15.5’ vi. Pole Heights 12’or 14’

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c. Neighborhood Minor – for simple roadway geometry, Table 1 may be used to produce a street lighting plan. For neighborhood minor streets with more complex roadway geometry, photogrammetric plans shall be required for all street lighting projects using the following design variables: i. LLF (Light Loss Factor): 0.95 ii. Avg fc: (min Illuminance level) 0.4 – 0.7 iii. Minimum Uniformity Ratio (ave/min) 6:1 iv. Max/Min 20:1 v. Mounting Height 13.5’ vi. Pole Heights 12’

d. When only one sidewalk is present and streetlights are placed on the other

side of the street, care should be taken to ensure adequate lighting levels are achieved on the sidewalk. It is recommended that a minimum illuminance level of 0.3fc be achieved on sidewalks.

4. All street lighting installed within the County excluding interstate lighting shall

comply with all County street lighting standards and specifications 5. All street lighting shall use County approved LED bulbs and be dark sky

compliant.

Street Width

(Face of Curb)

Roadway Classification

Pole Arrangement

Recommended Spacing

Pole Height

Lights Installed in Landscape & Utility Zone  (min 2.5’) 

20’‐25.9’ Neighborhood Minor

One Side of street

120’ 12’ 

26’ – 31.9’ Neighborhood Minor

One Side of street

90’ 12’ 

32’ – 36’ Neighborhood Minor

One Side of street

80’ 12’ 

Over  36’ Neighborhood Minor

Both sides - Staggered

160’ Each side

12’ 

Lights Installed behind Pedestrian Clear Zone and more than 5’ from face of curb (no  Landscape & Utility Zone )  

20’‐ 25.9’ Neighborhood Minor

One Side of street

90’ 12’ 

26’ – 31.9’ Neighborhood Minor

One Side of street

80’ 12’ 

32’ – 36’ Neighborhood Minor

One Side of street

70’ 12’ 

Over  36’ Neighborhood Minor

Both sides - Staggered

140’ Each side

12’ 

Table 1 - Arlington County Streetlight Spacing for Neighborhood Streets

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Notes: - The following assumptions have been used to generate the above table Road geometry

i. Street is straight ii. Street width is measured face of curb to face of curb iii. Right angles intersections are present iv. Pedestrian clear zone width is 5’ refer to Arlington County Horizontal Standards

H-3.10 Sidewalks for further information v. For more complex street geometry, such as the presence of significant

vertical/horizontal curves, skewed intersections or significant obstructions, then photogrammetric calculations may be required.

The lights are placed 2.25’ from the face of the curb. On conflict situations, the longitudinal spacing can be adjusted to +/-15’ of the

spacing above.

B. Materials 1. Carlyle streetlights

a. Brand: Relume (*.ies file available from TE&O streetlight engineering section)

b. Model: UA2(XRE LED) with Sentinel System c. Type (Typical Carlyle) LED (48 Total LED’s) d. Wattage: 57w

2. Cobra streetlight a. Brand: Lumec (*.ies file available from TE&O streetlight

engineering section) b. Model: GPLM-180W98LED4K-LE3-120-ARRA-BL-

CDMG-016-PH8-USA-WB7-NP with DYNADIMMER (Silver or Black)

c. Type LED (98 Total LED’s) d. Wattage: 180w

3. Schedule 40 PVC conduit may be used behind the curb. Steel conduit or schedule

80 PVC shall be used under road surfaces and commercial driveways.

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DETAILS

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