Difference between revisions of "901.11 Light Emitting Diode (LED) Luminaire Performance and Computation of Roadway Illumination"

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{|style="padding: 0.3em; margin-left:15px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="315px" align="right"  
 
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|'''Figures'''
 
|'''Figures'''
 
|-
 
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|[[media:901.11.2 Photometric Data 150W Type III.pdf|Photometric Data 150W Type III Medium Distribution, Semi-Cutoff]]
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|[[media:901.1.2 Typical Basic Lighting Plan.pdf|Fig. 901.1.2, Typical Basic Lighting Plan]]
 
|-
 
|-
|[[media:901.11.1 Type II.pdf|Photometric Data 250W Type II Medium Distribution, Semi-Cutoff]]
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|[[media:901.7.1.pdf|Fig. 901.7.1, Luminaire Locations For Lighting Island Noses]]
 
|-
 
|-
|[[media:901.11.3 Photometric Data 250W Type III.pdf|Photometric Data 250W Type III Medium Distribution, Semi-Cutoff]]
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|[[media:901.7.4.pdf|Fig. 901.7.4, Limit of Direct Reflectance Lighting]]
 
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|[[media:901.11.4Photometric Data 400W Type III.pdf|Photometric Data 400W Type III Medium Distribution, Semi-Cutoff]]
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|[[media:901.7.5.pdf|Fig. 901.7.5, Basic Lighting at Ramps]]
 
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|[[media:901.11.5 IES Distribution Diagrams.pdf|I.E.S. type of illumination]]  
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|[[media:901.11.5 IES Distribution Diagrams.pdf|Fig. 901.11.5, I.E.S. Type of Illumination]]  
 
|-
 
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|[[media:901.11.6 Continuous Lighting - Luminaires.pdf|staggered configurations]]
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|[[media:901.11.6.pdf|Fig. 901.11.6, Staggered Configurations]]
 
|-
 
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|[[media:901.11.7 Continuous Lighting - Luminaires.pdf|one-sided configurations]]  
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|[[media:901.11.7.pdf|Fig. 901.11.7, One-sided Configurations]]  
 
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==901.11.1 Iso-Footcandle Diagram==
 
==901.11.1 Iso-Footcandle Diagram==
  
An iso-footcandle (iso-lux) diagram is a means of showing the illumination on a roadway surface from one or more luminaires. Such a diagram is a graphical representation of points of equal illumination connected by a continuous line. Footcandle (lux) values on a horizontal plane from a single unit with a 30 ft. mounting height are available for  [[media:901.11.2 Photometric Data 150W Type III.pdf|150W]], [[media:901.11.3 Photometric Data 250W Type III.pdf|250W Type III]], [[media:901.11.4Photometric Data 400W Type III.pdf|400W]] and as shown  on Figure 901.11.1.  These curves are for a luminaire mounting height of 30 ft.  Correction factors as listed are used for other mounting heights.  Each [[media:901.11.5 IES Distribution Diagrams.pdf|I.E.S. type of illumination]] has a different pattern. The types of luminaires are: Type III medium distribution, semi-cutoff, with 150-watt clear lamp is mounted at 30 ft. and is mainly used for basic lighting; Type II medium distribution, semi-cutoff, with [[media:901.11.3 Photometric Data 250W Type III.pdf|250-watt clear lamp]] is mounted at 45 ft. and is used for continuous lighting; Type III medium distribution, semi-cutoff, with 250-watt clear lamp is mounted at 45 ft. and is used for continuous and basic lighting; the 400-watt Type III medium distribution, semi-cutoff is mounted at 45 ft. and is used for continuous and basic lighting.
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An iso-footcandle (iso-lux) diagram is a means of showing the illumination on a roadway surface from one or more luminaires. Such a diagram is a graphical representation of points of equal illumination connected by a continuous line. Each [https://epg.modot.org/files/b/bd/901.11.5_IES_Distribution_Diagrams.pdf Illuminating Engineering Society (I.E.S.) type of illumination] has a different pattern. MoDOT has also defined types of luminaires: LED-A is mounted at 30 ft. and is mainly used for basic lighting; LED-B is mounted at 45 ft. and is used for continuous and basic lighting; LED-C is mounted at 45 ft. and is used for continuous and basic lighting. Refer to MoDOT’s standard plans, specifications, and manufacturers’ data and utilization curves to assist in lighting design.
 
 
Luminaires used are the internal ballast type where the type of distribution is determined by the socket position of the lamp.  Different makes of luminaires produce a variety of light patterns.  The diagrams shown are typical and can be used for design purposes.  From these diagrams the initial level of illumination on the pavement from one or more luminaires can be determined.  The average maintained intensity at any point on the pavement can be obtained by multiplying the sum of the initial footcandle (lux), from the various contributing light sources, by the luminaire maintenance factor of 0.70.
 
  
 
Computer programs are available to calculate lighting intensity and other information such as uniformity.  These programs can be used for most lighting configurations.  Several figures have been developed for many typical layouts to aid the designer in determining location and type of luminaires.
 
Computer programs are available to calculate lighting intensity and other information such as uniformity.  These programs can be used for most lighting configurations.  Several figures have been developed for many typical layouts to aid the designer in determining location and type of luminaires.
  
'''901.11.1.1 Continuous Lighting.'''  The configuration, spacing and type of luminaires for continuous lighting depend on many factors, including the type of roadway, the adjacent roadway features, the roadway width, and the setback of the luminaires from the edge of the travelway.  Maximum spacing guidance for luminaires to achieve the required intensity and uniformity for [[media:901.11.6 Continuous Lighting - Luminaires.pdf|staggered configurations]] and [[media:901.11.7 Continuous Lighting - Luminaires.pdf|one-sided configurations]] is available.  The staggered configuration is preferred when possible since it provides better uniformity.  Other configurations are possible and can be considered.
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'''901.11.1.1 Continuous Lighting.'''  The configuration, spacing, and type of luminaires for continuous lighting depend on many factors, including the type of roadway, the adjacent roadway features, the roadway width, and the setback of the luminaires from the edge of the travelway.  Maximum spacing guidance for luminaires to achieve the required intensity and uniformity for [[media:901.11.6.pdf|staggered configurations]] and [[media:901.11.7.pdf|one-sided configurations]] is available.  The staggered configuration is preferred when possible since it provides better uniformity.  Other configurations are possible and can be considered.
  
'''901.11.1.2 Basic Lighting.'''  Basic lighting of 30 ft. mounting height uses 150-watt Type III medium distribution, semi-cutoff luminaires.  Basic lighting of 45 ft. mounting height normally uses 250-watt Type III medium distribution, semi-cutoff luminaires.  In some cases to obtain required intensities on island noses or in intersections, the 400-watt Type III medium distribution, semi-cutoff luminaires are used.  Figures [[media:901.7.1 Luminaire Locations For lighting.pdf|901.7.1]], [[media:901.7.3 Limit of Silhouette Discernments.pdf|901.7.3]], [[media:901.7.4 LimitOf Direct Refance Lighting.pdf|901.7.4]] and [[media:901.7.5 Basis Lighting At Ramps.pdf|901.7.5]] provide information for the location and types of luminaires to provide average maintained intensities for typical layouts.
+
'''901.11.1.2 Basic Lighting.'''  Basic lighting of 30 ft. mounting height uses LED-A luminaires.  Basic lighting of 45 ft. mounting height normally uses LED-B luminaires.  In some cases, to obtain required intensities on island noses or in intersections, the LED-C luminaires are used.  Figures [[media:901.7.1.pdf|901.7.1]], [[media:901.7.3.pdf|901.7.3]], [[media:901.7.4.pdf|901.7.4]] and [[media:901.7.5.pdf|901.7.5]] provide information for the location and types of luminaires to provide average maintained intensities for typical layouts.
  
For intersections with raised islands, [[media:901.1.4 (f8-01.4) Typical Basic Lighting for Signalized Interchange, Channelized Intersections and Roundabouts Using Divisional Islands.pdf|Figures 901.1.4]], [[media:901.7.1 Luminaire Locations For lighting.pdf|901.7.1]] and [[media:901.7.4 LimitOf Direct Refance Lighting.pdf|901.7.4]] are to be used in conjunction to determine locations and types of luminaires.  It is important for luminaire bracket arms to be oriented at right angles to the projected edge of through lanes, as shown in [[media:901.7.1 Luminaire Locations For lighting.pdf|Figure 901.7.1]], to provide the proper light distribution.
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For intersections with raised islands, [[media:901.1.2 Typical Basic Lighting Plan.pdf|Figures 901.1.2]], [[media:901.7.1.pdf|901.7.1]] and [[media:901.7.4.pdf|901.7.4]] are to be used in conjunction to determine locations and types of luminaires.  It is important for luminaire bracket arms to be oriented at right angles to the projected edge of through lanes, as shown in [[media:901.7.1.pdf|Figure 901.7.1]], to provide the proper light distribution.
  
 
==901.11.2 Utilization Curves==
 
==901.11.2 Utilization Curves==
  
Utilization curves provide a means of determining the average footcandle (lux) illumination over the pavement where lamp size, mounting height, width of pavement and spacing between luminaires is known or assumed. Conversely, the desired spacing or any other unknown factor may be determined if the other factors are given. The utilization factor varies to some extent with various makes of luminaires:  however, the curves shown on [[media:901.11.1 Type II.pdf|Figures 901.11.1]], [[media:901.11.2 Photometric Data 150W Type III.pdf|901.11.2]], [[media:901.11.3 Photometric Data 250W Type III.pdf|901.11.3]] and [[media:901.11.4Photometric Data 400W Type III.pdf|901.11.4]] are considered average and are used for design purposes.  These curves are for a luminaire mounting height of 30 ft.  Correction factors as listed are used for other mounting heights.  The utilization curves show how much light falls on the pavement, but does not show how the light is distributed. They must be used with the iso-footcandle (iso-lux) diagrams for the same luminaire to evaluate uniformity and the ratio of minimum intensity to average intensity.
+
Utilization curves provide a means of determining the average footcandle (lux) illumination over the pavement where lamp size, mounting height, width of pavement and spacing between luminaires is known or assumed. Conversely, the desired spacing or any other unknown factor may be determined if the other factors are given. The utilization curves show how much light falls on the pavement but does not show how the light is distributed. They must be used with the iso-footcandle (iso-lux) diagrams for the same luminaire to evaluate uniformity and the ratio of minimum intensity to average intensity.  
  
 
==901.11.3 Formulas for Computations==
 
==901.11.3 Formulas for Computations==
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Utiliz. Coef.  = Coefficient of Utilization
 
Utiliz. Coef.  = Coefficient of Utilization
  
Maint. Factor = 0.70
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Maint. Factor = 0.90 (for LED)
  
 
Spacing = either ft. or m
 
Spacing = either ft. or m
  
 
Width = Roadway width, either ft. or m
 
Width = Roadway width, either ft. or m
 +
  
  
 
[[Category:901 Lighting]]
 
[[Category:901 Lighting]]

Latest revision as of 14:40, 26 October 2021

Figures
Fig. 901.1.2, Typical Basic Lighting Plan
Fig. 901.7.1, Luminaire Locations For Lighting Island Noses
Fig. 901.7.4, Limit of Direct Reflectance Lighting
Fig. 901.7.5, Basic Lighting at Ramps
Fig. 901.11.5, I.E.S. Type of Illumination
Fig. 901.11.6, Staggered Configurations
Fig. 901.11.7, One-sided Configurations


901.11.1 Iso-Footcandle Diagram

An iso-footcandle (iso-lux) diagram is a means of showing the illumination on a roadway surface from one or more luminaires. Such a diagram is a graphical representation of points of equal illumination connected by a continuous line. Each Illuminating Engineering Society (I.E.S.) type of illumination has a different pattern. MoDOT has also defined types of luminaires: LED-A is mounted at 30 ft. and is mainly used for basic lighting; LED-B is mounted at 45 ft. and is used for continuous and basic lighting; LED-C is mounted at 45 ft. and is used for continuous and basic lighting. Refer to MoDOT’s standard plans, specifications, and manufacturers’ data and utilization curves to assist in lighting design.

Computer programs are available to calculate lighting intensity and other information such as uniformity. These programs can be used for most lighting configurations. Several figures have been developed for many typical layouts to aid the designer in determining location and type of luminaires.

901.11.1.1 Continuous Lighting. The configuration, spacing, and type of luminaires for continuous lighting depend on many factors, including the type of roadway, the adjacent roadway features, the roadway width, and the setback of the luminaires from the edge of the travelway. Maximum spacing guidance for luminaires to achieve the required intensity and uniformity for staggered configurations and one-sided configurations is available. The staggered configuration is preferred when possible since it provides better uniformity. Other configurations are possible and can be considered.

901.11.1.2 Basic Lighting. Basic lighting of 30 ft. mounting height uses LED-A luminaires. Basic lighting of 45 ft. mounting height normally uses LED-B luminaires. In some cases, to obtain required intensities on island noses or in intersections, the LED-C luminaires are used. Figures 901.7.1, 901.7.3, 901.7.4 and 901.7.5 provide information for the location and types of luminaires to provide average maintained intensities for typical layouts.

For intersections with raised islands, Figures 901.1.2, 901.7.1 and 901.7.4 are to be used in conjunction to determine locations and types of luminaires. It is important for luminaire bracket arms to be oriented at right angles to the projected edge of through lanes, as shown in Figure 901.7.1, to provide the proper light distribution.

901.11.2 Utilization Curves

Utilization curves provide a means of determining the average footcandle (lux) illumination over the pavement where lamp size, mounting height, width of pavement and spacing between luminaires is known or assumed. Conversely, the desired spacing or any other unknown factor may be determined if the other factors are given. The utilization curves show how much light falls on the pavement but does not show how the light is distributed. They must be used with the iso-footcandle (iso-lux) diagrams for the same luminaire to evaluate uniformity and the ratio of minimum intensity to average intensity.

901.11.3 Formulas for Computations

Avg. =


Spacing =

Where:

Avg. = Average footcandles (lumens/ft2) or Average lux (lumens/m2)

Lamp Lumens = Initial lamp lumen rating

Utiliz. Coef. = Coefficient of Utilization

Maint. Factor = 0.90 (for LED)

Spacing = either ft. or m

Width = Roadway width, either ft. or m