Mesopic Factors in Roadway Calculations
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Council for Optical Radiation Measurements
May 2013
D. Keith & S. Wentworth
Examples of Applying Mesopic Factors
in Roadway Calculations
Overview
What happens when different approaches are
used to incorporate mesopic factors into
roadway calculations?
How do different design luminance ranges &
sources’ Scotopic / Photopic (S/P) ratios
interact with calculation methods?
Overview: put TM12 into RP-8?
>>>
Factors as defined in TM-12
‘Effective Luminance Factor (ELF)’ defined as
ELF =
equivalent mesopic luminance
photopic luminance
- function of photopic luminance & S/P ratio
- range: 0.005 cd/m2 to 5 cd/m2
- at 5 cd/m2, factors converge to 1.0
- at 0.005 cd/m2 and lower, factors = S/P ratio
ANSI/IES definition of mesopic: 0.034 to 3.4 cd/m2
(‘Nomenclature & Definitions ..’, ANSI/IES RP-16-05)
Factors as proposed for RP-8
‘Mesopic Factor’ defined for proposed RP-8 as
MF =
photopic luminance
equivalent mesopic luminance
- function of photopic luminance & S/P ratio
- tabulated range: 0.3 cd/m2 to 5 cd/m2
- reiterative calculation procedure provided
with range extended down to 0.005 cd/m2
- at 5 cd/m2, factors converge to 1.0
this presentation, developed for the Roadway
Committee, uses the MF version of these factors so
‘Lmesopic’ = Lphotopic / Mesopic Factor
IES RP-8’s Mesopic Factors
IES RP-8’s Mesopic Factors
Typical Scotopic/Photopic (S/P) Ratios
CIE Illuminant A
1.41 (incandescent at 2856K)
CIE Illuminant D65
2.46
(daylight at 6500K)
HPS
0.6
to 0.7 (2000K to 2200K)
Mercury Vapor (ctd)
1.2
(3700K)
Fluorescent (& Induction)
1.1 to 1.8 (2700K to 5000K)
Ceramic MH
1.3 to 1.5 (2900K to 3600K)
'Conventional' MH
1.4 to 1.8 (3100K to 4300K)
LED (neutral to cool)
1.7 to 2.1 (4500K to 6300K)
(sources: CIE and NOAA/National Geophysical Data Center)
Luminance Values from RP-8 Table 3
Luminances RP-8 Table 3 (cd/m2)
Luminances RP-8 Table 3 (cd/m2)
Luminances RP-8 Table 3 (cd/m2)
Methodologies for Applying Factors
Average of all roadway pavement points (
Avg
)
Determine one factor using the mathematical average of
photopic values for all roadway pavement calculation points
Lavg changes, all other values remain the same
Grid treated as having overall adaptation ~ Lavg
Methodologies for Applying Factors
Each Point Individually (~TM-12) (
Pnts
)
Determine a factor using the photopic luminance value at
each roadway pavement calculation point
Each value shifts independently: average, maximum,
minimum and uniformity ratios
Each point is treated as if visibility is solely dependent on
the luminance of that point
No adaptation level is established
Methodologies for Applying Factors
Modified Veiling Luminance (
LvM
)
Determine one factor for the pavement luminances using
the mathematical average of photopic values for all roadway
pavement calculation points (same as Avg)
Determine one factor for the veiling luminance using the
maximum veiling luminance value
Lavg and LvMax each change , separately
pavement uniformity ratios remain the same
for LvRatio (LvR) use photopic value of average luminance
because this is a foveal phenomenon
grid treated as having overall adaptation ~ Lavg then
compared to adjusted veiling luminance value for ratio LvR
High Luminance, Low S/P Ratio
Design
demo
S/P Ratio
0.6
Ver: Base Avg Pnts LvM(rd) LvM(vl)
Factor
1
1.047
n.a.
1.047
1.099
Lavg
1.017
0.972
0.972
0.972
Lmax
2.749
2.627 2.709
2.627
Lmin
0.368
0.352
0.340
0.352
Lam
2.764
2.764
2.870
2.764
Lmm
7.470
7.470
7.971
7.470
LvMax
0.306
0.292
0.279
0.279
LvR
0.300
0.301
0.287
0.274
Design
demo_low
S/P Ratio
0.6
Ver: Base Avg Pnts LvM(rd) LvM(vl)
Factor
1
1.074
n.a.
1.074
1.140
Lavg
0.508
0.473
0.475
0.473
Lmax
1.374
1.279
1.322
1.279
Lmin
0.184
0.171
0.159
0.171
Lam
2.761
2.761
2.980
2.761
Lmm
7.467
7.467
6.317
7.467
LvMax
0.153
0.142
0.134
0.134
LvR
0.300
0.301
0.284
0.264
Low
Luminance, Low S/P Ratio
High Luminance, High S/P Ratio
Design
demo
S/P Ratio
2.4
Ver: Base Avg Pnts LvM(rd) LvM(vl)
Factor
1
0.880
n.a.
0.880
0.789
Lavg
1.017
1.156
1.145
1.156
Lmax
2.749
3.125 2.880
3.125
Lmin
0.368
0.418
0.461
0.418
Lam
2.764
2.764
2.486
2.764
Lmm
7.470
7.470
6.252
7.470
LvMax
0.306
0.348
0.388
0.388
LvR
0.300
0.301
0.335
0.381
Low Luminance, High S/P Ratio
Design
demo_low
S/P Ratio
2.4
Ver: Base Avg Pnts LvM(rd) LvM(vl)
Factor
1
0.827
n.a.
0.827
0.737
Lavg
0.508
0.614
0.608
0.614
Lmax
1.374
1.661
1.518
1.661
Lmin
0.184
0.222
0.240
0.222
Lam
2.761
2.761
2.530
2.761
Lmm
7.467
7.467
6.317
7.467
LvMax
0.153
0.185
0.208
0.208
LvR
0.300
0.301
0.338
0.409
Comparison by Luminance
Lavg = 0.5 cd/m
2
, 0.6 S/P Ratio
Lavg = 1.0 cd/m
2
, 0.6 S/P Ratio
Lavg = 0.5 cd/m
2
, 2.4 S/P Ratio
Lavg = 1.0 cd/m
2
, 2.4 S/P Ratio
Comparison by S/P Ratio
Luminance at
0.5
cd/m
2
Lavg = 0.5 cd/m
2
, 0.6 S/P Ratio
Lavg = 0.5 cd/m
2
, 0.9 S/P Ratio
Lavg = 0.5 cd/m
2
, 1.1 S/P Ratio
Lavg = 0.5 cd/m
2
, 1.4 S/P Ratio
Lavg = 0.5 cd/m
2
, 1.7 S/P Ratio
Lavg = 0.5 cd/m
2
, 2.0 S/P Ratio
Lavg = 0.5 cd/m
2
, 2.4 S/P Ratio
Comparison by Methodology
Luminance at
0.5
cd/m
2
Adjusted Using Average Method
Adjusted Using Point Method
Adjusted LvModified Method
Thanks to CORM!
& special thanks to Scott Wentworth who helped
make this presentation happen
References:
“Spectral Effects of Lighting on Visual Performance at
Mesopic Lighting Levels”, IES TM-12-12
“American National Standard Practice for Roadway
Lighting”, ANSI/IES RP-8-00
“Nomenclature and Definitions for Illumination
Engineering”, ANSI/IES RP-16-05
“Laboratory Spectra”, Earth Observation Group,
National Geophysical Data Center/NOAA
any questions?
Exploring the incorporation of mesopic factors into roadway calculations and how different design luminance ranges and Scotopic/Photopic (S/P) ratios interact with various calculation methods. The discussion includes factors as defined in TM-12 and proposed for RP-8, along with IES RP-8's Mesopic Factors and typical Scotopic/Photopic (S/P) Ratios for various lighting sources. These factors play a crucial role in determining lighting design standards for roadways.
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Presentation Transcript
Examples of Applying Mesopic Factors in Roadway Calculations Council for Optical Radiation Measurements May 2013 D. Keith & S. Wentworth
Overview What happens when different approaches are used to incorporate mesopic factors into roadway calculations? How do different design luminance ranges & sources Scotopic / Photopic (S/P) ratios interact with calculation methods? CORM 2013 Gaithersburg. MD
Overview: put TM12 into RP-8? >>> CORM 2013 Gaithersburg. MD
Factors as defined in TM-12 Effective Luminance Factor (ELF) defined as ELF = equivalent mesopic luminance photopic luminance - function of photopic luminance & S/P ratio - range: 0.005 cd/m2 to 5 cd/m2 - at 5 cd/m2, factors converge to 1.0 - at 0.005 cd/m2 and lower, factors = S/P ratio ANSI/IES definition of mesopic: 0.034 to 3.4 cd/m2 ( Nomenclature & Definitions .. , ANSI/IES RP-16-05) CORM 2013 Gaithersburg. MD
Factors as proposed for RP-8 Mesopic Factor defined for proposed RP-8 as MF = photopic luminance equivalent mesopic luminance - function of photopic luminance & S/P ratio - tabulated range: 0.3 cd/m2 to 5 cd/m2 - reiterative calculation procedure provided with range extended down to 0.005 cd/m2 - at 5 cd/m2, factors converge to 1.0 this presentation, developed for the Roadway Committee, uses the MF version of these factors so Lmesopic = Lphotopic / Mesopic Factor CORM 2013 Gaithersburg. MD
IES RP-8s Mesopic Factors 1.4 Mesopic 'Luminance' = f(photopic Luminance, S/P ratio) 1.3 1.2 1.1 SP 0.2 SP 0.6 SP 1.0 SP 1.4 SP 1.9 SP 2.4 SP 2.8 1 0.9 0.8 0.7 0.6 0 0.5 1 1.5 photopic Luminance (cd/m2) 2 2.5 3 3.5 4 CORM 2013 Gaithersburg. MD
IES RP-8s Mesopic Factors 1.4 Mesopic 'Luminance' = f(photopic Luminance, S/P ratio) 1.3 1.2 1.1 SP 0.2 SP 0.6 SP 1.0 SP 1.4 SP 1.9 SP 2.4 SP 2.8 1 0.9 0.8 0.7 0.6 0 0.5 1 1.5 photopic Luminance (cd/m2) 2 2.5 3 3.5 4 CORM 2013 Gaithersburg. MD
Typical Scotopic/Photopic (S/P) Ratios CIE Illuminant A CIE Illuminant D65 HPS Mercury Vapor (ctd) Fluorescent (& Induction) 1.1 to 1.8 (2700K to 5000K) Ceramic MH 'Conventional' MH LED (neutral to cool) (sources: CIE and NOAA/National Geophysical Data Center) 1.41 (incandescent at 2856K) 2.46 (daylight at 6500K) 0.6 to 0.7 (2000K to 2200K) 1.2 (3700K) 1.3 to 1.5 (2900K to 3600K) 1.4 to 1.8 (3100K to 4300K) 1.7 to 2.1 (4500K to 6300K) CORM 2013 Gaithersburg. MD
Luminance Values from RP-8 Table 3 Road Conflict Area Lavg Lavg/Lmin Lmax/Lmin Lvmax/Lavg Expressway High 1.0 3 5 0.3 Low 0.6 3.5 6 0.3 Major High 1.2 3 5 0.3 Low 0.6 3.5 6 0.3 Collector High 0.8 3 5 0.4 Low 0.4 4 8 0.4 Local High 0.6 6 10 0.4 Low 0.3 6 10 0.4 CORM 2013 Gaithersburg. MD
Luminances RP-8 Table 3 (cd/m2) Road Conflict Area Lavg Lavg/Lmin Lmax/Lmin Lvmax/Lavg Expressway High 1.0 3 5 0.3 Low 0.6 3.5 6 0.3 Major High 1.2 3 5 0.3 Low 0.6 3.5 6 0.3 0.8 3 5 0.4 Collector High Low 0.4 4 8 0.4 Local High 0.6 6 10 0.4 Low 0.3 6 10 0.4 CORM 2013 Gaithersburg. MD
Luminances RP-8 Table 3 (cd/m2) Road Conflict Area Lavg Lavg/Lmin Lmax/Lmin Lvmax/Lavg 1.0 Expressway High 3 5 0.3 Low 0.6 3.5 6 0.3 Major High 1.2 3 5 0.3 Low 0.6 3.5 6 0.3 Collector High 0.8 3 5 0.4 Low 0.4 4 8 0.4 Local High 0.6 6 10 0.4 Low 0.3 6 10 0.4 CORM 2013 Gaithersburg. MD
Luminances RP-8 Table 3 (cd/m2) Road Conflict Area Lavg Lavg/Lmin Lmax/Lmin Lvmax/Lavg Expressway High 1.0 3 5 0.3 Low 0.6 3.5 6 0.3 Major High 1.2 3 5 0.3 Low 0.6 3.5 6 0.3 Collector High 0.8 3 5 0.4 0.4 Low 4 8 0.4 0.6 Local High 6 10 0.4 0.3 Low 6 10 0.4 CORM 2013 Gaithersburg. MD
Methodologies for Applying Factors Average of all roadway pavement points (Avg) Determine one factor using the mathematical average of photopic values for all roadway pavement calculation points Lavg changes, all other values remain the same Grid treated as having overall adaptation ~ Lavg CORM 2013 Gaithersburg. MD
Methodologies for Applying Factors Each Point Individually (~TM-12) (Pnts) Determine a factor using the photopic luminance value at each roadway pavement calculation point Each value shifts independently: average, maximum, minimum and uniformity ratios Each point is treated as if visibility is solely dependent on the luminance of that point No adaptation level is established CORM 2013 Gaithersburg. MD
Methodologies for Applying Factors Modified Veiling Luminance (LvM) Determine one factor for the pavement luminances using the mathematical average of photopic values for all roadway pavement calculation points (same as Avg) Determine one factor for the veiling luminance using the maximum veiling luminance value Lavg and LvMax each change , separately pavement uniformity ratios remain the same for LvRatio (LvR) use photopic value of average luminance because this is a foveal phenomenon grid treated as having overall adaptation ~ Lavg then compared to adjusted veiling luminance value for ratio LvR CORM 2013 Gaithersburg. MD
High Luminance, Low S/P Ratio Design S/P Ratio Ver: Base Avg Pnts LvM(rd) LvM(vl) Factor 1 1.047 n.a. Lavg 1.017 0.972 0.972 Lmax 2.749 2.627 2.709 Lmin 0.368 0.352 0.340 Lam 2.764 2.764 2.870 Lmm 7.470 7.470 7.971 LvMax 0.306 0.292 0.279 LvR 0.300 0.301 0.287 demo 0.6 1.047 0.972 2.627 0.352 2.764 7.470 1.099 0.279 0.274 CORM 2013 Gaithersburg. MD
Low Luminance, Low S/P Ratio Design S/P Ratio Ver: Base Avg Pnts LvM(rd) LvM(vl) Factor 1 1.074 n.a. Lavg 0.508 0.473 0.475 Lmax 1.374 1.279 1.322 Lmin 0.184 0.171 0.159 Lam 2.761 2.761 2.980 Lmm 7.467 7.467 6.317 LvMax 0.153 0.142 0.134 LvR 0.300 0.301 0.284 demo_low 0.6 1.074 0.473 1.279 0.171 2.761 7.467 1.140 0.134 0.264 CORM 2013 Gaithersburg. MD
High Luminance, High S/P Ratio Design S/P Ratio Ver: Base Avg Pnts LvM(rd) LvM(vl) Factor 1 0.880 n.a. Lavg 1.017 1.156 1.145 Lmax 2.749 3.125 2.880 Lmin 0.368 0.418 0.461 Lam 2.764 2.764 2.486 Lmm 7.470 7.470 6.252 LvMax 0.306 0.348 0.388 LvR 0.300 0.301 0.335 demo 2.4 0.880 1.156 3.125 0.418 2.764 7.470 0.789 0.388 0.381 CORM 2013 Gaithersburg. MD
Low Luminance, High S/P Ratio Design S/P Ratio Ver: Base Avg Pnts LvM(rd) LvM(vl) Factor 1 0.827 n.a. Lavg 0.508 0.614 0.608 Lmax 1.374 1.661 1.518 Lmin 0.184 0.222 0.240 Lam 2.761 2.761 2.530 Lmm 7.467 7.467 6.317 LvMax 0.153 0.185 0.208 LvR 0.300 0.301 0.338 demo_low 2.4 0.827 0.614 1.661 0.222 2.761 7.467 0.737 0.208 0.409 CORM 2013 Gaithersburg. MD
Comparison by Luminance CORM 2013 Gaithersburg. MD
Lavg = 0.5 cd/m2, 0.6 S/P Ratio 140% Lavg Lmax Lmin Lavg/Lmin Lmax/Lmin Lvmax Lvmax/Lavg 130% 120% 110% 100% 90% 80% Base Adjusted Average Adjusted Points Adjusted LvModified CORM 2013 Gaithersburg. MD
Lavg = 1.0 cd/m2, 0.6 S/P Ratio 140% Lavg Lmax Lmin Lavg/Lmin Lmax/Lmin Lvmax Lvmax/Lavg 130% 120% 110% 100% 90% 80% Base Adjusted Average Adjusted Points Adjusted LvModified CORM 2013 Gaithersburg. MD
Lavg = 0.5 cd/m2, 2.4 S/P Ratio 140% Lavg Lmax Lmin Lavg/Lmin Lmax/Lmin Lvmax Lvmax/Lavg 130% 120% 110% 100% 90% 80% Base Adjusted Average Adjusted Points Adjusted LvModified CORM 2013 Gaithersburg. MD
Lavg = 1.0 cd/m2, 2.4 S/P Ratio 140% Lavg Lmax Lmin Lavg/Lmin Lmax/Lmin Lvmax Lvmax/Lavg 130% 120% 110% 100% 90% 80% Base Adjusted Average Adjusted Points Adjusted LvModified CORM 2013 Gaithersburg. MD
Comparison by S/P Ratio Luminance at 0.5 cd/m2 CORM 2013 Gaithersburg. MD
Lavg = 0.5 cd/m2, 0.6 S/P Ratio 140% Lavg Lmax Lmin Lavg/Lmin Lmax/Lmin Lvmax Lvmax/Lavg 130% 120% 110% 100% 90% 80% Base Adjusted Average Adjusted Points Adjusted LvModified CORM 2013 Gaithersburg. MD
Lavg = 0.5 cd/m2, 0.9 S/P Ratio 140% Lavg Lmax Lmin Lavg/Lmin Lmax/Lmin Lvmax Lvmax/Lavg 130% 120% 110% 100% 90% 80% Base Adjusted Average Adjusted Points Adjusted LvModified CORM 2013 Gaithersburg. MD
Lavg = 0.5 cd/m2, 1.1 S/P Ratio 140% Lavg Lmax Lmin Lavg/Lmin Lmax/Lmin Lvmax Lvmax/Lavg 130% 120% 110% 100% 90% 80% Base Adjusted Average Adjusted Points Adjusted LvModified CORM 2013 Gaithersburg. MD
Lavg = 0.5 cd/m2, 1.4 S/P Ratio 140% Lavg Lmax Lmin Lavg/Lmin Lmax/Lmin Lvmax Lvmax/Lavg 130% 120% 110% 100% 90% 80% Base Adjusted Average Adjusted Points Adjusted LvModified CORM 2013 Gaithersburg. MD
Lavg = 0.5 cd/m2, 1.7 S/P Ratio 140% Lavg Lmax Lmin Lavg/Lmin Lmax/Lmin Lvmax Lvmax/Lavg 130% 120% 110% 100% 90% 80% Base Adjusted Average Adjusted Points Adjusted LvModified CORM 2013 Gaithersburg. MD
Lavg = 0.5 cd/m2, 2.0 S/P Ratio 140% Lavg Lmax Lmin Lavg/Lmin Lmax/Lmin Lvmax Lvmax/Lavg 130% 120% 110% 100% 90% 80% Base Adjusted Average Adjusted Points Adjusted LvModified CORM 2013 Gaithersburg. MD
Lavg = 0.5 cd/m2, 2.4 S/P Ratio 140% Lavg Lmax Lmin Lavg/Lmin Lmax/Lmin Lvmax Lvmax/Lavg 130% 120% 110% 100% 90% 80% Base Adjusted Average Adjusted Points Adjusted LvModified CORM 2013 Gaithersburg. MD
Comparison by Methodology Luminance at 0.5 cd/m2 CORM 2013 Gaithersburg. MD
Adjusted Using Average Method 140% Lavg Lmax Lmin Lavg/Lmin Lmax/Lmin Lvmax Lvmax/Lavg 130% 120% 110% 100% 90% 80% SPR 0.6 SPR 0.9 SPR 1.1 SPR 1.4 SPR 1.7 SPR 2.0 SPR 2.4 CORM 2013 Gaithersburg. MD
Adjusted Using Point Method 140% Lavg Lmax Lmin Lavg/Lmin Lmax/Lmin Lvmax Lvmax/Lavg 130% 120% 110% 100% 90% 80% SPR 0.6 SPR 0.9 SPR 1.1 SPR 1.4 SPR 1.7 SPR 2.0 SPR 2.4 CORM 2013 Gaithersburg. MD
Adjusted LvModified Method 140% Lavg Lmax Lmin Lavg/Lmin Lmax/Lmin Lvmax Lvmax/Lavg 130% 120% 110% 100% 90% 80% SPR 0.6 SPR 0.9 SPR 1.1 SPR 1.4 SPR 1.7 SPR 2.0 SPR 2.4 CORM 2013 Gaithersburg. MD
Thanks to CORM! & special thanks to Scott Wentworth who helped make this presentation happen References: Spectral Effects of Lighting on Visual Performance at Mesopic Lighting Levels , IES TM-12-12 American National Standard Practice for Roadway Lighting , ANSI/IES RP-8-00 Nomenclature and Definitions for Illumination Engineering , ANSI/IES RP-16-05 Laboratory Spectra , Earth Observation Group, National Geophysical Data Center/NOAA any questions? CORM 2013 Gaithersburg. MD
