The document summarizes a meeting of the Roadway Lighting Committee in 2005. It discusses issues with luminance calculations increasing unexpectedly as pole distances increase, due to using incorrect r-table values beyond the charts' limits. The problem is identified and a correction is proposed: luminaires should only be included in luminance calculations if their angle of incidence is less than or equal to 12, rather than exceeding r-table values. This will prevent unexpectedly higher luminance readings from greater distances.

1. Ray Yeager, PE, LC, MBA
Sr. Project Engineer, Holophane
Roadway Lighting Committee Spring 2005 Meeting
April 5, 2005 – Tuscon, AZ

2. Recognizing the Problem
 Bench mark calculation to be used by
lighting calculation programmers to check
their calculations
– Intermediate Values
– Each luminaire
– Given Geometry
– Errata added luminaires
Roadway Lighting Committee Spring 2005 Meeting

3. Topics
 Recognizing the Problem: Calculated
luminance should not increase as pole
distance increases
 Source of Problem: r-Table values are
being used that are off the charts …
 Correction: Don’t use r-Values if
none exist
Roadway Lighting Committee Spring 2005 Meeting

4. Recognizing the Problem
 Errata
– Original Geometry
– Part 1 insured fixtures added to observer
– Part 2 added 6 cycles after calculation area
Roadway Lighting Committee Spring 2005 Meeting

5. Recognizing the Problem
 Bench mark
photometric file:
– 1000 cd nadir
to Horizon
Roadway Lighting Committee Spring 2005 Meeting
1000 cd
1000 cd
1000 cd
1000 cd
1000 cd
1000 cd
1000 cd
1000 cd
1000 cd
1000 cd
1000 cd
1000 c
1000 cd
1000 cd

6. Recognizing the Problem
Luminaire Number Average Luminance
from Luminaire
Percent Luminance
Contribution
1 0.0000 0
2 0.0564 11
3 0.2069 39
4 0.0616 11
5 0.0378 7
6 0.0402 7
7 0.0431 8
8 0.0449 8
9 0.0462 9
Roadway Lighting Committee Spring 2005 Meeting

7. Recognizing the Problem
1
2
3 4 5 6 7
Roadway Lighting Committee Spring 2005 Meeting

8. Recognizing the Problem
5
Roadway Lighting Committee Spring 2005 Meeting

9. Recognizing the Problem
7
Roadway Lighting Committee Spring 2005 Meeting

10. Recognizing the Problem
 Problem Identification:
Not reasonable to
expect luminance to
increase as distance
increases…
Roadway Lighting Committee Spring 2005 Meeting

11. Problem Source
Roadway Lighting Committee Spring 2005 Meeting
Example calculation point

12. Problem Source
 Luminance calculations at a point
Roadway Lighting Committee Spring 2005 Meeting

13. Problem Source
Roadway Lighting Committee Spring 2005 Meeting

14. Problem Source
Roadway Lighting Committee Spring 2005 Meeting

15. Problem Source
Roadway Lighting Committee Spring 2005 Meeting

16. Problem Source
1
2
3
4
5
6
789
Roadway Lighting Committee Spring 2005 Meeting

17. Problem Source
Detail of the r-Table for the last four point values – values increase
Roadway Lighting Committee Spring 2005 Meeting

18. Problem Source
 Current Method
– Uses last row when Tan
gamma exceeds 12
– The last 4 fixtures have
– R-Values increase for
decreasing beta at a
constant tan gamma
Roadway Lighting Committee Spring 2005 Meeting

19. Problem Source
Beta
Tan
Gamma
0 2 5 10 15 20
11.0 59 26 7.1 2.6 1.9 1.8
11.5 56 24 6.3 2.4 1.8 0
12 53 22 5.6 2.1 1.8 0
Increasing r-Values as Beta decreases
Roadway Lighting Committee Spring 2005 Meeting

20. Correction to Problem
 Recognize limits of table
– Add luminaires as long
as Tan gamma is
less than or equal to 12
– When Tan gamma is
greater than 12,
do not use the
luminance contribution
to the point in the average.
Roadway Lighting Committee Spring 2005 Meeting

21. Correction to Problem
1
2
3
4
5
Roadway Lighting Committee Spring 2005 Meeting
(>12)

22. Correction to Problem
1
2
3 4 5
Roadway Lighting Committee Spring 2005 Meeting

23. Correction to Problem
 Include or exclude a luminaire’s luminance
contribution to a point based upon the angle of
incidence.
 Never exceed the R-Table values
Roadway Lighting Committee Spring 2005 Meeting

24. Ray Yeager, PE, LC, MBA
Sr. Project Engineer, Holophane
Roadway Lighting Committee Spring 2005 Meeting
April 5, 2005 – Tuscon, AZ