06/15/07 Hansz/Lighting CommentsCity of Kalispell Public Works Department
Post Office Box 1997, Kalispell, Montana 59903-1997 - Telephone (406)758-7720, Fax (406)758-7831
TO: James H. Patrick, City Manager's �"
FROM: James C. Hansz, P.E., Director of Public Works /City En er
*�
SUBJECT: Lighting letter to Howard Mann from CTA, re: Silverbroo
DATE: 15 June 2007
We have reviewed the lighting letter to Howard Mann from CTA in connection with Mr.
Mann's project, Silverbrook. This correspondence was directed to Mr. Mann and not the City.
We have the following comments:
1. There is a desire to deviate from City lighting standards (July 2005) adopted by the City
Council.
2. The purpose of this deviation appears to be intended to create a light environment more
in keeping with the "dark.skies" concept on side streets with normal City standards to be
met on Silverbrook Drive.
3. The engineer points out that some areas of Kalispell do not meet the current City
standard. We assume the purpose of this is to either demonstrate we are not following
City standards with the approval of lighting plans, or show that different lighting
approaches are serving different areas of the City. While the latter is true, the former is
not. The examples selected for this are all projects that were initiated prior to City
Council's adoption of the current City standard.
4. The engineer indicates the City's standards cannot be met. We do not design street
lighting systems. Flathead Electric designs these systems. Their lighting department has
provided data to demonstrate their current residential subdivision lighting design meets
City standards.
5. CTA has provided examples of standards from other Cities. While this serves to show
there are other standards, it does not address the issue of meeting Kalispell's standards.
The correspondence also does not address or suggest an alternative standard to be met. It
only indicates that fewer lights are proposed in certain areas.
memo02O2007.doc
6. The engineer has been advised that this Department does not make unilateral decisions to
waive compliance with standards approved by the City Council.
7. Resolution of this issue would be materially assisted by submittal of a substantive
alternative lighting standard for this project that may be considered by City Council.
memo0202007.doc
June 7, 2007
93 & Church, LLC
Attn: Howard Mann
100 Hathaway Lane
Kalispell, MT 59901
Re: Street Lighting — Silverbrook Estates
Dear Mr. Mann:
In an earlier letter to Frank Castles, we had requested a deviation to the city standards
on street lighting requirements for the Silverbrook Estates project. The City of Kalispell
Public Works Department currently has a requirement of minimum maintained
illumination of 0.3 foot-candles and a uniformity ratio that shall not exceed 6:1,
throughout the sidewalks along all streets in the city.
What we had proposed to the City was to meet these requirements on Silverbrook
Drive, but on the side streets, have a light standard at each intersection as well as a
light that is a maximum of 750 feet from each intersection. This condition would create
more of a dark sky while providing adequate lighting for pedestrians to walk "to the light"
along Silverbrook Estates' sidewalks. This approach would eliminate a condition that
we strongly feel will result in excessive lighting in a suburban setting. It is our
understanding that the City did not approve this request, and is requiring that all streets
within the subdivision meet the current City lighting requirements.
We recently took some light readings at other subdivisions within Kalispell to see how
the lighting levels within these subdivisions compare with the current standards.
Following are the light levels we measured:
Glacier Commons:
• Directly under a lighting fixture —1.50 foot candles
• Across the street from the fixture — 0.07 foot candles
• Darkest spot between the fixtures — 0.00 foot candles
Granary Ridge:
• Directly under a lighting fixture — 7.41 foot candles
• Across the street from the fixture — 0.55 foot candles
• Darkest spot between the fixtures — 0.14 foot candles
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• Directly under a lighting fixture — 0.50 foot candies
• Across the street from the fixture —0.12 foot candle
• Darkest spot between the fixtures — 0.01 foot candli
As can be seen by these measurements, none of these subdivisions would meet the
current City requirement of minimum maintained illumination of 0.3 foot-Gandles. Based
on the minimum measured foot candles, it does not appear that the City required
uniformity ratio of 6:1 could be achieved either.
oil
M a A 1. M-1 41-15-
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Grand Junction, CO
http:/twww.ci.grancgd.co.usiCityDeptWebPages/PublicWorksAndUtilitiesfTranspatationEngineeringrrEFilesThatLINKintoDWStoreHerefTEDS/chaoR.p&
Table 8-1 Average Maintained Illuminance (Foot Candies) on Public Streets
Local Residential Streets *
* "On local residential streets, a standard light shall be located at each street intersection, at or near the throat of each
cul-de-sac, and at a maximum spacing of 250 feet measured along the centerline of the roadway. Additional lights may be
required on horizontal curves at other locations.'
Portland, OR (page I of each)
http:/Avww.portlandonlirte.corTVshared/eWimage.cfm?id=36176
City of Portland Street Lighting Standards
Local Service
>0.006 L Fl-
<5 Ave Min (Overall)
510 Max Min (Overall)
None Max Min (Longitudinal)
http:/Av,vw.portlandonlirie.conVauditor/index-cfm?a=dgbhe&c=dbb4e
1. The adopted Street Lighting Standards also currently recommends an average, horizontal fighting standard (Eh
Ave) of > .2 footcandles for all Local Service (residential) streets, plus a uniformity ratio of < 6 (average to
minimum footcandles) and the ratio of < 20 (maximum to minimum footcandles).
2. A recent study of street light spacing and distribution ratios by Lighting Systems Management for the City of
Portland Bureau of Street Lighting, determined that the Eh Ave. standard or > .2 is acceptable with lights spaced
from 250 feet to 295 feet; however, the < 6 and/or < 20 light distribution ratios on Local Service streets, where
light spacing is 295 feet or more, cannot be obtained. Therefore, the study recommends these latter ratios be
deleted from the Street Lighting Standards.
Bozeman, MT (page 42-16)
http:/tmww.bozeman.neffbozemaNChapef�_42_March —24_2007_1693.p&
Table 42-2 Local Street Lights (page 42-16)
1 Street lights are only required at intersections on local streets.
Tempe, AZ (page 5)
http://www.tempe.goviengineefingfstardarc�_detailsiniagL".Pdf
T-100.4 Subdivision Lighting (page 5)
"All intersections of residential subdivisions shall have street fighting. Street lighting shall be located on public road rights -
of -way, at the side lot line of the property where possible."
Vancouver, WA
W://www.cityoNarcouver,us/TrafficSafety.asp?menuid--10465&wjbmenuID=19947&itemiD=IBM
'The recommended "average luminance level" ranges from 0.3 Candelas per Square Meter for local, residential streets to
1.2 Candelas per Square Meter for Major Arterials in a Commercial area."
Naperville, IL (page 6)
http:fhv".napwville.il.us/emplibrary/Se-:-.tioM.pdf
Table 4.5.1 Performance Standards for Street Lighting
Local Streets
Max FC
< 3.5
Min FC
N/A
Ave FC
> 0.4
Ave/Min Ratio
N/A
Bulb Type
HPS
Wattage
100