October 26, 2011
Anton Foss, AIA, Principal
360 ARCHITECTURE
300 W 22nd Street
Kansas City, MO 64108
Re:
Milwaukie Oregon Baseball – Preliminary Lighting Analysis
WSP Flack + Kurtz Project No.: S11.20330.00
Dear Anton:
As requested, please find below a preliminary analysis of the field lighting for the proposed minor league
baseball stadium in Milwaukie, Oregon. The lighting analysis is based on planning information received
from your office on the 21 October 2011.
LIGHTING STANDARDS
Lighting design for sporting events at Minor League baseball fields is typically designed in accordance
with the Illumination Engineering Society of North America’s recommended practice guideline RP-6-01
“Sports and Recreational Area Lighting” and the “Lighting for Minor League Baseball Playing Fields”
published by the Office of the Commissioner of Baseball and the National Association of Professional
Baseball Leagues Inc.
Minor League fields are recommended to be lit to the following average illumination levels (measured in
footcandles (fc)) on the field of play:
Class A – Horizontal Illuminance:
 The infield is to be lit to 70fc with a maximum to minimum ratio of 1.5:1 or less
 The outfield is to be lit to 50fc with a maximum to minimum ratio of 2:1 or less
Milwaukie Oregon Baseball
October 26, 2011
WSP Flack+Kurtz Project No: S11.20330.00
Page 2
TYPICAL FIELD LIGHTING INSTALLATION
Pole locations are typically determined in such a manner as to avoid placement within the players primary
field of view to avoid direct glare that may impede play. The diagram on the following page indicates the
primary sightlines for players and the corresponding typical pole locations to avoid these zones.
A typical installation therefor involves four infield pole locations (A1, A2, B1, B2 above) and four outfield
pole locations (C1, C2, C3, C4 above). Typical floodlight quantities per pole for these locations are as
follows:
“A” Position Poles: 18-20 floodlights
“B” Position Poles: 35-40 floodlights
“C” Position Poles: 16-20 floodlights
Each floodlight is typically lamped with a 1500W-2000W metal halide lamp with rated average lumens of
approximately 130,000.
Typically the highest minimum pole height is determined based on established, formulaic design ratios
and applied to all pole locations for a consistent floodlight elevation for both aesthetic reasons and to
ensure that most fixtures are aimed at a downward angle. Standard pole heights will typically range from
100-150ft depending on the available locations relative to the field.
In situations where the floodlighting is to be integrated with the stadium structure, the stadium roof height
often determines the final floodlight positioning. If the roof height is below the minimum height as
determined from the guidelines listed above, this typically results in an increased pole height to ensure
that the stadium roof structure does not create any shadowing on the field from the floodlight positions
above.
Milwaukie Oregon Baseball
October 26, 2011
WSP Flack+Kurtz Project No: S11.20330.00
Page 3
Floodlights are aimed such that the top of the floodlights beam spread lies, at a minimum, 10 degrees
below a horizontal plane level with the maximum pole height. In addition to helping avoid glare for
players on the field, this approach results in a more efficient floodlighting layout, with all fixtures directed
down towards the field itself.
LIGHT TRESSPASS CONCERNS
Spill light or light trespass is considered any illumination occurring beyond the boundaries of the field
being illuminated and the surrounding stadium proper. Despite the height and aiming criteria mentioned
above, spill light can still be an issue for the lighting design if the installation is in close proximity to
adjacent properties. This can be controlled in a variety of ways and should be a carefully considered
element of the design.
The stadium lighting layout, the stadiums orientation on the site, and the architectural design itself may all
be designed in such a manner as to mitigate light trespass onto adjacent properties. For example the
field may be set below the surrounding grade, landscaped berms may be built up, trees may be
strategically placed, ancillary buildings may be positioned in such a way as to shield adjacent areas from
potential spill light, using low reflectance materials on the stadium surfaces, etc.
Selection of appropriate luminaires (floodlights) also plays a key role in reducing light trespass.
Luminaires with optical systems having defined beam spreads and careful aiming at the appropriate
mounting heights will help to reduce any potential spill light. Additionally many manufacturers offer
shielding options including external shields, internal louvers, baffles, etc. all of which serve to reduce
glare and potential light trespass outside the stadium. An example of such a shielding device specifically
addressing this issue is shown below.
In all sports lighting installations some spill light, as the result of light reflected off the field and the
stadium structure, is inevitable. A general glow can be observed at any existing installation as a result of
reflected light from the target surface (the field in this case) interacting with particulates in the air. Many
environmental factors contribute to this effect including air quality, climate, humidity, etc. The best way to
qualify this effect is through direct observation of a similar installation under similar environmental
conditions.
Milwaukie Oregon Baseball
October 26, 2011
WSP Flack+Kurtz Project No: S11.20330.00
Page 4
LOCAL CODE RESTRICTIONS
A review of the Milwaukie, Oregon Municipal Code (website: qcode.us/codes/milwaukie) did not identify a
specific light trespass requirement for commercial construction. However, section 19.606.3 PARKING
AREA DESIGN AND LANDSCAPING Additional Design Standards requires “lighting luminaires in parking
areas to have a cutoff angle of 90 degrees” and for “lighting trespass not to exceed 0.5 footcandles
measured vertically at the boundaries of the site”.
PRELIMINARY ANALYSIS
The following diagram provides a preliminary field lighting analysis for the project and is based on the
following assumptions.
1. Field lighting will be designed per RP-6-01 for Class A baseball sporting events (preliminary
values shown in the diagram are adequate for all levels of Minor League Baseball play).
2. Eight pole positions will be used to locate the sports lights per the diagram included above with
four infield and four outfield locations. Floodlights are located approximately 90 feet above field
level and use a mixture of 1000W and 1500W metal halide lamps.
3. The preliminary study does not take into account shielding due to stadium structure, nearby
buildings, fences/walls, or landscape nor does it account for field design set beneath surrounding
grade.
Very truly yours,
Jonathan Plumpton
Vice President
WSP FLACK + KURTZ
Erik Crowell
Senior Lighting Designer
WSP FLACK + KURTZ
Milwaukie Oregon Baseball
October 26, 2011
WSP Flack+Kurtz Project No: S11.20330.00
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