Mapping Nighttime Lighting Conditions for Walking Safety - An Exploratory Case Study from Duluth, MN
To explore the relationship between light intensity on Duluth streets and violent street crimes, such as assault and robbery.
Northeast Minnesota Sustainable Development Partnership
The UMD partners for this project were
1. Department of Geography
2. Geographic Information Sciences Lab, with Director Stacey Stark and Research Associate Steve Graham
3. Two student research assistants, Samantha Olson and Trey Schiefelbein.
1. Fit City Duluth
2. Neighborhood advocacy organizations
3. Rotary Clubs
4. Duluth schools
A first unique step of this project was the recording and measuring of nighttime light
intensity on Duluth Streets. Over the course of an entire year, two student researcher and
the PI repeatedly walked the streets of Duluth in an identified pilot area to record the
location of street lights, and to record the illuminance of streets under the streetlights and
along each block.
This project determined the actual light intensity on every city block in the city of Duluth.
The principal investigator as well as two student researchers, and additional volunteers
for this project, used light meters to record the intensity of lighting on every street in
Duluth, in a designated pilot area, at nighttime. Measurements were taken at eye level, to
identify the intensity of light as perceived by individual observers who would be walking
along a street. Every time a measurement was taken, the geographical coordinates of this
measurement were recorded, using a Global Positioning System (GPS). Measurements
of light intensity were also taken in the immediate proximity to lampposts, as well as in
several additional locations on each block. These measurements allowed for the creation
of a detailed map of lampposts in Duluth, and the resultant intensity of light right below them.
Secondly, all additional measurement of light intensity enabled the researchers to
determine if street lighting was sufficient to illuminate an entire city block, or if light
intensity away from lampposts decreases significantly. For all measurements taken at
a distance from lampposts, the research team will also record if there are obstruction
present at the location that reduced light intensity (Buildings, large trees etc), or if
additional lighting (from individual homes) contributes to additional light intensity. The
light meters for this project have already been acquired through a technology grant from
the College of Liberal Art at UM-D. Volunteers from the Duluth Eco-Rotary Club and Fit
City Duluth assisted in the collection of data.
A second, interrelated case study was conducted on the UMD campus, using the same
methods as described above.
Another component of this study was to involve the collection of comprehensive crime
data from the City of Duluth Police Department, and the mapping of particular types
of crimes. Especially, this project was to map the locations of street crimes such as
drug deals, assault, and robbery. In 2007 and 2008, there had been a marked increase of
these types of crimes in the city of Duluth, with student population particularly targeted
and affected (Kelleher 2008). The principle investigator first established a working
relationship with the Duluth Police Department in 2004, when crime data was made
available to the Department of Geography for a research project by an undergraduate
student interested in crime mapping. In continuation of this effect to map crimes in
the city of Duluth, this project will focus on examining if there is a spatial relationship
between street crimes and areas of poor nighttime lighting conditions. Geographic
Information System software (Arc GIS) were to be used to create overlays of various
types of crime data, and the measured lighting conditions, to establish if darkness acts
as significant contributor to the factual and potential location of crimes. In turn, this
was to allow the Duluth Police department to direct their patrolling efforts to certain
crime hot spots, as well as enable citizens to choose the safest possible routes, when
walking at nighttime. This aspect of the project was not completed, primarily due to the
unexpectedly extensive fieldwork involved in step 1 described above.
Despite the fact that the mapping of crime in the City of Duluth (Steps 2 and 3 of the
original project) did not occur, the project was still successful for several reasons: 1.
A new, innovative methodology was created for mapping sidewalk illuminance. This
process alone took several months to complete, and was necessary because no existing
methodology for comprehensive nighttime mapping did previously exist. 2. The project
created a series of prototypical maps that can be used in other studies to replicate the
research procedures and visualization of illuminance demonstrated here.