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Using Geospatial Mapping and “Hot Spots” to Fight Crime
Introduction:
The origin of using GIS in policing began decades ago with pushpin maps. Detectives would use these pushpin maps to try and find
geographic patterns to a series of crimes that would hopefully lead them to the perpetrator. It was an inexact science with only obvious visible
patterns being identified. It was used largely in high profile serial murders, serial robberies, and serial burglaries where one suspect or group
of suspects was thought to have committed numerous crimes. Recently, however, the advent of computers and modeling has led to many more
uses including deployment of resources and even predictive policing. This project will look at crime in San Francisco, specifically robberies
and crimes involving weapons to illustrate how the identification of patterns can lead to more efficient deployment of resources for SFPD.
*All data compiled from the SFGIS online catalogue (http://gispub02.sfgov.org/)
Background Information: San Francisco is broken up into nine districts and 51 sectors serviced by
approximately 2,370 officers. Although the exact number of officers on the
street at any given time is unknown, with 51 sectors, I would approximate 120+
officers on the street at any daytime hour (many “beat cars” having 2 officers
riding in each car plus supervisors, street crimes, mounted units, traffic units,
etc.). These first two maps show the districts, sectors, and a short range area of
coverage for the police stations. Although normally most police officers are on
patrol in their area of responsibility, major calls would have officers in the
station responding.
Robberies: For robberies, I ran Hot Spot Analysis and it showed three main problem
areas. The first was almost identical to one of the “Weapons” hotspots:
the block bounded by Mission St. in the west, 15th St. in the north, Capp
St. in the east and 16th St. in the south. The second area was O’Farrell
Street and Geary Street just west of Market Street. The last area is
centered on the intersection of Hyde St. and Ellis St. With the specificity
of hot spots, undercover officers and uniformed officers on directed
patrol can focus on these areas for greater efficiency.
Weapons Charges: While data from one month (October) is not ideal, it shows trends that could
help locate areas to saturate with police for crime prevention. I began by
running Hot Spot Analysis on arrests that included weapons charges. The hot
spots were predominantly limited to three smaller areas: the intersection of
Geary St. and Larkin St., the area near Taylor St. and Eddy St., and the block
bounded by Capp St. in the west, 15th St. in the north, South Van Ness Ave. in
the east and 16th St. in the south. With this type of specificity, directed patrols
including heavy probation and parole stops could significantly impact weapons
related violence in the city.
Conclusion: The most heavily concentrated areas for crime were in the Tenderloin,
Northern, Central, Mission and Southern Districts. While this is not news to
any police officers that work in these areas, this project looked at the
possibility of getting enough specificity in where the true “Hot Spots” are that
patrol officers and other ancillary units could effectively target certain blocks
for heavy enforcement to break up hot spots and make the community safer
for its residents. The next step would be trying to take this information and
put in use at the command level to see how effective it might be it making
patrols more efficient.
Three Hot Spots for Weapons Violations Three Hot Spots for Robberies
Analysis conducted by: James Baird