GIS Fights Crime in Chicago
Chicagos homicide rate led the nation last year, so the Chicago Police Department knew it had to find new methods for targeting crime.
In an effort to help prevent murders and aggravated battery with firearms, the CPDs Deployment Operations Center deployed GIS (geographic information system) technologies to present crime information in geographic context. The point of using GIS technologies, which were deployed last June, is to allow officers to make better-informed decisions about which areas of the city need additional police power.
In the second half of last yearthe first six months of GIS deploymentthe CPD saw an 18 percent drop in murders compared with the same period the year before. So far this year, Chicago has had 23 fewer homicides compared with the same period last year.
"The commander of the Deployment Operations Center saw the importance of having the ability to do some mapping and analysis that would allow them to make key judgments of where they should create police deployment areas," said Joe Kezon, GIS manager for the CPD.
"Our desire is to ensure zero tolerance in crime areas, and the technology enables us to determine where those areas are," Kezon said.
Governmentsbe they city, county, state or federalare increasingly turning to GIS to tap large amounts of data that can help agencies function more smoothly. A survey released in December by Public Technology Inc., a nonprofit research group in Washington, found that about 97 percent of local governments serving populations of at least 100,000 are benefiting from the use of GIS applications and mapping technologies.
In addition, Public Technologys survey indicated that 28 percent of local governments with populations of any size use GIS technologies to support crime tracking and investigative activities similar to the CPDs.
Before deploying GIS technologies, the CPD used a client/server application developed in-house that enabled police officers to associate crimes with property information. While that application provided officers with information as they investigated crimes, keeping the data up-to-date was tedious because the application had to be loaded onto each computer individually, and new data had to be added every few weeks.
Individual maps were stored locally on roughly 400 PCs. "Any time there was an update to a map layer or a coding change, we had to manually ... update all of those personal computers," Kezon said. "The maintenance of the application was pretty cumbersome."
Next page: A specialized Web site provides maps and data to officers via the CPD intranet.
The CPD, which has an annual budget of more than $125,000 for GIS software and consulting services, decided to leverage ArcIMS 9 from Environmental Systems Research Institute Inc., also in Chicago, to build a specialized Web site that would provide maps and up-to-date data to officers via the CPD intranet.
To tap into the queries built using its legacy data warehouse, which was built in-house, the Deployment Operations Center created an application using ESRIs ArcSDE for database maintenance and ArcIMS to serve data to the Web.
The data warehouse provides the querying tool. Query pages are ASP (Active Server Pages)-driven and access an Oracle Corp. Oracle9i database to provide mapping and geographic information.
Using ArcIMS, officers can view and edit data. For example, an officer can search through 300 crime types and have the crimes mapped for a particular neighborhood or area. Once the map is built, an officer can use an icon to retrieve mug shots from the Oracle9i database to build a virtual lineup of potential suspects in a crime investigation.
"The fact that you can actually see these mug shots is the bigger key for police officers, especially once we add GIS capabilities to department vehicles," Kezon said. "Accessing this information quickly is a very nice resource."
Using the CPDs legacy system, an officer would have to search for all persons arrested within a certain area and then sift through that information to determine who had been arrested for aggravated battery with a firearm, for example.
Using ESRIs GIS tools, officers can now tie spatial information to related tabular data and map both. For example, an officer can search for all persons arrested for aggravated battery with a firearm within a geographic area. The officer can analyze the data using Business Objects S.A.s Crystal Reports.
More than 14,000 Chicago police officers have access to the intranet. There is also limited civilian access to run queries against the data warehouse. If changes are made to the base data set, those changes are reflected in subsequent viewings.
The GIS system deployment received the full backing of the police department, Kezon said.
Every time a query is run through the data warehouse, the user needs to provide a user name and password. And every time a mug shot is accessed, that transaction is also logged to ensure no one misuses the information.
In the future, Kezon and Scott Hamilton, who is a GIS developer at the department, said they hope to provide GIS information to police officers that is accessible from their patrol vehicles.
Right now, a bandwidth issue prevents police officers from accessing the department intranet from their vehicles. But after the department resolves bandwidth limitations this year, Hamilton said, it will be easier for officers to perform their jobs outside the office.
The GIS department also plans to use ArcIMS technologies to analyze where surveillance cameras should be placed around Chicago to deter crime.
"Weve done some analysis on existing cameras, and its been shown that cameras displace crime around the locations of those cameras significantly," Hamilton said. "GIS will enable us to place cameras in areas where theyre needed and enable us to increase the number of arrests in those areas."
Senior Writer Anne Chen can be reached at firstname.lastname@example.org.