Crime in the city of Los Angeles has been a major problem in Southern California. While most cities in the L.A.-area have shown a constant decrease of criminal activities over the recent years, part of the county still have shown some increase in crime in recent years. For example, South Central Los Angeles was a notoriously dangerous region of the City of Los Angeles, which had an extensive history of gang violence.
The impact factors of crime are complicated. But the urban physical environment provides the opportunity for the crime, as it is where the victim and the offender converge in space and time. Crime has an inherent geographical quality. To explore and discover the “place” and geographic characters of crime, this analysis of the area was performed using ARCMap, US 2000 Census data, Los Angeles zoning plan and original research. Then several recommendations have been made.
Materials and methods
Chesterfield square neighborhood, one of the highest crime rate places, is located in the central of South Central Los Angeles. And the neighboring communities, such as Harvard Park, Hyde Park, Vermont Square, are the places where crimes were happened frequently. So the study area stretches from Central Ave on the east to the edge of Inglewood Park Cemetery on the west and from Manchester Blvd on the south to Vernon Ave on the north. Map. 1 (See the website.) shows the location of this project area. It has a total land area of 34.13 km2.
To investigate the spatial distribution of crime and the physical environment, data consisting of a total of 1976 reported crime incidents over a period of 8 months (August, 2011- February, 2012), were collected and visualized. First, GIS hotspot maps of crime were analyzed to identify areas where the incidence of crime was highest as priorities for intervention. Second, qualitative community appraisal was conducted according to some basic social information, in order to figure out the areas identified as most problematic and unstable. Third, comparative analysis of crime hotspots with the existing physical environment was generated to support the future community redevelopment.
Analyses and results
(1). GIS hotspot mapping
The hotspot mapping describes approaches to identify concentrations in the spatial distribution of crime locations.
A. The valuation of dangerous-safe area in general.
Map 2 shows different parts in this area perform various securities, not only taking into account the historical crime points, but the risky level of crimes. By going through the process of converting to roster layers, reclassifying each value and calculating by map algebra, the total area indicates that the north area in the neighborhood was more dangerous than the south part, and the east part, especially around the highway area, was concentrated higher crimes. Roughly, the most “problematic” area can be identified from the results, which are summed up as “2 spots + 2 areas”.
B. The analysis of the distribution of crimes in various periods.
Map. 3 was created to explore the “problem” places changed due to the main people’s activities in different times. The crime points layer uploaded by using “Geocoding” tool and selected according to the time of each case by using selection tool. Then, going through the process of “density analysis”, the changes of the crime hotspots location can be figure out. Those maps show that each period has its popular hotspot, while the crime locations were dispersing on the basis of time change, from morning to night.
Map.3 Crime hotspots changes in in various periods
C. The analysis of the distribution of crimes in different place.
Map. 5 describes clearly that the number of crimes concentrated on several vertical streets. After the crime data was joined the streets layer, as well as the bus stops layer, the number and the density of crimes around each street and bus stops can be created by modifying the “Symbology” in properties and using “Kernel Density” tool.
Map.4 The “problematic” places distribution
(2) GIS neighborhood feature mapping
The feature mapping indicates that the impacts on the social and physical environment from basic background.
A. The analysis of stability in neighborhood and hypotheses of unsafe area.
The correlation studies show that some social elements of local residents, such as “unemployment rate”, “percentage of family below the poverty”, “density of population”, education levels and the ownership of properties, would be reflected the safety of the neighborhood on a certain extent. Map 4 shows that the analysis of results by using “Map Algebra” tool.
Map 5 exhibits the count of accidents calculated in each district, which shows following the Slauson Ave and the “110” highway area would be the unstable regions. Moreover, on the south area of Florence Ave also shows more instable than the north side.
Map.5 The basic social background analysis of the community
Map.6 Instability area based on the social elements
B. The analysis of existing land-use
Map.7 shows the category of land-use and the density of development in this area. Meanwhile,Many researches proved that the environment quality and spatial forms may influence the occurrence of crime. In brief, on the east side of the Normandie Ave, there are more high density residential land-use and commercial facilities, but fewer single family land-use than the west side. And the buildings and parcels of land around the crossroad of Slauson Ave and Denker Ave are bigger sizes and scales than their vicinity.
(3) The “google” mapping and the analysis of special street views
Comparing with the “problematic” place, it is obvious that they share some basic spatial characters, for example, discontinuous interfacial configuration, unfriendly lanes to pedestrians, underused land in the crossroads and so on.
Map.8 The landscape of Slauson Ave & the Normande Ave spots
Map.9 The landscape of Slauson Ave& the Western Ave spots
Map.10 The landscape of Vermont & South Park area
Map.11 The landscape of Vermont-Slauson& Florence area
Planning Recommendation: Reshaping the street Life
The interfering factors of crimes are various and complicated. But physical environment features can influence the chances of a crime occurring. They affect potential offenders’ perceptions about a possible crime site, their evaluations of the circumstances surrounding a potential crime site, and the availability and visibility of one or more natural guardians at or near a site.
To reshape a safety community, the improvements of physical environment features will be effective.
The recommendation would be reshaping the street life. This includes four aspects: first, control or reduce the access to the inner neighborhood which means redesign the access for vehicle and pedestrian in the commercial use lands, and reduce the interference of transportation; second, reshaping the space along the streets will activate the neighborhood communication, which can deterrence and restraint the would-be crimes; third, mix-use development, clean landscape and beautiful street views will help to reduce the local crimes.
The Usefulness of GIS
The first challenge is finding enough data. The crime data available through the “crimemapping.com” does not coincide with the neighborhood boundary in US 2000 Census.
The second challenge is the processes of transforming works to “google” system are complex and limited.
 S. Chainey and J. Ratcliffe, GIS and crime mapping. West Sussex, England: John Wiley and Sons, Ltd., 2005, pp. 1
 The result was produced by using “geocoding” tool.
 The result was produced mainly by using some spatial analysis tools: kernel density estimation, reclassify, and so on.