Figure 2. Created in ESRI ArcMap 9.2. NAD 1983 StatePlane Pennsylvania North FIPS 3701 (Feet). Map showing candidate city (Driggs, PA) for ice creme shop based on first set of project criteria and additional project criteria.Click on image for larger view.
Project 1: Decision Support with a GIS
Sachin Chand
This project presents the challenge of finding a suitable location for an ice creme shop. The location is to be based on a set of seven requirements as follows: have a low crime index, at least one recreation area within 10 miles, population density of less than 150 people/sq. mile, near a college or university, within 20 miles of an interstate, labor pool of 25,000 individuals between the ages of 18 and 64 years and finally, greater than 500 farms for milk production. Working with four data layers, we are able to perform all our analysis within ESRI ArcMap and complete the site selection process. The four data layers are cities, counties, recreation areas and interstates.
To begin, we query the counties attribute data and select ones that have more than 500 farms ("NO_FARMS87" >500), an 18-64 aged population thats greater than 25000 and a population density of less than 150 people per sqare mile. We use this subset of counties and select cities that are "completely within" the selected counties. This is our first "spatial query" in this process. At this point we have a selection of citites(citiesquery1) that satisfy three of the seven requirements. Next, we query the attributes of citiesquery1 for cities that have a University and cities that have a low crime index. The "University" field in the cities layer is populated with a 1 (has University) or a 0 (does not have a University) so we query it for a value of 1. Crime index level being relative, we query the "CRIME_INDE" field as ""CRIME_INDE" <=0.02". This narrows down the cities to a total of 9(citiesquery2). We now perform two spatial queries. The first is selecting from citiesquery2, that "are within distance of" 20 miles of a highway. The second is a similar process to the first except it applies to recreation areas instead of interstates and the distance is 10 miles. At this point we are left with a total of four cities (out of an original total of 48 cities) shown in figure 1 that satisfy the seven initial requirements.
Two additional requirements are added to refine the search further. The location must now also be within 10 miles of a river or lake and within 40 miles of a landmark. To satisfy these additional requirements, we download hydrology and landmark data. Realizing that hydrology includes more than just lakes and rivers, we query the "feature" field of the hydrology layer to highlight just rivers and lakes. We now take the four cities from our initial analysis and use the "select by location" tool to select a subset of the four cities these that are within 10 miles of the selected features (lakes and rivers) of the hydrology layer. We then use the "select by location" tool to select cities "from the currently selected features" that are within 10 miles of a landmark. This leaves us with the single city of Driggs, PA as shown in figure 2.
We are able to provide information for this spatial challenge using both spatial and attribute queries on our data.
Figure 1. Created in ESRI ArcMap 9.2. NAD 1983 StatePlane Pennsylvania North FIPS 3701 (Feet). Map showing candidate cities for ice creme shop based on first set of project criteria .
Click on image for larger view.