In addition to the three primary data sources listed above, the US Cities Geographic Information System (GIS) file provided by TransCAD® (Caliper, Inc.) was used in the analysis. The US Cities GIS file locates US cities on the basis of latitude and longitude.
Geocoding of research institution and vendor locations from the primary data sources was accomplished using TransCAD®. Specifically, data on the location of the institutions were matched with the city and state data fields in the US Cities GIS file to determine the geographic coordinates (latitude and longitude) of the institution or vendor locations. A TransCAD® macro was written to automate the process. Some 80% of the research institutions and all of the vendor locations were geocoded using the automated procedure. However, the US cities GIS file did not have city data fields corresponding to the remaining 20% of research institutions. For these, we used internet websites to manually determine geographic coordinates of the cities in which the research institutions were located.
The geocoding of the locations of utilization points and supply locations was followed by an overlay procedure in TransCAD® in which the geocoded locations were overlaid on the TransCAD® highway file and mapped to the nearest highway network node. A TransCAD® shortest-path routine was then run to obtain distances between utilization points and supply locations.
The objective of the quantitative analysis was to locate additional supply points optimally, with an assessment of the potential benefit of doing so. The fundamental motivation was to answer the following questions: If one additional breeding facility is being considered in the United States, where should it be to make the new total distance in the animal transportation system lowest? By how much is the new total transportation distance shorter than the former total distance? The questions could then be extended to more than one additional breeding facility. The facility-location model is thus a minimization model that considers various alternative location possibilities and determines the ones that provide the shortest transportation distance.