Data Description: Schools data were obtained from the 2007 Homeland Security Infrastructure Program (HSIP) database of schools, which contains data relevant from Sept-Dec 2005 pertaining to schools with any grades from preschool-12 in all 50 states, the District of Columbia, and Puerto Rico. This file is based on data collected by MCH, a compiler of institutional data, which was geocoded against the NAVTEQ streets file and, secondarily, the GDT streets file. The source is updated Annually and maintained for analysis relevant to emergency response. The National Highway Planning Network (NHPN), a spatial dataset maintained and distributed by the Federal Highway Administration, was used to obtain roads data. In addition to containing ample metadata, the NHPN has the benefit of being freely and publicly available. The version used was published in August 2005 and therefore describes roads conditions much as they were when the schools data was collected in 2005. Processing: A new NHPN file was created with only designated interstates, federal highways, and state highways – those records where the variable “signT1” was equal to “I” “U” or “S.”
The resultant layer was then joined to the 2007 HSIP schools layer through a one-to-one spatial join based on the closest match within a search radius of 500 feet. Only matched records were kept in the join to create an additional layer of “exposed” schools.