Analysis of Emergency Medical Service Calls for
St. Johns County, Florida

This map illustrates how emergency medical services (EMS) data taken from one year of emergency calls can be displayed and analyzed using GIS. The data used to create this map came from St. Johns County Fire Rescue's Computer-Aided Dispatch database containing more than 12,000 emergency call records. Each of these emergency call records has an address attribute that could be geocoded and imported into a GIS layer for analysis.

Along with an address attribute, each record contains information such as call type, elapsed travel time, and which rescue unit was dispatched to the call's location. With this GIS-linked database, questions such as What percent of dispatched calls did each EMS unit respond to within its assigned zone? could be answered. This question is the basis of the analysis for this map.

To help visualize the answer, spider diagrams were created for each EMS rescue unit to view its destination. Each line of the spider diagram represents a trip from an EMS station to an address where an emergency was reported. This illustration shows where each rescue unit responded and whether that location was within or outside of its assigned EMS zone. Additional maps depicting information such as repeat calls, travel time to hospital, and routes based on driving distance were also created to show other ways the raw data can be visually represented. This serves as an example of how GIS can assist in the decision-making process as well as any future planning activities.