Why Should Public Safety Use GIS
Firefighters, Law Enforcement, and EMS responders and other Public Safety Professionals are jobs that rely on an intimate knowledge of geography. We understand principles related to geography more than most GIS professionals. You might say that being a geographer is a natural skill that we have. We understand which unit is closer to a call, the demographics of a neighborhood we are responding to, and what are the hazards in the neighborhood, known crime locations, hospital types (i.e.: trauma and burn centers), etc. However we also have a need to do the following:
Communicate that “geography” to other responders not associated with a particular area
Communicate our “geography” to decision makers to request resources
This is why we use GIS!
How does GIS work? In simple terms.
Geographic Information Systems (GIS) is a representation of real world features digitized as a point, line or polygon. Features can include anything that is needed for the types of maps and analysis that is necessary. Basemap features are needed for all industries.
Examples of basemap features are:
Road Centerlines (lines)
Building Footprints (polygons)
City / Town areas (polygons)
Bodies of Water such as Oceans, Lakes, Rivers, etc (polygons)
Political Districts (polygons)
Industry specific data will be created to identify assets related to that industry. Within Public Safety, data is important to certain agencies and may be used for analysis across agencies.
Examples of Public Safety data are:
Fire Hydrants (points)
Fire, EMS and Law Enforcement response areas (polygons)
Fire, EMS and Law Enforcement stations (points)
911 Public Safety Answering Points-PSAP (polygons)
Hurricane Evacuation Zones (polygons)
Emergency Shelters (points)
NOTE: The above examples are a small list and many other agency specific datasets can be added.
Each of the datasets collected need to be stored as their own entities then layered to create a complete map for viewing and analysis. All of these individual layers will have data stored with attribute information of that feature. Hydrant points can contain attribute data such as Hydrant type, main size, hydrant ID number, last inspected. Firehouse data can contain data such as address, phone number, apparatus type, speciality apparatus or equipment.
What are Layers?
Layers are a general term used to describe separate features on a map. If you take any map and break it down into parts you may notice that features “lay” in a certain order on top of each other.
How to create a map together
This is a basic primer into how a map is put together. To create a simple map, a user can add“base” layers. These layers are usually layers that are represented by polygons. Polygon layers are added at the bottom of a stack of layers. Polygons such as city/towns, bodies of water, parks, fire districts, police precincts, etc. Some features can be labeled to easily identify the boundaries.
Note: Online basemaps are available and can be utilized with local data layered on top of the basemap.
Next add line data such as road centerline and railroad centerline. These features can be labeled to identify the streets and rail lines.
Point data is added on the top. Hydrants. firehouses, police stations are a few examples.
When all these layers are combined, symbolized, and labeled the desired map is complete. This example is intended to give a general idea. However these principles are true whether you are a traditional cartographer or a GIS Analyst.
Analysis is taking geographic data and comparing the data to other geographic data or using the attribute information to identify certain parts within the data. Another option is a combination of geographic and attribute data analysis. With these layers, a fire department can then identify which fire hydrants are within their department area and identify the hydrants that are due for inspection. If crime data is available, a law enforcement agency can perform an analysis of types of crime within a precinct area.
Where you can get data
There are many places you can get data. Sources include:
- Cities, County, State Government
- Many county, state and large cities have GIS Data Clearinghouses to download data
- Utilities (Electrical Companies, Water Companies)
- Indian tribes
- Commercial sources have been getting better over the years. Some of those sources includes
- HERE (formerly NAVTEQ)
- Collect your own data using mobile apps
Using GIS for Decision Making
As previously mentioned, data layers are invidualized and then added to the map separately. With these layers, analysis of the data can be done spatially or tabular.
Scenario 1: A fire department has a super tanker apparatus that responds to multiple districts. The super tanker apparatus requires continuous amount high volume of water. Due to this requirement, the apparatus needs to connect to a hydrant with at least
a 20 inch main size. With GIS, a user can spatially identify all the hydrants within the super tankers response area. Then in the attribute data, a query (selection) can be completed to identify the hydrants with a main size of 20 inches or greater.
Scenario 2: An Emergency Management office is preparing for a Hurricane. The agency has worked with the Federal Emergency Management Agency (FEMA) to create evacuation zones based on FEMA’s flood maps. Using GIS, the Emergency Management office can identify buildings for shelters that are not in the evacuation areas and can handle a large capacity of evacuees. During the actual hurricane, the shelter location data can be continually updated with the amount of people in the shelters to prevent overcrowding.
Scenario 3: A police department geographically locates crime data. (i.e.: homicides, robbery, auto theft). As more data is collected on these crimes, patterns are noticeable to specific crimes. The police precinct commander decides to deploy tactical police units to deter these crimes from being committed.
When discussed how personnel can ask questions and get answers from GIS, these simple scenarios demonstrate spatial and tabular queries that can be performed to obtain resulting information. Spatial and tabular queries can be more complicated to obtain all sorts of answers to questions.