The Role of GIS in 9-1-1 and NG9-1-1

GIS plays many roles in 9-1-1. Since the late 1990s, GIS is most commonly used to provide tactical mapping for 9-1-1 telecommunicators, Computer Aided Dispatch (CAD) dispatchers, and emergency responders. Tactical mapping systems reduce emergency response time by identifying the location of emergency calls on a map, and compute best routes to the scene for emergency responders. Valuable supplemental “on the ground” information, not limited to fire hydrant locations and valve specifications, network camera locations, and premise information including contacts, physical structure information, and owner and tenant data, is also provided by GIS.


NG9-1-1 Call Routing

GIS plays an even more critical role in NG9-1-1 by determining which public safety answering point (PSAP) to route a 9-1-1 call to, based on the location of the calling device, and also for location validation prior to a caller making an emergency call (replacing an E9-1-1 MSAG). Geospatial call routing enables more accurate call routing than traditional E9-1-1 systems and can reduce the number of 9-1-1 call transfers due to misrouted 9-1-1 calls. This in turn can help reduce emergency response times and save more lives and property; a primary goal of emergency responders and public safety management and stakeholders.

When an NG9-1-1 call is being routed, an Emergency Services Routing Proxy (ESRP) queries an ECRF to determine which PSAP to route the call. The ECRF query contains the location of the device calling 9-1-1. This location may be a civic location (house number / street name style address) or a geodetic location (a latitude / longitude coordinate, circle, ellipse, polygon, or arc-band). Civic locations may be used for fixed location devices such as wireline or VoIP phone services. Geodetic locations may be used for mobile devices such as cell phones. In either case, when routing a 9-1-1 call, an ESRP will query an ECRF with the location of the device and the type of service being requested (such as 9-1-1 or a selective transfer from the 9-1-1 center to a responding agency). The ECRF will intersect the location provided in the query against a map of the PSAP service area boundaries to determine the PSAP which should receive the call.

To route 9-1-1 calls based on location, an ECRF must be provisioned with GIS data depicting the PSAP service area boundaries. If the location provided in the query is a civic location, this must be converted into map coordinates to be intersected with the PSAP boundary polygon map. This conversion can be accomplished using an address point layer in the GIS, a site/structure polygon layer where each polygon is tagged with civic address location attributes, or an address ranged road centerline layer. Minimally, an ECRF needs to be provisioned with PSAP service area boundaries and one form of civic location GIS data such as address point data.

Location Validation

In addition to being used when routing 9-1-1 calls, NG9-1-1 systems use GIS data before a 9-1-1 call is placed. As Communications Service Providers (CSPs) prepare subscriber records for 9-1-1, they must confirm subscriber records have addresses usable for 9-1-1. This process is similar to checking an E9-1-1 ALI record for MSAG validation. In this case, a Location Information Server (LIS) queries an LVF with the location in question. The LVF examines its GIS database to see if the address is valid for 9-1-1. The GIS data provisioned to the LVF is identical to the GIS database provisioned to the ECRF.

9-1-1 GIS Data Maintenance

GIS data provisioned to an ECRF/LVF or PSAP mapping system must first be created, and must also be maintained over time. GIS data can be authored and maintained using a variety of different GIS software applications. The dominant provider of GIS software in state and local government is Esri (Environmental Systems Research Institute, Other vendors, such as Pitney Bowes and Manifold, provide GIS software to state and local government as well. In addition, there are some open source GIS applications such as QGIS, MapServer, MapGuide, and others.

A number of 9-1-1 GIS vendors, such as Geo-Comm Inc. (GeoComm), provide 9-1-1 GIS data management applications and services on top of existing broadly horizontal GIS platforms. These platforms are used in a variety of different industries ranging from utilities, to defense, to natural resources mapping, to business analytics, and beyond. NENA has not standardized any particular end-user GIS application or platform. 9-1-1 authorities are free to pick and choose the best GIS platform, software, and vendor services for editing and maintaining GIS data for 9-1-1, based upon their own particular needs and individual enterprise requirements.