Shelby County is the largest county in Tennessee in both population (927,644) and geographic area (785 mi²). Memphis is the county seat, home to the county’s Emergency Communications District, for the operations of the local 9-1-1 emergency system. The District provides Shelby County residents with an efficient emergency telephone number service using the latest technology, equipment and training for the various emergency service providers and dispatch centers.
For each dispatch center, the District provides county address location mapping. A secure database known as an ALI (Automatic Location Identification) contains the exact 9-1-1 address for any given associated phone numbers. This database is queried by the Public Safety Answering Point at the time of a 9-1-1 call to obtain the caller’s location. This data is then placed in the computer aided dispatch software and 9-1-1 mapping software used by the district to help fire and rescue, emergency medical services and law enforcement get instant access to updated maps containing GIS data needed to get to the right locations as soon as possible.
For years, Shelby County’s aerial image process required a contracted flight to photograph the county areas. Because of the high cost of capturing those images, the county purchased images once every two years, after pooling resources from various county entities.
“While the images were high resolution, there were issues with mosaicing the separate images together, and since the imagery was taken every two years, many rural and unincorporated areas were out of date,” said Timothy Zimmer, the GIS Administrator for Shelby County’s Emergency Communications District. With out of date images, the county had to develop alternate methods to locate addresses for the 9-1-1 systems.
A couple of years ago, Zimmer found and implemented Nearmap, which provides high-quality, aerial imagery that is frequently updated and delivered through the cloud as a subscription service.
With Nearmap, Zimmer and his team access the current Nearmap imagery to geocode new addresses and developments as well as plot new roads into the 9-1-1 mapping systems.
One benefit to Neamap’s photo maps is imagery is taken at least twice a year, both leaf-on and leaf-off to provide different views of locations in different seasons.
For Zimmer, Nearmap’s biggest advantage is that the Nearmap imagery integrates directly into his ArcMap, ArcPro and ArcGIS Online applications, so he can overlay GIS information directly over the high-resolution imagery.
“I really like how Nearmap is integrated into the GIS stack,” Zimmer said. “We’re able to stay on top of new developments, roads, and addresses. Being able to have Nearmap imagery integrated into our GIS systems helps us be much more accurate.”
The combined impact of data services, base maps, Nearmap imagery, and third-party data are improving all aspects of public safety, including law enforcement, fire, and emergency medical services. Even other agencies are using the district’s imagery and GIS data.
For the future, Zimmer and his team are implementing a new mapping application to plot 9-1-1 calls, and plans to have Nearmap integrated into that solution.
The Emergency Communications District of Shelby County, Tennessee (the District) was established on November 21, 1984, pursuant to the provisions of Chapter 867 of the Public Acts of 1984 of the State of Tennessee. The District is responsible for establishing local emergency telephone service and providing the network, call-handling equipment, and geographic information systems (GIS) data for each Public Safety Answering Point (PSAP) within Shelby County, Tennessee. The District is governed by a nine member board of directors, which is nominated by the Mayor of Shelby County, Tennessee, and approved by the Board of Commissioners of Shelby County, Tennessee. The State of Tennessee has the authority to levy an emergency telephone service charge to be used to fund the operation of the District.