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Data Replication

This resource is maintained by Regional Outreach


This document is a basic overview for local government agencies that are interested in using GIS data replication to update GIS data at their PSAP (Public Safety Answering Point) or 9-1-1 Call Center. In addition, this document summarizes the localities that have received funding from Virginia’s PSAP Grant Program to utilize GIS data replication for updating data at their PSAPs, and it concludes with suggestions that help make a successful GIS data replication project. For more detailed information about GIS data replication, various papers exist. Esri, for example, has resources for utilizing GIS data replication using its ArcGIS tools. Also, other publications and resources are available online and in print.

Geospatial data that is both accurate and current is critical in public safety. The goal of GIS data replication is to streamline the transfer and synchronizing of GIS data from one location to another. A successful replication process requires communication, collaboration and proper planning for efficiency and long-term sustainability. Without tight synchronization of both personnel and technology GIS data replication is prone to fail. When implemented properly, GIS data replication is able to integrate data from various locations and simplify the process of keeping the data up-to-date.

In many cases it is necessary to have current, consistent, location-based (geospatial) information in multiple places for use in various systems. For example, in Virginia, most localities have a staff member who creates and maintains geospatial data which is used by many of the departments and systems within the jurisdiction. One of the primary consumers of that type of data is the PSAP. It is imperative that the PSAP have current, accurate geospatial data to use when determining the location of a 9-1-1 caller and to dispatch the appropriate responding agencies.

Over the past several years, some localities in Virginia have requested and received grant money, through the PSAP Grant Program, to establish GIS data replication between or among GIS departments and PSAPs. GIS data replication is the means of maintaining geospatial information in multiple locations by copying data from one location to another. This may involve a GIS office replicating current GIS data to a database at the PSAP or may involve GIS Departments from multiple counties replicating data to a central database at a regional 911 Center. Other, more elaborate projects may span across various offices on local, state, federal and/or international levels and involve multiple users making edits to different components of the data. Depending on the users and goal of each replication project, the set up varies.

Different methods of applying GIS data replication exist. In basic replication, the process commonly involves two geodatabases, known as a replica pair: the parent replica (original data) and the child replica (copy of the data to replicate). Some replicas enable one-way editing, in which the parent replica is the only one that may be edited, and all changes are transferred to the child replica. More elaborate replicas enable both parent and child replicas to be edited. The relationship between the databases in a replication depends on the roles of the users and the goal of the project.


GIS data replication projects funded by PSAP Grant Program

The PSAP Grant Program is administered by the E-911 Board and in turn provides funding to primary PSAPs and GIS offices that support PSAPs and public safety. The Wireless E-9-1-1 fund is the financial source of the PSAP Grant Program. The fund comes from a surcharge that each individual in Virginia pays for cellular phone service.

In the fiscal year 2008 grant cycle, the PSAP Grant Program started funding GIS data replication projects in order to improve the data updating process at the PSAP. Below are localities that have received funding and a brief description of their projects.


Grant Award Year: 2008
Grant Amount: $297,500.00
Amount Spent: $282,384.00
Contractor: Timmons Group
Description: Harrisonburg-Rockingham is the first local government agency that received funding for GIS data replication project by Virginia’s PSAP Grant Program. It is also one of the first regional replication projects involving the GIS offices at Rockingham County and the City of Harrisonburg. The goal of this project is for the GIS offices to funnel its GIS data to the Harrisonburg-Rockingham Emergency Communications Center.

Grant Award Year: 2010
Amount: $314,500.00
Amount Spent: $263,631.00
Contractor: WorldView Solutions
Description: The goal of the project is to develop GIS data replication to assist in executing the mutual aid agreement between the City of Richmond and the County of Henrico through the integration of GIS data used for public safety.

Campbell County Regional
Grant Award Year: 2010
Amount Spent: $624,700.00
Contractor: Timmons Group
Description: The goal of this project was to improve emergency response through automated data sharing among localities and PSAPs. This is project was broken up into 2 main components. First was the establishment of ESRI Geodatabase Replication among the participating localities (Campbell, Lynchburg, Bedford, Amherst and Appomattox) and their PSAPs, so they have GIS data for their entire response areas (even outside their respective political boundaries). The second component of the project was adding automation to the transformation of data from the GIS Geodatabases to a format compatible with the respective PSAP mapping system.

Mountain Empire Regional GIS (MERG)
Grant Award Year: 2010
Amount: $775,000.00
Amount Spent: $772,143.00
Contractor: WorldView Solutions
Description: The Mountain Empire Regional Geographic Information System (MERG) is a regional collaboration that originally included the following local government agencies: City of Bristol, Lee County, Russell County, Scott County, Smyth County and Washington County. Subsequently, Pulaski County, Wise County, Wythe County and the Town of Wytheville have joined the project. The use of GIS data replication facilitates the transfer of data from each locality to the regional data repository. WorldView Solutions is the contractor that has worked with the localities in developing a one-stop shop through the use of GIS data replication. This project is successful because of the multi-jurisdictional planning, collaboration and data sharing. It has won a few awards, including the 2011 VACO (Virginia Association of Counties) Achievement Award.

New River Valley (NRV)
Grant Award Year: 2013
Amount: $148,100.00
Amount Spent: $ 46,638.00 to date
Description: The goal of this project was to streamline updating and merging of GIS data used by NRVECA. This will be accomplished through data model standardization, timely updating, data transformation, quality assurance, and merging of critical GIS data from each jurisdiction into a GIS database that the NRVECA will use operationally.
1 – Review current (and incubating) database models at a regional and broader perspective.
2 – Review current GIS data in use at each jurisdiction and in each jurisdiction’s PSAP Computer-Aided Dispatch (CAD) and mapping display applications.
3 – Select a data model and modify as appropriate (NENA draft data model was selected with modifications.)
4 – Build scripts to collect applicable GIS data from each jurisdiction, merge the data, and provide a merged dataset for the NRV 911 Authority. (ESRI Arc Server and database replication will be used along with database scripting.)
5 – Investigate how our NRV 911 Authority GIS database can be merged into a statewide data model.

Northern Virginia (Alexandria, Arlington, Fairfax, Loudoun and Prince William)
Grant Award Year: 2010
Amount: $737,000.00
Description: It should be noted that this project had multiple facets, with the GIS and RCL (road centerline) being part of the award.  The purpose of the Northern Virginia Regional Routable Centerline (NVRRCL) Project was to create a street centerline data model and dataset that could support the routing of emergency (911) vehicles across the Northern Virginia region and would be maintained and supported by the Virginia Geographic Information Network (VGIN) and local jurisdictions participating in the project. The goal of the project was not to replace the data submittal processes that were in place to VGIN but rather to redefine the data model populated in the process and enhance a unified delivery method to and from VGIN by all participating jurisdictions. Localities can now use local data published within a regional centerline through the NVRRCL and VGIN RCL products.

Page County
Grant Award Year: 2013
Amount Awarded: $99,748.00
Amount Spent: $75,136.03 to date
Contractor: GeoComm
Description: Page County’s Emergency Communications Center underwent mapping upgrades, including software and hardware at the ECC and the GIS Department. As part of the upgrade, GeoComm implemented GIS data replication to update the data at the 911 Center. GeoComm’s GeoLynx Sync Advanced with replication is the software application Page County uses to update GIS data at the ECC.


Localities use GIS data replication to synchronize and maintain consistent data in two or more locations. Some local government agencies and regions in Virginia have received funding from the PSAP Grant Program for GIS data replication projects for public safety. Although various methods exist in setting up GIS data replication, in order to have a successful process in place, important considerations include the following: communication throughout the process, mutual understanding between departments and/or localities, infrastructure and connectivity preparations, and long-term support and sustainability.

Many components play a role in the success and efficiency in the GIS data replication process. Therefore, clear communication between the PSAPs, GIS personnel, IT personnel and contractors (if used), enables better collaboration that assists in planning the replication project. It is important for everyone to understand the workflow of the project, and their roles in it. Questions may include the following:

  • What does this replication project need to accomplish? If Any?
  • What form of GIS data replication works best for my locality?
  • What departments are involved in keeping the GIS data up-to-date?
  • Who are the appropriate contacts when there is a problem?
  • In case of network failure or other connectivity issues, does a manual or back up process exist?

When two or more localities funnel data updates to a central location, a mutual understanding between the localities prevents miscommunication and problems that may jeopardize the project. A signed, formal agreement between the localities, such as a memorandum of understanding, is recommended so that the localities involved understand their responsibilities as well as the scope of the project. Also, the agreement defines the expectations from each locality, which would facilitate in keeping the project running, regardless of changes in personnel.

Understanding the IT infrastructure is also important for replication to work properly. Prior to starting on the project, the proper hardware and software should be in place, and all connections should be working properly. If proper hardware and software are not in place, they must be procured, installed and tested. We have found that the technology is unforgiving if anything gets out of sync (a change of personnel, software versions, compatible databases).

Lastly, localities should consider sustainability and long-term support. Financially sustaining the project after grant funding ceases means proper budgeting and planning of resources. Among other resources, hardware, software and annual maintenance costs are things to consider when making financial plans. Knowledge sharing also benefits in the longevity of the project. For example, when a GIS Manager with detailed knowledge of the replication process shares the knowledge with coworkers, others can take over in the event the GIS Manager is absent. In addition to knowledge sharing, detailed documentation of the project, including contacts for support, is recommended. Prosperity of GIS replication depends upon the commitment of all involved. Though not easy, it can be successful and due to the complex nature of GIS data replication as described in this report, VITA recommends that all aspects be fully considered prior to committing to this type of effort.



Esri. “An Overview of Distributing Data With Geodatabases.” September 9, 2007. Accessed June 5, 2014.

Virginia Association of Counties. “MERG: Mountain Empire Regional Geographic Information System Project.” 2011. Accessed June 5, 2014.

WorldView Solutions. “GIS Support Services Contract/E911 Data Replication.” Accessed June 27, 2014.


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