Community Update Brings Faster, More Accurate Updating of Data

Success in running a city depends in large part on success in managing massive amounts of geospatial data. Public works, emergency response, sanitation, environmental protection, planning, zoning, voting and taxation all require a Community Update screen shotcurrent, accurate inventory of streets, addresses and other geographic features. For big cities the challenge is the sheer size of their infrastructure. For fast-growing cities the challenge is keeping up. And for smaller towns the challenge lies in providing resources to maintain the data.

Esri and Geographic Data Technology, Inc. (GDT), an Esri Business Partner, have embarked on a pioneering program to help U.S. cities meet these challenges with a faster, more accurate, and more cost-effective means of maintaining geospatial data. The Community Update program is a free, public/private partnership for maintaining and distributing street centerline data. Through a data-sharing agreement, municipal and regional government agencies use an Internet-based system to send new and updated information about local streets to GDT, where it is validated, cross-referenced, and integrated with other data, then returned to a central server for downloading by those agencies and their constituencies.

An important component of the Community Update program is ArcIMS, Esri's Internet mapping and distributed GIS software solution. ArcIMS transforms a standard Web browser into a GIS editing tool, allowing users to interact with data online and perform editing functions. Additionally, program data is stored on a Windows NT server at GDT using Esri's ArcSDE.

All types of government agencies—from those just getting started with a GIS to those with established GIS operations—are eligible to participate in Community Update. Generally, applicants to the program should be local mapping authorities that require a street centerline layer as part of their core database and that have allocated personnel to maintain that layer.

According to John Auble, GDT's state and local government Business manager, "The goal is to create a system that improves any local government's ability to produce complete and accurate street centerline data. By providing professional data maintenance and distribution, Community Update will free governmental resources for the core tasks of applying spatial data to local planning and management tasks." Benefits of the program include access to state-of-the-art data management services, data distribution support with extensive GIS format and map projection options, and continuous data quality verification through GDT's commercial sector clients as they serve local communities.

The content of a Community Update data set begins with its street centerline layer, supporting geocoding and transportation routing. The database also includes a variety of reference layers such as landmarks, water, administrative boundaries, recreation areas and more. Other layers being considered for future implementation include point addresses, emergency service providers, fire response zones, and digital orthophoto quadrangle imagery.

In addition to using ArcIMS, participants may also submit edits for their geographic areas through conflation and offline editing. Conflation merges two data sets for the same area, combining the best geometry and attributes from each to create a superior end product. Offline editors use their own editing tools to revise data and then upload it to the Community Update server. ArcIMS allows agencies to participate without making great investments in GIS software and training—a solution for smaller municipalities.

Community Update actually includes two copies of the database: a "working" database and "active" database. The working database is the repository of all edits submitted by program participants. The active database incorporates all edits that have passed through GDT's quality control process; it is the source of all downloads. The two databases are routinely brought into synch on a state-by-state basis through a scheduled process that imputs final, verified changes.

Participating municipalities may make Community Update data available to their constituencies through a password-controlled download system. In this way, any legitimate user may access the full range of data within the geographic jurisdiction.

Every Community Update partner will manage a unique geographic extent such as a town, county, or a collection of towns within a region. Users may select multiple layers for downloading, with all data compressed into a single file for downloading. All files are in the GIS format and map projection chosen by the user.

For more information, contact John Auble, Community Update program (tel.: 800-331-7881, ext. 1751; e-mail: or visit

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