Fairfax County, Virginia, Puts Enterprise GIS Online

Fairfax County, Virginia, now has its enterprise GIS online and in use by the County agencies and the public. The current system is the product of more than 17 years of research, planning, and overcoming the economic cycle challenges of the early '90s. It is built on Esri enterprise products to serve the County's GIS needs.

From the first requirements study of GIS in the mid '80s until the present, an increasingly in-depth and comprehensive GIS has been developed. The first controlled aerial photography was flown for the purposes of creating an accurate land base for Fairfax in 1990. Ongoing planning and analysis was conducted for the GIS and, in 1995, Fairfax developed its large-area (small-scale) GIS and published a CD-ROM containing the data. Based on that success, a Request for Proposal (RFP) to create a detailed photogrammetric and cadastral land base was issued. That work is now complete and is accessible online.

Originally, the system was to be UNIX-based and run on different and separate workstations than the standard County desktop systems. Additionally, the software would not have handled the vast quantity of County data within an acceptable response time. Fortunately, today the adoption of ArcSDE has provided dramatic improvements in response time. Web-enabled GIS has also dramatically changed the cost and ability to serve virtually all County employees and residents.

"In the past three years, new tools and techniques have helped us implement GIS initiatives in a more cost-effective manner," said Tom Conry, GIS branch manager. "The use of Web browsers as front ends for both internal employee users and external constituents has significantly reduced the investment in software and hardware."

The County's current environment is made up of a heterogeneous system ranging from laptops to mainframes. The typical end user accesses the GIS through a standard desktop PC using a Web browser to run ArcInfo, ArcView GIS, or MapObjects applications residing on a high-end application server.

With several hundred remote offices and potentially a thousand or more casual users, Fairfax is implementing a server-based computing model for distributing the GIS technology. This model consists of a three-tiered approach.

In the first tier are "professional" users that perform daily edits to the GIS database as well as intensive interactive tasks such as 3D modeling. They access high-end Windows NT workstations from their local CPU.

In the second tier are "intermediate" users that perform typical display, query, analysis, and mapping tasks. They use normal desktop PCs that access a Windows NT Citrix server. By accessing the Citrix server, virtually all processing and data transfer tasks are performed on a farm of application servers. Since all data transfers occur between the application server farm, the file server, and the Oracle database server, the requirement for a high bandwidth network is limited to the computer room where the application, data, and file servers are located. The only network traffic that occurs between the client and the application server farm are screen scrapes and mouse clicks, which require about 10k of network bandwidth.

In the third tier are "casual" users that use either very generic data browsers or highly customized and easy-to-use applications. They use normal desktop PCs that will access either the Citrix application server farm or theMapObjects Internet Map Server farm.

The data warehouse is contained in Oracle and uses ArcSDE to manage the spatial features. The database contains both raster and vector information.

The data warehouse houses more than 300 GB of raster data. The raster data consists of color digital orthoimagery. The digital orthoimagery has a resolution of one-half foot and covers all 399 square miles of the County, and it is updated on a four-year cycle. Every other year the entire County is flown and a quarter of the images are updated annually. MrSID, by LizardTech, is used for image compression.

The data warehouse contains 10+ GB of vector data. The vector data comprises more than 30 million data elements in more than 100 data layers. The vector data consists of property information-320,000 parcels, 340,000 addresses, and 11,000 subdivisions; planimetric information—600,000 contour lines, 4,000 miles of roads, 3,000 miles of waterways, and 250,000 buildings; and thematic information-school attendance areas, public facilities, and fire response zones.

The property and zoning data layers are maintained daily. A custom editing application was developed in ArcInfo 8. There are seven technicians that concurrently update the database.

Metadata is being maintained for all data layers. The software Fairfax County has chosen to use is SMMS. This software maintains all the metadata in a Microsoft Access database. This automatically generates an FGDC-compliant output for display on the Web site and to accompany data when it is distributed.

The GIS staff has provided training to County agencies on GIS tools for more than four years. The current curriculum consists of three distinct classes that are designed to take potential GIS users from an introduction to GIS to performing GIS analysis with ArcView GIS. The Fairfax County GIS Overview class introduces new users to GIS and the County's Web GIS applications. This half-day presentation is offered on a monthly basis. Users wishing to perform basic GIS analysis take the Basics of ArcView GIS class offered by Esri on their Virtual Campus. The skills from this class are a prerequisite to the County's two-day Using ArcView GIS with County Data class. This class features exercises utilizing Fairfax County's data warehouse. Customized overviews and ArcView GIS courses are prepared for specific agencies, depending on their interest and need.

Now that an enterprise set of data is available that has the level of detail and accuracy needed for many County operations, the demand for both the data and the applications to simplify and customize the use of the data is increasing rapidly. The GIS branch, using the Department of Information Technology guidelines, has developed an application development framework for all GIS projects.

"Fairfax County's investment in GIS is providing major benefits to our users. Reductions in expenses, more efficient routing, and time savings using spatial analysis are allowing our local government to provide better services to constituents in a more efficient manner," said Gordon Jarratt, director of the Enterprise Systems Division.

With more and more users becoming increasingly proficient in the use of the software and having access to the digital data, Business processes have been made more efficient. Business process redesign has now become part of the application process by every department that utilizes the data. With all of this data, process and tasks that previously were only in tabular form and within many different mainframe file structures can now be accomplished through the GIS. By doing this the staff of Fairfax County can respond better to the needs of the citizens of the County. The Department of Taxation, Fire and Rescue Services, and the Police Department have incorporated GIS data within their applications. Environmental offices such as Urban Forestry and Gypsy Moth have also used the GIS for special studies. The Department of Planning and Zoning regularly and heavily use GIS in their operations. Digital orthophoto imagery is reducing field check time of a number of agencies.

There are many uses and applications that are being incorporated into Business processes within the GIS and Mapping section. A parcel maintenance application is used to aid in the update of Fairfax County's parcel map. Up until now, this map has been maintained by the pen and ink method. With the aid of ArcSDE and ArcInfo 8, the County is making updates as the data comes in, therefore keeping the data more up-to-date. The Board of Equalization application provides an interface for the real estate appraisers (both residential and commercial) to locate and print maps to help visually support their decisions. This application accesses the Department of Taxation database in conjunction with the GIS data to provide the appraiser with the ability to see spatially what has only been available in tabular form. There will be many more applications and more data sets in the future.

For more information, contact Robert Shankman; Fairfax County, Virginia; (tel.: 703-324-3516, fax: 703-324-3937, e-mail: robert.shankman@co.fairfax.va.us).

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