By Chris McCarthy, GIS Technician, Office of Mapping and Geographic Information, Loudoun County, Virginia

Loudoun County, Virginia, is located approximately 45 minutes northwest of Washington, D.C. The fastest growing county in the nation between 2000 and the present, this community of 260,000 spans from the Potomac River to the Appalachian Trail and is home to horse farms, historic villages, wineries, bustling towns, busy suburbs, and Washington Dulles International Airport. Loudoun is also home to a thriving high-tech industry; three-fourths of the world's Internet traffic flows through the county. America Online and MCI both have headquarters there.

Loudoun County began its GIS in 1987 when it purchased ArcInfo (site license number 34) and began creating digital parcel, soils, and floodplain data. Now based out of the Office of Mapping and Geographic Information (OMAGI), the enterprise-wide system has grown to include more than 100 data layers, including land records data (e.g., parcels, addresses), basemap data (topography, buildings, etc.), environmental features (e.g., floodplain, forest), and public safety information (police, fire, and rescue zones, etc.).

To keep up with advances in geospatial technology, Loudoun is in the process of migrating the management and storage of GIS data from ArcInfo Librarian to the ArcSDE geodatabase model. Over the years, the county has developed many tools and applications to serve the needs of the public, businesses, and county staff members using ARC Macro Language (AML). One frequently used tool was created for the Public Information Division of OMAGI. It allows users to query, perform basic analyses, and print maps and reports used in the submission of building permits and in land development assessments. As part of the transition, OMAGI looked to the ArcGIS Desktop application ArcMap to replace the existing tool and upgrade it to allow on-demand printing of 1:2,400-scale topographic, floodplain, soils, soils and floodplain, and mountainside overlay district maps.

The goals established at the beginning of the project create two graphic user interfaces (GUIs) to select and zoom to features and switch between map types, allow panning and centering to selected features by staff, standardize symbology between map types, and create a complete legend of symbols and a symbol style folder.

User-friendly GUIs were developed using ArcInfo software's integrated forms and Visual Basic for Applications to simplify querying and map type selection. Public Information manager Pam Ridgell says, "The map query and selection interface are quick and easy to use, and the map display in the layout has been helpful in showing customers their area of interest."

The GUIs are accessed through a toolbar. The first GUI allows the user to enter the feature of interest, and the second GUI allows staff members to select the type of map being requested. Three types of features can be queried by the tool: map tiles, tile and cell, and parcels. In the Librarian data structure, the entire county was divided into a series of 6,000 feet by 4,000 feet tiles used to manage and store data. The tile system also made it necessary for the original tool to print one tile at a time.

The conversion of the tiled data into individual countywide datasets allowed for the most significant advancement of the map tool. Instead of being constrained by tile boundaries, the Public Information staff can now pan and center to the customer's feature of interest. With the old tool, customers had to purchase additional maps if a feature of interest crossed a tile boundary. Ridgell states, "In most cases where parcels crossed multiple tiles, customers would have required several of the old, tile-based maps. With the new map tool, even parcels that cross at the corner of a tile can sometimes be mapped to just one or two maps. This has resulted in a cost savings for our customers."

In fiscal year 2004, 423 front-counter maps were printed at a cost of $10 each. Ridgell says, "Since the launch of the new tool in June 2005, customer requests can be fulfilled with nearly half the maps of the original program." If one-third of these maps are produced with the new map product, the public sees a cost savings of nearly $1,400. According to Larry Stipek, director of the Office of Mapping and Geographic Information, "We are always looking for ways to save our customers money. Our fees cover just the cost of reproducing the map."

The greatest effort in the development of the new product was in the creation of map symbols and the way the features of the map are displayed. More than 15 data layers and more than 25 symbols and labels are used on each type of map. Consistency was the goal. The county wanted a product that was representative of the original map layout but with improved symbology. Three sources were utilized in the symbol selection process: United States Geological Survey 1:24,000 quadrangle maps, U.S. Natural Resources Conservation Service soil survey maps, and the original Loudoun map products.

"Many of the symbols were developed piecemeal on the original map product as spatial data was developed and requested to be added to the application," recalls David Torraca, GIS manager. For example, spot elevations were represented by different size dots on the soils and floodplain maps. On the new maps, standard symbology used by government agencies with some enhancements in color and size has replaced arbitrary symbols used in the original tool. Symbology review and standardization enabled the development of a complete legend to be handed out to customers and has allowed GIS users to access public information tool map styles for use in other mapping projects.

Once development began, two added benefits were realized: creation of 11-inch by 17-inch versions of the maps and elimination of annotation maintenance by using labeling. These benefits were directly related to the adaptability of the layout and the control of labeling offered by ArcInfo.

The adaptability of the layout has enabled the development of a small version of the new map tool, meeting the needs of the many customers who only require a small size map to attach to a building permit. Giving the customers a 36-inch by 27-inch sheet of paper is unnecessary and wasteful, and the new process allows the use of an 11-inch by 17-inch printer, further reducing operational expenses associated with plotter paper and ink. In addition, the combination of continuous countywide GIS data and the labeling functionality within ArcInfo has meant that the maintenance of annotation of street names and route numbers could be eliminated. Data maintenance time savings have proven so valuable that other annotation layers are being considered for elimination as label fields are added to datasets.

Customer response to the new map products has been positive, with remarks made about cost savings and the improved, updated symbology. Since implementation, there are plans to add orthophoto imagery to the application from the county's recent basemap update. Incorporating new data layers will also be pursued.

For more information, contact Chris McCarthy, GIS technician, Loudoun County Office of Mapping and Geographic Information (e-mail: cmccart1@loudoun.gov).