As our nation becomes increasingly urbanized, the need for geographic mapping and asset management grows. Geographic information systems (GIS) have become essential tools for land and transportation planning, parcel identification, watershed modeling and infrastructure management. For most local governments below the state level, the need for geographic mapping coordination is critically existent-but the resources are not.
Prior to the rush of residential development, paper maps and drawings were adequate for the management of municipal systems. Now, digital data is capable of being created, stored, processed and analyzed by computers and software programs, replacing those paper resources. This new digital source has exponentially expanded the ability to analyze data rapidly in new and different ways. Results that took days to derive in the past can now be obtained almost instantly.
While technological advancement has become a priority in our society, and while GPS and GIS data, and remote satellite imagery are now available for widespread public access and use, a new concern exists: the need for new skills for operators. The capabilities that technology has created over the past 20 years surpass the experience level of many personnel working at the county and municipal level. While established governments in major urban areas can support the salaries of individuals specifically educated and trained in the skills required for these tasks, many developing counties lack the financial and organizational resources to hire personnel dedicated to the development and establishment of GIS. The rapid development and complexity of these new technologies has created a gap-vast amounts of precise information are now available, but end users lack the technical ability to transform it for practical applications.
This is the GIS dilemma.
From Rural to SuburbanLimestone County is located at the northernmost part of Alabama, directly below the Tennessee state line. The city of Athens is the county seat and population center. Athens is located halfway between Birmingham and Nashville along the Interstate 65 corridor. Proximity to this major north-south transportation artery spurred Athens' growth as the central node of Limestone County. The larger urban centers of Decatur, Florence and Huntsville all lie within a 40-mile radius of Athens and contribute additional influence for development.
Limestone County is like many other geographic areas caught in the transition from a rural/agricultural economy to an economy based on jobs and businesses that maintain our modern-day lifestyle. Today, the majority of employed residents are working in management, administration, sales and professional occupations. Agricultural occupations account for less than four percent of employment. With a projected population of 70,000 for the year 2005, Limestone County is just beginning to experience rapid growth. And like many other developing cities and counties, Athens/Limestone faces several challenges. In 2003, the local levels of government set a goal to implement a countywide GIS. The concept was to establish a system that would serve the governments of the city of Athens and Limestone County, law enforcement agencies, public works departments and utilities.
But there were a number of circumstances to overcome. The economic base of the county could not support the sizeable investment required to purchase hardware and software, or the salaries of qualified personnel dedicated to GIS tasks. Some of the participating agencies had existing databases. Many of the employees slated to be involved with the operation of the system had no prior experience with GIS. And finally, there was much diversity in the needs and operating methods of the participating entities.
With all these factors taken into consideration, the question became: Is there a cost-effective, affordable solution that will provide for the information needs of each participant and yet be integrated to serve the county as a whole?
GTAC Bridges the GapThe Geospatial Training and Application Center (GTAC) is a unique organization that provides solutions to the GIS dilemma at multiple levels within the state of Alabama. Based at the U.S. Space and Rocket Center in Huntsville, GTAC is operated as a not-for-profit agency of the state of Alabama. GTAC provides assistance to governmental agencies across the state with education and assistance in the design, implementation and management of GIS programs. The Center's multi-pronged approach to GIS includes education about emerging software and hardware options, strategies for technical issues and management, and hands-on experience with software, hardware, methodologies and applications. This assistance can be adapted to a variety of users, providing resources for individual towns as well as larger governmental and geographic areas.
The city of Athens contacted GTAC for assistance in September 2003. Chris Johnson, GISP, vice president of GTAC, created a unique solution for GIS development in Limestone County based on data and cost sharing, and guided the creation of a GIS consortium. One representative from each participating county and city agency, as well as from the other organizations involved in the GIS database, serves on the steering committee of the consortium. This team initiated a high-level needs analysis to guide future development efforts in the county. Members of the steering committee interviewed individual agencies and took inventory of existing data sets to assist in the development of a strategic plan. The goals of the project are to build a series of collaborative agreements between government agencies (local, state and federal) to develop and maintain a strategic plan for GIS technology, while identifying appropriate initiatives that encourage public agencies to share in the creation, use and maintenance of GIS data sets at the least possible cost. This, in turn, will provide citizens and other data users with easy access to the resource.
In July 2004, participating members signed a written Memorandum of Understanding that formally established the Athens/Limestone County GIS Consortium. The consortium's mission is the creation of a countywide GIS system in which each member is also part owner. The consortium acts as the central authority and owns the base geographic data. Costs of GIS development not specifically owned by the individual members, such as aerial mapping, are shared.
GTAC's major contribution to this project is coordination, oversight and support of the work done by the GIS steering committee and the Athens/Limestone County Consortium. GTAC also performed the initial assessment of facilities and data. To ensure that the goals and objectives of the development plan are met, GTAC continues to oversee the administration of the contract and advises the consortium on technical matters.
The Problem of Data AcquisitionTo create a functional GIS database, both base geographic information and mapping of existing facilities is required. Base geographic maps are derived from aerial surveys and generally include topography, transportation components (highways, local roads and railroads) and hydrographic elements (stream, rivers and lakes). The first step in the consortium's plan was to densify the geodetic control network throughout Limestone County. Lack of monumentation had been an issue for the surveying community. As a result of the densification plan, the surveyors of Barge, Waggoner, Sumner and Cannon established 75 new primary control monuments. In addition, 25 of the primary control monuments have an intervisible azimuth mark set to facilitate local surveying efforts. The new geodetic control network provided exceptional ground control for accurate acquisition of digital orthophotos. The 100 new survey control points were established using GPS static surveying techniques. Six dual-frequency GPS receivers where utilized in the survey field effort. This ensured that there were multiple base line solutions for each new survey control point. The raw GPS data was downloaded and post-processed daily in order to check base line accuracy. The 100 new control points were then "tied in" to existing NGS horizontal and vertical control located throughout Limestone County. The Cooperative CORS Station "GTAC" located at the U.S. Space and Rocket Center in Huntsville served as a base horizontal and vertical station.
Prior to the flight for the orthophotography, each primary control monument was targeted to show its location in the photography and to utilize it in the aerotriangulation and mapping process. Targeting at this magnitude far exceeds the standard for photo control. The comprehensive flyover of Limestone County will be completed in the fall of 2005, providing updated geographic information. Each member of the consortium is sharing in the cost of the aerial photogrammetry. Limestone County was successful in attaining NGS grant monies through the Alabama Height Modernization Grant Program, administered by the Alabama Department of Revenue, to subsidize the survey effort. Mapping of existing facilities and features, such as utility systems, must be acquired in the field and merged with the geographic base. Each individual participant is responsible for obtaining this information to establish the database.
One of the agencies involved in the project is the Water Services Department of Athens Utilities, which manages water and wastewater systems for the city of Athens and nearby areas, and serves approximately 14,700 customers. Athens Utilities also owns and operates gas and electric distribution systems. All of these essential utilities will be included in the Limestone/Athens GIS system.
Water Services faces several challenges in establishing its segment of the countywide database. In addition to the task of mapping existing systems features-lines, hydrants, valves, manholes and treatment plants-Water Services needs tools that will facilitate modeling and design of new sanitary sewer facilities. For mapping purposes, submeter grade GPS instruments are adequate, attaining horizontal positioning accuracy to approximately 3 feet. This accuracy is sufficient for water systems that are not dependent on grade and elevation for operation.
Sanitary sewer systems, however, depend on slope and elevation for proper flow and functioning. Knowing the exact elevation of pipe inverts and manholes is essential. Position information obtained with submeter systems would be grossly inadequate for these purposes. Survey grade instruments provide the precise horizontal and vertical information required for modeling and design tasks. They also function as mapping tools.
Both water and sanitary sewer system operations involve easements across private lands. Accurate location of property corners and boundaries in the field is essential to constructing new installations in exact planned and legal locations. For these tasks, survey grade instruments are also required.
Jonathan Bedsole, staff engineer for Water Services, was charged with developing a strategy to create and manage the GIS database for his department. Bedsole holds a bachelor's of science degree in civil engineering from Auburn University and had prior experience with asset management software for GIS applications. The current staffing profile of Water Services does not provide personnel that can assist him with these tasks, so he developed a strategy that will initially enable him to do it as an efficient one-man operation.
The Correct Tools to Meet Multiple ObjectivesBedsole's first step was acquiring the right instruments. As a municipal employee, he is bound to make major equipment purchases through a competitive public bid process. After extensive research into the features of products of a few manufacturers, Bedsole wrote a specification for instruments that would meet his criteria. The bid solicitation was posted at several municipal facilities and advertised in the local newspaper.
Hayes Instrument Company of Shelbyville, Tenn., was the successful bidder. Hayes supplied Bedsole with two systems, a Topcon (Livermore, Calif.) HiPer Lite GPS system and a GTS 235W wireless total station. The HiPer Lite GPS system is used for mapping existing facilities, functions that involve horizontal and vertical accuracy to within one-tenth of a foot, and establishing initial positions in the field with reference to the Alabama State Plane West coordinate system. The GTS 235W total station, which provides accuracy to within a few hundredths of a foot, is used for determining the precise locations of property corners, easement boundaries and pipe inverts on very flat grades.
These instruments offer several features that facilitate day-to-day use. All communications between the field computer and both survey systems are wireless. This eliminates specialized cables that might inadvertently be left at the office or damaged in the field. Both instruments share the same database, so Bedsole can switch between GPS and optical instruments as the situation demands. All data is seamlessly collected on one field computer, eliminating the cost of separate computers for each survey system. Using these instruments, Bedsole is building a location database for the systems under his jurisdiction.