What is a geographic information system (GIS)?
A GIS stores maps and files layers of information in a way that makes it possible to perform complex analyses. For example, a GIS user can query a specific location, object, or area on the screen to retrieve recorded information about it from off-screen files. A GIS can also recognize and analyze the spatial relationships among mapped phenomena to determine adjacency (what is next to what), containment (what is enclosed by what), and proximity (how close something is to something else). It is also possible to assign values such as direction and speed to simulate movement through a network. GIS also has the ability to produce graphics on the screen or on paper that convey the results of analysis to people who have input to and make decisions about resources.
Some of the many broad uses of GIS include:
Mapmaking - Incorporating the mapmaking experience of traditional cartographers into GIS technology for the automated production of maps.
Site Selection - Analysis of multiple physical factors when they must be considered and integrated over a large area.
Emergency Response Planning - Analysis of the impacts of natural disasters on surface structures, size of affected populations, and emergency response time and available routes.
Simulating Environmental Effects - Realistic, three-dimensional "before and after" perspective views of the environmental impacts of a given project.
Source: Geographic Information Systems, U.S. Department of the Interior, U.S. Geological Survey
Why is it useful?
GIS provides a richness of data that is unlike traditional paper maps. Complex information can be presented graphically in one place. In addition, GIS maps will typically have more depth of information. For example, while a paper map may show where toxic sites are located, a GIS map of the same information will often be backed up by a full database of information on those toxic sites. Information from a GIS may also be more current than a paper map. While paper maps may be updated on a regular schedule (e.g., annually), recent satellite or aerial photos could be digitized for GIS use to create "up to the minute" maps of an area.
GIS offers public involvement professionals flexibility in displaying information. Users determine how and at what levels associated information is displayed. As a result, maps can be quickly customized to a particular purpose. Maps can also be used interactively with the public to gather input and display the possible scenarios resulting from that input in a real-time setting.
GIS also allows conditions to be analyzed over time. For example, the San Diego Association of Governments (SANDAG) has been using GIS for over 25 years to assist in regional and local planning efforts. By working with its partners, SANDAG has developed cost efficient techniques to update its land use database on a regular schedule. SANDAG's GIS website also offers interactive maps that can be customized to demographic, economic, transportation, and trans-border themes; downloadable GIS files, and access to printed maps.
Does it have special uses?
GIS can be used in participatory/collaborative mapping. For example, practitioners and community residents can collaboratively sketch community boundaries, as seen by local residents and identify important community assets and liabilities (e.g., cultural resources, historic sites, toxic sites). GIS also supports "what-if" scenario planning. Mapping of roads, bus routes, pedestrian paths and bikeways commonly can help assess those used and/or preferred by local residents. The results can be overlaid with current and proposed transportation projects for a quick snapshot of potential impacts and can be ultimately integrated with new projects. The following example shows the results of a GIS analysis done by the Orange County (CA) Transportation Authority (OCTA) to determine what effect a proposed change in bus service would have on accessibility to the new service. OCTA used a variety of information, including population density, land use, and "catchment" areas (i.e., the area from which potential riders would be willing to walk to and from the stop) to develop this analysis. The first figure shows population accessible to the existing bus system. The second shows the change in accessibility based on a proposed change. Additional examples from OCTA can be found in FHWA's Toolbox for Regional Policy analysis, Orange County Case Study, http://www.fhwa.dot.gov/planning/toolbox/orange_overview.htm.
A GIS can be used to survey residents about their local environments (cross-link to section in guide on surveys). For example, the National Science Foundation has funded a project at the University of Illinois at Urbana-Champaign to help in understanding of elements of local environments that are important to people's lives. Through a face-to-face interview, participants are asked to assess perceptions about a neighborhood's boundaries, services, strengths and assets, problems and deficiencies. The interview uses a GIS interactively to plot responses on a map and prompt follow-up questions, as well as to present study findings.
GIS also provides information to citizens about community information, services, and projects. On its community Web pages, the City of Vancouver hosts a "Projects and Construction" section that includes information about city initiatives, projects, development proposals, construction and roadwork. Information is searchable by community, department, project type, street name or location, and project dates. This information is also mapped using VanMap, a city-wide map application that also provides information on property lines, zoning information, sewer and mains, addresses, and public places.
Other examples of GIS used to provide information to the public include:
"Seattle's Neighborhoods - A Graphical Guide to Services and Activities" maps neighborhoods by census tract. It provides information on City of Seattle services within tracts, as well as brief demographic information.
North Central Texas COG Transportation Improvement Program Information System provides information about transportation improvement plan projects in the Dallas-Ft. Worth metropolitan planning area through an interactive map.
The EPA Enviromapper maps various types of environmental information, including air releases, drinking water, toxic releases, hazardous wastes, water discharge permits, and Superfund sites. Maps can be created at the national, state, and county levels.
Who participates? And how?
GIS can be used interactively with participants at public meetings, open houses, and small group meeting. Practitioners may engage participants as a group or in a one-to-one setting. In addition, the GIS tool could be set up as a stand-alone interactive display for meeting participants to review and comment on proposed plans or analysis. GIS products could also be part of interim and final project or plan documents.
A GIS tool can also be part of a website. Like many of the community information services described in the preceding section, individuals who are computer-oriented are most likely to participate. Usage would be limited to those with access to computers and Internet connections. However, the public would have the convenience of accessing information from their homes at any time. Agencies must publicize the availability of on-line material. (See On-line Services)
A GIS may also be available for plan or text mark-up software. For example, GIS images of proposed routes or service corridors may be placed on a website and through appropriate mark-up software, the public would be able to comment from remote locations at prescribed review cycles.
How do agencies use the output?
Agencies can use GIS to gather community reaction and obtain community opinion on projects and plans. Through GIS, agencies may gain a better understanding of importance of neighborhood/community elements to public. GIS may also assist with joint decision-making and empathy building. Interactively mapping scenarios can help all parties better understand each other's interests and concerns.
Also, because of the electronic interchangeability of the GIS data files, agencies may save time and resources once a final concept is approved by using the same materials for the next stages of the project or plan development using materials developed, in part, for public involvement purposes.
What are the costs?
Costs to implement GIS systems may be high depending on the strategic interest and information technology resources of the agency. In some cases, a project may already have a GIS component. In addition, agencies may have the necessary hardware and software, as well as professionals trained in GIS on staff and available to assist in its use for public involvement. If not, staff training or hiring consultants may be necessary.
GIS does involve a substantial time commitment on the part of the agency. Depending on data sources available, maps may have to be generated for intended purposes. In most case, information for public display would need to be customized to the particular project.
If a GIS is to be available via the Internet, some type of outreach may be beneficial to advertise the service and ensure return on investment. In addition, set-up and/or licensing costs may apply.
How is it used with other techniques?
GIS can be used to:
What are the drawbacks?
As mentioned above, cost and training may be a drawback to using GIS. If the hardware, software, and personnel capabilities do not exist in the agency, or are not being currently employed on the project, significant costs can be incurred to purchase computer equipment and train staff, or hire consulting expertise. The availability of datasets and compatibility of data may also impact the cost of using GIS.
Because of its electronic format, GIS has the potential for mass media appeal and distribution. However, agencies must take care to ensure that false impressions are minimized through accurate representations.
If a GIS tool is to be web-based, project staff needs to consider that the use of on-line services is limited due to access, expense, and skill. As a result, web-based GIS should be used with other public involvement techniques (i.e., meetings, other on-line services).
When is it used most effectively?
GIS is most effective when there is:
A need to convey complex information graphically;
Information that can be tailored to particular users or audiences; and
Support or complementarities from other public involvement techniques.
For further information:
San Diego Association of Governments GIS Resources
http://www.sandag.org/index.asp?classid=21&fuseaction=home.classhome
FHWA's Toolbox for Regional Policy Analysis, Orange County Case Study
http://www.fhwa.dot.gov/planning/toolbox/orange_overview.htm
FHWA's Toolbox for Regional Policy Analysis, San Francisco Case Study
http://www.fhwa.dot.gov/planning/toolbox/sanfrancisco_overview.htm
FHWA Transportation Case Studies in GIS
http://tmip.fhwa.dot.gov/clearinghouse/docs/gis
"Neighborhood Evaluation using GIS", Dr. Emily Talen, University of Illinois at Urbana-Champaign
http://www.urban.uiuc.edu/faculty/talen/GISweb/summary.html
City of Vancouver, communityWEBpages
http://www.city.vancouver.bc.ca/community_profiles/index.htm
"Seattle's Neighborhoods - A Graphical Guide to Services and Activities"
http://www.pan.ci.seattle.wa.us/don/neighmap.htm
North Central Texas COG Transportation Improvement Program Information System
http://dfwinfo.com/trans/tipins/index.html
EPA Enviromapper
http://maps.epa.gov/enviromapper/
Community University Regional Consortium for Regional Environmental Justice
http://www.danj.org/~gelobter/cucrej
Integrated Approaches to Participatory Development
http://www.iapad.org/
Hillsborough Project
http://www.eos.ncsu.edu/eos/info/ce400_info/roundabout/index.html
