GIS

INTRODUCTION

In October 1999, KYOVA Interstate Planning Commission began working on the formation of a transportation specific geographic information system, or a GIS-T.  The areas covered by the GIS include the HIATS (Huntington-Ironton Area Transportation Study) region and the outlying rural parts of Cabell and Wayne Counties, West Virginia and Lawrence County, Ohio.  The purpose of the GIS was to combine and display several different types of information to help increase the speed and efficiency at which the planning process progresses.  Planning tends to be a spatial process outside of the political realm.  When a project is considered or studied, it is studied as a location or place.  For this reason, GIS is supremely suited for aiding in the flow of information in the process.  Instead of searching tables, publications, or spread sheets for information, one can simply point and click on a computer monitor to where the project occurring, and depending on the quality of the database, find all the information they need in a fraction of the time.

THE SOFTWARE—ARCVIEW 3.2

KYOVA’s platform for developing the GIS is ArcView 3.2 produced by Environmental Systems Research Institute, Inc. (ESRI).  ArcView 3.2 is considered a mid-weight program in the GIS community.  It is excellent at displaying geographic information either digitally (i.e. on the computer’s monitor) or producing hard copy maps.  It uses vector topological structures; points, lines and polygons; which enable it to represent virtually any real world object or geographic feature in accurate coordinates.  Though it relies on vector topology, raster data, like aerial photography, can be incorporated in the system but not manipulated without extended software like ESRI’s Spatial Analyst or Image Analyst.

Despite a few shortcomings, ArcView is very useful in manipulating the geographic data that KYOVA uses.  It comes with several tools for manipulating a view of a map, selecting particular records and a recent addition, an advanced geoprocessing function that allows for advanced geospatial query and data manipulation.  ArcView also operates on a proprietary programming language called Avenue.  This object-based computer language is easy to learn and easy to manipulate.  If a tool in the ArcView interface needs the extra of function of another, it is simple to append the scripts and get the desired result from one tool.  One of the most significant advantages ArcView, from a data entry point-of-view, is the Theme Table.
 
ArcView uses primarily three kinds of files—a shapefile (.shp), which is the actual drawing, an index file (.shx) that links the shapefile to the data and the incorporation of a dBase file (.dbf) as the data carrier.  This dBase file is represented in ArcView as a Theme Table (Layers in ArcView are called Themes.  Each Theme represents one shapefile and each shapefile has a dBase file.  Therefore, the dBase files for a particular Theme is a Theme Table.).  The Theme Table can be manipulated much like a spreadsheet in ArcView.  A user can manually type in data cell-by-cell or given the right conditions, populate the fields with data from other tables or files.  A field calculator is also available to populate a field in several records in one operation.  Because of the dBase format, several other programs like Microsoft Access or Lotus can import the Theme Tables and their data. 

Another quality of ArcView is the relative easy at which it can handle geographic projections, the mathematical operations that turn a three dimensional object (the earth’s surface) to a two dimensional object (a map).  KYOVA’s situation is somewhat unique from our major benefactors (WVDOT and ODOT) in that we cross state lines.  Geographic data produced by state agencies or a consultant operating entirely within one state is often in a state-specific projection like Ohio State Plane South, North American Datum of 1927.  Obviously, some datasets for West Virginia would never be projected to this coordinate system.  For this reason, all datasets either produced or used by KYOVA are in basic decimal degrees.  Using decimal degrees as the base coordinates allows any dataset KYOVA uses, whether from Ohio or West Virginia, to overlay and display properly.  For reasons of positional accuracy, KYOVA uses a Universal Transverse Mercator Projection for Zone 17 north in the 1983 North American Datum.  However, our data is not locked into this coordinate system.  ArcView can project the data into a variety of standard projections and both North American datum’s commonly used.  If a dataset is received that is not in decimal degrees, it can be converted using the Projection Conversion Utility supplied with ArcView 3.2.

DATA SOURCES AND TYPES

 A GIS is unique in its ability to incorporate several different kinds of data on a variety of objects into one “location”.  This is good because often time’s, data comes from varied sources.  Data sources can range from hand-entered information to hyper-accurate maps produced using global positioning systems (GPS).  In our case, our budget forces us to avoid any costly forms of data.  Therefore the most accurate-for-the-money sources were sought out.
 
The first data acquired were base maps.  For this, the United Census Bureau was the obvious choice.  The Bureau produces a nation-wide database called the Topologically Integrated Geographic Encoding and Referencing system data, better known as TIGER/Line files.  TIGER files are phenomenal for their scale.  They contain loads of information and are available for any county in the United States.  The most efficient place to retrieve these files is from ESRI’s web site.  The TIGER files are already in a shapefile format and free to anyone.  There are several files for one county including road center lines, census blocks with demographic data and hydrological features, to name a few.  This was the main data source for Cabell and Wayne Counties.

Despite the breadth and acceptable accuracy of the TIGER files, they did need extra data to serve our purposes.  Information like ADT, function class and road conditions had to be entered by hand.  To save KYOVA time and extensive funding (not to mention verification and justification), the database was constructed with information from the West Virginia Department of Highways.  It contained the information needed and required several man-hours to incorporate it into ArcView.  However, the information is considered accurate and useful to planning purposes.

Ohio is another issue.  The Ohio Department of Transportation (ODOT) maintains an extensive GIS for all the counties in Ohio.  To have a complete KYOVA database, we needed the files for Lawrence County.  Rather than use TIGER files, we acquired the files for Lawrence County from the ODOT GIS division.  With some slight modification and data entry, they fit together quite well with the TIGER files.

*****For an extensive field description of West Virginia data, see Appendix 1.   For Ohio data, see the “Data Dictionary for the State Route Basic Road Inventory File as Referenced by ODOT’s Geographic Information System” (ODOT, 2-14-00).

DATA ENTRY AND STORAGE

The key to any low maintenance GIS is good data entry and a structured storage system from the onset of construction.  The ODOT database was not and never will be modified in form or function except for a projection conversion of the shapefiles.  The West Virginia database however, had to be created from scratch.  Rather then use a plain TIGER file, KYOVA designed its own format for the roads database.  By using the ODOT database as a template, the data was entered to a severely overhauled TIGER road database.  Several fields were added to contain the information (Appendix 1).  After restructuring the database, the actual data entry could begin.

The WVDOT inventory was created by actual field measurements on every state maintained road in Cabell and Wayne counties.  They generally started from the west or south, depending on the road, and continued east and north collecting information on every piece of road.  If something changed on the road (i.e. surface type, ADT, etc.), then a new record would be created in the database.  This method of collection and recording yields high amounts of data for virtually each foot of road.  This is also where the need for manual entry became apparent.  The TIGER files have a high degree of segmentation.  In fact, every time a TIGER line intersected with another line, regardless of feature, it would be segmented.  Due to the fact that the road inventory was not collected in this way, a simple process of joining could not be done even though the two shared common fields.  By using a simple method of measuring the length of road segment from the inventory then selecting those records in the ArcView database, the data was manually entered cell-by-cell or using the ArcView Field Calculator.  Though this activity is very time-consuming and opens several avenues for human error, it moves at a low steady pace allowing for quality control procedures to be performed simultaneously.  The information for Cabell and Wayne counties was designed to be easily manageable and understandable.

The same principle was considered for data storage as well.  A simple method was developed to store information for the tri-county area.  One folder was created that would house subfolders for each county and any special projects that would cross the county lines.  In each county folder, there are loose files that make up the bulk of the information for that county and subfolders that contain information of special data like TIP projects (Figure 1).  All of this information is stored on one drive that is accessible from a number of machines on KYOVA’s local area network (LAN).  To view or edit the data, each county has its own ArcView Project stored in the respective folder.  These are just general files for data querying or entry.  If a special project emerges and maps are needed for that project, then new ArcView Projects are created and stored in appropriate locations using the same layers as in the mother files.

Updates are also an important issue in GIS.  One fact of life about transportation planning that will aid in developing an update schedule is the long time frames of projects.  Roads, in general, do not change rapidly and new projects take years to go from the drawing board to reality.  Road inventories are generally performed on a two-year schedule.  This leaves ample time for updating the GIS with new data.  Projects, as well, once coded can be easily edited to show progress or completion.  The most dynamic aspect of the KYOVA GIS will be the updates to the TIP database.  New TIPs are received from West Virginia every month and Ohio every quarter.

EXPECTED PRODUCTS

By far, the most useful thing about a GIS is its versatility.  Given the right information, a GIS can aid in the decision-making and presentation of anything from new road construction to environmental justice issues.  The universal information forming the basis of KYOVA’s GIS will perform in such a manner.  By overlaying several datasets, KYOVA will be to visualize complex relationships between road construction and projects and demographic characteristics.  Or KYOVA will be able to graphically represent the location of TIP projects, something often missing in the planning process until the public involvement stages.

Another valuable product that can be easily produced is a traffic flow map.  In the past, this type of thematic map was difficult to create.  By utilizing the functional characteristics of ArcView’s Legend Editor, a traffic flow map (Figure 2) can be generated in a matter of minutes, given the correct data has been entered.   By using the Legend Editor to its fullest extent, the number of layers or themes in a project can be limited to as few as possible.  This same principal will be applies to the census blocks layers (blocks, block groups and tracts) to demonstrate distributions of poverty, unemployment, and minorities, all important to the transportation planning process.

One minor, but important, function of the GIS is the quick availability of information it provides.  KYOVA receives several calls requesting data on traffic counts, dates of projects, etc.  Before the inclusion of GIS to KYOVA, it could take personnel a considerable amount of time to locate this information.  The GIS centralizes this information and places it a mouse click away.  Data will be able to be given to the requested information at the time of the call, reducing the time a KYOVA staff member would have to spend searching through hard copies.  If the information could not be obtained by a simple point-and-click, database queries are possible in ArcView or the theme table could be opened and queried in a database program like Microsoft Access to achieve the desired results.

Jody Sigmon
Associate Planner/GIS
KYOVA Interstate Planning Commission
720 Fourth Avenue
Huntington, WV 25712
Phone: 304-529-3357
Fax: 304-529-7229
Email:Jsigmon@ntelos.net

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GIS Applications

There are currently three applications available on the HEPGIS interactive web site.  Users may switch between applications by clicking

http://hepgis.fhwa.dot.gov/hepgis_v2/GeneralInfo/Map.aspx

1. General Information - This application presents thematic maps of selected demographic characteristics from the 2000 decennial Census.  Current demographic themes include:

-          Median HH Income

-          Percent of families below poverty level

-          Percent Hispanic

-          Percent Black

-          Percent Native American

-          Percent Minority

-          Median Age of Population

-          Percent of HH owning one or more vehicles

-          Percent of workers taking public transit to work

-          Urban Clusters and Urbanized Areas

-          Urbanized Area Populations

 

2. Highway Information - This application presents thematic maps displaying characteristics for segments of the National Highway Planning Network (NHPN).  Current highway themes include:

-          The National Highway System

-          Highway Functional Classification

-          The Strategic Highway Network (STRAHNET)

-          Average Annual Daily Traffic (AADT)

 

 

Boundaries - This application displays the geographic relationships between various boundaries

used in metropolitan and statewide transportation planning.  Current boundaries that may be

displayed include:

-          2000 urban and urbanized areas (Census) 

-         1990 adjusted urbanized areas (FHWA) 

-          2000 metropolitan planning areas (FHWA) 

-          2000 places (Census)

-          2000 metropolitan statistical areas (OMB)

-          Federal and Tribal Lands

-          Air quality non-attainment and maintenance areas (EPA, FHWA)