IMPLEMENTATION OF A GIS AT THE
ILLINOIS DEPARTMENT OF TRANSPORTATION

Authors:	Hall, James P., Illinois Department of Transportation
		Paulis, Mary Ann, Illinois Department of Transportation
		Wright, James A., Illinois Department of Transportation
		Lindquist, Robert C., GIS Solutions, Inc.
		Romanelli, A. J., GIS Solutions, Inc.

To ensure Department-wide assimilation, the Illinois Department of 
Transportation (IDOT) has taken a formalized, structured approach in its 
implementation strategy for Geographic Information Systems (GIS).  The focus 
of GIS development has been not only on products to enhance existing 
functions, but also to provide a stable Department-wide geographic base to 
assimilate, integrate and display transportation information for organizational 
decision making purposes.

This paper describes the general strategy for GIS implementation in IDOT, the 
technical aspects of using ArcInfo as the GIS platform, current projects under 
development, and future strategy for GIS deployment.

To effectively manage the state’s transportation network, IDOT has recognized 
the necessity to integrate data from a variety of sources and provide 
summarized, strategic information in an easily understandable format for decision 
makers.  However, the disparity of multiple roadway references and the extent 
and diversity of legacy databases hindered this integration.  In 1985, the 
Department initiated a project to create a stable roadway link/node base which 
would provide the interfacing mechanism for roadway related information.  
Concurrently, IDOT upgraded its roadway, structure and railroad-highway grade 
crossing data files with a direct reference to this link/node base.

The source for the link/node base is IDOT’s 1:64,000 scale county map series 
tied to state plane coordinates.  The base is a centerline coverage of all state, 
county and township jurisdiction roadways.  Municipal routes were also included 
except residential streets.  The link/node base encompasses 224,000 digitized link 
segments representing over 107,000 miles.

This strategy has provided IDOT with the flexibility to provide multiple references 
to the GIS base.  The route systems that are interfaced to link/node and the data 
tied to link/node are stored on a mainframe computer.  Historical changes to the 
route systems are maintained.

This GIS development philosophy will enable the Department to provide a wide 
variety of GIS products to multiple areas using the same geographic base.  
The Department is currently verifying the inventory data on the file.

Almost all organization areas within the Department potentially have some use 
for GIS capabilities for any of their geographically referenced data.  Table 1 lists 
the major organizational areas with the greatest use for a functional GIS.  Table 
2 lists a sampling of Department applications.

	Design & Environment				
	Mapping
	Traffic Safety
	Statewide Program Planning
	Urban Program Planning
	Operations (Traffic and Maintenance)
	Physical Research
	Bridges
	Permits
	9 District Offices

	Accident Location and Analysis
	Multi-Year and Annual Program Development
	Ad Hoc Analysis
	Legislative and Executive Office Presentation Products
	Intelligent Mapping
	Data Verification
	Functional Classification Management
	Pavement Condition Mapping and Analysis
	Operations Work Assignments
	Corridor Analysis
	Project Impact Assessment
	Internet Roadway Condition Map
	Automated Routing for Permits
	Emergency Re-routing
	Flood Modeling
	Hazardous Materials Routing
	Pavement Management
	Bridge Management
	Congestion Management
	Safety Management
	Intermodal Management

The Department, in conjunction with technical expertise provided by GIS 
Solutions, Inc., has successfully integrated the link/node base with Department 
databases using ArcInfo software.  The Department collects and maintains a 
wide variety of data bases and map files to support these applications.  Most of 
the information that will be input into the Department’s GIS is stored on an IBM 
mainframe.  This data includes:

• The link/node coordinate data (graphic elements digitized in the CADD environment).
• Linear Route Systems tied to the link/node base.
• Attribute data such as road inventory, structure, rail crossing, accident and Highway Performance Monitoring System data.

GIS software provides the tools to integrate, analyze, display and query these 
data. For example, graphics representing roadway geometry have been 
maintained in the CADD environment, while attribute data associated with 
roadway segments (such as roadway condition rating, average annual daily 
traffic, pavement type, etc.) have been stored on a mainframe computer.  The 
establishment of a GIS, especially one with the ability to create and utilize routes 
and route systems for dynamic segmentation, greatly expands the Department’s 
ability to use the data that it has maintained throughout the years.  Now, data 
such as number of lanes, average annual daily traffic, or accidents can be 
placed onto linear features as events. The resulting benefits to planners, 
analysts, and cartographers are wide-ranging.  
 
Esri software products, ArcInfo and ArcView, have been the choice of the 
Department for GIS development. ArcInfo contains the tools necessary to 
generate coverages from CADD based graphics, to create relational database
files from mainframe data files, and to create the route systems and routes needed 
to dynamically segment event data as points or linear events onto routes.  ArcView 
is the software of choice for the majority of users who perform such varied tasks as:
determining rail crossings at which accidents have occurred or plotting a map of all 
multi-year program projects scheduled for a particular county in a specific year.

The major benefit of IDOT’s approach is the ability to maintain route systems and 
data on the mainframe.  This eliminates the need for Department personnel to 
enter and maintain route systems and data on the GIS servers.

Data conversion, generating coverages from the link/node graphics, and creating 
the INFO data files, from which to create route systems was the first task toward 
building a GIS data set.  The Arc Macro Language (AML) was used extensively 
for this purpose.  AML programs were written to:

• Convert the link/node coordinate data into coverages.
  This AML takes generate files formed from a conversion routine and their associated data files and creates an ArcInfo line coverage. It then joins the associated data file to the line coverage. Next, a node attribute table (NAT) is created based on the FROM and TO nodes of the link/node data. ARCSECTION is then run to create a “mini route system” that will later be used by the route system creation AMLs.

• Convert data files into INFO files.
  This AML is used to create INFO files from Department interface data files. These files are then imported into tables by the AML which creates an INFO file for each one.

• Create route systems

  								
IDOT has maintained a database of roadway information on a mainframe since the 1960’s.  
This database containing over 224,000 links was structured much like the ArcInfo coverage 
format (link/node), but without topology.  GIS Solutions, Inc. was contracted to convert the
database to ArcInfo coverage format, then looked at several methods of building route systems
on the coverages.  After experimenting with several of the out-of-the-box solutions for 
route system creation in conjunction with AML, all were decided to take far too long for 
general use.  GIS Solutions, Inc. and the IDOT technical computer staff worked together to 
devise a methodology for using the very fast ARCSECTION, EVENTSOURCE, and EVENTSECTION commands 
to generate a “mini-route system upon which the real route systems could be created.  The 
database mini-route system is then manipulated using tables commands (RESELECT, CALCULATE, SORT,
and PURGE) and arc commands (PULLITEMS, FREQUENCY, ADDITEM, JOINITEM) to turn a pair of INFO 
files into a route system (RAT and SEC tables).  By operating off of the databases that have 
been maintained over the years by IDOT and using that data to create the route systems, data 
processing times were dramatically dropped (i.e. four hours using traditional route system
creation tools, to five minutes using tabular data manipulation).  

Maintenance of the link/node base has historically been accomplished in the CADD environment.
However, since shifting to GIS, it was apparent that ArcInfo offered tools to make the task 
not only easier to accomplish, but also to avoid many of the inevitable errors that accompany 
digitizing and manual attribute editing.  An interface was developed to perform all link/node
maintenance tasks through a series of four threaded menus created with the Form Editor.  The 
functions provided are primarily those of Arcedit, and Arcplot, but also include provisions for
image registration to provide backgrounds for digitizing when appropriate.  The user invokes the 
interface as an ATOOL, and is then guided through the maintenance process (which includes both 
graphic and attribute updating).  Tolerances and snapping environments are pre-set depending 
upon the type of action selected by the user.  Attribute updating and error checking is done in 
a highly-automated fashion, eliminating much of the key input which had been previously 
necessary.  

For the general user community within the Department, the software of choice is 
ArcView.  Numerous display, query, and analysis functions are available to users 
through a series of customized graphical user interfaces.  Like any large 
organization which utilizes GIS, IDOT employs users whose GIS skills and needs 
vary from “occasional/focused-on-one-task” to “daily/wide-variety-of-tasks”.  
Consequently, the ArcView interface has been customized to suit various needs.  
A number of specialized menu options, buttons and tools have been 
incorporated into prototype projects to suit specific needs such as updating 
winter roadway snow conditions on some regular schedule,  displaying critical 
environmental themes relative to proposed roadway alignments, or displaying 
high accident intersections.  

The Department, after evaluating preliminary prototype GIS products, initiated 
the development of three extensive GIS applications:  a GIS demonstration 
package, a roadway program development tool and a roadway condition map.

The Department, in conjunction with GIS Solutions, Inc., undertook the 
development of an extensive GIS demonstration package in ArcView.  The 
purpose of this demonstration package (demo) is to raise the level of 
understanding throughout the Department of ArcInfo and ArcView GIS 
capabilities and the potential applicability to the Department at various 
organizational levels.

The focus of this demo is at three broad levels of detail:  statewide for the 
interstate network, one District (15 counties) for the state highway network, and 
several individual counties which incorporate the local agency highway networks.  
Different applications were included at each of these levels to demonstrate 
capabilities.  The development group refined the demo to reflect comments of 
focus groups for interested areas.  Table 3 summarizes the broad applications 
eventually incorporated into the demo.  The group designed the demo to run on 
ArcView 2.1 and on a Pentium class portable computer to ensure flexibility in 
presentation. The demo emphasizes speed with canned sequences providing 
immediate access through buttons and drop down menus, yet allows flexibility to 
answer individual queries with displays and plots and provides opportunities to 
expand the presentation towards specific areas of interest.

Statewide

	Interstate Roadway Network
	District Offices
	Roadway Condition
	Legislative Districts

District

	Detailed Roadway Information
	Airports, Ports, Railroad lines and stations
	Illinois Department of Natural Resources Information
	Multi-year Program Information
	Aerial Photography

County

	State and Local Agency Roadway Information
	Railroad Crossing with photos
	Bridges
	Accidents
	Natural Resource Information
	Roadway video images
	Accident analysis and query tools
	Scanned in paper maps
	Census Data
	Corporate Limits


The Department usually shows the demo to groups of 5 or less on an individual 
screen; however presentation have been made to groups of up to 500 
individuals.  Length of the demo ranged from 20 minutes to 2 hours with 45 
minutes on average.

The demonstration package has been an effective tool to raise Department-wide 
understanding of the capabilities and potentialities of GIS.  This provides a basis 
where an individual organizational area can determine real applications in order 
to quantify benefits.

The Department has also used the demonstration package to show external 
organizations, such as other state agencies, local agencies and special interest 
groups, the direction of its GIS implementation.

The first major GIS product selected for development is a Program Development 
tool.  IDOT annually develops and publishes an Annual and a Multi-Year 
Program for roadway improvements.  The development of these Programs 
involve information on roadway condition, traffic levels, traffic capacity, 
accident history, bridge condition and economic development.  This 
programming process also requires extensive communication between the 
Districts and Central Bureaus on specific aspects such as project limits, scope 
and funding options.

The GIS Program Development tool is being developed in ArcView to facilitate 
ease of use at the roadway programmer level at both the District and Central 
Office.  It incorporates program-relevant information from the roadway, structure, 
railroad crossing inventory files and the accident history file.  It also includes data 
from the Multi-Year and Annual program files.

The ArcView interface has been modified by the addition of a menu selection 
incorporating a number of menu items.  Multi-Year and Annual program 
information is held in three files.  One contains information about the roadway 
name, the segment of roadway to be addressed in some fashion and the location 
of any affected structures, a second is a 2,400 byte file containing information 
about the project (costs, improvement type, program year, etc.), and a third file 
relates to  roadway inventory data.  It is useful to display spatial locations and 
relationships of projects to other projects and to other geographic features such 
as highway districts.  This is accomplished by adding an event theme in ArcView.  
The roadway stationing of the roadway project can be used to place a new 
theme in the ArcView project which illustrates linear or point location of Annual or 
Multi-Year projects.  An ArcView JOIN can be performed, joining the shape 
theme attribute table to the file containing detailed information about the roadway 
project.  Finally, the user may LINK this table to the table containing roadway 
inventory data in order to get a complete picture of the project.  Specialized 
query functions and an easy-to-use mapping menu choice have been built into 
the ArcView project to enable users to perform common queries, and to produce 
maps without the necessity of knowing a great deal about ArcView.


In the program development process, key information must be readily 
transferred.  The mapping capabilities of the GIS will provide the ad hoc access 
to information in a readily understandable format.  This project has a high 
potential for payoff at the program development level and at the executive level.

Finally, the Department, even before the availability of ArcView Internet Map 
Server (IMS) or the MapObjects  Internet Map Server (IMS), has used ArcView 
to enable the placement of winter time roadway snow conditions onto the 
Internet, in map form.  During the winter, when weather conditions warrant, 
roadway conditions are updated every two hours.  This information is sent to 
ArcView, a roadway theme is automatically updated, a new layout is created, the 
layout is rasterized and finally served on the Internet in gif format.   Future 
options include consideration of an IMS to provide more flexible information, that 
is dynamic rather than static, to the public.

The Department will direct GIS implementation towards high benefit applications, 
especially those that have an immediate impact on operations.  The Department 
is determining the best method on which to prioritize those applications.

The present strategy is to develop packages of ArcView applications focused on 
specific user areas.  The priority of package development will be based on a 
cost/benefit analysis of the potential application looking specifically at time 
savings and the benefits of more informed decision making.  Emphasis is placed 
on using existing geographic related databases to the largest extent possible to 
avoid large scale system changes.

The capabilities of ArcInfo and ArcView have provided a solid base to 
develop GIS products using existing Department information system 
infrastructure.  IDOT is continuing its efforts to use GIS technology to promote 
efficiencies.