Highways are vital to our economy. We depend on them to transport people and goods from one place to another across vast distances and over all kinds of terrain. It should be no surprise that one of the largest agencies within each state government office is its Department of Transportation (DOT).

Our highway infrastructure consists not only of streets, roads and highways but also includes bridges, drainage structures along roads, traffic signals and signs, roadway lighting, and other related structures. Highway infrastructure components are spatial assets, meaning they have a geographically well-defined location. Consequently, their inventory and management is perfectly suited to take advantage of GIS technologies.

In this article we examine how Maryland State Highway Administration (SHA) uses GIS at the enterprise level and what initiatives it is looking to embrace over the coming years.

Background on SHA

The Maryland State Highway Administration is responsible for a vast highway infrastructure that consists of over 17,000 long lane-miles of interstate, primary and secondary roads; over 2,500 bridges; and thousands of highway drainage, sign and lighting structures.

In addition to designing and constructing highways and associated structures, the Administration is responsible for clearing snow and hazardous spills from the State's roads, and ensuring that procedures and processes they use are friendly to the environment.

To give you a sense of the size of the Administration, here are some statistics:

SHA employs approximately 3,200 people;

In addition to its headquarters in Baltimore, Maryland and the Offices of Maintenance, and Traffic and Safety in Hanover, Maryland, SHA maintains seven District Offices throughout the state;

Its various offices include Construction, Environmental Design, Equal Opportunity, Communications, Highway Policy and Technology Utilization, Planning and Preliminary Engineering, Highway Development and Bridge Development as well as the offices of Real Estate, Finance and Information Technology, Legal Counsel and Administration;

SHA serves all 23 counties in the state of Maryland;

Office of Traffic and Safety designs approximately 400 traffic signal projects annually;

SHA spends approximately $120 million annually on consultant services;

In addition to the Materials and Technology Lab in Brooklandville for testing and investigating construction and maintenance materials, SHA maintains four regional labs throughout the state.

Highway Location Reference Standard

SHA recognized early on that if it were to manage its ever-growing network of highways and associated structures, it must acquire and implement software to facilitate the process. Consequently, a division named Highway Information Services Division (HISD) was created to maintain a map of the State's highways along with an electronic infrastructure that would enable it to integrate databases describing highway-related assets.

When it began creating maps electronically in the late 1980s/early 1990s, SHA adopted Intergraph's MGE (MicroStation Geographic Environment) software as its GIS solution. MGE was selected because of its file format compatibility with MicroStation, the organization's standard CAD platform. All digitally generated maps published by SHA continue to be created to this day in the MicroStation DGN file format.

In 1994 a new GIS Team was created within HISD to coordinate the integration of vital enterprise databases, such as the Traffic Monitoring System (TMS) and Pavement Management System (PMS), within the GIS environment. The team reviewed the use of GIS both within SHA and the industry at large. It made a recommendation that SHA adopt the ESRI ArcInfo and ArcView product line for its GIS needs. In 1996, SHA made a significant investment in ESRI GIS products.

There are two methods in which to spatially locate features within GIS: point coordinates and location reference. In the former method a point is spatially located on a map by its coordinates. In the latter method a point is located in relation to a linear feature, such as a mile point on a specific highway. Because a highway is the primary focus of SHA, and highways are linear themes, the organization has standardized on a linear location-referencing standard.

This means that to spatially enable a database so that its records can be displayed on a map in the SHA GIS system as points or lines, the database administrator must create a location reference field consistent with the appropriate syntax. The location reference field includes county, route number and mile point information.

Present GIS Infrastructure

The SHA GIS Team is made up of the Mapping Section and the GIS Section. The Mapping Section Manager Greg Cooley has been with the state for over 20 years and is responsible for overseeing the publishing of nearly 300 maps. The Section publishes 1:100,000 scale county maps, 1:24,000 scale grid maps and town maps.

The maps are drawn in MicroStation and include road names, route shields, and a large number of natural and cultural features. ArcView is capable of using these maps as a background to add visual detail to the roadway network.

The GIS Section takes the linework prepared by the Mapping Section and imports it along with any additional GPS data in ArcInfo where proper milepoint attributes are assigned allowing the system to perform dynamic segmentation. The line work from the grid maps was the initial basis for the route network and has since been corrected through the use of GPS data.

Hardware and Software

The GIS hardware infrastructure consists of an application server, a file server and an enterprise GIS database server running Oracle 8.3. This hardware infrastructure resides in the server room at Information Technology Division, but is maintained and operated by HISD.

We felt it was important for us to retain maintenance and operational responsibility of the GIS application, file and database servers because of the unique nature of spatial data and its storage and processing needs, says Jack Martin, Assistant Division Chief, GIS and Mapping Teams.

The software used by SHA includes nearly a dozen licenses of ArcInfo running on Windows NT. This full-blown GIS software is used by the GIS Team to create and maintain GIS data such as ArcInfo coverages and ArcView shape files. Other SHA Offices and Divisions also use the software to create and maintain spatial data.

The Mapping Section uses MicroStation/J from Bentley Systems to create and maintain the highway reference graphics. The 400+ licenses of ArcView are spread throughout the various SHA Offices and Districts. These licenses are used primarily by end users to display ArcInfo coverages, ArcView shape files, and MicroStation DGN map files as a backdrop to their own dataset.

Databases

Oracle RDBMS is used to store copies of enterprise-scope databases developed and maintained by user Divisions. Following is a list of the databases maintained on the enterprise GIS server:

Highway Performance Monitoring System

Bridge Inventory

Pavement Inventory and Condition Data

Accident Data

Traffic Control Device Inventory

Highway Needs Data

Extra Lands Data

These databases are spatially enabled using County route and milepoint and can be mapped by applying dynamic segmentation to the ArcInfo routes.

Applications

Soon after initiating the adoption of ESRI GIS products, SHA invested in the development of a custom ArcView software called the SHA GIS Data Viewer. The purpose of the software is to provide users with graphical front-end access to the enterprise GIS databases listed above. The software is written in AVENUE and is compatible with ArcView 3.2.

With the availability of GIS data, many divisions have taken advantage of it. Some of the more significant applications in use at SHA includes: the use of SHA GIS Data Viewer application to pull up property ownership maps; superimposition of aerial imagery on maps for proposed roadway studies; study of accident patterns at roadway intersections; and mapping of the most current data from the databases listed above using dynamic segmentation in addition to about 60 other data themes.

SHA recently made the maps developed by its Mapping Team available on the Internet. The maps may be found by browsing the site:

http://www.marylandroads.com/oppe/dprindex.htm

SHA uses Intergraph's Digital Print Room technology at this site. Working with maps at the site requires a free browser plug-in download to view, print, zoom and pan the maps online.

The Mapping Section is presently engaged in editing the County Maps so that features do not cross over county boundaries. This will allow users to view multiple counties without encountering duplicate elements along county boundaries.

Plans for the Future

Most GIS users at SHA have ArcView installed on their computers along with the basic set of state map files. This data set is approximately 350 MB in size. It is stored on the client computer to reduce network traffic and keep the software responsive. ArcView is a fat client, meaning it requires a powerful computer and the bulk of the processing is performed locally on the client machine.

Web-Based GIS Initiative

SHA recognizes the benefits of Web-based GIS: thin client, no software installation except a Web browser, and easy to use interface for most queries. Consequently, new GIS application development at many Divisions is Web-based.

When the Traffic Engineering Design Division at the Office of Traffic and Safety wanted to make its database of traffic signal plans available to users via a map-based interface, Morteza Tadayon, Team Leader for the Division's Systems Engineering Team decided that the application should be Web-based. ESRI's ArcIMS (Internet Map Server) running in conjunction with Microsoft's Internet Information Server was selected as the development platform. The beta version of the Signal Plan Locator software was completed recently.

We are convinced of the value a Web-based GIS interface for traffic engineering-related data provides our engineers and designers; our future GIS application development efforts will continue to take advantage of it, says Barry King, Chief, Traffic Engineering Design Division.

Outside of the GIS Team at SHA headquarters in Baltimore, Maryland, CHART - an acronym for Coordinated Highways Action Response Team - has the largest GIS development initiative at SHA. CHART is responsible for monitoring and improving real-time operations and responsiveness to traffic and highway emergency conditions. Additional information about CHART is at the Website:

http://www.chart.state.md.us

ArcSDE (Spatial Data Engine)

As was alluded to earlier, GIS datasets at SHA are in several formats: ArcInfo coverages, ArcView shape files, MicroStation DGN files, aerial images, Oracle tables, and Microsoft Access databases. These are created and maintained by various Offices and Divisions at SHA and by several other state agencies. The GIS Section imports a copy of the databases on a regular basis on its Enterprise GIS Oracle database server.

ArcSDE from ESRI is a technology to manage spatial databases that are maintained by multiple users. Of the four supported RDBMS systems, SHA is using Oracle because that platform is already in place within the organization. ESRI also has the product ArcSDE for Coverages to enable it to serve up file-based data to its desktop products (ArcView, ArcEditor, ArcInfo) and ArcIMS. Presently, SHA has no plans to use SDE for Coverages. SHA intends to convert its ArcInfo dynamic segmentation route coverages into SDE measured layers to do dynamic segmentation over the next year or so.

ArcSDE supports long transactions, alternate versions, and history to manage spatial databases. It implements an object-based development environment that allows developers to associate rules of behavior to images, networks, and features with integrated topology and shared geometry. It supports RDBMS systems, such as Oracle Spatial, that define a spatial field data types to store GIS data and integrates the spatial (geometric) search capability provided by the DBMS vendors within the ArcGIS client software applications.

SHA likes what ArcSDE promises and is beginning a pilot research project to investigate the technology before incorporating it into their production environment. This pilot is expected to last 18 months at the end of which they will have a prototype geodatabase and will serve it to the desktop browser using ArcIMS. They will also continue to use ArcView for the users needing more functionality, tools, and flexibility using a variety of data sets both spatial and tabular.

Mobile Computing Initiative

SHA is considering the use of Palm OS and Windows CE-based devices, GPS (Global Positioning System) tools, voice recognition and image capture technologies to shorten, improve and enhance map production activities. Use of these technologies has the potential to improve data collection and attributing procedures and network map updates.