Webinar 3
Evolution of Maryland State Highway Administration’s
Road Centerline and One Maryland, One Map

June 10, 2009

Summary of the Federal Highway Administration’s Quarterly Webinar: Applications of Geospatial Technologies in Transportation

These notes provide a summary of the PowerPoint presentation discussed during the webinar and detail the question-and-answer session that followed the presentation. The presentation is available upon request from the webinar speakers, Graham Petto (gpetto@mdp.state.md.us), Joe White (jwhite4@sha.state.md.us), Lindsay Major (lmajor@gov.state.md.us), and Ashley Buzzeo (abuzzeo@towson.edu).


Graham Petto
Maryland Department of Planning

Joe White
Team Leader
Maryland SHA

Ashley Buzzeo
GIS Specialist
Center for GIS at Towson University

Lindsay Major
StateStat Analyst
Maryland Governor's Office


Approximately 70 participants attended the webinar.

Introduction to Presentation

Mark Sarmiento of the Federal Highway Administration's (FHWA) Office of Interstate and Border Planning thanked participants for joining the webinar. This webinar was the third in a quarterly series of webinars dealing with the application of geospatial information systems (GIS) and other geospatial technologies to transportation. This webinar focused on the evolution of the road centerline at the Maryland State Highway Administration (MDSHA) and the development of One Maryland, One Map (MD iMap).



Over the past ten years, several initiatives within the state of Maryland have been developed with the purpose of building a unified, comprehensive, enterprise GIS framework. These initiatives have evolved over time. In 2001, the MDSHA Shared Centerline Program instigated development of a statewide centerline dataset. In 2007, this program evolved into the Maryland Statewide Addressing Initiative. The addressing initiative sought to develop and maintain address ranges, which were not included as part of the Shared Centerline Program. The development of MD iMap in 2008 furthered the state's vision for building an enterprise GIS. Finally, the StateStat program was created to serve as a GIS-based tracking tool for state asset management. MD iMap provides the basemap and foundation for StateStat.

History of MDSHA's Shared Centerline Program

In 2001, MDSHA created the Shared Centerline Program initiative. The purpose of the program was to develop a unified, enterprise centerline dataset from which both the state and counties could access current and accurate geospatial information. Local governments from some of Maryland's 23 counties provided centerline, address, and other geospatial information.

Before 2001, MDSHA had maintained five separate map databases in computer-aided design (CAD) format. The databases included municipality, county, grid, highways, and tourist maps and were updated on a two-year cycle. The road centerline was a separate product based on county maps at 1:100,000 scale.

Prior to development of the unified centerline system, the state routing system contained only major roads and did not include any local or county roads, or highway ramps, unless they were state-owned and -maintained. In addition, two-way roads were represented by a single line in the inventory direction. Route measures were generated from a 'from/to measure' field on the centerline routes. Measurements were derived from MDSHA's inventory database of public access roads. Each route contained 13-character field, including county number, municipality number, and route suffix/prefix.

To improve data integration and better meet the agency's business needs, MDSHA determined that a unified, cooperative centerline system was required. As a first step to developing this system, MDSHA worked with Howard County, Maryland, to test vertical integration of transportation data using the county's attributed centerline. Next, MDSHA, Towson University (located in Baltimore, Maryland), and several pilot counties partnered to develop a methodology that would allow counties to share their centerline data with the state.

As MDSHA collected data from counties, more detail was added to state routes (e.g., highway ramps and bi-directional geometry). For example, routes now contain a unique 32-character ID. This new ID contained values for the original 13-character ID but added milepoint direction, calibrated direction, an associated route ID prefix, and an exit and ramp numbers for highways. Municipality, county, grid, and highways maps were then replaced with the new centerline. The current route system included in the centerline includes over 80,000 routes (up from 4,400 in the original centerline) and over 32,000 arcs (up from 15,000 in the original centerline).

Evolution to the Maryland Statewide Addressing Initiative

In 2007, the Shared Centerline Program evolved into the Maryland Statewide Addressing Initiative. The goals for the initiative were to:

  • Meet a statewide need for developing and maintaining address ranges, which were not included as part of the creation of routing geometries for the Shared Centerline Program.
  • Improve ease with which MDSHA could pull updates from the county digital datasets to meet federal reporting requirements.
  • Contribute to the development of a comprehensive statewide centerline to support addressing, linear referencing, routing, and cartography.

Counties regularly provide updates for the statewide addressing dataset, which is then synchronized with the unified centerline. Counties’ submissions can occur via a File Transfer Protocol (FTP) shared website or via ArcGIS Server geodatabase replication technology (i.e., all updates/changes from counties within a given time period are "synchronized" with the centerline).

The Towson University Center for GIS hosts the FTP site and database and maintains the geodatabase replication processes that allow counties to synchronize changes to the centerline, including the extract, transform, and load tool. The addressing initiative was successfully completed in October 2008 and has been in continued maintenance since that time.

The addressing initiative was successfully completed in October 2008 and has been in continued maintenance since that time.

Benefits of the Shared Centerline Program and Statewide Addressing Initiative

Some of the benefits of the unified centerline and addressing initiative include:

  • MDSHA routes are now more complete due to the addition of local data to the centerline.
  • MDSHA has increased its ability to quickly update maps. Maps are now updated on an annual basis rather than a two-year cycle.
  • Quicker, easier data exchange between the state and counties.
  • Improvement of cross-jurisdictional emergency response by providing responders with quick access to crucial routing data.

Evolution to One Maryland, One Map

One Maryland, One Map (MD iMap) comprises the overall project vision for a unified, statewide GIS framework. MD iMap is designed to be the authoritative data source for a diverse community of users, including stakeholders from the public, private, and academic sectors. More information is available at https://imap.maryland.gov/.

To begin coordinating the state's GIS resources, contributing developers identified key foundation layers on which to construct the MD iMap system, such as transportation, cadastral, and elevation layers. Currently, iMap developers are working to coordinate and acquire datasets from contributors and task a state-level agency to be data stewards.

To help provide foundational support for MD iMap, Towson University's Center for GIS serves as the initiative's central hosting institution and web service point.

The central data store and web service in MD iMap will provide a base-level GIS foundation. The foundation will enable partners without substantial GIS operations the ability to store and serve geospatial data without having to make a significant investment in GIS. The foundation, called the Gazetteer basemap, will provide a common look and feel for all new State of Maryland maps.

Two committees oversee development of the MD iMap initiative:

  • The Technical Committee is comprised of GIS analysts, managers, and specialists from contributing partners. This committee develops guidance to support MD iMap operations, reviews data consistency issues, and addresses technical concerns.
  • The Executive Committee is comprised of executive management officials from supporting contributors to MD iMap. This committee supports the Technical Committee and reviews/approves documentation while addressing data coordination concerns.

The StateStat Initiative

StateStat is a performance measurement and management tool developed by Maryland Governor Martin O'Malley to improve Maryland government's accountability and efficiency. GIS serves as a key component of StateStat, which is available at https://gopi.maryland.gov/.

StateStat was constructed utilizing the state centerline as a core, foundational base layer. Various tools within the program allow users to 'zoom in' on details about current transportation and business development projects.

Several MD iMap GIS-based applications also provide information to support StateStat. These applications include:

  • GreenPrint Maryland, a web-enabled, GIS-based map showing the state's conserved and protected land. More information is available at https://dnr.maryland.gov/land/Pages/Green-Infrastructure-Mapping.aspx.
  • AgPrint, an initiative to target agricultural land preservation. An interactive, GIS-based map displays layers such as preserved agricultural lands and protected ecological areas. More information is available at https://imap.maryland.gov/.
  • SHA iMap, a GIS-based framework to help the agency measure and monitor progress of internal operations, such as storm water management, fuel consumption, highway beautification, and highway safety. The SHA iMap is still in development.
  • A GIS-based tool to track progress on Maryland's American Recovery and Reinvestment Act (ARRA)-funded projects.


With the development of the shared state centerline, addressing initiative and MD iMap, the objective to build a statewide GIS framework is being realized. Data maintained at the county level is being shared to other counties, throughout state agencies, up to the Federal level, and out to the public. However, work on building the shared centerline is still ongoing. Other ongoing work includes improving the user-friendliness of the addressing initiative site, adding private roads to the shared centerline, and refinement of data-sharing and -maintenance policies.

Questions and Answer Session

How are centerlines being used as a framework data layer?
Centerlines are the core layer upon which the data structure is being developed. The structure will sit on the base services to inform application development across jurisdictions. MDSHA will catalog and develop a core level of information to develop throughout the state.

What are the data layers in the centerline system?
The centerline includes road layers, tax parcels, and points of interest.

Is MDSHA establishing a program for counties to maintain the inventory attributes on the local centerlines?
The maintenance of inventory attributes is completed by MDSHA. Counties report to MDSHA on their improvement program. MDSHA and counties collaborate to develop the centerline but road attributes for state-maintained roads only are collected by MDSHA.

What is MDSHA's timeframe for completing work on the centerline?
MDSHA already has a fairly complete database. Changes are processed on an annual basis. Each year, MDSHA sends an improvement package to counties, which report back any changes. The agency is also developing an inventory to track changes that are reported.

How did MDSHA revise its inventory process to develop a divided route with a double centerline?
This information was included as part of the Highway Performance Monitoring System. To develop double centerlines, route data was 'split' and a sister route ID created. MDSHA is also now starting to collect milepoints for inventory and reverse inventory direction.

What is the total cost of the project?
It is difficult to provide a total figure due to the many components of the Shared Centerline Program, the Statewide Addressing Initiative, and One Maryland, One Map. Individuals interested in obtaining specific figures related to these components can contact Graham Petto, Joe White, Ashley Buzzeo, or Lindsay Major.

What type of legislative support existed or what were the incentives for local governments to participate in the unified centerline?
There is an existing memorandum of understanding between MDSHA and the counties for developing the shared centerline. MDSHA took the initiative to edit the county-supplied data for the centerline and is negotiating with the counties about maintenance and update policies. There is no legislative agreement in place for the shared centerline.

Are county maintenance policies consistent?
Not currently. However, MDSHA has developed a centerline working group meeting to discuss way to develop more consistency between county maintenance policies.

Does the shared centerline facilitate the development of the StateStat website?
Yes. The centerline is being used as a key foundation layer to construct the rest of the site.

What efforts has MDSHA developed to ensure good working relationships between all the counties and agencies involved with creating the shared centerline?
The centerline working group meets on a bi-weekly basis to address stakeholders' issues and concerns. It was very difficult to create the centerline; however, now that the system exists, it is easier to focus on maintenance.

Has MDSHA looked to other states to see which State Departments of Transportation (DOTs) are conducting similar efforts?
MDSHA does not have detailed information regarding the efforts of other states.

Comment: An audience member commented that there are several states moving in the direction to combine road networks and centerlines. A unified GIS framework can be a significant source of time- and cost-savings.

Closing Information

To conclude the webinar, Mr. Sarmiento presented some other information and resources related to applications of GIS in transportation:

  • FHWA has developed a new quarterly GIS in Transportation newsletter to share information about significant geospatial transportation news, events, and applications. Newsletters are available at https://www.gis.fhwa.dot.gov/newsletters.asp.
  • FHWA's GIS in Transportation website highlights innovative uses of GIS for transportation and offers related information, opportunities, and resources for sharing uses and applications of GIS. The website is available at https://www.gis.fhwa.dot.gov/.
  • The GIS Tools for Strategic Conservation Planning course will take place in Shepherdstown, West Virginia, on October 27-30, 2009. More information about the course is available at https://www.conservationfund.org/node/670.
  • The 2009 GIS in Transit Conference will occur November 16-18 in St. Petersburg, Florida. More information about the conference is available at https://www.urisa.org/education-events/gis-in-transit-conference/.
  • The next webinar in the FHWA-sponsored GIS in Transportation webinar series will occur in approximately three months. Details for the future event and other upcoming webinars will be publicized on the GIS-T yahoo group distribution list, in emails to state DOT GIS managers, and on FHWA's GIS in Transportation website.

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