Mapping automation using GPS, GIS, and programming
David Bochenek
Former Manager, Data Collection Highway Information Service Division
Maryland State Highway Administration 707 North Calvert Street
Baltimore, Maryland 21202
Rosemary S. Davis
Manager, Highway Mapping Team Highway Information Service Division
Maryland State Highway Administration 707 North Calvert Street
Baltimore, Maryland 21202
Lawrence B. Swift
Former Manager, Highway Mapping Team Highway Information Service Division
Maryland State Highway Administration-707 North Calvert Street
Baltimore, Maryland 21202
Joseph M. White
GIS/GPS Technical Specialist Highway Information Service Division
Maryland State Highway Administration 707 North Calvert Street
Baltimore, Maryland 21202
Andy Shaw
President, CADDScan Engineering, Inc.
9861 Broken Land Parkway, Suite 168
Columbia, Maryland 21046
Abstract
Maryland State Highway Administration maintains and updates Maryland Index Maps and Grid
Maps on a continuous basis. The collection and verification of new and modified road data used to
be performed by field crews using survey equipment, notes, and sketches. Before this project, the
update of the maps required operators to open map files and manually copy, edit, and label the road
data.
This presentation demonstrates the automated procedure using a Trimble GPS system to generate
road alignment vectors with attributes. Satellite image files are used to verify the GPS data. Once
the data is approved, a program automatically clip-cuts the GPS vector data and copies the data to
each of the corresponding Index and Grid Maps. Both the GPS and the office added attributes are
tagged to the graphic elements. Utilities are developed to retrieve and edit the attributes for labeling
and identification purposes.
The procedure developed by this project greatly reduces the required time and cost associated with
road map maintenance at Maryland. This project is a good example of integrating GPS, GIS, and
CADD programming for mapping productivity improvement.
Background
The Statewide Grid Maps are produced and maintained at a scale of 1“=2000’ (1:24,000) by the
Maryland State Highway Administration (SHA), Highway Mapping Team. The original maps, as
well as the digital Statewide Grid Maps, were created from the United States Geological Survey
(USGS) 7 1/2 Minute Quads. Neighboring states have also used these quad maps as their base.
These maps are an accurate mapping source and have been in use by engineers and planners for
man y years.
The Highway Mapping Team began producing the Statewide Grid Maps using digital methods in
the winter of 1989. The team was given the mission to produce a final printed Statewide Grid Map
of acceptable quality using computer methods at an equal or lower cost than the manually drafted
maps.
Initial production of the digital maps was accomplished using both digital and manual methods.
The roads and road names were produced digitally and plotted using a pen plotter and the park and
reservations, swamps, and water fills were produced manually with a cut and peel method. The
final map was put together photographically and produced on mylar. In 1992, with the purchase of
a thermal plotter, it was possible to create a final reproducible grid map in a completely digital
fashion. This expedited the production of the maps.
The conversion to digital format of the Statewide Grid Maps was completed during December
1994. Before December 1994 the maps were updated every three years. However, it was quickly
realized that this cycle could be shorter because the maps were digital. The only drawback was that
compilation or data collection was performed in a manual fashion. It was possible to create maps
faster than the new data could be gathered or edited.
Past Compilation Process
The compilation entails data gathering from various sources. Most of the new information
comes from the County Improvement Reports and Index Maps or record maps. The counties are
required to report annually to the SHA any road improvements and formally identify changes on
official record maps. The required information is sent to the SHA’s Data Support Team of the
Highway Information Services Division. The data is processed so that the counties can receive
funding from the Highway Trust Fund for the highways they maintain. These reports are due by
December 31 of each year.
When the road improvements are reported they are field-verified by the SHA’S Data Collection
Team. The Data Collection Team updates the official road inventory (straight line diagram) if the
report is correct. If the improvement is new construction, a straight line diagram of the road is
made, and a field sketch is made on the Index Map. The field information was then taken back to
the office and the inventory data entered into the master data base. After this process, it was sent to
the Highway Mapping Team and from the straight line diagram, field sketch and notes, the
preliminary alignment was placed on the correction grid map. Generally this sketch was not the
proper alignment of the new roadway. Therefore, other sources of information were also
referenced. They may have included tax maps, subdivision maps, survey data, access permits, and
aerial photography. These sources may or may not have the subject improvement depicted. All of
this information was then manually placed on a correction copy of the map (paper or mylar) and
digitized into the correct grid map file.
The factors that slow down the map update cycle are fitting the road improvement data to the map
scale and obtaining aerial photography with the improvement on it. The Highway Mapping Team
obtained aerial photography for one third of the state each year.
