Mapping automation using GPS, GIS, and programming

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.

Present Compilation Process
New technologies are also improving the field data collection. Global Positioning System (GPS) pilot projects have shown that it is possible to bring digital highway positional data back from the field and enter it directly onto the map design file.

The GPS highway alignment data has been used for the collection and verification of the county highway improvement packages. The Field Inventory Team is able to bring back to the Mapping Team the exact alignments of the new county roads and is also able to verify the positional location of new features not contained on any aerial imagery. This new GPS unit can also be used to verify positional accuracy of the existing mapping now maintained by the SHA. SPOT Satellite Imagery was purchased in the effort to obtain current, accurate and affordable compilation o~ data “col~ection”w& perfo”rtriid in a’manu”al fakhion. It was “p6ssible to create map~ aerial photography. An added bonus to the increased accuracy was that they were referenced to the digital map base eliminating the need to use projectors or cameras to change scales. From the first day the Mapping Team received the SPOT data they began using it. It has become a valuable information source for correcting roadway alignments for the local road systems. The new county road improvements are also easily digitized from this information.

Now when the road improvements are reported they are still field-verified by the SHA’S Data Collection Team. The Data Collection Team updates the official road inventory if the report is correct. If the improvement is new construction (or new location), the road alignment is now GPS collected. The field information is then taken back to the office where the inventory data is still entered into the master data base and GPS collected line work is post processed. After this process, all the new data is sent to the Highway Mapping Team and the corrected GPS data is referenced over a grid map. Other sources of information may still be referenced, such as tax maps, subdivision maps, survey data, access permits, aerial photography and newly added SPOT Satellite Imagery. All of the new information is then placed on a correction copy of the map and then heads-up digitized into the correct grid map file.

The team has selected the Trimble Aspen Pro System which is capable of dynamic data collection. This equipment and software has been successfully implemented to collect alignment data and inventory data at near highway speeds, and to be compatible with the Intergraph equipment and software the SHA now utilizes. The Aspen Pro System provides everything needed for efficient collection and processing of GPS/Inventory data. It will display our map as the background map on the notebook computer so our field staff can easily navigate to the data collection sites, and collect data directly using the grid map as the base. This will save time eliminating transcribing from the paper forms and diagrams. The Aspen Pro System is Microsoft Windows compliant.

Proposed Compilation Process
The proposed compilation process has two main objectives. First to update the map base within a timely fashion and to compile the majority of the data digitally. The two objectives are closely related. The major work efforts for the map base update are the visual scanning of aerial photographs for new features and adding the county improvements to the map base. Other feature data collection which can be automated now include adding new political boundaries (annexations), park or other delineated boundaries, and locating new roadway alignments from the construction plans (state system).

A MicroStation MDL program HWYTOOL was developed by CADDScan Engineering, Inc. to provide a user friendly environment that is fully integrated in MicroStation for the purpose of importing and updating GPS data into Statewide Grid Map files. The program is developed for three major objectives. The first is to import GPS data into MicroStation .dgn files. Second is to assist querying and reviewing attribute data associated with road line work, and the third, to automatically update the Statewide Grid Map files.

When the program imports the GPS data into MicroStation, this process will result in a time saving later in the map updating process. The collected GPS alignment data is converted into graphic elements and the attribute data is populated into a database table. An association between the database and the graphics element is established. All the graphics are automatically placed onto appropriate levels and their color, line style and weight are changed according to the existing file setting scheme. This greatly reduces the manual editing required for map updates. In addition, all the attribute data collected in the field are linked to the graphics. Querying, reviewing, and editing the data become easy through a dialog box. The stored attribute data can also be easily placed as labels on the roads on, or exported to text reports.

The GPS data is still overlaid against existing Grid Maps, aerial photography and SPOT satellite images to insure quality. After the verification is finished, the grid map updating module can automatically update the map file into appropriate Grid Map sheets. There are more than one hundred map sheets that cover the State of Maryland. First, the program “cookie-cuts” the road alignment data along the grid map boundaries, then finds the map sheets they belong to, and updates them. This eliminates all edge matching problems. The Highway Information Services Division is now investigating Electronic Road Inventory to automate downloading GPS data into our databases. This would eventually save more time with the maps and database updates collected and performed in the same process.

Conclusions
Several new technologies will improve the map base update cycle. A few years ago the cycle was three (3) years for maps, mainly due to the manual methods of mapping. With the completion of the digital grid maps, the maps can be updated faster than the data can be collected. At the present time the update cycle has been reduced to 18 months. It is hoped that within the next few years the cycle can be reduced to less than one (1) year.