The GIS-based Rail Crossing Decision Support System for the North Carolina Department of Transportation

Jeffrey W. Fitzgerald and Jason S. Brewington

A geographic information systems (GIS) was used to support North Carolina Department of Transportation’s (NCDOT) rail inventory safety compliance efforts. Carter & Burgess combined CADD, GPS, digital orthophotography, ground photography, and a modified USDOT AAR database to produce an easy to use and fully functional rail inventory decision support system. The ArcView 3.0 based application shows tabular, graphic, and image data at the click of a mouse. This decision support system allows NCDOT planners and engineers to make more informed decisions about crossing closures and maintenance. Users can query and browse the multimedia database one crossing at a time, or gather summary data for multiple crossings. The decision support system is an excellent tool for public involvement meetings, where NCDOT representatives can use the application to help citizens visualize pertinent crossing information. Database development is ongoing. Currently, an inventory of 150 crossing has been built. Ultimately, the system will provide access to data for some 10,000 crossings in the State of North Carolina.

In 1995, The North Carolina Department of Transportation (NCDOT), in response to a need for better evaluation of transportation safety, initiated a program to upgrade their existing rail crossing information system. Prior to this project, rail crossing data for transportation planning and engineering came from the United States Department of Transportation (USDOT) in a format designed by the American Association of Railroads (AAR). The AAR database is an inventory of railroads that includes crossing location, infrastructure, and safety characteristics. These data are often outdated and do not contain much of the qualitative information used by transportation planners and engineers. Typically, a complete crossing evaluation requires an on-site inspection, interpretation of aerial photographs, and a survey of crossing elevations and of land use. The NCDOT Rail Division and Traffic Engineering Division, recognizing the need to create a more versatile database, contracted Carter & Burgess to design and build the crossing database and to develop a GIS-based rail crossing decision support system (Figure 1).

Figure 1 - Rail Crossing Inventory GIS ArcView Application

There are an estimated 10,000 rail crossings which over the next few years will be inventoried and added to the NCDOT’s database. In preparation for this effort, a pilot study was initiated, in part, to create inventory requirements and guidelines and to optimize data collection and conversion methodology.

Inventory Acquisition

To address the NCDOT’s specific requirements of crossing attribute data, several modifications were made to the existing AAR format. While the use of dBASE file format was preserved, several fields relative to traffic safety were added or were reformatted to more useful data types. Carter & Burgess, Inc. in cooperation with subconsultants Hobbs & Upchruch and Gannett Flemming, conducted GPS survey and site assessments for the each crossing. The crossing inventory included: A GPS survey of each crossing, updates to the modified AAR database, ground photos taken along and across the tracks, and digital black and white orthophotography. Using MicroStation CADD software, a digital version of the crossing infrastructure and adjacent land use was compiled from the GPS survey and aerial photographs. To ensure accuracy and increase efficiency, a set of standards for CADD file creation were developed and adopted. The field crew updated the AAR forms and saved the changes in a dBASE file. Initially, 30 crossing in or near four towns (Benson, Monroe, Gastonia, and Union) were inventoried for the pilot study. Following the pilot study, a prototype for the Rail Crossing Inventory GIS was developed, more modifications were made to the AAR database format, and changes were made to CADD design standards. Under these new standards, data for some 120 crossings have been added to the database.

Using ArcView 3.0, the rail crossing inventory GIS combines the tabular crossing database with CADD drawings, orthophotography, ground photos, statewide basemaps (i.e., GPS surveyed crossing locations, county and city boundaries, rail lines, primary and secondary roads). GPS survey data of crossing location are converted to as ArcView shapefiles. Rail lines county and City Boundaries can from the maintained by the North Carolina Center for Geographic Information and Analysis (CGIA). Primary and Secondary roads were obtained from Esri7 Data and Maps. Road data will be updated when available from the CGIA.

Crossing inventories and the aerial photographs are processed into GIS compatible files using ArcInfo v.7.0.4. MicroStation design (DGN) files, digitized from aerial photography, are converted into ArcInfo v.7.04 point, line and annotation coverages. Even though ArcView 3.0 can interpret DGN files, line weight information is needed to correctly symbolize planimetric features, therefore conversion of DGN files into ArcInfo coverages is necessary. For final preparation, the inventory coverage for each crossing is converted into North Carolina state plane coordinates. The TIFF formatted aerial photographs are registered to state plane, using links established with the inventory coverage.

The final data processing validate the AAR dBASE files. In particular, field definitions of the dBASE table were checked for compliance with NCDOT’s Oracle tables. The AAR form in the GIS was maintained in dBASE format to permit database access on computers not connected to the Oracle server. An NCDOT database administrator is responsible for updating Oracle’s AAR table.

Ground photographs, aerial photographs, GPS survey data, CADD file and dBASE tables are added to the system quickly. Data for each crossing are integrated into the applications’s file structure in approximately one hour. Speed of database creation is important, because the per crossing cost is critical to project success. To achieve efficiency, Carter & Burgess, Inc. developed AML and Avenue routines to automate the conversion process.

NCDOT’s Rail Crossing GIS was developed using AVENUE, ArcView’s programming language. The Rail Crossing Inventory GIS application offers many customized tools to effectively browse and manage the inventory database. Delphi7, Borland International’s object-oriented Pascal Development Language, was used to develop a customized data entry form which allows a user to browse and edit a selected crossing’s AAR information. Users interact with the system through a window called the AOverview Screen@. Overview Screen functions as the main view of the Rail Crossing Inventory GIS (Figure 2). This window contains the basemap and is the visual link to the data stored in the Rail Crossing Inventory GIS.

Figure 2 - Overview Screen

The most important component of the Overview screen is its Graphical User Interface (GUI). In fact, the entire set of customized features reside in the GUI of the Overview Screen. With the basic functionality of a view class ArcView document, the Overview Screen’s GUI is also highly customized to provide special zoom, query and visualization buttons (Figure 3). So, not only is the Overview Screen the visual center of the GIS but is also the GIS’s functional centerpiece.

Figure 3 - Customized Buttons of Overview Screen

The Overview Screen’s GUI can run in two different modes: SingleMode and GeneralMode. The application’s functionality, as provided by the Overview Screen’s GUI, changes according to the mode. The application’s operational mode can be changed at any time by the user.

By using the highly customized tools developed for the Rail Crossing Inventory GIS, SingleMode provides a multimedia interface to the crossing inventory’s database. During SingleMode operation, most of the basic tools provided by ArcView are disabled. Once a crossing is selected by the user, SingleMode provides tools to view the crossing’s ground photos (four directions), aerial photograph, planimetrics, and elevation profile (Figure 4).

Figure 4 - Example of SingleMode access to crossing data.

SingleMode also makes use of the custom AAR data access and editing form. Due to the number of fields contained in the AAR dBASE table (over 100) and concerns regarding data integrity, Delphi was used to develop the AAR data entry form. By using the form, the user can browse or edit the selected crossing’s data. Changes are saved to a separate file where the database administrator can review them before making official updates to the state’s Oracle AAR database (Figure 5).

Figure 5 - AAR Data Entry Form

GeneralMode allows for multiple crossing queries and access to the basic view document functionality provided with ArcView. This mode allows users to analyze multiple crossings and produce charts and maps (Figure 6).

Figure 6 - GeneralMode Usage

ArcView 3.0 is an excellent system for development of multimedia decision support systems. The AVENUE API provides a versatile collection of classes and requests for handling spatial and feature attribute data. Using these tools, Carter and Burgess combined CADD, GPS, digital orthophotography, ground photography, and a modified USDOT AAR database to produce an intuitive, user-friendly decision support tool. While the application development phase is complete, development of a statewide multimedia rail crossing inventory database is ongoing.

This project was completed for the North Carolina Department of Transportation by Carter & Burgess, Inc. The authors acknowledge leadership and insight of Paul Worley, Fred Rosendahl, and Sara Smith of NCDOT. Dean Sarvis, Carter & Burgess, Inc. was instrumental in managing the survey and site inventory activities. The following Carter & Burgess, Inc. personnel made significant contributions to the final decision support GIS: Franzi Brun, Ravi Devulapalli, Steve Korezkwa, and Steve Veal.

Authors

Jeffrey W. Fitzgerald, Ph.D.

GIS Manager

Carter & Burgess, Inc.

3880 Hulen

Ft Worth, TX 76107

Jason S. Brewington

GIS Specialist

Carter & Burgess, Inc.

3880 Hulen

Fort Worth, TX 76107