3.3.2 An Open Systems Approach

The CSC/PBFI Teamís design approach will produce an open system. An open system means that MDSHA will be able to include devices from different vendors, incorporate legacy systems, and communicate with other regional operations centers in as seamless a manner as possible.

The CSC/PBFI Team employed several tools to ensure the openness of our approach. At the highest level, we ensured that our design was consistent with the National ITS Architecture. We met this goal by matching the CHART II requirements derived from our identification and analysis process with pertinent National ITS Architecture process specifications to ensure that no requirement was overlooked. The CSC/PBFI Team also ensured traceability among the CHART II requirements, the National ITS Architecture process specifications, and the CHART II physical architecture. Guidance was provided by Mr. Cliff Heise, Eastern Regional Manager of Odetics, Inc., one of the developers of the National ITS Architecture.

A view of the CHART II physical architecture is shown in figure 3-1.

Figure 3-1. The CHART II Physical Architecture

CSC/PBFI Advantage: The CHART II physical architecture is consistent with the National ITS Architecture.


Our approach to guidance offered by the National ITS Architecture was one that we think is shared by the ITS industry and consistent with Catalyst. We have used it to ensure that all organizational and functional elements of a federally sponsored ITS program exist in our design and that all necessary logical and physical interfaces between transportation modes and regional jurisdictions are properly treated in the design. Both of these have occurred, without constraining the designers with respect to design tools and software implementation technique.

Appendix A contains information that demonstrates traceability among the CHART II requirements, the National ITS Architecture process specifications, and the CHART II physical architecture.

Of course, all of the system information flows envisioned by this architecture can become a reality only if the CHART II software is actually able to communicate with a variety of devices and operations centers. To ensure this communication, the CSC/PBFI Team reflected the latest information from ongoing national ITS standards activities, especially the National Transportation Communications for ITS Protocols (NTCIP), and the Transportation Management Data Dictionary (TMDD) in our CHART II design.

Because of PBFIís extensive and active involvement in these national standards activities, the CSC/PBFI Team is strongly positioned to develop CHART II software that will allow the system to grow as painlessly as possible. PBFI has voting membership on the following NTCIP committees:

More important, PBFI is also leading in the deployment of the NTCIP concept.

Projects in which PBFI assumed the lead role include the following:

PBFI is also leading a team working under the guidance of a Steering Committee selected by the Institute of Transportation Engineers and AASHTO to support the development of the TMDD. The TMDD consists of specific data elements that make up messages used within an advanced traffic management system (ATMS) and exchanged with external systems and subsystems, including traffic control devices, surveillance systems, and motorist information systems.

PBFI developed the structure and specific data dictionary format, including specific attributes and syntax of presentation; and an initial prototype of a selected section of the TMDD to identify development issues and to establish an accepted format. PBFI is also completing sections of a standardized TMDD consisting of data element definitions, including relationships among data elements in terms of where used, when used, and other attributes.

The use of a physical architecture consistent with the National ITS Architecture and compliance with emerging ITS standards ensures an "open" system solution for CHART II. This open system solution is supported by Object Oriented Analysis, Design, and Implementation, described in the following section.