Design of the Gary-Chicago-Milwaukee Gateway: A Multi-Modal Traveler Information System

Abstract

The Gary-Chicago-Milwaukee (GCM) Corridor was one of the four priority corridors established under the ISTEA legislation of 1991. The Gateway Traveler Information System (TIS) is the core system that facilitates the integration and interoperation of the many Intelligent Transportation Systems (ITS) in the Corridor. The Gateway TIS collects transportation related information from geographically dispersed agencies of varied natures, validates and fuses the information collected, and disseminates it to interested public and private entities and the general public via Internet and Intranet. The foundation for the Gateway architecture is the Common Object Request Broker Architecture (CORBA). CORBA is one of the two NTCIP Center-to-Center (C2C) communication protocols. CORBA supports both C2C communications and internal, distributed, object oriented computing. CORBA is rapidly gaining popularity and momentum in the current software engineering trend of object orientation and distributed computing. It is likely that CORBA will become a popular solution to both C2C communication and distributed computing for next generation ITS. The experience of the Gateway TIS provides useful insights to other ITS center systems currently being planned, designed, and implemented. This paper presents a high level view of the CORBA based system architecture design of the GCM Gateway TIS. It focuses on the perspective of ITS C2C interoperability. The object oriented Gateway external data model and the Gateway Publisher/Subscriber based data collection and distribution are introduced. The decision to utilize an object oriented Database Management Structure versus a relational database management system is discussed. This paper also serves as a call for the development of CORBA oriented specifications of national ITS standards, which to this point have focused on DATEX. Based on the authors' experience with CORBA as the foundation for the Gateway architecture they recommend CORBA be considered for future systems.