California Partners for Advanced Transportation Technology

This report discusses the development of system architecture for Intelligent Transportation Systems (ITS) applications for Bus Rapid Transit (BRT) systems. In the course of the development of system architecture, it is critical to take a system engineering approach in the development of BRT architecture to assess BRT service needs (or features), the functional realization of these service needs and the means of technological implementation. Motivated by the National ITS architecture, the BRT architecture has a hierarchy of three layers: application, physical, and logical. The application layer consists of the BRT service needs or features. For the physical layer, we first discuss a functional analysis that begins with the identification of system operational features, followed by an identification of the functions that are needed to achieve these operational features. We create a physical architecture modeled around each of the BRT features. In the final step, the logical architecture is traced or mapped from the physical architecture in such a way that the physical layer will implement the processes identified in the logical architecture and assign them to subsystems, and the data flows that originate from one subsystem and end at another are grouped together into architecture flows.