Austroads recognised the need to develop a new generation of traffic signal controllers, making use of modular, scalable design with an open architecture. An earlier project (NS1377) produced a stakeholder consultation and literature review report and another report on the functional requirements of an Advanced Australian Traffic Signal Controller (AATSC). From the point of view of asset management, the project team decided that some level of backward compatibility be maintained so legacy sites can be more easily managed. The level of interoperability is to be limited to the physical interfaces between the controller box and outside. The interfaces correspond to the bolt holes and terminal blocks for cabling to the lanterns and detectors. Further, the consensus from the project team was that the project should encourage innovation. What is inside the new controller should start from a ‘blank sheet’. This report provided the business and logical architectural layers for the new controller. Two key components in the architecture are the Signal Group Switch Module (SGSM) and the Control Module. The SGSM shall perform the function of signal group switching with high safety integrity on receiving commands from the Control Module. The Control Module shall have the flexibility to use a range of traffic control algorithms in the form of ‘plug-in’ applications. The default control algorithm shall be one that provides for user-configurable fixed-time signal operations. An important contribution from the project is the application of Australian Standards AS/IEC 61508 for the specification of the safety integrity levels (SIL) for key functional components in AATSC. (Author/publisher)
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