When implementing an advanced urban traffic control system, it is not enough to adopt a centralised control network. The system's success will depend of many other factors, including system architecture, capacity for handling field data, location of measurement sites, communication between system elements, distribution of information to drivers and other controllers, and the degree of saturation of roads. This article focuses on some of the most critical aspects of traffic control and the approach adopted by Self Sime to optimise the control system. At the bottom level are PMI real-time data collectors and S400 traffic controllers. Above this level, there are urban traffic controllers (UTCs), which are personal computers (PCs), whose software can handle up to 30 PMIs and 30 S400s. The UTCs have seven main functions. Communication between these elements is very important, and it has been successful with radio systems. The system level above the UTCs is the Input Output Processor (IOP), which separates automatic regulation from operators and other central control systems. Through a local network the IOP links to other computers or servers, and to the system's user-friendly interface. The system's modularity enables it to be adapted to the specific needs of any local authority or traffic authority.
Abstract