This article outlines the development of standard traffic controllers in the USA, and emphasises future requirements for Advanced Transportation Controllers (ATCs). The three widely-used standard traffic controllers in the USA have been: (1) NEMA TS-1; (2) CALTRANS 170; and (3) NEMA TS-2. However, new 'intelligent' highway applications require more traffic monitoring and processing than before; this has created a demand for ATCs, which are now being used increasingly on American roads. Common features of modern ATCs include: (1) a VME computer bus; (2) operating temperatures between -34 and 74 degrees C; and (3) an OS-9 realtime operating system. These ATCs have very powerful and flexible data processing facilities, incorporating open systems standards and state-of-the-art processor technology. The following features make them very powerful, flexible, and cost-effective: (1) high-level programming; (2) high processing power; (3) fast data transmission; (4) accurate scanning; (5) ability to control many more devices than previously; and (6) modularity. ATCs differ significantly from conventional personal computers (PCs). A table compares highway needs with the capabilities of the three US standard traffic controllers and Matrix Corporation's SmartATC range of modern ATCs, which is described briefly.
Abstract