Scats

The Sydney Coordinated Adaptive Traffic System, abbreviated SCATS, is an intelligent transportation system developed in Sydney, Australia by former constituents of the Roads and Maritime Services in the 1970s, used in Melbourne since 1982, Adelaide, South Australia since 1982 and Western Australia since 1983. It is also used in New Zealand, Hong Kong, Shanghai, Guangzhou, Amman, Tehran, Dublin, Rzeszów, Gdynia, Central New Jersey, and soon in part of Metro Atlanta, among several other places.

The system may be referred to by an alternative name in a specific installation (except Sydney), although since deployment wider than Australia, New Zealand and Singapore, these localised names do not appear to be commonly used. The following are some local alternative names that have been or are in use:

In total, about 42000 intersections in over 154 cities in 25 countries use the system. In Australia, the majority of signalised intersections are SCATS operated (around 11,000).

SCATS primarily manages the dynamic (on-line, real-time) timing of signal phases at traffic signals, meaning that it tries to find the best phasing (i.e. cycle times, phase splits and offsets) for the current traffic situation (for individual intersections as well as for the whole network). This is based on the automatic plan selection from a library in response to the data derived from loop detectors or other road traffic sensors.

The system uses sensors at each traffic signal to detect vehicle presence in each lane and pedestrians waiting to cross at the local site. The vehicle sensors are generally inductive loops installed within the road pavement. The pedestrian sensors are usually push buttons. Various other types of sensors can be used for vehicle presence detection, provided that a similar and consistent output is achieved. Information collected from the vehicle sensors allows SCATS to calculate and adapt the timing of traffic signals in the network.

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Wikipedia